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MAPLE GROVE, Minn., Aug. 16, 2013 /PRNewswire/ — Upsher-Smith Laboratories, Inc., today announced that it has received tentative approval from the U.S. Food and Drug Administration (FDA) for its New Drug Application (NDA) for Vogelxo™ (testosterone) gel for topical use CIII

http://www.pharmalive.com/upsher-smith-gets-tentative-nda-approval-for-vogelxo-gel

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128196-01-0 ESCITALOPRAM

Escitalopram (also known under various trade names) is an antidepressant of the selective serotonin reuptake inhibitor (SSRI) class. It is approved by the U.S. Food and Drug Administration (FDA) for the treatment of adults and children over 12 years of age with major depressive disorder and generalized anxiety disorder. Escitalopram is the (S)-stereoisomer (enantiomer) of the earlier Lundbeck drug citalopram, hence the name escitalopram. Escitalopram is noted for its high selectivity with serotonin reuptake inhibition. The similarity between escitalopram and citalopram has led to accusations of “evergreening“, an accusation that Lundbeck has rejected.^[1]

Escitalopram has FDA approval for the treatment of major depressive disorder and generalized anxiety disorder in adults.^[2]

Off-label uses

Escitalopram is sometimes prescribed off-label for the treatment of other conditions: social anxiety disorder,^[3] panic disorder^[4]and obsessive-compulsive disorder.^[5] There is some evidence favouring escitalopram over the antidepressants citalopram andfluoxetine in the first two weeks of major depression.^[6] Concerns of sponsorship bias with the studies are however noted.^[6] In another review escitalopram and sertraline had the highest rate of efficacy and acceptability among adults receiving treatment for major depression with second-generation antidepressants.^[7]

Efficacy

There is some controversy over selective publishing of SSRI clinical trials.^[8] A meta-analysis analyzing published as well as unpublished trials found placebos to be similarly effective to SSRIs in treating mild depression, although SSRIs were more effective than placebo in more severe cases, with the magnitude of SSRI superiority increasing with increasing depression severity.^[9]

A series of randomized, double-blind trials have found Escitalopram to be more efficacious and have fewer adverse effects than Citalopram.^{[10][11][12][13]} Meta-analysis show a “small” but statistically significant improvement in effect strength ^[14][15] and some dispute these findings.^[16]

Pharmacology

Cipralex brand escitalopram 10mg package and tablet sheet

Escitalopram increases intrasynaptic levels of the neurotransmitter serotonin by blocking the reuptake of the neurotransmitter into the presynaptic neuron. Of the SSRIs currently on the market, escitalopram has the highest affinity for the human serotonin transporter (SERT). The enantiomer of escitalopram ((R)-citalopram) counteracts to a certain degree the serotonin-enhancing action of escitalopram. As a result, escitalopram has been claimed to be a more potent antidepressant than citalopram, which is a mixture of escitalopram and (R)-citalopram. In order to explain this phenomenon, researchers from Lundbeck proposed that escitalopram enhances its own binding via an additional interaction with another allosteric site on the transporter.^[42] Further research by the same group showed that (R)-citalopram also enhances binding of escitalopram,^[43] and therefore the allosteric interaction cannot explain the observed counteracting effect. In the most recent paper, however, the same authors again reversed their findings and reported that R-citalopram decreases binding of escitalopram to the transporter.^[44] Although allosteric binding of escitalopram to the serotonin transporter is of unquestionable research interest, its clinical relevance is unclear since the binding of escitalopram to the allosteric site is at least 1000 times weaker than to the primary binding site.

In vitro studies using human liver microsomes indicated that CYP3A4 and CYP2C19 are the primary isozymes involved in the N-demethylation of escitalopram. The resulting metabolites, desmethylescitalopram and didesmethylescitalopram, are significantly less active and their contribution to the overall action of escitalopram is negligible.

History

Escitalopram was developed in close cooperation between Lundbeck and Forest Laboratories. Its development was initiated in the summer of 1997, and the resulting new drug application was submitted to the U.S. FDA in March 2001. The short time (3.5 years) it took to develop escitalopram can be attributed to the previous extensive experience of Lundbeck and Forest with citalopram, which has similar pharmacology.^[45] The FDA issued the approval of escitalopram for major depression in August 2002 and for generalized anxiety disorder in December 2003. Escitalopram can be considered an example of “evergreening“^[46] (also called “lifecycle management”^[47])– the long-term strategy pharmaceutical companies use in order to extend the lifetime of a drug, in this case of the citalopram franchise. Escitalopram is an enantiopure compound of theracemic mixture citalopram, used for the same indication, and for that reason it required less investment and less time to develop. Two years after escitalopram’s launch, when the patent on citalopram expired, the escitalopram sales successfully made up for the loss. On May 23, 2006, the FDA approved a generic version of escitalopram by Teva.^[48]On July 14 of that year, however, the U.S. District Court of Delaware decided in favor of Lundbeck regarding the patent infringement dispute and ruled the patent on escitalopram valid.^[49]

In 2006 Forest Laboratories was granted an 828 day (2 years and 3 months) extension on its US patent for escitalopram.^[50] This pushed the patent expiration date from December 7, 2009 to September 14, 2011. Together with the 6-month pediatric exclusivity, the final expiration date was March 14, 2012.

Brand names

Escitalopram is sold under the following brand names:

References

• “A Drug Maker’s Playbook Reveals a Marketing Strategy” article in The New York Times by Gardiner Harris, September 1, 2009

• Royal Pharmaceutical Society of Great Britain (September 2009). British National Formulary (BNF 58). UK: BMJ Group and RPS Publishing. ISBN 978-0-85369-778-7.

• U.S. National Library of Medicine: Drug Information Portal — Escitalopram
• Lexapro (Forest Laboratories) Official Lexapro homepage
• Cipralex (Lundbeck) Official Cipralex homepage
• Pharmacological information Lexapro
• Cipla Medpro Official Cipla Medpro homepage

http://www.sciencedirect.com/science/article/pii/S0040402011015249

http://www.sciencedirect.com/science/article/pii/S0040402011015249

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niaspan

Teva Announces Exclusive Launch of Generic NIASPAN® in the United States

JERUSALEM–(BUSINESS WIRE)–Teva Pharmaceutical Industries Ltd. (NYSE:TEVA) today announced the launch of the generic equivalent to NIASPAN® (niacin extended-release) tablets, 500, 700, and 1000mg in the United States. Teva was first to file, making the product eligible for 180 days of marketing exclusivity.

NIASPAN® is marketed by AbbVie and used with diet to reduce elevated TC, LDL-C, Apo B and TG levels, and to increase HDL-C in patients with primary hyperlipidemia and mixed dyslipidemia. NIASPAN® had annual sales of approximately $1.12 billion in the United States, according to IMS data as of June 30, 2013.  read more at

http://www.pharmalive.com/teva-launches-generic-niaspan-in-us

niacin,  vit B3

Niacin (also known as vitamin B₃, nicotinic acid, or less commonly vitamin PP; archaic terms include pellagra-preventive and anti-dermatitis factor) is an organic compound with the formula C
6H
5NO
2 and, depending on the definition used, one of the 40 to 80 essential human nutrients.

Niacin is one of five vitamins (when lacking in human diet) associated with a pandemic deficiency disease: niacin deficiency (pellagra), vitamin C deficiency (scurvy), thiamin deficiency (beriberi), vitamin D deficiency (rickets and osteomalacia), vitamin A deficiency (night blindness and other symptoms). Niacin has been used for over 50 years to increase levels of HDL in the blood and has been found to decrease the risk of cardiovascular events modestly in a number of controlled human trials.^[3]

This colorless, water-soluble solid is a derivative of pyridine, with a carboxyl group (COOH) at the 3-position. Other forms of vitamin B₃ include the corresponding amide, nicotinamide (“niacinamide”), where the carboxyl group has been replaced by a carboxamide group (CONH
2), as well as more complex amides and a variety of esters. Nicotinic acid and niacinamide are convertible to each other with steady world demand rising from 8500 tonnes per year in 1980s to 40,000 in recent years.^[4]

Niacin cannot be directly converted to nicotinamide, but both compounds could be converted to and are precursors of NAD andNADP in vivo.^[5] Nicotinic acid, nicotinamide, and tryptophan (via quinoline acid) are co-factors for nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). NAD converts to NADP by phosphorylation in the presence of the enzyme NAD+ kinase. NADP and NAD are coenzyme for many dehydrogenases, participating in many hydrogen transfer processes.^[6] NAD is important in catabolism of fat, carbohydrate, protein, and alcohol, as well as cell signaling and DNA repair, and NADP mostly in anabolism reactions such as fatty acid and cholesterol synthesis.^[6] High energy requirements (brain) or high turnover rate (gut, skin) organs are usually the most susceptible to their deficiency.^[7]

Although the two are identical in their vitamin activity, nicotinamide does not have the same pharmacological effects (lipid modifying effects) as niacin. Nicotinamide does not reduce cholesterol or cause flushing.^[8] Nicotinamide may be toxic to the liver at doses exceeding 3 g/day for adults.^[9] Niacin is involved in both DNA repair, and the production of steroid hormones in theadrenal gland.

1. “Niacin”. DrugBank: a knowledgebase for drugs, drug actions and drug targets. Retrieved 14-January-2012.
2.  PubChem 938
3.  Bruckert, E; Labreuche, J; Amarenco, P (2010 Jun). “Meta-analysis of the effect of nicotinic acid alone or in combination on cardiovascular events and atherosclerosis”.Atherosclerosis 210 (2): 353–61. doi:10.1016/j.atherosclerosis.2009.12.023.PMID 20079494.
4.  Cantarella, L; Gallifuoco, A; Malandra, A; Martínková, L; Spera, A; Cantarella, M (2011). “High-yield continuous production of nicotinic acid via nitrile hydratase-amidase cascade reactions using cascade CSMRs”. Enzyme and microbial technology 48 (4–5): 345–50. doi:10.1016/j.enzmictec.2010.12.010. PMID 22112948.
5.  Cox, Michael; Lehninger, Albert L; Nelson, David R. (2000). Lehninger principles of biochemistry. New York: Worth Publishers. ISBN 1-57259-153-6.
6. ^ Jump up to:^a b Wan, P; Moat, S; Anstey, A (2011). “Pellagra: A review with emphasis on photosensitivity”. The British journal of dermatology 164 (6): 1188–200.doi:10.1111/j.1365-2133.2010.10163.x. PMID 21128910.
7.  Ishii, N; Nishihara, Y (1981). “Pellagra among chronic alcoholics: Clinical and pathological study of 20 necropsy cases”. Journal of neurology, neurosurgery, and psychiatry 44 (3): 209–15. doi:10.1136/jnnp.44.3.209. PMC 490893.PMID 7229643.
8.  Jaconello P (October 1992). “Niacin versus niacinamide”. CMAJ 147 (7): 990.PMC 1336277. PMID 1393911.
9.  Knip M, Douek IF, Moore WP, et al. (2000). “Safety of high-dose nicotinamide: a review”. Diabetologia 43 (11): 1337–45. doi:10.1007/s001250051536.PMID 11126400.

Food sources

“Food Data Chart – Niacin”. Retrieved 7 September 2012.

Niacin is found in variety of foods, including liver, chicken, beef, fish, cereal, peanuts and legumes, and is also synthesized from tryptophan, an essential amino acid found in most forms of protein.

Animal products:

• liver, heart and kidney (9 – 15 mg niacin per 100 grams)
• chicken, chicken breast (6.5 mg)
• beef (5 – 6 mg)
• fish: tuna, salmon, halibut (2.5 – 13 mg)
• eggs (0.1 mg)
• venison (8.43 mg)

Fruits and vegetables:

• avocados (1 mg niacin per 100 grams)
• dates (2 mg)
• tomatoes (0.7 mg)
• leaf vegetables (0.3 – 0.4 mg)
• broccoli (0.6 mg)
• carrots (0.3 – 0.6 mg)
• sweet potatoes (0.5 – 0.6 mg)
• asparagus (0.4 mg)

Seeds:

• nuts (2 mg niacin per 100 grams)
• whole grain products (4 – 29.5 mg)
• legumes (0.4 – 16 mg)
• saltbush seeds

Fungi:

• mushrooms, shiitake mushrooms (3.5 – 4 mg niacin per 100 grams)
• brewer’s yeast (36 mg)

Other:

• Monster Energy drink (40 mg per 16 ounces)
• Rockstar Energy (100% in the Super Sours flavors)
• Red Bull Energy Drink (28 mg per 12 ounces)
• Five Hour Energy drink (30 mg per 1.93 ounces)
• Ovaltine (18 mg)
• Peanut butter (15 mg)
• Tofu
• Soy sauce (0.4 mg)
• Vegemite (from spent brewer’s yeast) (110 mg niacin per 100 grams)
• Marmite (from spent brewer’s yeast) (110 mg niacin per 100 grams)

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cilnidipine

西尼地平

CAS 132203-70-4

• (E) – (±) 1 ,4 a dihydro-2 ,6 – dimethyl-4 – (3 – nitrophenyl) -3,5 – pyridinedicarboxylic acid, 2 – methoxy- ethyl butylester 3 – phenyl – 2 – propenyl ester FRC-8653 Cinalong
• More FRC 8653 1,4-Dihydro-2 ,6-dimethyl-4-(3-nitrophenyl) 3 ,5-pyridinedicarboxylic acid 2-methoxyethyl (2E)-3-phenyl-2-propenyl ester
• Molecular formula:C ₂₇ H ₂₈ N ₂ O ₇
• Molecular Weight:492.52

We (Nilesh Hirpara) are glad to inform you that our new venture is launching a product “Cilnidipine” in India.

Nilesh Hirpara

Managing Director at N-cube pharmaceutical pvt ltd

We are glad to inform you that our new venture is launching a product “Cilnidipine” in India. Cilnidipine is calcium channel blocker pharmaceutical ingredients and we are looking forward to the company for the formulation of it and distributor . If you are interested in formulating or distribute to our product kindly contact on the below given contact. We promise the best quality and assurance for the longevity in healthy trade

thanking you

ncube pharma
ncubepharma@gmail.com

Established in the year 2011, Ncube Pharmaceuticals is a Ahmedabad, India based firm involved inmanufacturing, supplying and exporting pharmaceutical products. ncube pharma (we)  are dedicated to provide our esteemed clients with research-based technologically advanced products that meet all their requirements. We understand that top-notch research facilities are critical requirement of our industry and hence have developed a state-of-art research lab at our plant. Our team of qualified professional regularly upgrade themselves with latest know-how of various processes involved in production process. This enables us to improve our product range and provides an edge over our competitors. Furthermore, we are capable to offer our range in bulk quantities as per the requirements of our clients. We follow client-centric approach with focus on providing superior quality products at reasonable prices.

MORE INFO

Cilnidipine (INN) is a calcium channel blocker. It is sold as Atelec in Japan, asCilaheart, Cilacar in India, and under various other trade names in East Asian countries.

Cilnidipine is a dual blocker of L-type voltage-gated calcium channels in vascular smooth muscle and N-type calcium channels in sympathetic nerve terminals that supply blood vessels. However, the clinical benefits of cilnidipine and underlying mechanisms are incompletely understood.

Clinidipine is the novel calcium antagonist accompanied with L-type and N-type calcium channel blocking function. It was jointly developed by Fuji Viscera Pharmaceutical Company, Japan and Ajinomoto, Japan and approved to come into market for the first time and used for high blood pressure treatment in 1995. in india j b chemicals & pharmaceuticals ltd and ncube pharmaceutical develope a market of cilnidipine.

Hypertension is one of the most common cardiovascular disease states, which is defined as a blood pressure greater than or equal to 140/90 mm Hg. Recently, patients with adult disease such as hypertension have rapidly increased. Particularly, since damages due to hypertension may cause acute heart disease or myocardial infarction, etc., there is continued demand for the development of more effective antihypertensive agent.

Meanwhile, antihypertensive agents developed so far can be classified into Angiotensin II Receptor Blocker (ARB), Angiotensin-Converting Enzyme Inhibitor (ACEI) or Calcium Chanel Blocker (CCB) according to the mechanism of actions. Particularly, ARB or CCB drugs manifest more excellent blood pressure lowering effect, and thus they are more frequently used.

However, these drugs have a limit in blood pressure lowering effects, and if each of these drugs is administered in an amount greater than or equal to a specific amount, various side-effects may be caused. Therefore, there have been many attempts in recent years to obtain more excellent blood pressure lowering effect by combination therapy or combined preparation which combines or mixes two or more drugs.

Particularly, since side-effect due to each drug is directly related to the amount or dose of a single drug, there have been active attempts to combine or mix two or more drugs thereby obtaining more excellent blood pressure lowering effect through synergism of the two or more drugs while reducing the amount or dose of each single drug.

For example, US 20040198789 discloses a pharmaceutical composition for lowering blood pressure combining lercanidipine, one of CCB, and valsartan, irbesartan or olmesartan, one of ARB, etc. In addition, a combined preparation composition which combines or mixes various blood pressure lowering drugs or combination therapy thereof has been disclosed.

cilnidipine Compared with other calcium antagonists, clinidipine can act on the N-type calcium-channel that existing sympathetic nerve end besides acting on L-type calcium-channel that similar to most of the calcium antagonists. Due to its N-type calcium-channel blocking properties, it has more advantages compared to conventional calcium-channel blockers. It has lower incidence of Pedal edema, one of the major adverse effects of other calcium channel blockers. Cilnidipine has similar blood pressure lowering efficacy as compared to amlodipine. One of the distinct property of cilnidipine from amlodipine is that it does not cause reflex tachycardia.

In recent years, cardiovascular disease has become common, the incidence increased year by year, about a patient of hypertension in China. 3-1. 500 million, complications caused by hypertension gradually increased, and more and more young patients with hypertension technology. In recent years, antihypertensive drugs also have great development, the main first-line diuretic drug decompression 3 – blockers, calcium channel blockers, angiotensin-converting enzyme inhibitors, ar blockers and vascular angiotensin II (Ang II) receptor antagonist.

In the anti-hypertensive drugs, calcium antagonists are following a – blockers after another rapidly developing cardiovascular drugs, has been widely used in clinical hypertension, angina and other diseases, in cardiovascular drugs in the world, ranked first.

Cilnidipine for the long duration of the calcium channel blockers, direct relaxation of vascular smooth muscle, dilation of peripheral arteries, the peripheral resistance decreased, with lower blood pressure, heart rate without causing a reflex effect.

Cilnidipine is a dihydropyridine CCB as well as an antihypertensive. Cilnidipinehas L- and N-calcium channel blocking actions. Though many of the dihydropyridine CCBs may cause an increase in heart rate while being effective for lowering blood pressure, it has been confirmed that cilnidipine does not increase the heart rate and has a stable hypotensive effect. (Takahiro Shiokoshi, “Medical Consultation & New Remedies” vol. 41, No. 6, p. 475-481)

• http://www.mcyy.com.cn/e-product2.asp
  
• Löhn M, Muzzulini U, Essin K, et al. (May 2002). “Cilnidipine is a novel slow-acting blocker of vascular L-type calcium channels that does not target protein kinase C”. J. Hypertens. 20 (5): 885–93. PMID 12011649.

Cilnidipine (CAS NO.: 132203-70-4), with its systematic name of (+-)-(E)-Cinnamyl 2-methoxyethyl 1,4-dihydro-2,6-dimethyl-4-(m-nitrophenyl)-3,5-pyridinedicarboxylate, could be produced through many synthetic methods.

Following is one of the synthesis routes: By cyclization of 2-(3-nitrobenzylidene)acetocetic acid cinnamyl ester (I) with 2-aminocrotonic acid 2-methoxyethyl ester (II) by heating at 120 °C.

MORE

U.S Patent No. 4,572,909 discloses amlodipine; U.S Patent No. 4,446,325 discloses aranidipine; U.S Patent No. 4,772,596 discloses azelnidipine; U.S Patent No. 4,220,649 discloses barnidipine; U.S Patent No. 4,448,964 discloses benidipine; U.S Patent No. 5,856,346 discloses clevidipine; U.S Patent No. 4,466,972 discloses isradipine; U.S Patent No. 4,885,284 discloses efonidipine; and U.S Patent No. 4,264,61 1 discloses felodipine.

U.S Patent No. 5,399,578 discloses Valsartan; European Patent No. 0 502 314 discloses Telmisartan; U.S Patent No. 5,138,069 discloses Losartan; U.S Patent No. 5,270,317 discloses Irbesartan; U.S Patent No. 5,583,141 and 5,736,555 discloses Azilsartan; U.S Patent No. 5,196,444 discloses Candesartan; U.S Patent No. 5,616,599 discloses Olmesartan; and U.S Patent No. 5,185,351 discloses Eprosartan.

U.S Patent No. 4,374,829 discloses enalapril; U.S Patent No. 4,587,258 discloses ramipril; U.S Patent No. 4,344,949 discloses quinapril; U.S Patent No. 4,508,729 discloses perindopril; U.S Patent No. 4,374,829 discloses lisinopril; U.S Patent No. 4,410,520 discloses benazepril; U.S Patent No. 4,508,727 discloses imidapril; U.S Patent No. 4,316,906 discloses zofenopril; U.S Patent Nos. 4,046,889 and 4,105,776 discloses captopril; and U.S Patent No. 4,337,201 discloses fosinopril.

• Planar chemical structures of these calcium blockers of formula (I) are shown below.
• [0017]
  Amlodipine is 2-(2-aminoethoxymethyl)-4-(2-chlorophenyl)-3-ethoxycarbonyl-5-methoxycarbonyl-6-methyl-1,4-dihydropyridine disclosed in USP 4,572,909, Japanese patent publication No. Sho 58-167569 and the like.
• [0018]
  Aranidipine is 3-(2-oxopropoxycarbonyl)-2,6-dimethyl-5-methoxycarbonyl-4-(2-nitrophenyl)-1,4-dihydropyridine disclosed in USP 4,446,325 and the like.
• [0019]
  Azelnidipine is 2-amino-3-(1-diphenylmethyl-3-azetidinyloxycarbonyl)-5-isopropoxycarbonyl-6-methyl-4-(3-nitrophenyl)-1,4-dihydropyridine disclosed in USP 4,772,596, Japanese patent publication No. Sho 63-253082 and the like.
• [0020]
  Barnidipine is 3-(1-benzyl-3-pyrrolidinyloxycarbonyl)-2,6-dimethyl-5-methoxycarbonyl-4-(3-nitrophenyl)-1,4-dihydropyridine disclosed in USP 4,220,649, Japanese patent publication No. Sho 55-301 and the like.
• [0021]
  Benidipine is 3-(1-benzyl-3-piperidinyloxycarbonyl)-2,6-dimethyl-5-methoxycarbonyl-4-(3-nitrophenyl)-1,4-dihydropyridine and is described in the specifications of U.S. Patent No. 4,501,748, Japanese patent publication No. Sho 59-70667 and the like.
• [0022]
  Cilnidipine is 2,6-dimethyl-5-(2-methoxyethoxycarbonyl)-4-(3-nitrophenyl)-3-(3-phenyl-2-propenyloxycarbonyl)-1,4-dihydropyridine disclosed in USP 4,672,068, Japanese patent publication No. Sho 60-233058 and the like.
• [0023]
  Efonidipine is 3-[2-(N-benzyl-N-phenylamino)ethoxycarbonyl]-2,6-dimethyl-5-(5,5-dimethyl-1,3,2-dioxa-2-phosphonyl)-4-(3-nitrophenyl)-1,4-dihydropyridine disclosed in USP 4,885,284, Japanese patent publication No. Sho 60-69089 and the like.
• [0024]
  Elgodipine is 2,6-dimethyl-5-isopropoxycarbonyl-4-(2,3-methylenedioxyphenyl)-3-[2-[N-methyl-N-(4-fluorophenylmethyl)amino]ethoxycarbonyl]-1,4-dihydropyridine disclosed in USP 4,952,592, Japanese patent publication No. Hei 1-294675 and the like.
• [0025]
  Felodipine is 3-ethoxycarbonyl-4-(2,3-dichlorophenyl)-2,6-dimethyl-5-methoxycarbonyl-1,4-dihydropyridine disclosed in USP 4,264,611, Japanese patent publication No. Sho 55-9083 and the like.
• [0026]
  Falnidipine is 2,6-dimethyl-5-methoxycarbonyl-4-(2-nitrophenyl)-3-(2-tetrahydrofurylmethoxycarbonyl)-1,4-dihydropyridine disclosed in USP 4,656,181, Japanese patent publication (kohyo) No. Sho 60-500255 and the like.
• [0027]
  Lemildipine is 2-carbamoyloxymethyl-4-(2,3-dichlorophenyl)-3-isopropoxycarbonyl-5-methoxycarbonyl-6-methyl-1,4-dihydropyridine disclosed in Japanese patent publication No. Sho 59-152373 and the like.
• [0028]
  Manidipine is 2,6-dimethyl-3-[2-(4-diphenylmethyl-1-piperazinyl)ethoxycarbonyl]-5-methoxycarbonyl-4-(3-nitrophenyl)-1,4-dihydropyridine disclosed in USP 4,892,875, Japanese patent publication No. Sho 58-201765 and the like.
• [0029]
  Nicardipine is 2,6-dimethyl-3-[2-(N-benzyl-N-methylamino)ethoxycarbonyl]-5-methoxycarbonyl-4-(3-nitrophenyl)-1,4-dihydropyridine disclosed in USP 3,985,758, Japanese patent publication No. Sho 49-108082 and the like.
• [0030]
  Nifedipine is 2,6-dimethyl-3,5-dimethoxycarbonyl-4-(2-nitrophenyl)-1,4-dihydropyridine disclosed in USP 3,485,847 and the like.
• [0031]
  Nilvadipine is 2-cyano-5-isopropoxycarbonyl-3-methoxycarbonyl-6-methyl-4-(3-nitrophenyl)-1,4-dihydropyridine disclosed in USP 4,338,322, Japanese patent publication No. Sho 52-5777 and the like.
• [0032]
  Nisoldipine is 2,6-dimethyl-3-isobutoxycarbonyl-5-methoxycarbonyl-4-(3-nitrophenyl)-1,4-dihydropyridine disclosed in USP 4,154,839, Japanese patent publication No. Sho 52-59161 and the like.
• [0033]
  Nitrendipine is 3-ethoxycarbonyl-2,6-dimethyl-5-methoxycarbonyl-4-(3-nitrophenyl)-1,4-dihydropyridine disclosed in USP 3,799,934, Japanese patent publication (after examination) No. Sho 55-27054 and the like.
• [0034]
  Pranidipine is 2,6-dimethyl-5-methoxycarbonyl-4-(3-nitrophenyl)-3-(3-phenyl-2-propen-1 -yloxycarbonyl)-1,4-dihydropyridine disclosed in USP 5,034,395, Japanese patent publication No. Sho 60-120861 and the like.

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Formulation development of insoluble drugs has always been a challenge in pharmaceutical development. This presentation reviews some current options to old problem.

by PharmaDirections, Inc., Working at PharmaDirections, Inc

…

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US 8,007,830, US 5,565,473*PED, MERCK

MK-0476 (Montelukast, L-706631)

MONTELUKAST (Singulair® Oral Granules) helps to reduce asthma symptoms (coughing, wheezing, shortness of breath, or chest tightness) and control your asthma. It does not provide instant relief and cannot be used to treat a sudden asthma attack. It works only when used on a regular basis to help reduce inflammation and prevent asthma attacks. This drug is also helpful in improving seasonal allergies, like hay fever. Montelukast is effective in adults and children

Amongst the US approvals, tentative FDA approvals have been identified for generic Montelukast sodium, awarded to Endo, Glenmark, Mylan, Roxane, Sandoz, Teva and Torrent. The large number of generic authorisations awaiting launch in the UK is indicative of the likely competition the Singulair product will face across Europe upon SPC expiry

EP Pat. No. 480,717 discloses Montelukast sodium along with other related compounds and the methods for their preparation. The reported method of synthesis proceeds through corresponding methyl ester namely, Methyl 2-[(3S)-[3-[(2E)-(7-chloroquinolin - 2yl) ethenyl] phenyl] – 3 – hydroxypropyl] benzoate and involves coupling methyl 1- (mercaptomethyi) cyclopropaneacetate with a mesylate generated in-situ. The methyl ester of Montelukast is hydrolyzed to free acids and the latter converted directly to Montelukast Sodium salt (Scheme -1). The process is not particularly suitable for large – scale production because it requires tedious chromatographic purification of the methyl ester intermediate and / or the final product and the product yield is low.

Scheme -1

U.S. Pat. No. 5,614632 disclosed a process for the preparation of crystalline Montelukast sodium, which comprises of the following steps (Scheme – 2):

■ Reaction of methyl 2-[3(S)-[3-[2-(7-chloroquinolin -2-yl) ethenyl] phenyl] -3- hydroxypropyl benzoate (I) with Grignard reagent, methyl magnesium chloride in presence of cerium chloride to give Diol (II) ■ Reaction of Diol (II) with methane sulfonyl chloride to afford 2-[2-[3 (s)-[3- (2-(7-chloro quinolin-2yl) ethenyl] phenyl]- 3 – methane sulfonyloxy propyl] phenyl] -2-propanol (III)

^■ Condensation of 2-[2-[3(s)-[3-(2-(7-chloro quinolin - 2-yl) ethenyl] phenyl] -

3 – methane sulfonyloxypropyl] phenyl] – 2- propanol (III) with dilithium anion of 1-mercaptomethyl) cyclopropaneacetic acid, which has been generated by the reaction of l-(mercaptomethyl)cyclopropaneacetic acid (IV)with n-Butyl lithium

^■ Isolation of the condensed product, Montelukast as solid Montelukast dicyclohexylamine salt

■ Purification and conversion of Montelukast dicyclohexylamine salt into Montelukast sodium

■ Crystallization of Montelukast sodium from a mixture of toluene and acetonitrile

The process disclosed in U.S Pat. No. 5,614,632 further involved the reaction of Diol (II) with methane sulfonyl chloride involves the reaction temperature of about – 25°C and the storage condition of the intermediate, 2-[2-[3(s)-[3-(2-(7-chloro quinolin - 2-yl) ethenyl] pheny] -3 -methane sulfonyloxy propyl] phenyl] -2-propanol (III) at temperature below – 15⁰C for having the stability. The process further involves the reaction, formation of dilithium anion of l-(mercaptomethyl) cyclopropaneacetic acid which requires the usage of n-Butyl lithium, a highly flammable and hazardous reagent and the reaction is at temperature below -5°C further requires anhydrous conditions. Scheme – 2

Montelukast (trade names Singulair, Montelo-10, and Monteflo and Lukotas in India) is a leukotriene receptor antagonist(LTRA) used for the maintenance treatment of asthma and to relieve symptoms of seasonal allergies.^[1][2] It is usually administered orally once a day. Montelukast is a CysLT₁ antagonist; it blocks the action of leukotriene D4 (and secondary ligands LTC4 and LTE4) on the cysteinyl leukotriene receptor CysLT₁ in the lungs and bronchial tubes by binding to it. This reduces the bronchoconstriction otherwise caused by the leukotriene and results in less inflammation.

Because of its method of operation, it is not useful for the treatment of acute asthma attacks. Again because of its very specificmechanism of action, it does not interact with other asthma medications such as theophylline.

Another leukotriene receptor antagonist is zafirlukast (Accolate), taken twice daily. Zileuton (Zyflo), an asthma drug taken four times per day, blocks leukotriene synthesis by inhibiting 5-lipoxygenase, an enzyme of the eicosanoid synthesis pathway.

The Mont in Montelukast stands for Montreal, the place where Merck developed the drug.^[3]

Singulair was covered by U.S. Patent No. 5,565,473^[9] which expired on August 3, 2012.^[10] The same day, the FDA approved several generic versions of montelukast.^[11]

On May 28, 2009, the United States Patent and Trademark Office announced their decision to launch a reexamination of the patent covering Singulair. The decision to reexamine was driven by the discovery of references that were not included in the original patent application process. The references were submitted through Article One Partners, an online research community focused on finding literature relating to existing patents. The references included a scientific article produced by a Merck employee around the key ingredient of Singulair, and a previously filed patent in the same technology area.^[12]

On December 17, 2009, the U.S. Patent and Trademark Office determined that the patent in question was valid based on the initial reexamination and new information provided.^[13]

Montelukast is currently available in film coated tablet and orodispersible tablet formulations for once-daily administration, and also available as an oral granule formulation which is specifically designed for administration to paediatric patients.

Patent family US17493193A claims crystalline Montelukast sodium and processes for its preparation . Patents within this family are not considered to be a constraint to generic competition because the protected technology may possibly be circumvented by the synthesis and use of different molecular forms and/or salts. Patent family US33954901P relates to the specific marketed oral granule formulation of Montelukast.

The chemical name of montelukast sodium is: Sodium 1-[[[(1R)-1-[3-[(1E)-2-(7-chloro-2-quinolinyl)ethenyl]phenyl]-3-[2-(1-hydroxy-1-methylethyl)phenyl]propyl]thio]methyl]cyclopropaneacetic acid and its structure is represented as follows:

• Montelukast is apparently a selective, orally active leukotriene receptor antagonist that inhibits the cysteinyl leukotriene CysLT₁ receptor.

• The chemical name for montelukast sodium is [R-(E)]-1-[[[1-[3-[2-(7-chloro-2-quinolinyl)ethenyl]phenyl]-3-[2-(1-hydroxy-1-methylethyl)phenyl]propyl]thio]methyl] cyclopropaneacetic acid, monosodium salt. Montelukast sodium salt is understood to be represented by the following structural formula:
• U.S. patent No. 5,565,473 (“’473 patent”) is listed in the FDA’s Orange Book for montelukast sodium. The ’473 patent recites a broad class of leulcotriene antagonists as “anti-asthmatic, anti-allergic, anti-inflammatory, and cycloprotective agents” represented by a generic chemical formula. ’473 patent, col. 2,1. 3 to col. 4,1. 4. Montelukast is among the many compounds represented by that formula. The ’473 patent also refers to pharmaceutical compositions of the class of leukotriene antagonists of that formula with pharmaceutically acceptable carriers. Id. at col. 10,11. 42-46.
• Montelukast sodium is currently marketed by Merck in the form of film coated tablets and chewable tablets under the trade name Singular^®. The film coated tablets reportedly contain montelukast sodium and the following inactive ingredients: microcrystalline cellulose, lactose monohydrate, croscarmellose sodium, hydroxypropylcellulose, magnesium stearate, titanium dioxide, red ferric oxide, yellow ferric oxide, and carnauba wax. The chewable tablets reportedly containmontelukast sodium and the following inactive ingredients: mannitol, microcrystalline cellulose, hydroxypropylcellulose, red ferric oxide, croscarmellose sodium, cherry flavor, aspartame, and magnesium stearate. Physicians’ Desk Reference, 59th ed. (2005), p. 2141.
• However, there is a need in the art to improve the stability of compositions of montelukast and particularly those of the sodium salt.

Montelukast sodium is a leukotriene antagonist and inhibits the leukotriene biosynthesis. It is a white to off-white powder that is freely soluble in methanol, ethanol, and water and practically insoluble in acetonitrile.

A montelukast sodium salt is a substance which exhibits efficacy of Singulair (available from Korean MSD) generally used for the treatment of asthma as well as for the symptoms associated with allergic rhinitis, which is pharmaceutically known as a leukotriene receptor antagonist. Leukotrienes produced in vivo by metabolic action of arachidonic acid include LTB4, LTC4, LTD4 and LTE4. Of these, LTC4, LTD4 and LTE4 are cysteinyl leukotrienes (CysLTs), which are clinically essential in that they exhibit pharmaceutical effects such as contraction of airway muscles and smooth muscles and promotion of secretion of bronchial mucus.

Montelukast sodium salt is a white and off-white powder which has physical and chemical properties that it is well soluble in ethanol, methanol and water and is practically insoluble in acetonitrile.

A conventionally known method for preparing a montelukast sodium salt is disclosed in EP Patent No. 480,717. However, the method in accordance with the EP Patent requires processes for introducing and then removing a tetrahydropyranyl (THP) protecting group and purification by chromatography, thus being disadvantageously unsuitable for mass-production. In addition, the method disadvantageously requires investment in high-cost equipment, for example, to obtain amorphous final compounds by lyophilization.

Meanwhile, U.S. Pat. No. 5,614,632 discloses an improved method for preparing a montelukast sodium salt by directly reacting a methanesulfonyl compound (2) with 1-(lithium mercaptomethyl)cyclopropaneacetic acid lithium salt, without using the tetrahydropyranyl protecting group used in EP Patent No. 480,717, purifying in the form of a dicyclohexylamine salt by adding dicyclohexylamine to the reaction solution, and converting the salt into a montelukast sodium salt (1).

However, the method in accordance with the US patent should use n-butyl lithium as a base in the process of preparing the 1-(lithium mercaptomethyl)cyclopropaneacetic acid lithium salt and thus requires an improved process due to drawbacks that n-butyl lithium is dangerous upon handling and is an expensive reagent.

PCT International Patent Laid-open No. WO 2005/105751 discloses a method for preparing a montelukast sodium salt, comprising coupling methyl 1-(mercaptomethyl)cyclopropane acetate (3) used in step 10 shown in Example 146 of EP Patent 480,717 with a methanesulfonyl compound (2) in the presence of a solvent/cosolvent/base, performing hydrolysis, recrystallizing the resultingmontelukast acid (4) in the presence of a variety of solvents to obtain highly puremontelukast acid (4), and converting the same into a montelukast sodium salt (1).

In addition, WO 2005/105751 claims that, in the coupling reaction, one is selected from tetrahydrofurane and dimethylcarbonate as a solvent, a highly polar solvent is selected from dimethylformamide, dimethylacetamide and N-methylpyrrolidone as a cosolvent, and one is selected from sodium hydroxide, lithium hydroxide, sodium hydride, sodium methoxide, potassium tert-butoxide, lithium diisopropylamine and quaternary ammonium salts, as a base.

However, WO 2005/105751 discloses that, since the coupling reaction requires use of a mixed solvent and the mixed solvent is different from the solvent used for hydrolysis, a process for removing the cosolvent through distillation under reduced pressure or extraction is further required prior to hydrolysis.

Further, in accordance with the method of WO 2005/105751, recrystallization is performed in the presence of a variety of solvents in order to obtain a highly puremontelukast acid (4) and the resulting recrystallization yield is varied in a range of 30 to 80%, depending on the solvent. In the case where desired purity is not obtained, recrystallization is repeated until montelukast acid (4) with a desired purity can be obtained. Disadvantageously, the method causes deterioration in overall yield.

European Patent No. 480,717 discloses montelukast sodium and its preparation starting with the hydrolysis of its ester derivative to the crude sodium salt, acidification of the crude to montelukast acid, and purification of the crude acid by column chromatography to give montelukast acid as an oil. The resulting crude oil in ethanol was converted to montelukast sodiumby the treatment with an equal molar aqueous sodium hydroxide solution. After removal of the ethanol, the montelukastsodium was dissolved in water and then freeze dried. The montelukast sodium thus obtained is of a hydrated amorphous form as depicted in FIG. 2.

The reported syntheses of montelukast sodium, as pointed out by the inventor in EP 737,186, are not suitable for large-scale production, and the product yields are low. Furthermore, the final products, as the sodium salts, were obtained as amorphous solid which are often not ideal for pharmaceutical formulation. Therefore, they discloses an efficient synthesis of montelukastsodium by the use of 2-(2-(3-(S)-(3-(7-chloro-2-quinolinyl)ethenyl)phenyl)-3-methanesulfonyloxypropyl)phenyl)-2-propanol to couple with the dilithium salt of 1-(mercaptomethyl)cyclopropaneacetic acid. The montelukast acid thus obtained is converted to the corresponding dicyclohexylamine salt and recrystallized from a mixture of toluene and acetonitrile to obtain crystallinemontelukast sodium. This process provides improved overall product yield, ease of scale-up, and the product sodium salt in crystalline form.

According to the process described in EP 737,186, the chemical as well as optical purities of montelukast sodium depends very much on the reaction conditions for the mesylation of the quinolinyl diol with methanesulfonyl chloride. For instance, the reaction temperature determinates the chemical purity of the resulting coupling product montelukast lithium, due to the fact that an increase in the reaction temperature resulted in decreased selectivity of mesylation toward the secondary alcohol. Mesylation of the tertiary alcohol occurred at higher temperature will produce, especially under acidic condition, the undesired elimination product, the styrene derivative. This styrene impurity is difficult to remove by the purification procedure using DCHA salt formation; while excess base, butyl lithium in this case, present in the reaction mixture causes the formation of a cyclization by-product, which will eventually reduce the product yield.

PCT WO 2005/105751 discloses an alternative process for preparing montelukast sodium by the coupling of the same mesylate as disclosed in ’186 patent with 1-(mercaptomethyl)cyclopropane alkyl ester in the presence of a base. In this patent, the base butyl lithium, a dangerous and expensive reagent, is replaced with other milder organic or inorganic base. However, the problem concerning the formation of the styrene impurity is still not resolved.

CA 2649189 A1

https://www.google.co.in/patents/CA2649189A1?cl=en&dq=montelukast+sodium&hl=en&sa=X&ei=MMFwUvOrKsztkgXCsoD4Cg&ved=0CFUQ6AEwBA

Process for the manufacture of 1-[[[(1R)-1-[3-[(1E)-2-(7-chloro-2-quinolinyl)ethenyl]phenyl]-3-[2-(1-hydroxy-1-methylethyl)phenyl]propyl]thio]methyl]cyclopropane acetic acid, sodium salt [montelukast sodium (I)] consisting of: i. Converting methyl 1-(mercaptomethyl)-cyclopropaneacetate to a metal salt (X) using a metal hydroxide, ii. Subjecting the metal salt (X) to monometallation to provide a dimetallide (XI). iii. Converting a diol of formula (II) to a mesylate of formula (III) and reacting (III) in situ with (XI) affordin the metal salt of 1-[[[(1R)-1-[3-[(1E)-2-(7-chloro-2-quinolinyl)ethenyl]phenyl]-3-[2-(1-hydroxy-1-methylethyl)phenyl]propyl]thio]methyl]cyclopropane acetic acid. iv. Reacting the metal salt in-situ with a base and purifying to afford an amine salt (XII). v. Treating (XII) with a sodium base and precipitating out montelukast sodium (I).

 more info

European Patent No. 480,717 disclose the montelukast and its preparation method first be hydrolyzed to the crude ester derivatives sodium, then this crude product was acidified to montelukast acid (montelukastacid), Finally, column chromatography purification of this crude acid into oily montelukast acid. This oilMontelukast acid in ethanol, by equimolar amounts of sodium hydroxide solution and converted to montelukast sodium. The ethanol was removed aftermontelukast sodium dissolved in water, followed by freeze-drying. Finally obtainedmontelukast shown in Figure 2 is amorphous hydrated.

The invention, in European Patent No. 737,186 points out, thismontelukast synthesis method is not suitable for mass production, and the low yield. Moreover, the resulting amorphous solid salt, are generally not used in pharmaceutical formulations. Therefore, they disclose the synthesis of an effective method of montelukast sodium, which uses 2 – (2 – (3 – (S) – (3 – (7 – chloro-2 – quinolinyl) ethenyl) phenyl) -3 – methylsulfonyl) phenyl) -2 – propanol and 1 – (methylthio alcohol) cyclopropane coupling the lithium salt of acetic acid, the resulting Montelukast acid is converted into a corresponding bicyclic hexyl amine salt, and from a mixture of toluene and acetonitrile recrystallization to prepare crystalline montelukast. This method greatly improves the productivity, ease of mass production, and the product is crystalline sodium salt.

According to European Patent No. 737,186 described method for preparingmontelukast chemical purity and optical purity depends largely quinoline diol with methanesulfonyl chloride in the reaction between the mesylated condition. For example, the reaction temperature resulted in an increase of the secondary alcohols methanesulfonyl selective reduction, the reaction temperature determines the coupling product (montelukast lithium) chemical purity. Occurs at a higher temperature mesylation tertiary alcohols, in particular under acidic conditions, will produce impurities, such as styrene derivatives. This impurity is difficult styrene generated by using the DCHA salt (DCHA salt formation) in the purification process to remove; present in the reaction mixture and excess base, butyl lithium cyclized by-products resulting in the formation will eventually reduce the yield of the product.

W02005/105751 disclose another preparation method of montelukast sodium, which is the methanesulfonic acid (European Patent No. 737,186 is the same) in an alkaline state where 1_ (methyl mercaptan yl) cyclopropyl alkyl ester and coupling thereof. In this patent, the dangerous and expensive alkaline-butyl lithium reagent, is replaced by other more moderate organic or inorganic base. However, the formation of styrene impurity problem is still not resolved

1.  Lipkowitz, Myron A. and Navarra, Tova (2001) The Encyclopedia of Allergies (2nd ed.) Facts on File, New York, p. 178, ISBN 0-8160-4404-X
2.  “Asthma / Allergy “. Mascothealth.com. Retrieved 9 April 2011.
3.  http://www.merckfrosst.ca/mfcl/en/corporate/research/accomplishments/singulair.html
4.  “Montelukast Sodium”. The American Society of Health-System Pharmacists. Retrieved 3 April 2011.
5.  FDA Investigates Merck Drug-Suicide Link
6.  Updated Information on Leukotriene Inhibitors: Montelukast (marketed as Singulair), Zafirlukast (marketed as Accolate), and Zileuton (marketed as Zyflo and Zyflo CR). Food and Drug Administration. Published June 12, 2009. Accessed June 13, 2009.
7.  Rubenstein, Sarah (April 28, 2008). “FDA Sneezes at Claritin-Singulair Combo Pill”. The Wall Street Journal.
8.  Schering-Plough press release – Schering-Plough/MERCK Pharmaceuticals Receives Not-Approvable Letter from FDA for Loratadine/Montelukast
9.  5,565,473
10.  Singular patent details
11.  “FDA approves first generic versions of Singulair to treat asthma, allergies”. 03 August 2012. Retrieved 15 August 2012.
12.  “U.S. Reexamines Merck’s Singulair Patent”. Thompson Reuters. May 28, 2009.
13.  “Merck Says U.S. Agency Upholds Singulair Patent”. Thompson Reuters. December 17, 2009.

GENERAL METHOD1

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https://data.epo.org/publication-server/rest/v1.0/publication-dates/20110302/patents/EP1812394NWB1/document.html

READ ABOUT S ISOMER

http://file.scirp.org/Html/8-2200440_26971.htm

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Improved Process for the Preparation of Montelukast: Development of an Efficient Synthesis, Identification of Critical Impurities and Degradants

(a) Ray, U. K.;Boju, S.; Pathuri, S. R.; Meenakshisunderam, S. (Aurobindo Pharma Limited, India). PCT Patent Application WO/2008/001213, 2008.

(b) Wang, Y.; Wang, Y.; Brand, M.; Kaspi, J. (Chemagis Ltd., Israel). PCT Patent Application WO/2007/088545, 2007.

(c) Turchetta, S.;Tuozzi, A.; Ullucci, E.; de Ferra, L. (Chemi S.P.A.; Italy). European Patent Application EA 1,693,368, 2008.

(d) Srinivas, P. L.; Rao, D. R.; Kankan, R. N.; Relekar, J. P. (Cipla Limited, India). PCT Patent Application WO/2006/064269, 2006.

(e) Reguri, B. R.; Bollikonda, S.;Bulusu, V. V. N. C. S.; Kasturi, R. K.; Aavula, S. K. (Dr. Reddy’s Laboratory, India). U.S. Patent Application U.S.2005/0107612, 2005.

(f) Coppi, L.; Bartra Sanmarti, M.; Gasanz Guillen, Y.; Monsalvatje Llagostera, M.; Talavera Escasany, P. (Esteve Quimica, S.A., Spain). PCT Patent Application WO/2007/051828, 2007.

(g) Hung, J. T.; Wei, C. P. (Formosa Laboratories, Inc., Taiwan). U.S. Patent Application U.S.2008/0097104, 2008.

(h) McGarrity, J.; Bappert, E.; Belser, E. (Lonza A.G., Switzerland). PCT Patent Application WO/2008/131932, 2008.

(i) Suri, S.; Sarin, G. S.; Mahendru, M. (Morepen Laboratories Limited, India). PCT Patent Application WO/2006/021974, 2006.

(j) Avdagic, A.; Mohar, B.;Sterk, D.; Stephan, M. (Pliva-Istrazivanje Razvoj D.O.O., Croatia). PCT Patent Application WO/2006/000856, 2006.

(k) Overman, A.; Gieling, R. G.; Zhu, J.; Thijs, L. (Synthon B.V., Holland). PCT Patent Application WO/2005/105479, 2005.

(l) Shapiro, E.; Yahomoli, R.;Niddam-Hildesheim, V.; Sterimbaum, G.; Chen, K. (Teva Pharmaceuticals Industries Ltd., Israel). PCT Patent Application WO/2005/105751, 2005.

(m) Achmatowicz, O.; Wisniewski,K.; Ramza, J.; Szelejewski, W.; Szechner, B. (Zaklady Farmaceutyczne Polpharma, S.A., Poland). PCT Patent Application WO/2006/043846, 2006.

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J. Liang*, J. Lalonde, B. Borup, V. Mitchell, E. Mundorff, N. Trinh, D. A. Kochrekar, R. N. Cherat, G. G. Pai
Codexis, Inc., Redwood City, USA and Arch PharmaLabs Limited, Mumbai, India
Development of a Biocatalytic Process as an Alternative to the (-)-DIP-Cl-Mediated Asymmetric Reduction of a Key Intermediate of Montelukast
Org. Process Res. Dev.  2010,  14:  193-198

Montelukast sodium (Singulair®) is a leukotriene receptor antagonist prescribed for the treatment of asthma and allergies. Workers at Codexis used directed evolution and high-throughput screening to engineer a robust and efficient ketoreductase enzyme (CDX-026) that accomplished the asymmetric reduction of ketone A, which is essentially water insoluble, at a loading of 100 g/L in the presence of ca. 70% organic solvents at 45 ˚C. The (S)-alcohol B was obtained in >95% yield in >99.9% ee and in >98.5% purity on a >500 mol scale.

The enzymatic reduction entails the reversible transfer of a hydride from isopropanol to the ketone A with concomitant formation of acetone. The reaction is driven to completion by the fortuitous crystallization of the monohydrate B. The four-step conversion of B into montelukast sodium is described in the Merck process patent (M. Bhupathy, D. R. Sidler, J. M. McNamara, R. P. Volante, J. J. Bergan US 6320052, 2001). This biocatalytic reduction is superior to the reduction of A with (-)-DIPCl previously used in the manufacture of montelukast

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TEVETEN® (eprosartan mesylate) is a non-biphenyl non-tetrazole angiotensin II receptor (AT1) antagonist. A selective non-peptide molecule, TEVETEN® is chemically described as the monomethanesulfonate of (E)-2-butyl-1 -(p-carboxybenzyl)-α-2-thienylmethylimid-azole-5 -acrylic acid.

Its empirical formula is C23H24N2O4S•CH4O3S and molecular weight is 520.625. Its structural formula is:

EPROSARTAN MESYLATE

tevetenEprosartan mesilate, SK&F-108566-J(?, SK&F-108566, Teveten SB, Navixen, Regulaten, Tevetenz, Teveten

US 5656650

exp Aug 12, 2014

Eprosartan is an angiotensin II receptor antagonist used for the treatment of high blood pressure. It is marketed as Teveten byAbbott Laboratories in the United States.It is marketed as Eprozar by INTAS Pharmaceuticals in India and by Abbott Laboratorieselsewhere. It is sometimes paired with hydrochlorothiazide, marketed in the US as Teveten HCT and elsewhere as TevetenPlus.

The drug acts on the renin-angiotensin system in two ways to decrease total peripheral resistance. First, it blocks the binding ofangiotensin II to AT₁ receptors in vascular smooth muscle, causing vascular dilatation. Second, it inhibits sympatheticnorepinephrine production, further reducing blood pressure.

As with other angiotensin II receptor antagonists, eprosartan is generally better tolerated than enalapril (an ACE inhibitor), especially among the elderly.^[1]

^{Eprosartan is an angiotensin II receptor antagonist used for the treatment of high blood pressure. It acts on the renin-angiotensin system in two ways to decrease total peripheral resistance. First, it blocks the binding of angiotensin II to AT1 receptors in vascular smooth muscle, causing vascular dilatation. Second, it inhibits sympathetic norepinephrine production, further reducing blood pressure.}

1.  Ruilope L, Jäger B, Prichard B (2001). “Eprosartan versus enalapril in elderly patients with hypertension: a double-blind, randomized trial”. Blood Press. 10 (4): 223–9. doi:10.1080/08037050152669747. PMID 11800061.

• Teveten website

PAT            APR                EXP

J Med Chem1991,34,(4):1514-7

J Med Chem1993,36,(13):1880-92

Synth Commun1993,23,(22):3231-48

AU 9056901, EP 403159, JP 91115278, US 5185351.

Drugs Fut1997,22,(10):1079

Eprosartan mesylate was developed successfully by SmithKline Beecham Corporation in 1997, and marketed in Germany in 1998 under the trade-name Teveten and in the United States later in 1999. Eprosartan mesylate, as an angiotensin II receptor blocker, is an antihypertensive drug of the latest generation. Eprosartan mesylate is potent to lower systolic and diastolic pressures in mild, moderate and severe hypertensive patients, and is safe and tolerable. Eprosartan mesylate is rapidly absorbed when administrated orally, with a bioavailability of 13% and a protein binding rate of 98%. The blood peak concentration and AUC (Area Under Curve) can be elevated by about 50% in patients with liver and kidney dysfunction, or fullness after administration, and can be elevated by 2 to 3 folds in elderly patients. Eprosartan mesylate has a structure shown as follows:

U.S. Pat. No. 5,185,351 discloses a method for preparing eprosartan mesylate using Eprosartan and methanesulfonic acid in isopropanol (U.S. Pat. No. 5,185,351, Example 41 (ii)). However, it is found when following this method for preparing eprosartan mesylate in industry, an esterification reaction can occur between eprosartan and isopropanol and the following two impurities can be generated:

In addition to the above two esterification impurities, the salifying method provided by the above patent is prone to produce isopropyl mesylate. Considering currently known potential risk of gene toxicity of methylsulfonic acid ester on human as well as the stringent requirements of methylsulfonic acid ester from the Europe and the America authorities, it is important to produce eprosartan mesylate in a non-alcohol solvent during the process of producing eprosartan mesylate, since it avoids the formation of methylsulfonic acid ester and the residue thereof in the final product. Since the dosage of eprosartan mesylate is high, it is particularly important to strictly control methylsulfonic acid ester in eprosartan mesylate.

In addition, for the above salifying method, solid eprosartan is suspended in propanol at a low temperature, then methanesulfonic acid is added, about ten seconds later a great deal of eprosartan mesylate precipitate is obtained. Therefore, solid eprosartan may be embedded by the precipitated eprosartan mesylate. Since isopropyl alcohol has a high viscosity at low temperature, a heavy filtering operation burden is needed to obtain solid from isopropanol, and the obtained solid contains quite an amount of isopropanol.

Eprosartan has been obtained by several different ways: 1) The iodination of 2-butylimidazole (I) with I2 and Na2CO3 in dioxane/water gives 2-butyl-4,5-diiodoimidazole (II), which is treated with benzyl chloromethyl ether (III) and K2CO3 in DMF yielding the imidazole derivative (IV). The condensation of (IV) with N-methyl-N-(2-pyridyl)formamide (V) by means of butyllithium in THF affords 1-(benzyloxymethyl)-2-butyl-4-iodoimidazole-5-carbaldehyde (VI), which is deprotected with concentrated HCl ethanol to give 2-butyl-4-iodoimidazole-5-carbaldehyde (VII). The acylation of (VII) with methyl 4-(bromomethyl)benzoate (VIII) by means of K2CO3 in hot DMF yields 4-(2-butyl-5-formyl-4-iodoimidazol-1 ylmethyl)benzoic acid methyl ester (IX), which is deiodinated by hydrogenation with H2 over Pd/C in methanol affording compound (X). The condensation of (X) with methyl 3-(2-thienyl)propionate (XI) by means of lithium diisopropylamide (LDA) in THF gives (XII), which is acylated with acetic anhydride and dimethylaminopyridine (DMAP) in dichloromethane yielding the corresponding acetate (XIII). Elimination of acetic acid from (XIII) with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in hot toluene affords the expected propenoic ester (XIV), which is finally saponified with NaOH or KOH in ethanol/water.

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WO 1998035962 A1

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TAMOXIFEN

10540-29-1 CAS

READ ABOUT TITLE AT……….http://www.rsc.org/chemistryworld/sites/default/files/CIIE_Tamoxifen.mp3

Molecular Formula: C₂₆H₂₉NO•C₆H₈O₇
CAS Number: 54965-24-1
Brands: Nolvadex, TAMOXIFEN CITRATE

Chemically, NOLVADEX (tamoxifen citrate) is the trans-isomer of a triphenylethylene derivative. The chemical name is (Z)2-[4-(1,2-diphenyl-1-butenyl) phenoxy]-N, N-dimethylethanamine 2 hydroxy-1,2,3- propanetricarboxylate (1:1). The structural and empirical formulas are:

Tamoxifen citrate has a molecular weight of 563.62, the pKa’ is 8.85, the equilibrium solubility in water at 37°C is 0.5 mg/mL and in 0.02 N HCl at 37°C, it is 0.2 mg/mL.

NDA021807 APPR2005-10-29 DARA BIOSCIENCES,

US PATENT  6,127,425

Tamoxifen is an antagonist of the estrogen receptor in breast tissue via its active metabolite, hydroxytamoxifen. In other tissues such as the endometrium, it behaves as an agonist, and thus may be characterized as a mixed agonist/antagonist. Tamoxifen is the usual endocrine (anti-estrogen) therapy for hormone receptor-positive breast cancer in pre-menopausal women, and is also a standard in post-menopausal women although aromatase inhibitors are also frequently used in that setting.

Some breast cancer cells require estrogen to grow. Estrogen binds to and activates the estrogen receptor in these cells. Tamoxifen is metabolized into compounds that also bind to the estrogen receptor but do not activate it. Because of this competitive antagonism, tamoxifen acts like a key broken off in the lock that prevents any other key from being inserted, preventing estrogen from binding to its receptor. Hence breast cancer cell growth is blocked.

Tamoxifen was discovered by pharmaceutical company Imperial Chemical Industries (now AstraZeneca) and is sold under the trade names Nolvadex, Istubal, and Valodex. However, the drug, even before its patent expiration, was and still is widely referred to by its generic name “tamoxifen.

Breast cancer

Tamoxifen is currently used for the treatment of both early and advanced ER+ (estrogen receptor positive) breast cancer in pre- and post-menopausal women.Additionally, it is the most common hormone treatment for male breast cancer. It is also approved by the FDA for the prevention of breast cancer in women at high risk of developing the disease. It has been further approved for the reduction of contralateral (in the opposite breast) cancer.

In 2006, the large STAR clinical study concluded that raloxifene is equally effective in reducing the incidence of breast cancer, but after an average 4-year follow-up there were 36% fewer uterine cancers and 29% fewer blood clots in women taking raloxifene than in women taking tamoxifen, although the difference is not statistically significant.

Nolvadex (tamoxifen) 20 mg tablets

In 2005, the ATAC trial showed that after average 68 months following a 5 year adjuvant treatment, the group that received anastrozole (Arimidex) had significantly better results than the tamoxifen group in measures like disease free survival, but no overall mortality benefit. Data from the trial suggest that anastrozole should be the preferred medication for postmenopausal women with localized breast cancer that is estrogen receptor (ER) positive.Another study found that the risk of recurrence was reduced 40% (with some risk of bone fracture) and that ER negative patients also benefited from switching to anastrozole.

Crystallographic structure of 4-hydroxy-tamoxifen (carbon = white, oxygen = red, nitrogen = blue) complexed with ligand binding domain of estrogen receptor alpha (cyan ribbon)

Tamoxifen

Adequate patent protection is required to develop an innovation in a timely manner. In 1962, ICI Pharmaceuticals Division filed a broad patent in the United Kingdom (UK) (Application number GB19620034989 19620913). The application stated, “The alkene derivatives of the invention are useful for the modification of the endocrine status in man and animals and they may be useful for the control of hormone-dependent tumours or for the management of the sexual cycle and aberrations thereof. They also have useful hypocholesterolaemic activity”.

This was published in 1965 as UK Patent GB1013907, which described the innovation that different geometric isomers of substituted triphenylethylenes had either oestrogenic or anti-oestrogenic properties. Indeed, this observation was significant, because when scientists at Merrell subsequently described the biological activity of the separated isomers of their drug clomiphene, they inadvertently reversed the naming. This was subsequently rectified.

Although tamoxifen was approved for the treatment of advanced breast cancer in post-menopausal women in 1977 in the United States (the year before ICI Pharmaceuticals Division received the Queen’s Award for Technological Achievement in the UK), the patent situation was unclear. ICI Pharmaceuticals Division was repeatedly denied patent protection in the US until the 1980s because of the perceived primacy of the earlier Merrell patents and because no advance (that is, a safer, more specific drug) was recognized by the patent office in the United States. In other words, the clinical development advanced steadily for more than a decade in the United States without the assurance of exclusivity. This situation also illustrates how unlikely the usefulness of tamoxifen was considered to be by the medical advisors to the pharmaceutical industry in general. Remarkably, when tamoxifen was hailed as the adjuvant endocrine treatment of choice for breast cancer by the National Cancer Institute in 1984, the patent application, initially denied in 1984, was awarded through the court of appeals in 1985. This was granted with precedence to the patent dating back to 1965! So, at a time when world-wide patent protection was being lost, the patent protecting tamoxifen started a 17 year life in the United States. The unique and unusual legal situation did not go uncontested by generic companies, but AstraZeneca (as the ICI Pharmaceuticals Division is now called) rightly retained patent protection for their pioneering product, most notably, from the Smalkin Decision in Baltimore, 1996. (Zeneca, Ltd. vs. Novopharm, Ltd. Civil Action No S95-163 United States District Court, D. Maryland, Northern Division, March 14, 1996.)

 

Title: Tamoxifen

CAS Registry Number: 10540-29-1

CAS Name: (Z)-2-[4-(1,2-Diphenyl-1-butenyl)phenoxy]-N,N-dimethylethanamine

Additional Names: 1-p-b-dimethylaminoethoxyphenyl-trans-1,2-diphenylbut-1-ene

Molecular Formula: C26H29NO

Molecular Weight: 371.51

Percent Composition: C 84.06%, H 7.87%, N 3.77%, O 4.31%

Literature References: Nonsteroidal estrogen antagonist.

Prepn: BE 637389 (1964 to ICI). Identification and separation of isomers: G. R. Bedford, D. N. Richardson, Nature 212, 733 (1966); BE 678807; M. J. K. Harper et al., US 4536516 (1966, 1985 both to ICI). Stereospecific synthesis: R. B. Miller, M. I. Al-Hassan, J. Org. Chem. 50, 2121 (1985). Review of chemistry and pharmacology: B. J. A. Furr, V. C. Jordan, Pharmacol. Ther. 25, 127-205 (1984). Reviews of clinical experience in treatment and prevention of breast cancer: I. A. Jaiyesimi et al., J. Clin. Oncol. 13, 513-529 (1995); C. K. Osborne, N. Engl. J. Med. 339, 1609-1618 (1998).

Properties: Crystals from petr ether, mp 96-98°.

Melting point: mp 96-98°

Derivative Type: Citrate

CAS Registry Number: 54965-24-1

Manufacturers’ Codes: ICI-46474

Trademarks: Kessar (Pharmacia); Nolvadex (AstraZeneca); Tamofène (Aventis); Zemide (Alpharma); Zitazonium (Servier)

Molecular Formula: C26H29NO.C6H8O7

Molecular Weight: 563.64

Percent Composition: C 68.19%, H 6.62%, N 2.49%, O 22.71%

Properties: Fine, white, odorless crystalline powder, mp 140-142°. Slightly sol in water; sol in ethanol, methanol, acetone. Hygroscopic at high relative humidities. Sensitive to uv light. LD50 in mice, rats (mg/kg): 200, 600 i.p.; 62.5, 62.5 i.v.; 3000-6000, 1200-2500 orally (Furr, Jordan).

Melting point: mp 140-142°

Toxicity data: LD50 in mice, rats (mg/kg): 200, 600 i.p.; 62.5, 62.5 i.v.; 3000-6000, 1200-2500 orally (Furr, Jordan)

Derivative Type: (E)-Form

CAS Registry Number: 13002-65-8

Properties: mp 72-74° from methanol.

Melting point: mp 72-74° from methanol

Derivative Type: (E)-Form citrate

Manufacturers’ Codes: ICI-47699

Properties: mp 126-128°.

Melting point: mp 126-128°

CAUTION: Tamoxifen is listed as a known human carcinogen: Report on Carcinogens, Eleventh Edition (PB2005-104914, 2004) p III-239.

Therap-Cat: Antineoplastic (hormonal).

Keywords: Antineoplastic (Hormonal); Antiestrogens; Selective Estrogen Receptor Modulator (SERM).

Synthesis of the E and Z isomers of the antiestrogen Tamoxifen. David W.Robertson and John A. Katzenellenbogen. Journal of Organic Chemistry 1982 , 47, Pages 2387-2393. An early synthesis of Tamoxifen : Production of non stereo specific products. 

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 For easy of understanding the complete synthesis has been broken down into a number of steps.Step 1.  Step 1. This step shows use of a simple friedel-craft acylation involving Anisole(A) and Phenylacetic acid (B). The acylating agent in this process was a mixture of PCl5 / SnCl4. The ketone C was formed in a 78% yield.

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Step 2.

 

 

 

Step 2. 

Alkylation was promoted by treating the ketone C with Sodium hydride (NaH). This removed the acidic protons (located on the position alpha to the carbonyl group) to produce the enolate ion. This could be isolated as the sodium enolate of the ketone treatment of this with ethyl iodide resulted in the formation of compound (D) in a 94% yield. The Ethyl iodide was chosen as the acylating agent probably as it contains the iodide ion , which is an excellent leaving group. It can therefore facilitate an SN2 substitution reaction with relative easy. 

 

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Step 3.

 

 

 

Step 3.  The phenol was deprotected using Lithium ethanthiolate in DMF ( Dimethyl This facilitated the removal of the methyl group and replaced it with a H to form a hydroxl group. Thus forming compound (E) in a 96% yield.

 

This is a key step as it has left a chink in the armour of the molecule. This can then be used to build up a characteristic part of the Tamoxifen molecule. (eg the (diemthylamino)ethyl group can be added easily from here) 

 

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Step 4.

 

 

 

 

Step 4. 

Then product E can be alkylated by treatment with 2-(dimethylamino) ethy chloride. The most facile site of alklation is the OH group on the phenyl ring. This can be interpreted roughly by using HSAB theory. e.g Hard and Soft acid/base theory. The carbon adjacent to the chloride ion of the reactant 2-(dimethylamino)ethyl chloride is made slightly harder due to the process of symbiosis. This can rationalise the formation between the hard oxygen atom to the normally soft carbon atom. In this case the carbon atom has become slightly harder due to the presence of the hard chorine atom. Hence the interaction is favourable by HSAB theory. The above reaction gives product F via a SN2 substitution reaction in 70% yield. 

 

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Step 5.

 

 

Step5. 

F on treatment with PhMgBr forms the tertiary alcohol (G). 

Formation of the Grignard reagent can be achieved via reaction of PhBr + Mg —–> PhMgBr. The Grignard reagent has effectively formed a carbanion species eg C delta negative (-ve). This is due to the presence of the C-Mg bond. the fact that Magnesium is a more electropositive element thus making the Carbon atom the more electronegative element and hence acquiring a negative charge. As a result of the negative nature of the carbon atom it can now attack the delta positive (+ve) Carbon atom of the carbonyl group. 

 

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step 6.

 

 

 

 

Step 6.The dehydration of F was initiated by treatment of methanoic hydrogen chloride. this gives the required structure of Tamoxifen. However it gives a racemic mixture of both cis and trans isomers. 

The ratio of the Cis / Trans isomers was (1.3 / 1). These isomers of Tamoxifen can be separated by Silica gel thin layer chromatography with benzene / triethylamine (9:1) as the developing solvent. Analysis of this technique revealed that the Z (Trans) isomer was more mobile than the E (Cis) isomer.

Synthetic Route 2: A Stereospecific Approach.

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Stereospecific Synthesis of (Z) – Tamoxifen via carbometalation of Alkynylsilanes.

Studied for historical reasons rather than synthetic brilliance. This synthesis was the first stereo specific synthesis of (Z) Trans Tamoxifen. Comparison between this synthesis and the previous route I believe can illustrate the development of synthetic approaches to large molecules. In particular the quest for stereo specific reactions. So starting from an alkynylsilane (A) and through a series of reactions we can generate only the (Z) – Trans isomer of Tamoxifen.

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Again for ease of understanding the complete synthesis has been broken down into a number of steps.

Step1.

 

Step1.

 

 

This step contains the vital stereo specific step. Namely the carbometalation of the alkynylsilane.It is this step which establishes the stereochemistry about the double bond. The phenyl (trimethyl silyl) – acetylene was carbometalated with diethylaluminium chloride – titanocene dichloride reactant to produce an organometallic intermediate. This organometallic intermediate was then cleaved with N bromosucciniamide to produce the alkene (B) in 85% yield.

The stereochemistry was assigned as E (Cis) mechanistic evidence suggests that this is linked to some steric reasons.

(Earlier work dedicated to this reaction see : Miller, R.B. Al-Hassan.M.I J.Org.Chem. 1984, 49, 725)

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Step2.

Step 2.

The second step shows the stereo specific replacement of the Br group by a phenyl group. This was achieved by use of Palladium – catalysed coupling of compound (B) with phenyl zinc chloride to form (C) the vinylsilane in a 95% yield.

Step3.

 

Step3.

This step during the synthesis was reported to be tricky and several approaches were attempted before a successful technique was discovered.

 

The objective of this step was to replace the trimethyl Silyl group by a suitable halogen atom (e.g. Bromine or Iodine)

However a facile reaction was reported when (C) was treated with bromine – sodium methoxide at -78�C to produce the vinyl bromide (D) in a yield of 85%

 

Step 4.

 

Step 4.

The vinyl bromide (D) coupled well with a Zinc organometallic species to produce (E) the ethyl triaryl olefin in a yield of 84%.

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Step 5.

 

Step 5.

The formation of (F) Tamoxifen was achieved by demethylation with sodium ethylthoilate in refluxing dimethyl formamide. then reaction of the phenoxide ion with 2-( dimethylamino)ethyl chloride via a SN2 substitution.

Purification of the crude product was achieved via it’s hydrochloride salt ( via a reaction with HCl (g)) then F was regenerated by treatment with dilute base this produced the stereospecific (Z)- Trans isomer in an overall yield of 60%.

a synthesis

Palladium-Catalyzed Fluoride-Free Cross-Coupling of Intramolecularly ActivatedAlkenylsilanes and Alkenylgermanes: Synthesis of Tamoxifen as a Synthetic Application (pages 642–650)Kenji Matsumoto and Mitsuru ShindoArticle first published online: 23 FEB 2012 | DOI: 10.1002/adsc.201100627

• Abstract
• Full Article (HTML)
• PDF(262K)

 

 

http://pubs.rsc.org/en/content/articlelanding/2011/cs/c0cs00129e#!divAbstract

 

 

 

 

EP 0883587 A1  WO1997026234A1)

 

Preparation of Z isomer of Tamoxifen

A solution of bromobenzene (3.92g, 25mmol) in ether (5ml) containing a crystal of iodine was added dropwise to a suspension of magnesium turnings (0.63g, 26mmol) in ether (5ml) at reflux, under nitrogen. After the addition was complete, the reaction mixture was cooled to room temperature and a solution of l- [ 4- ( 2- chloroethoxy)phenyl]-2-phenyl-l-butanone (3.75g, 12.4mmol) in ether (15ml) was added over 1 hour. The resulting mixture was refluxed for 16 hours, then poured into dilute hydrochloric acid (50ml) and extracted with ether (3x40ml) . The combined ether layers were concentrated, the residual oil was dissolved in ethanol (10ml) and refluxed with concentrated hydrochloric acid (5ml) for 4 hours. The organic phase was separated, dried (Na₂S0₄) and evaporated to dryness to give a yellow oil. Η NMR (see Figures 1 to 4 and discussion below) showed this to be a 2:1 mixture of the Z and E isomers. The oil was then dissolved in warm methanol (about 40°C) and allowed to cool to room temperature. The colourless crystals formed proved to be pure Z isomer of 2-chloroethoxy tamoxifen (4.12g, 11.4mmol, 92% yield) . M.p. 107-109°C, m/z 362/364 (chlorine atom present), <S_H 0.92 (3H, t, J = 7.33 Hz, CH₃) , 2.46 (2H, q, J = 7.33 Hz, CH₂CH₃) , 3.72 (2H, t, J = 5.86 Hz, 0CH₂CH₂C1) , 4.09 (2H, t, J = 5.86 Hz, 0CH₂CH₂C1) , 6.55 (2H, d, J = 8.79 Hz, aromatic protons ortho to 0CH₂CH₂C1) , 6.79 (2H, d, J = 8.79 Hz, aromatic protons meta to 0CH₂CH₂C1) , 7.10-7.38 (10H, m, the two remaining C₆H₅ ^,s) (see Figure 5) . The 2-chloroethoxy tamoxifen was reacted with dimethylamine in ethanol, under reflux, to produce the desired Z isomer of tamoxifen.

Analysis of Η NMR data

Figures 1 to 4 represent a mixture of the E- and Z- forms of compound XI described above.

The expansion of the region ό^* 0.80 to 1.05 shows two overlapping triplets corresponding to the CH₃ groups in the

Z- and E- derivatives respectively. The critical point is the ratio of the heights of the peaks at 0.92 (for the Z) and 0.94 (for the E) , which is approximately 2:1. The expansion of the 4.00 to 4.35 region reveals similar information where ratios are 10:6.4 and 5.56:3.43.

Similarly expansion of the region 3.6 to 3.9 shows the ratio to be 2.46:1. All of these measurements suggest an approximate 2:1 ratio.

Referring to Figure 5, this shows almost pure Z- isomer. It should be noted that there is 660 mg of this from an original mixture of a 2:1 ratio mixture of 780 mg which would contain only 520 mg of the Z-isomer.

 

 

 

Z isomer of tamoxifen and 4-hydroxytamoxi en include stereoselective syntheses (involving expensive catalysts) as described in J. Chem. Soc, Perkin Trans I 1987, 1101 and J. Org. Chem. 1990, 55, 6184 or chromatographic separation of an E/Z mixture of isomers as described in J. Chem. Res., 1985 (S) 116, (M) 1342, 1986 (S) 58, (M) 771.

(Z)-tamoxifen (1) as a white solid, mp: 95.8-96.3 ºC. ¹H-NMR (500 MHz, CDCl₃) d 0.92 (3H, t, J 7.3 Hz), 2.29 (6H, s), 2.45 (2H, q, J 7.3 Hz), 2.65 (2H, t, J 5.8 Hz), 3.93 (2H, t, J 5.8 Hz), 6.68 (2H, d, J 9.5 Hz), 6.78 (2H, d, J 9.5 Hz), 7.08-7.28 (10H, m).¹³C-NMR (125 MHz, CDCl₃) d 13.6 (CH₃), 29.0 (CH₂), 45.8 (CH₃), 58.2 (CH₂), 65.5 (CH₂), 113.4 (C), 126.0 (C), 126.5 (CH), 127.8 (CH), 128.1 (C), 129.7 (C), 131.8 (CH), 135.6 (CH), 138.2 (CH), 141.3 (CH), 142.4 (CH), 143.8 (C), 156.7 (C). IR (KBr film) n_max/cm^-1: 3055, 2979, 2925, 2813, 2769, 1606, 1509, 1240, 1035, 707. GC-MS (EI) m/z 371(5%), 58(100%).

 

(Z)-tamoxifen (1) and (E)-tamoxifen (2) in 52% yield. ¹H-NMR (300 MHz, CDCl₃) d 0.91 (Z isomer. 3H, t, J 7.3 Hz), 0.94 (E isomer. 3H, t, J 7.3 Hz), 2.28 (Z isomer. 6H, s), 2.34 (E isomer. 6H, s), 2.42-2.52 (Z and Eisomers. 4H, m), 2.63 (Z isomer. 2H, t, J 5.9 Hz), 2.74 (E isomer. 2H, t, J 5.9 Hz), 3.94 (Z isomer. 2H, t, J 5.9 Hz), 4.07 (E isomer. 2H, t, J 5.9 Hz), 6.68 (Z isomer. 2H, d, J 9.7 Hz), 6.76 (E isomer. 2H, d, J 9.3 Hz), 6.86-7.36 (Z and E isomers. 10H, m). IR (KBr film) n_max/cm^-1: 3081, 3056, 2974, 2826, 2770, 1611, 1509, 1238, 1044. GC-MS (EI) m/z: Z isomer, 371(4%), 72 (24%), 58(100%); E isomer, 371(3%), 72 (24%), 58(100%). (the diastereoisomeric ratio was determined by capillary GC analysis and the configuration of the major diastereoisomer established by comparison of the NMR data of the synthetic mixture with an authentic sample of (Z)-tamoxifen (1).

 

 

nmr

 

 

ir

FTIR

shows the typical spectra’s of pure tamoxifen citrate, PCL, a physical mixture of tamoxifen citrate and PCL and drug-loaded implants. The spectrum of tamoxifen citrate shows characteristic absorption bands at 3027 cm⁻¹ (=C-H stretching), 1507 and 1477 (C=C ring stretching) and 3180 cm ^-1 (-NH2). PCL displays a characteristic absorption band at strong bands such as the carbonyl stretching mode around 1727 cm⁻¹ (C=O), asymmetric stretching 2949 cm⁻¹ (CH ₂ ) symmetric stretching 2865 cm⁻¹ (CH ₂ ). No changes in the spectrum of the physical mixture and drug-loaded microspheres were evident by FTIR spectroscopy. The strong bands such as the carbonyl peak were clear at all points.

Figure 2: Transmission FTIR spectra of (a) tamoxifen-loaded implant, (b) physical mixture of drug+PCL, (c) pure PCL, (d) pure tamoxifen citrate

enlarged view

 

FTIR spectra of A) tamoxifen citrate; B) PLGA; C) mixture of drug and excipients; D) freshly prepared nanoparticles in the formulation (BS-3HS).

Mentions: The pure drug tamoxifen citrate, PLGA-85:15, PVA, a mixture of PLGA and PVA, and a mixture of tamoxifen citrate, PLGA, and PVA; and a freshly prepared formulation were mixed separately with IR grade KBr in the ratio of 1:100 and corresponding pellets were prepared by applying 5.5 metric ton pressure with a hydraulic press. The pellets were scanned in an inert atmosphere over a wave number range of 4000–400 cm−1 in Magna IR 750 series II, FTIR instrument (Nicolet, Madison, WI, USA).

 

dsc

 

DSC thermograms of pure tamoxifen (a), pure PCL (b), physical mixture of drug+PCL (c) and (d) drug-loaded implant. The experiment was carried with crimped aluminum pans and a heating rate of 10ºC/min

 

 

xrd

X-ray diffraction studies of pure drug (a), pure PCL (b), physical mixture of drug+PCL (c) and (d) drug-loaded implant

 

synthesis

J.Chem. Research,1985(S) 116, (M) 1342 and 1986 (S) 58, (M) 0771.

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http://cen.acs.org/articles/91/i45/Improving-Drug-Delivery.html

Nanoparticles are promising cargo ships for targeted drug delivery. But the materials have had limited success treating cancer, because they often can’t penetrate deep into tumors. The nanoparticles are stalled by the extracelluar matrix and compressed blood vessels.

http://cen.acs.org/articles/91/i45/Improving-Drug-Delivery.html

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The plant hormone methyl jasmonate can be used to increase broccoli’s antitumoral properties

Read more

http://www.chemistryviews.org/details/news/5428251/Boosting_Broccoli_Power.html

back to home for more updates

DR ANTHONY MELVIN CRASTO Ph.D

amcrasto@gmail.com

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PITAVASTATIN, LIVALO, Itavastatin calcium, Nisvastatin, NKS-104, NK-104,

CAS REGISTRY NUMBER

rotation is +

alpha(D20) +6.8° (c 1.74, CHCl3)

ALSO

Bioorganic and Medicinal Chemistry Letters, 1999 ,  VOL 9,  20  pg. 2977 – 2982…….alpha(D20) +23.1° (c 1.0, acn/water(1:))

Helvetica Chimica Acta, 2007 ,  vol. 90, 6  pg. 1069 – 1081…alpha(D20) +22.9° (c 1.0, acn/water)

(3R,5S,6E)-7-[2-cyclopropyl-4-(4-fluorophenyl)quinolin-3-yl]-3,5-dihydroxyhept-6-enoic acid

Pitavastatin a lipid-lowering agent that belongs to the statin class of medications for treatment of dyslipidemia. It is also used for primary and secondary prevention of cardiovascular disease. FDA approved in Aug 3, 2009.

2-C25-H23-FN-O4.Ca, 881.01

Nissan Chemical (Originator), Kowa (Licensee), Novartis (Licensee), Recordati (Licensee), Sankyo (Licensee)

LIVALO (pitavastatin) is an inhibitor of HMG-CoA reductase. It is a synthetic lipid-lowering agent for oral administration.

The chemical name for pitavastatin is (+)monocalcium bis{(3R, 5S, 6E)-7-[2-cyclopropyl-4-(4-fluorophenyl)-3-quinolyl]-3,5dihydroxy-6-heptenoate}. The structural formula is:

The empirical formula for pitavastatin is C50H46CaF2N2O8 and the molecular weight is 880.98. Pitavastatin is odorless and occurs as white to pale-yellow powder. It is freely soluble in pyridine, chloroform, dilute hydrochloric acid, and tetrahydrofuran, soluble in ethylene glycol, sparingly soluble in octanol, slightly soluble in methanol, very slightly soluble in water or ethanol, and practically insoluble in acetonitrile or diethyl ether. Pitavastatin is hygroscopic and slightly unstable in light.

Each film-coated tablet of LIVALO contains 1.045 mg, 2.09 mg, or 4.18 mg of pitavastatin calcium, which is equivalent to 1 mg, 2 mg, or 4 mg, respectively of free base and the following inactive ingredients: lactose monohydrate, low substituted hydroxypropylcellulose, hypromellose, magnesium aluminometasilicate, magnesium stearate, and film coating containing the following inactive ingredients: hypromellose, titanium dioxide, triethyl citrate, and colloidal anhydrous silica.

Pitavastatin (usually as a calcium salt) is a member of the blood cholesterol loweringmedication class of statins,^[1] marketed in the United States under the trade nameLivalo. Like other statins, it is an inhibitor of HMG-CoA reductase, the enzyme that catalyses the first step of cholesterol synthesis. It has been available in Japan since 2003, and is being marketed under licence in South Korea and in India.^[2] It is likely that pitavastatin will be approved for use in hypercholesterolaemia (elevated levels of cholesterol in the blood) and for the prevention of cardiovascular disease outside South and Southeast Asia as well.^[3] In the US, it received FDA approval in 2009.^[4]

Pitavastatin is used to lower serum levels of total cholesterol, LDL-C, apolipoprotein B, and triglycerides, and raise levels of HDL-C for the treatment of dyslipidemia.

Like the other statins, pitavastatin is indicated for hypercholesterolaemia (elevated cholesterol) and for the prevention of cardiovascular disease. A 2009 study showed that pitavastatin increased HDL cholesterol (24.6%), especially in patients with HDL lower than 40 mg/dl, in addition to greatly reducing LDL cholesterol (–31.3%).^[5] As a consequence, pitavastatin is most likely to be appropriate for patients with metabolic syndrome with high LDL, low HDL and diabetes mellitus.

Common statin-related side effects (headaches, stomach upset, abnormal liver function tests and muscle cramps) were similar to other statins. However, pitavastatin seems to lead to fewer muscle side effects than certain statins that are lipid-soluble, as a result of the fact that pitavastatin is water-soluble (as is pravastatin, for example).^[6] One study found that coenzyme Q₁₀ was not reduced as much as with certain other statins (though this is unlikely given the inherent chemistry of the HMG-CoA reductase pathway that all statin drugs inhibit).^[3][7]

Hyperuricemia or increased levels of serum uric acid have been reported with pitavastatin.^[8]

Most statins are metabolised in part by one or more hepatic cytochrome P450enzymes, leading to an increased potential for drug interactions and problems with certain foods (such as grapefruit juice). Pitavastatin appears to be a substrate ofCYP2C9, and not CYP3A4 (which is a common source of interactions in other statins). As a result, pitavastatin is less likely to interact with drugs that are metabolized via CYP3A4, which might be important for elderly patients who need to take multiple medicines.^[3]

Pitavastatin (previously known as itavastatin, itabavastin, nisvastatin, NK-104 or NKS-104) was discovered in Japan by Nissan Chemical Industries and developed further byKowa Pharmaceuticals, Tokyo.^[3] Pitavastatin was approved for use in the United States by the FDA on 08/03/2009 under the trade name Livalo. Pitavastatin has been also approved by the Medicines and Healthcare products Regulatory Agency (MHRA) in UK on 17 August 2010.

1.  Kajinami, K; Takekoshi, N; Saito, Y (2003). “Pitavastatin: efficacy and safety profiles of a novel synthetic HMG-CoA reductase inhibitor”.Cardiovascular drug reviews 21 (3): 199–215. PMID 12931254. edit
2.  Zydus Cadila launches pitavastatin in India
3. Mukhtar, R. Y. A.; Reid, J.; Reckless, J. P. D. (2005). “Pitavastatin”. International Journal of Clinical Practice 59 (2): 239–252.doi:10.1111/j.1742-1241.2005.00461.x. PMID 15854203. edit
4.  The Seventh Statin; Pitavastatin
5.  http://www.ncbi.nlm.nih.gov/pubmed/19907105
6.  ScienceDaily (11 May 2013). “Alternative Cholesterol-Lowering Drug for Patients Who Can’t Tolerate Statins”. ScienceDaily.
7.  Clin Pharmacol Ther. 2008 May;83(5):731-9. Epub 2007 Oct 24. Comparison of effects of pitavastatin and atorvastatin on plasma coenzyme Q10 in heterozygous familial hypercholesterolemia: results from a crossover study. Kawashiri MA, Nohara A, Tada H, Mori M, Tsuchida M, Katsuda S, Inazu A, Kobayashi J, Koizumi J, Mabuchi H, Yamagishi M.
8.  Ogata, N.; Fujimori, S.; Oka, Y.; Kaneko, K. (2010). “Effects of Three Strong Statins (Atorvastatin, Pitavastatin, and Rosuvastatin) on Serum Uric Acid Levels in Dyslipidemic Patients”. Nucleosides, Nucleotides and Nucleic Acids 29 (4–6): 321.doi:10.1080/15257771003741323. edit

• FDA approval history

JP 1993310700, JP 1994025092

Tetrahedron Lett 1993, 34, 51, 8263-6.

Bioorg Med Chem2001, 9, (10): 2727

Drugs Fut1998, 23, (8) :847-859

Bull Chem Soc Jpn1995, 68, (1) :364-72

Tetrahedron Asymmetry1993, 4, (2) :201-4

Tetrahedron Lett1993, 34, (51) :8267-70

A Endo; J. Med. Chem. 1985, 28, 401.
AM Gotta; LC Smith; IXth International Symp. Drugs Affecting Lipid Metabolism, 1986, 30- 31
Y Fujikawa, Nissan Chemical Industries Ltd, EP304063 (A3), 1989.
S Ahmed; CS Madsen; PD Stein; J. Med. Chem. 2008, 51, 2722-2733.
K Turner; Org. Process. Res. Dev, 2004, 8, 823-833.
Z Casar; M Steinbocher; J Kosmrlj; J. Org. Chem. 2010, 75(19), 6681-6684.
KL Baumann; Tetrahedron Letters, 1992, 33, 2283-2284.
N Miyachi; Y Yanagawa; H Iwasaki; Tetrahedron Lett. 1993, 34, 8267-8270.
T Minami; K Takahashi; T Hiyama; Tetrahedron Lett. 1993, 34, 3, 513-516.
DA Evans; AH Hoveyda; J. Org. Chem. 1990, 55, 5190-5192.
J Castorer; LA Sorbera; PA Leeson; Drugs Fut. 23(8), 1998, 847-859.
T Hiyama; K Takahashi; T Minami; Bull. Chem. Soc. Jpn. 1995, 68, 364-372.
MS Reddy; M Bairy; K Reddy; Oriental Journal of Chemistry. 2007, 23, 559-564.
RN Moore; G Bigam; JK Chan; AM Hogg; JC Vederas; J. Am. Chem. Soc. 1985, 107 3694-3701.
DS Johnson; JJ Li; Art of Drug Synthesis, John Wiley & Sons, New Jersey, 2007, 177-181.
MT Stone; Organic Lett. 2011, 13, 2326-2329.
SR Manne, SR Maramreddy, WO2007132482 (A2), 2007.
SD Dwivedi, DJ Patel, AP Shah, Cadila Healthcare Ltd, US0022102 (A1), 2012.

……………………………………………………..

……………………………

The reaction of 1 (R) ,7,7-trimethylbicyclo [2.2.1] heptan-2-one (I) with 1 -naphthylmagnesium bromide (II) gives the tertiary alcohol (III), which by reaction with SOCl2 and then with NaHCO3 yields 2 – (1-naphthyl) -1 (R) ,7,7-trimethylbicyclo [2.2.1] heptene (IV ). Hydroboration of (IV) with BH3 followed by oxidation with H2O2 affords 4 (S) ,7,7-trimethyl-3exo-(1-naphthyl) bicyclo [2.2.1] heptan-2exo-ol (V), which is submitted to transesterification with methyl acetoacetate (VI) and dimethyl-aminopyridine (DMAP) to give the corresponding ester (VII). The condensation of (VII) with N-methoxy-N-methyl-3-[2-cyclopropyl-4-( 4-fluorophenyl) quinolin-3-yl] -2 (E)-propenamide (VIII) by means of NaH yields the corresponding chiral 3,5-dioxoheptenoic acid ester (IX), which is selectively reduced first with diisobutylaluminum hy-dride acid (DIBAL) and then with diethylmethoxyborane and sodium borohydride affording the 3 (R), 5 (S)-dihydroxyheptenoic ester (X). Finally, this compound is saponified with NaOH and treated with acetic acid / sodium acetate. The intermediate amide (VIII ) is obtained by condensation of 2-cyclopropyl-4-(4-fluorophenyl) quinoline-3-carbaldehyde (XI) with N-methoxy-N-methylacetamide (XII) by means of butyllithium to the hydroxy propionamide (XIII), which is then dehydrated with methanesulfonyl chloride and triethylamine in the usual way).

…………………

A systematic chiral synthesis of NK-104 and its enantiomer (X) has been reported: The oxidation of the already known 2-cyclopropyl-4-(4-fluorophenyl)quinoline-3-methanol (I) with DMSO, P2O5 and triethylamine gives the corresponding aldehyde (II), which is condensed with diethyl cyanomethylphosphonate by means of NaOH in toluene yielding the propenenitrile (III). The reduction of (III) with DIBAL affords the unsaturated aldehyde (IV), which is condensed with ethyl acetoacetate by means of NaH and n-BuLi to provide the 3-oxo-5-hydroxy-6-heptenoic acid ethyl ester derivative (V). The highly syn stereoselective reduction of (V) by means of diethylmethoxyborane and NaBH4 yields the desired syn racemic mixture of erythro-beta,delta-dihydroxyesters (VII), which is submitted to optical resolution with chiral (+)-alpha-methylbenzylamine [(+)-MBA] to obtain NK-104 free acid (VIII), which is finally treated with NaOH and CaCl2. The enantiomer of NK-104 has been obtained by optical resolution of the racemic mixture (VII) with (-)-alpha-methylbenzylamine to obtain the enantiomeric free acid (IX), which is treated with NaOH and CaCl2 as before.

Fujikawa, Y.; Suzuki, M.; Iwasaki, H.; Kitahara, M.; Sakashita, M.; Sakoda, R.;. Synthesis and biological evaluations of quinolone-based HMG-CoA reductase inhibitors Bioorg Med Chem 2001, 9 , 10, 2727

………

ADDITIONAL UPDATED INFO

Pitavastatin calcium is a novel member of the medication class of statins. Marketed in the United States under the trade name Livalo, it is like other statin drugs an inhibitor of HMG-CoA reductase, the enzyme that catalyses the first step of cholesterol synthesis. It is likely that pitavastatin will be approved for use in hypercholesterolaemia (elevated levels of cholesterol in the blood) and for the prevention of cardiovascular disease outside South and Southeast Asia as well.

Pitavastatin calcium is chemically known as (3R,5S)-7-[2-cyclopropyl-4-(4-fluorophenyl)quinolin-3-yl]-3,5-dihydroxy-6(E)-heptenoic acid calcium salt having the formula IA is known in the literature.

Pitavastatin is a synthetic lipid-lowering agent that acts as an inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme a (HMG-CoA) reductase (HMG-CoA Reductase inhibitor). This enzyme catalyzes the conversions of HMG-CoA to mevalonate, inhibitors are commonly referred to as “statins”. Statins are therapeutically effective drugs used for reducing low density lipoprotein (LDL) particle concentration in the blood stream of patients at risk for cardiovascular disease. Pitavastatin is used in the treatment of hyperchloesterolemia and mixed dyslipidemia.

Pitavastatin calcium has recently been developed as a new chemically synthesized and powerful statin by Kowa Company Ltd, Japan. On the basis of reported data, the potency of Pitavastatin is dose-dependent and appears to be equivalent to that of Atorvastatin. This new statin is safe and well tolerated in the treatment of patients with hypercholesterolaemia. Significant interactions with a number of other commonly used drugs can be considered to be extremely low.

Pitavastatin was disclosed for the first time in US patents US 4,761,419, US 5,01 1 ,930 and US 5,753,675. The process disclosed in these patents for the preparation of Pitavastatin is as shown below:

wherein R is hydrogen or protecting group.

US 5,284,953 discloses a process for the preparation of Pitavastatin calcium, which employs optically active a-methylbenzylamine as a resoluting agent.

The above processes are economically not viable, as resolution is carried out in final stage.

US 6,835,838 B2 discloses a process for the preparation of Pitavastatin calcium, which is as shown below:

However, it has been observed that the above process of lactonization results in ~10- 15% of unreacted Pitavastatin ethyl ester and therefore results in low yield. Further, -10% of Pitavastatin acid results during the above lactonization process and therefore does not produce a single product which is required to keep adequate control for an intermediate through specifications to have consistently better quality of the finished product.

Processes for the preparation of Pitavastatin are described in EP-A-0304063 and EP-A-1099694 and in the publications by N. Miyachi et al. in Tetrahedron Letters (1993) vol. 34, pages 8267-8270 and by K. Takahashi et al. in Bull. Chem. Soc. Japan (1995) Vol. 68, 2649-2656. These publications describe the synthesis of Pitavastatin in great detail but do not describe the hemi-calcium salt of Pitavastatin. The publications by L A. Sorbera et al. in Drugs of the Future (1998) vol. 23, pages 847-859 and by M. Suzuki at al. in Bioorganic & Medicinal Chemistry Letters (1999) vol. 9, pages 2977-2982 describe Pitavastatin calcium, however, a precise procedure for its preparation is not given. A full synthetic procedure for the preparation of Pitavastatin calcium is described in EP-A-0520406. In the process described in this patent Pitavastatin calcium is obtained by precipitation from an aqueous solution as a white crystalline material with a melting point of 190-192° C.

US20090182008 A1 discloses polymorphic form A, B, C, D, E, and F, and the amorphous form of Pitavastatin Calcium salt (2:1). In particular, crystalline Form A having water content from about. 5% to about 15% and process for its preparation are disclosed.

US20090176987 A1 also discloses polymorphic form crystal form A of Pitavastatin Calcium which contains from 5 to 15% of water and which shows, in its X-ray powder diffraction as measured by using CuKa radiation, a peak having a relative intensity of more than 25% at a diffraction angle (20) of 30.16°.

WO2007/132482 A1 discloses a novel process for the preparation of Pitavastatin Calcium by condensing bromide salt of formula-3 with aldehyde compound of formula-4 to obtain olefinic compound of formula-5 and converting olefinic compound to Pitavastatin Calcium via organic amine salt for purification.

Pitavastatin and its process were disclosed in U.S. Pat. No. 5,753,675.

Pitavastatin calcium and its process were disclosed in U.S. Pat. No. 5,856,336. PCT publication no. WO 2004/072040 (herein after referred to ’040 patent) disclosed crystalline polymorph A, polymorph B, polymorph C, polymorph D, polymorph E, polymorph F and amorphous form of pitavastatin calcium

• Synthesis of pitavastatin via cross-coupling reaction is disclosed inTetrahedron Lett. 1993, 34, 8263-8266, and in Tetrahedron Lett. 1993, 34, 8267-8270.
• A method for the preparation of pitavastatin via epichlorohydrin is described in Tetrahedron: Asymmetry 1993, 4, 201-204.
• Synthesis of pitavastatin heterocycle and pitavastatin molecule assembly via aldol condensation reaction is disclosed in Bioorg. Med. Chem. Lett. 1999, 9, 2977-2982, and Bioorg. Med. Chem. 2001, 9, 2727-2743:
• PCT application WO 2003/064382 describes a method for preparation of pitavastatin by asymmetric aldol reaction, in which titanium complex is used as a catalyst.
• HWE route to pitavastatin by utilization of 3-formyl substituted pitavastatin heterocycle is disclosed in Helv. Chim. Acta 2007, 90, 1069-1081:
• Methods for preparation of pitavastatin heterocycle derivatives are described in Bull. Chem. Soc. Jpn. 1995, 68, 364-372, Heterocycles 1999, 50, 479-483, Lett. Org. Chem. 2006, 3, 289-291, and in Org. Biomol. Chem. 2006, 4, 104-110, as well as in the international patent applications WO 95/11898 and WO 2004/041787 
• WO 95/11898 and Bull. Chem. Soc. Jpn. 1995, 68, 364-372 disclose synthesis of PTVBR from PTVOH with PBr₃:

WO 1995/1 1898 Al discloses a process for the preparation of Pitavastatin, which is as shown below:

wherein Y represents P⁺RnRi₂Ri3Hal^“ or P(W)Ri₄R₁₅; R_9a, R_% and R_]0 are protecting groups each of Rn, Rj_2> R^_, Ri₄ and R15 which are independent of one another, is optionally substituted alkyl or optionally substituted aryl group; R14 and Rj₅ together form a 5- or 6-membered ring; Hal is chlorine, bromine or iodine; and W is O or S.

The above process results in 2-5% of Cis isomer of Pitavastatin which requires further purification and therefore results poor yield.

US 6,875,867 B2 discloses a process for the preparation of Pitavastatin arginine salt, which is as shown below:

Saponification / Base

During the above process Trifluoroacetic acid or hydrochloric acid is used to break the acetonide and the Pitavastatin ester formed is converted in situ to its corresponding alkali salt by treating with base, such as sodium hydroxide.

US20090182008 A1 discloses polymorphic form A, B, C, D, E, and F, and the amorphous form of Pitavastatin Calcium salt (2:1). In particular, crystalline Form A having water content from about. 5% to about 15% and process for its preparation are disclosed.

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nmr

http://scholarsresearchlibrary.com/dpl-vol4-iss5/DPL-2012-4-5-1553-1557.pdf

calcium bis-(E)-3,5-dihydroxy-7-[4’-(4’’-flurophenyl)-2’-
cyclopropyl-quinoline-3-yl]-hept-6-enoate , pitavastatin calcium
Melting Point: 207 degC;

IR υmax (KBr) cm-1: 3366 (OH), 2911, 1603 (C=O), 1567 (C=N), 1513 (C=C),

1488 (C-H), 1416 (C-H), 1313, 1275, 1221 (C-O-C), 1158, 1065 (C-H), 972, 843, 763.

1H-NMR (500MHz, DMSO-d6):

δ 1.01 (m, 2H), 1.09 (m, 1H), 1.19 (m, 2H), 1.41 (m, 1H),

1.98 (dd, 1H, J1 =8.5,
J2 =15.5Hz), 2.11(d, 1H, J1 =3.0, J2 =15.5Hz), 2.50 (m, 2H),

3.66 (m, 1H), 4.13 (m, 1H), 4.95 (s, 1H), 5.58 (dd, 1H,
J1 =5.5, J2 =10.5Hz), 6.49 (d, 1H, J = 16.0Hz),

7.35 (m, 6H), 7.59 (m, 1H, J = 7.0Hz), 7.83 (d, 1H, J =8.5Hz).

13CNMR & DEPT (125.76MHz, DMSO-d6):

δ 11.12(CH2, C-17), 11.23(CH2,C-18), 15.80(CH2, C-16), 44.29(CH2,
C-22), 44.61(CH2, C-24), 66.61(C-O, C-23),

69.34(C-O,C-21),115.53(C=C, C-20), 15.62(CH), 115.79(CH),
123.59(CH), 126.07(C=C, C-19),

128.79(CH),129.20(CH),130.07(CH), 32.30(CH),

132.56(CH), 133.51(C),
142.60(C), 144.09(C), 146.37(C),

161.02(C), 163.00(C), 179.13(C=O, C-25).

ESI-MS: m/z (%) 318 (100), 274 (23), 423 (13), 422 (M+, 70); EI calcd for C25H24FNO4, 421.461; found, 422.220
(M+).

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………………

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AVANAFIL

A phosphodiesterase (PDE5) inhibitor, used to treat erectile dysfunction.

Avanafil is a new phosphodiesterase-5 inhibitor that is faster acting and more selective than other drugs belonging to the same class. Chemically, it is a derivative of pyrimidine and is only available as the S-enantiomer. FDA approved on April 27, 2012.

CAS RN: 330784-47-9
4-{[(3-chloro-4-methoxyphenyl)methyl]amino}-2-[(2S)-2-(hydroxymethyl)pyrrolidin-1-yl]-N-(pyrimidin-2-ylmethyl)pyrimidine-5-carboxamide

Molecular Formular: C23H26ClN7O3

Molecular Mass: 483.95064

• Stendra
• TA 1790
• TA-1790
• UNII-DR5S136IVO
• NDA 202276

INNOVATOR  –  VIVUS

APPROVED FDA  27/4/2-12

U 155… TREATMENT OF ERECTILE DYSFUNCTION

Stendra (avanafil) was given the green light by the US Food and Drug Administration 27/4/2012, but there has been no launch yet as Vivus has been seeking a partner. The latest data should be attractive to potential suitors and could help Stendra take on other phosphodiesterase type 5 (PDE5) inhibitors, notably Pfizer’s Viagra (sildenafil) but also Eli Lilly’s Cialis (tadalafil) and Bayer’s Levitra (vardenafil).

read all at

http://www.pharmatimes.com/Article/13-06-20/Vivus_ED_drug_gets_to_work_in_less_than_15_mins.aspx

STENDRA (avanafil) is a selective inhibitor of cGMP-specific PDE5.

Avanafil is designated chemically as (S)-4-[(3-Chloro-4-methoxybenzyl)amino]-2-[2-(hydroxymethyl)-1-pyrrolidinyl]-N-(2pyrimidinylmethyl)-5-pyrimidinecarboxamide and has the following structural formula:

Avanafil occurs as white crystalline powder, molecular formula C23H26ClN7O3 and molecular weight of 483.95 and is slightly soluble in ethanol, practically insoluble in water, soluble in 0.1 mol/L hydrochloric acid. STENDRA, for oral administration, is supplied as oval, pale yellow tablets containing 50 mg, 100 mg, or 200 mg avanafil debossed with dosage strengths. In addition to the active ingredient, avanafil, each tablet contains the following inactive ingredients: mannitol, fumaric acid, hydroxypropylcellulose, low substituted hydroxypropylcellulose, calcium carbonate, magnesium stearate, and ferric oxide yellow.

AVANAFIL

Avanafil is a PDE5 inhibitor approved for erectile dysfunction by FDA on April 27, 2012 ^[1] and by EMA on June 21, 2013.^[2] Avanafil is known by the trademark names Stendra and Spedra and was developed by Vivus Inc. In July 2013 Vivus announced partnership with Menarini Group, which will commercialise and promote Spedra in over 40 European countries plus Australia and New Zealand.^[3] Avanafil acts by inhibiting a specificphosphodiesterase type 5 enzyme which is found in various body tissues, but primarily in the corpus cavernosum penis, as well as the retina. Other similar drugs are sildenafil, tadalafil and vardenafil. The advantage of avanafil is that it has very fast onset of action compared with other PDE5 inhibitors. It is absorbed quickly, reaching a maximum concentration in about 30–45 minutes.^[4] About two-thirds of the participants were able to engage in sexual activity within 15 minutes.^[4]

Avanafil is a highly selective PDE5 inhibitor that is a competitive antagonist of cyclic guanosine monophosphate. Specifically, avanafil has a high ratio of inhibiting PDE5 as compared with other PDE subtypes allowing for the drug to be used for ED while minimizing adverse effects. Absorption occurs quickly following oral administration with a median Tmax of 30 to 45 minutes and a terminal elimination half-life of 5 hours. Additionally, it is predominantly metabolized by cytochrome P450 3A4. As such, avanafil should not be co-administered with strong cytochrome P450 3A4 inhibitors. Dosage adjustments are not warranted based on renal function, hepatic function, age or gender. Five clinical trials suggest that avanafil 100 and 200 mg doses are effective in improving the Sexual Encounter Profile and the Erectile Function Domain scores among men as part of the International Index of Erectile Function. A network meta-analysis comparing the PDE5 inhibitors revealed avanafil was less effective on Global Assessment Questionnaire question 1 while safety data indicated no major differences among the different PDE5 inhibitors. The most common adverse effects reported from the clinical trials associated with avanafil were headache, flushing, nasal congestion, nasopharyngitis, sinusitis, and dyspepsia.

A “phosphodiesterase type 5 inhibitor” or “PDE5 inhibitor” refers to an agent that blocks the degradative action of phosphodiesterase type 5 on cyclic GMP in the arterial wall smooth muscle within the lungs and in the smooth muscle cells lining the blood vessels supplying the corpus cavernosum of the penis. PDE5 inhibitors are used for the treatment of pulmonary hypertension and in the treatment of erectile dysfunction. Examples of PDE5 inhibitors include, without limitation, tadalafil, avanafil, lodenafil, mirodenafil, sildenafil citrate, vardenafil and udenafil and pharmaceutically acceptable salts thereof.

“Avanafil” refers to the chemical compound 4-[(3-Chloro-4-methoxybenzyl)amino]-2-[2-(hydroxymethyl)-1-pyrrolidinyl]-N-(2-pyrimidinylmethyl)-5-pyrimidinecarboxamide, and its pharmaceutically acceptable salts. Avanafil is described in Limin M. et al., (2010) Expert Opin Investig Drugs, 19(11):1427-37. Avanafil has the following chemical formula:

Avanafil is being developed for erectile dysfunction. Avanafil currently has no trademarked term associated with it but it is being developed by Vivus Inc.

…………………………………

DESCRIPTION IN A PATENT

US6797709

EXAMPLE 92-145

The corresponding starting compounds are treated in a similar manner to give the compounds as listed in the following Table 7.

TABLE 7

Amorphous MS(m/z): 484(MH+)

ENTRY 98 IS AVANAFIL

…………………………………………………….

/CN103254180A

The invention discloses a preparation method of Avanafil (Avanafil, I), which comprises the following steps: carrying out a substitution reaction on 6-amino-1, 2-dihydro pyrimidine-2-keto-5-carboxylic acid ethyl ester (XII) and 3-chloro-4-methoxy benzyl chloride (XIII) so as to obtain 6-(3-chloro-4-methoxy benzyl amino)-1, 2-dihydro pyrimidine-2-keto-5-carboxylic acid ethyl ester (IXV); carrying out condensation on the compound (IXV) and S-hydroxymethyl pyrrolidine (II) so as to generate 4-[(3-chloro-4-methoxy benzyl) amino]-2-[2-(hydroxymethyl)-1-pyrrole alkyl] pyrimidine-5-carboxylic acid ethyl ester (XI); and carrying out hydrolysis on the compound (XI) and then carrying out an acylation reaction on the compound (XI) and the compound (XI) so as to obtain Avanafil (I). The preparation method is simple in process, economic and environmental-friendly, suitable for the requirements of industrialization amplification.

……………………………………………………

/CN103265534A

The invention discloses a method for preparing avanafil (Avanafil, I). The method comprises the steps of taking cytosine as an initial material; and orderly carrying out replacement, halogen addition and condensation reaction on a side chain 3-chlorine-4-methoxy benzyl halide (III), N-(2-methylpyrimidine) formamide (IV) and S-hydroxymethyl pyrrolidine (II), so as to obtain a target product avanafil (I). The preparation method is available in material, concise in technology, economic and environment-friendly, and suitable for the demands of industrial amplification.

…………………………………………………….

SYNTHESIS

Avanafil can be synthesized from a benzylamine derivative and a pyrimidine derivative REF 5:Yamada, K.; Matsuki, K.; Omori, K.; Kikkawa, K.; 2004, U.S. Patent 6,797,709

………………………………………………………

SYNTHESIS

A cutting that phenanthrene by a methylthio urea ( a ) and ethoxy methylene malonate ( 2 ) cyclization of 3 , chloride, phosphorus oxychloride get 4 , 4 with benzyl amine 5 occurred SNAr the reaction product after oxidation with mCPBA 6 . In pyrimidine, if the 2 – and 4 – positions are active simultaneously the same leaving group in the case, SNAr reaction occurs preferentially at 4 – position, but does not guarantee the 2 – side reaction does not occur. Here is an activity of the poor leaving group sulfide spans 2 – bit, and a good leaving group active chlorine occupy four – position, thus ensuring a high regioselectivity of the reaction. 4 – position after completion of the reaction, then the 2 – position of the group activation, where sulfide sulfoxide better than the leaving group. Amino alcohols 7 and 6 recurrence SNAr reaction 8 , 8 after alkaline hydrolysis and acid alpha amidation get that phenanthrene.

AVANAFIL

…………………………….

1. FDA approves Stendra for erectile dysfunction” (Press release). Food and Drug Administration (FDA). April 27, 2012.
2.  http://www.ema.europa.eu/ema/index.jsp?curl=pages/medicines/human/medicines/002581/human_med_001661.jsp&mid=WC0b01ac058001d124
3.  http://ir.vivus.com/releasedetail.cfm?releaseid=775706
4. Kyle, Jeffery; Brown, Dana (2013). “Avanafil for Erectile Dysfunction”. Annals of Pharmacotherapy (Sage Publishing). doi:10.1177/1060028013501989. Retrieved 28 September 2013.
5.  Yamada, K.; Matsuki, K.; Omori, K.; Kikkawa, K.; 2004, U.S. Patent 6,797,709
6. • Peterson CA. Hemodynamic effect of avanafil and glyceryl trinitrate coadministration. , Drugs Context , Volume 2013 , 2013 Feb 26
   • Gur S. The Effect of Intracavernosal Avanafil, a Newer Phosphodiesterase-5 Inhibitor, on Neonatal Type 2 Diabetic Rats With Erectile Dysfunction. , Urology , 2013 Dec 9
   • Hill JK. Avanafil for erectile dysfunction. , Ann Pharmacother , Volume 47 , Issue 10 , 2013 Oct
   • Sanford M. Avanafil: a review of its use in patients with erectile dysfunction. , Drugs Aging , Volume 30 , Issue 10 , 2013 Oct
   • Hellstrom WJ. PDE5 inhibitors: considerations for preference and long-term adherence. , Int J Clin Pract , Volume 67 , Issue 8 , 2013 Aug
   • Aversa A. An update on pharmacological treatment of erectile dysfunction with phosphodiesterase type 5 inhibitors. , Expert Opin Pharmacother , Volume 14 , Issue 10 , 2013 Jul
   • Oelke M. Phosphodiesterase inhibitors in clinical urology. , Expert Rev Clin Pharmacol , Volume 6 , Issue 3 , 2013 May
   • Kukreja RC. Sildenafil and cardioprotection. , Curr Pharm Des , Volume 19 , Issue 39 , 2013
   • Day WW. An open-label, long-term evaluation of the safety, efficacy and tolerability of avanafil in male patients with mild to severe erectile dysfunction. , Int J Clin Pract, Volume 67 , Issue 4 , 2013 Apr
   • Tang J. Comparative effectiveness and safety of oral phosphodiesterase type 5 inhibitors for erectile dysfunction: a systematic review and network meta-analysis. , Eur Urol , Volume 63 , Issue 5 , 2013 May

United States	APPROVED 6656935	2012-04-27	EXPIRY 2020-09-13
United States	7501409	2012-04-27	2023-05-05

• Faster-Working Erectile Dysfunction Drug?. CBS News. November 24, 2009.
• Vivus says men taking avanafil were more likely to be ready for sex within 15 minutes. The Gaea Times. January 11, 2010.
• “Avanafil is the New Player in The Erectile Dysfunction Field”. June 28, 2011.

• • Hatzimouratidis, K., et al.: Drugs, 68, 231 (2008)

• US7927623	4-20-2011	Tablets quickly disintegrated in oral cavity
  US2010179131	7-16-2010	Combination treatment for diabetes mellitus
  US2009215836	8-28-2009	Roflumilast for the Treatment of Pulmonary Hypertension
  US2008027037	1-32-2008	Cyclic compounds

US5242391	Oct 30, 1991	Sep 7, 1993	ALZA Corporation	Urethral insert for treatment of erectile dysfunction
US5474535	Jul 19, 1993	Dec 12, 1995	Vivus, Inc.	Dosage and inserter for treatment of erectile dysfunction
US5773020	Oct 28, 1997	Jun 30, 1998	Vivus, Inc.	Treatment of erectile dysfunction
US6656935	Aug 10, 2001	Dec 2, 2003	Tanabe Seiyaku Co., Ltd.	Aromatic nitrogen-containing 6-membered cyclic compounds

EXTRAS

A “phosphodiesterase type 5 inhibitor” or “PDE5 inhibitor” refers to an agent that blocks the degradative action of phosphodiesterase type 5 on cyclic GMP in the arterial wall smooth muscle within the lungs and in the smooth muscle cells lining the blood vessels supplying the corpus cavernosum of the penis. PDE5 inhibitors are used for the treatment of pulmonary hypertension and in the treatment of erectile dysfunction. Examples of PDE5 inhibitors include, without limitation, tadalafil, avanafil, lodenafil, mirodenafil, sildenafil citrate, vardenafil and udenafil and pharmaceutically acceptable salts thereof. In one aspect, the PDE5 inhibitor is tadalafil.

“Tadalafil” or “TAD” is described in U.S. Pat. Nos. 5,859,006 and 6,821,975. It refers to the chemical compound, (6R-trans)-6-(1,3-benzodioxol-5-yl)-2,3,6,7,12,12a-hexahydro-2-methyl-pyrazino[1′,2′:1,6]pyrido[3,4-b]indole-1,4-dione and has the following chemical formula:

Tadalafil is currently marketed in pill form for treating erectile dysfunction (ED) under the trade name Cialis® and under the trade name Adcirca® for the treatment of PAH.

“Avanafil” refers to the chemical compound 4-[(3-Chloro-4-methoxybenzyl)amino]-2-[2-(hydroxymethyl)-1-pyrrolidinyl]-N-(2-pyrimidinylmethyl)-5-pyrimidinecarboxamide, and its pharmaceutically acceptable salts. Avanafil is described in Limin M. et al., (2010) Expert Opin Investig Drugs, 19(11):1427-37. Avanafil has the following chemical formula:

Avanafil is being developed for erectile dysfunction. Avanafil currently has no trademarked term associated with it but it is being developed by Vivus Inc.

“Lodenafil” refers to the chemical compound, bis-(2-{4-[4-ethoxy-3-(1-methyl-7-oxo-3-propyl-6,7-dihydro-1H-pyrazolo[4,3-d]pyrimidin-5-yl)-benzenesulfonyl]piperazin-1-yl}-ethyl)carbonate and has the following chemical formula:

More information about lodenafil is available at Toque H A et al., (2008) European Journal of Pharmacology, 591(1-3):189-95. Lodenafil is manufactured by Cristália Produtos Químicose Farmacêuticos in Brazil and sold there under the brand-name Helleva®. It has undergone Phase III clinical trials, but is not yet approved for use in the United States by the U.S. FDA.

“Mirodenafil” refers to the chemical compound, 5-Ethyl-3,5-dihydro-2-[5-([4-(2-hydroxyethyl)-1-piperazinyl]sulfonyl)-2-propoxyphenyl]-7-propyl-4H-pyrrolo[3,2-d]pyrimidin-4-one and has the following chemical formula:

More information about mirodenafil can be found at Paick J S et al., (2008) The Journal of Sexual Medicine, 5 (11): 2672-80. Mirodenafil is not currently approved for use in the United States but clinical trials are being conducted.

“Sildenafil citrate,” marketed under the name Viagra®, is described in U.S. Pat. No. 5,250,534. It refers to 1-[4-ethoxy-3-(6,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-5-yl)phenylsulfonyl]-4-methylpiperazine and has the following chemical formula:

Sildenafil citrate, sold as Viagra®, Revatio® and under various other trade names, is indicated to treat erectile dysfunction and PAH.

“Vardenafil” refers to the chemical compound, 4-[2-Ethoxy-5-(4-ethylpiperazin-1-yl)sulfonyl-phenyl]-9-methyl-7-propyl-3,5,6,8-tetrazabicyclo[4.3.0]nona-3,7,9-trien-2-one and has the following chemical formula:

Vardenafil is described in U.S. Pat. Nos. 6,362,178 and 7,696,206. Vardenafil is marketed under the trade name Levitra® for treating erectile dysfunction.

“Udenafil” refers to the chemical compound, 3-(1-methyl-7-oxo-3-propyl-4,7-dihydro-1H-pyrazolo[4,3-d]pyrimidin-5-yl)-N-[2-(1-methylpyrrolidin-2-yl)ethyl]-4-propoxybenzenesulfonamide and has the following chemical formula:

More information about udenafil can be found at Kouvelas D. et al., (2009) Curr Pharm Des, 15(30):3464-75. Udenafil is marketed under the trade name Zydena® but not approved for use in the United States.

 

THANKS AND REGARD’S

DR ANTHONY MELVIN CRASTO Ph.D GLENMARK SCIENTIST , NAVIMUMBAI, INDIA

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I was  paralysed in dec2007, Posts dedicated to my family, my organisation Glenmark, Your readership keeps me going and brings smiles to my family

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DOXOFYLLINE

LAUNCHED 1987, Istituto Biologico Chemioterapico ABC

69975-86-6  CAS NO

7-(1,3-dioxolan-2-ylmethyl)-1,3-dimethylpurine-2,6-dione

1H-Purine-2,6-dione, 3,7-dihydro-7-(1,3-dioxolan-2-ylmethyl)-1,3-dimethyl- (9CI)

7-(1,3-Dioxolan-2-ylmethyl)-3,7-dihydro-1,3-dimethyl-1H-purine-2,6-dione; 7-[1,3-(Dioxolan-d4)-2-ylmethyl)]theophylline; 2-(7�-Theophyllinemethyl)-1,3- dioxolane; ABC 12/3; ABC 1213; Ansimar; Dioxyfilline; Doxophylline; Maxivent; Ventax;

Synonyms

• ABC 12/3
• Ansimar
• BRN 0561195
• Dioxyfilline
• Doxofilina
• Doxofilina [INN-Spanish]
• Doxofylline
• Doxofyllinum
• Doxofyllinum [INN-Latin]
• Doxophylline
• EINECS 274-239-6
• Maxivent
• UNII-MPM23GMO7Z
• Ventax

Doxofylline (INN), (also known as doxophylline) is a xanthine derivative drug used in the treatment of asthma.^[1]

Doxofylline is a xanthine molecule that appears to be both bronchodilator and anti-inflammatory with an improved therapeutic window over conventional xanthines such as Theophylline and the evidence supporting the effects of Doxofylline in the treatment of lung diseases

It has antitussive and bronchodilator^[2] effects, and acts as aphosphodiesterase inhibitor.^[3]

In animal and human studies, it has shown similar efficacy to theophylline but with significantly fewer side effects.^[4]

Unlike other xanthines, doxofylline lacks any significant affinity for adenosine receptorsand does not produce stimulant effects. This suggests that its antiasthmatic effects are mediated by another mechanism, perhaps its actions on phosphodiesterase.^[1]

Doxofylline, [7-(1, 3-dioxolan-2-ylmethyl)-3, 7-dihydro-1, 3-dimethyl-1H-purine-2, 6-dione] is a new bronchodilator xanthine based drug which differs from theophylline by the presence of dioxalane group at position 7. It is used in the treatment of bronchial asthma, chronic obstructive pulmonary disease (COPD), and chronic bronchitis . The mechanism of action is similar to that of theophylline in that it inhibits phosphodiesterase (PDE-IV), thereby preventing breakdown of cyclic adenosine monophosphate (cAMP). Increase in cAMP inhibits activation of inflammatory cells resulting in bronchodilating effect [52]. In contrast to theophylline, doxofylline has very low affinity towards adenosine A1 and A2 receptors which explain its better safety profile

Doxofylline (7-(l,3-dioxalan-2-ylmethyl)-theophylline) is a drug derived from theophylline which is used in therapy as a bronchodilator, with anti-inflammatory action, in reversible airway obstruction. It is commonly administered in doses ranging from 800 to 1200 mg per day, orally, according to a dosage which provides for the intake of two to three dosage units per day in order to maintain therapeutically effective haematic levels. The doxofylline tablets commercially available generally contain 400 mg of active ingredient and release almost all the drug within one hour from intake. The half- life of the drug is around 6-7 hours and for this reason several administrations are required during the 24-hour period.

Obviously a drop in haematic concentration of the drug in an asthmatic patient or patient suffering from COPD (chronic obstructive pulmonary disease) can result in serious consequences, in which case the patient must have recourse to rescue medication, such as salbutamol inhalers.

Pharmaceutical techniques for obtaining the modified release of drugs have been known for some time, but no modified release formulation of doxofylline is known. In fact the present inventors have observed that there are significant difficulties in the production of a doxofylline formula that can be administered only once a day and in particular have encountered problems correlated with bioequivalence.

Various attempts to formulate doxofylline in modified release systems, with different known polymers, have not provided the desired results, i.e. a composition that can be administered once a day, bio equivalent to the plasmatic concentration obtained with the traditional compositions currently on sale. In fact currently, dosage units containing 400 mg of active ingredient are currently administered two/three times a day for a daily average of approximately 1000 mg of active ingredient, a dosage considered necessary to maintain the therapeutic haematic levels of doxofylline.

Such a dosage unit is currently marketed by Dr. Reddy’s Laboratories Ltd as DOXOBID and has the following quali-quantitative composition: doxofylline (400 mg), colloidal silicon dioxide (13 mg), corn starch (63 mg), mannitol (40 mg), povidone (7 mg), microcrystalline cellulose (64 mg), talc (30 mg), magnesium stearate (3 mg) and water (0.08 ml).

Xanthine is a dioxypurine that is structurally related to uric acid. Xanthine can be represented by the following structure:

Caffeine, theophylline and theobromine are methylated xanthines. Methylated xanthines such as caffeine and theophylline are typically used for their bronchodilating action in the management of obstructive airways diseases such as asthma. The bronchodilator effects of methylxanthines are thought to be mediated by relaxation of airway smooth muscle. Generally, methylxanthines function by inhibiting cyclic nucleotide phosphodiesterases and antagonizing receptor-mediated actions of adenosine.

Theophylline can be represented by the following structure:

However, when administered intravenously or orally, theophylline has numerous undesired or adverse effects that are generally systemic in nature. It has a number of adverse side effects, particularly gastrointestinal disturbances and CNS stimulation. Nausea and vomiting are the most common symptoms of theophylline toxicity. Moderate toxicity is due to relative epinephrine excess, and includes tachycardia, arrhythmias, tremors, and agitation. Severe toxicity results in hallucinations, seizures, dysrhythmias and hypotension. The spectrum of theophylline toxicity can also include death.

Furthermore, theophylline has a narrow therapeutic range of serum concentrations above which serious side effects can occur. The pharmacokinetic profile of theophylline is dependent on liver metabolism, which can be affected by various factors including smoking, age, disease, diet, and drug interactions.

Generally, the solubility of methylxanthines is low and is enhanced by the formation of complexes, such as that between theophylline and ethylenediamine (to form aminophylline). The formation of complex double salts (such as caffeine and sodium benzoate) or true salts (such as choline theophyllinate) also enhances aqueous solubility. These salts or complexes dissociate to yield the parent methylxanthine when dissolved in aqueous solution. Although salts such as aminophylline have improved solubility over theophylline, they dissociate in solution to form theophylline and hence have similar toxicities.

Dyphylline is a covalently modified derivative of xanthine (1,3, -dimethyl-7-(2,3-dihydroxypropl)xanthine. Because it is covalently modified, dyphylline is not converted to free theophylline in vivo. Instead, it is absorbed rapidly in therapeutically active form. Dyphylline has a lower toxicity than theophylline. Dyphylline can be represented by the following structure:

Dyphylline is an effective bronchodilator that is available in oral and intramuscular preparations. Generally, dyphylline possesses less of the toxic side effects associated with theophylline.

U.S. Pat. No. 4,031,218 (E1-Antably) discloses the use of 7-(2,3-dihydroxypropyl)-1,3-di-n-propylxanthine, a derivative of theophylline, as a bronchodilator. U.S. Pat. No. 4,341,783 (Scheindlin) discloses the use of dyphylline in the treatment of psoriasis and other diseases of the skin by topical administration of dyphylline. U.S. Pat. No. 4,581,359 (Ayres) discloses methods for the management of bronchopulmonary insufficiency by administering an N-7-substituted derivative of theophylline, including dyphylline, etophylline, and proxyphylline.

At present, domestic synthetic Doxofylline composed of two main methods: one is by the condensation of theophylline prepared from acetaldehyde and ethylene glycol, but this method is more complex synthesis of acetaldehyde theophylline, require high periodate oxidation operation. Another is a halogenated acetaldehyde theophylline and ethylene glycol is prepared by reaction of an organic solvent, the method were carried out in an organic solvent, whereby the product Theophylline caused some pollution, conducive to patients taking.

current domestic Doxofylline synthetic methods reported in the literature are: 1, CN Application No. 94113971.9, the name “synthetic drugs Doxofyllinemethod” patents, the patent is determined by theophylline with a 2 – (halomethyl) -1,3 – dimethoxy-dioxolane in a polar solvent, with a base made acid absorbent,Doxofylline reaction step. 2,  CN Application No. 97100911.2, entitled “Synthesis of Theophylline,” the patent, the patent is obtained from 7 – (2,2 – dialkoxy-ethyl) theophylline with ethylene glycol in N, N-dimethylformamide solvent with an alkali metal carbonate to make the condensing agent, p-toluenesulfonic acid catalyst in the condensation Doxofylline.

Doxofylline of xanthine asthma drugs, and its scientific name is 7 – (1,3 – dioxolan – ethyl methyl) -3,7 – dihydro-1,3 – dimethyl-1H – purine-2 ,6 – dione. The drug developed by the Italian Roberts & Co. in 1988, listed its tablet tradename Ansimar. This product is compared with similar asthma drugs, high efficacy, low toxicity, oral LD50 in mice is 1.5 times aminophylline, non-addictive. Adenosine and its non-blocking agents, it does not produce bronchial pulmonary side effects, no aminophylline like central and cardiovascular system. U.S. patent (US4187308) reported the synthesis of doxofylline, theophylline and acetaldehyde from ethylene glycol p-toluenesulfonic acid catalyst in the reaction of benzene as a solvent Doxofylline. Theophylline acetaldehyde by the method dyphylline derived reaction with a peroxy periodate or 7 – (2,2 – dialkoxy-ethyl) ammonium chloride aqueous solution in the decomposition of theophylline converted to acetaldehyde theophylline . Former method is relatively complex, and the high cost of using periodic acid peroxide, low yield after France. And theophylline acetaldehyde and ethylene glycol solvent used in the reaction of benzene toxicity, harm to health, and the yield is low, with an average around 70%, not suitable for industrial production.

SYN 1

Theophylline-7-acetaldehyde (I) could react with ethylene glycol (II) in the presence of p-toluenesulfonic acid in refluxing benzene to produce Doxofylline.

SYN 2

Doxofylline can be prepared by N-alkylation of theophylline (I) with bromoacetaldehyde ethylene glycol acetal (II) using Na2CO3 in refluxing H2O (1).

.…………………………………….

Synthesis

US4187308

EXAMPLE

A mixture of 15 g of theophyllineacetic aldehyde, 30 ml of ethylene glycol and 1.5 g of p-toluenesulphonic acid in 600 ml of benzene is heated under reflux in a flask provided with a Marcusson apparatus.

After two hours the separation of the water is complete.

The reaction mixture is washed with 200 ml of a 3.5% aqueous solution of sodium bicarbonate.

The organic phase is dried and concentrated to dryness under reduced pressure, to leave a product residue which is taken up in ethyl ether, separated by filtration and purified by ethanol.

2-(7′-theophyllinemethyl)-1,3-dioxolane is obtained.

M.P. 144

Average yield 70%

Analysis: C.sub.11 H.sub.14 N.sub.4 O.sub.4 : M.W. 266.26: Calculated: C%, 49.62; H%, 5.30; N%, 21.04. Found: C%, 49.68; H%, 5.29; N%, 21.16.

………………………………..

CN102936248A

the reaction is:

a, anhydrous theophylline and bromoacetaldehyde ethylene glycol as the basic raw material, purified water as a solvent with anhydrous sodium carbonate as acid-binding agent;

NMR

Doxofylline

UV (95% C2H5OH, nm) λmax273 (ε9230); λmin244 (ε2190)

IR (KBr, cm-1) 1134 (CO); 1233 (CN) ; 1547 (C = N); 1656 (C = C); 1700 (C = O); 2993 (CH)

1H-NMR [CDCl3, δ (ppm)] 3.399 (s, 3H, N-CH3); 3.586 (S, 3H, N-CH3); 3.815-3.885 (m, 4H, OCH2 × 2); 4.581 (d, 2H, CH2); 5.211 (t, 1H, CH ); 7.652 (S, 1H, CH = N)

13C-NMR [CDCL3, δ (ppm)] 27.88 (CH3); 29.69 (CH3); 47.87 (CH2); 65.37 ( OCH2); 100.76 (CH); 107.26 (C = C); 142.16 (CH = N); 148.22 (C = C); 151.59 (C = O); 155.25 ( C

……………………………

HPLC

http://www.scipharm.at/download.asp?id=1401

…………………..

1. Cirillo R, Barone D, Franzone JS (1988). “Doxofylline, an antiasthmatic drug lacking affinity for adenosine receptors”. Arch Int Pharmacodyn Ther 295: 221–37.PMID 3245738.
2. Poggi R, Brandolese R, Bernasconi M, Manzin E, Rossi A (October 1989). “Doxofylline and respiratory mechanics. Short-term effects in mechanically ventilated patients with airflow obstruction and respiratory failure”. Chest 96 (4): 772–8.doi:10.1378/chest.96.4.772. PMID 2791671.
3.  Dini FL, Cogo R (2001). “Doxofylline: a new generation xanthine bronchodilator devoid of major cardiovascular adverse effects”. Curr Med Res Opin 16 (4): 258–68.doi:10.1185/030079901750120196. PMID 11268710.
4. Sankar J, Lodha R, Kabra SK (March 2008). “Doxofylline: The next generation methylxanthine”. Indian J Pediatr 75 (3): 251–4. doi:10.1007/s12098-008-0054-1.PMID 18376093.
5. Dali Shukla, Subhashis Chakraborty, Sanjay Singh & Brahmeshwar Mishra. Doxofylline: a promising methylxanthine derivative for the treatment of asthma and chronic obstructive pulmonary disease. Expert Opinion on Pharmacotherapy. 2009; 10(14): 2343-2356, DOI 10.1517/14656560903200667, PMID 19678793
6. Farmaco, Edizione Scientifica, 1981 ,  vol. 36,   3  pg. 201 – 219, mp  144 – 144.5 °C
7. Drugs Fut 1982, 7(5): 301

………………………………………………………………………………………..

I n case Images are blocked on your computer, VIEW AT

14-chapter 4.pdf – Shodhganga

SPECTRAL DATA

DOXOFYLLINE
The ESI mass spectrum exhibited a protonated molecular ion peak at m/z 267 in positive ion mode indicating the molecular weight of 266. The tandem mass spectrum showed the fragment ions m/z 223, 181.2, 166.2, 138.1, 124.1 and 87.1.

The FT-IR spectrum, two strong peaks at 1697cm-1 and 1658cm-1 indicated presence of two carbonyl groups. A strong peak at frequency 1546cm-1 indicated presence of C=N stretch. A medium peak at 1232cm-1 was due to C-O stretch

FT IR

1H and 13C-NMR spectra of doxofylline and its degradation products were recorded by using Bruker NMR 300MHz instrument with a dual broad band probe and z-axis gradients. Spectra were recorded using DMSO-d6 as a solvent and tetramethylsilane as an internal standard.
4.2.6 Validation

1H NMR

13 C NMR

COMPARISONS

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FONDAPARINUX

Fondaparinux is a drug belonging to the group of the antithrombotic agents and are used to prevent deep vein thrombosis in patients undergoing orthopedic surgery. It is also used for the treatment of severe venous thrombosis and pulmonary

фондапаринукс (fondaparinux) | EMA:Link, US FDA:link

114870-03-0  ………..10x SODIUM SALT

GSK-576428  Org-31540  SR-90107SR-90107A  

launched 2002

Arixtra, Quixidar, Fondaparinux sodium, Fondaparin sodium, Arixtra (TN), Fondaparinux, Org-31540, AC1LCS4W, SR-90107A

Fondaparinux (Arixtra) is a synthetic pentasaccharide anticoagulant. Apart from the O-methyl group at the reducing end of the molecule, the identity and sequence of the five monomeric sugar units contained in fondaparinux is identical to a sequence of five monomeric sugar units that can be isolated after either chemical or enzymatic cleavage of the polymeric glycosaminoglycan heparin and heparan sulfate (HS). This monomeric sequence in heparin and HS is thought to form the high affinity binding site for the natural anti-coagulant factor, antithrombin III (ATIII).

Binding of heparin/HS to ATIII has been shown to increase the anti-coagulant activity of antithrombin III 1000-fold. Fondaparinux potentiates the neutralizing action ofATIII on activated Factor X 300-fold. Fondaparinux may be used: to prevent venous thromboembolism in patients who have undergone orthopedic surgery of the lower limbs (e.g. hip fracture, hip replacement and knee surgery); to prevent VTE in patients undergoing abdominal surgery who are are at high risk of thromboembolic complications; in the treatment of deep vein thrombosis (DVT) and pumonary embolism (PE); in the management of unstable angina (UA) and non-ST segment elevation myocardial infarction (NSTEMI); and in the management of ST segment elevation myocardial infarction (STEMI).

FONDAPARINUX

Fondaparinux (trade name Arixtra) is an anticoagulant medication chemically related to low molecular weight heparins. It is marketed byGlaxoSmithKline. A generic version developed by Alchemia is marketed within the US by Dr. Reddy’s Laboratories.

Fondaparinux is a synthetic pentasaccharide Factor Xa inhibitor. Apart from the O-methyl group at the reducing end of the molecule, the identity and sequence of the five monomeric sugar units contained in fondaparinux is identical to a sequence of five monomeric sugar units that can be isolated after either chemical or enzymatic cleavage of the polymeric glycosaminoglycans heparin and heparan sulfate (HS). Within heparin and heparan sulfate this monomeric sequence is thought to form the high affinity binding site for the anti-coagulant factor antithrombin III (ATIII). Binding of heparin/HS to ATIII has been shown to increase the anti-coagulant activity of antithrombin III 1000 fold. In contrast to heparin, fondaparinux does not inhibit thrombin.

Fondaparinux is given subcutaneously daily. Clinically, it is used for the prevention of deep vein thrombosis in patients who have had orthopedic surgery as well as for the treatment of deep vein thrombosis and pulmonary embolism.

One potential advantage of fondaparinux over LMWH or unfractionated heparin is that the risk for heparin-induced thrombocytopenia (HIT) is substantially lower. Furthermore, there have been case reports of fondaparinux being used to anticoagulate patients with established HIT as it has no affinity to PF-4. However, its renal excretion precludes its use in patients with renal dysfunction.

Unlike direct factor Xa inhibitors, it mediates its effects indirectly through antithrombin III, but unlike heparin, it is selective for factor Xa.^[1]

Fondaparinux is similar to enoxaparin in reducing the risk of ischemic events at nine days, but it substantially reduces major bleeding and improves long term mortality and morbidity.^[2]

It has been investigated for use in conjunction with streptokinase.^[3]

Fondaparinux sodium, a selective coagulation factor Xa inhibitor, was first launched in the U.S. in 2002 by GlaxoSmithKline in a subcutaneous injection formulation for the prophylaxis of deep venous thrombosis (DVT) which may lead to pulmonary embolism in patients at risk for thromboembolic complications who are undergoing hip replacement, knee replacement, hip fracture surgery or abdominal surgery. The product is available in Japan for the treatment of acute deep venous thrombosis and acute pulmonary thromboembolism. In 2004, GlaxoSmithKline launched fondaparinux as an injection to be used in conjunction with warfarin sodium for the subcutaneous treatment of acute pulmonary embolism and DVT.

In 2007, GlaxoSmithKline received approval in the E.U. for the treatment of acute coronary syndrome (ACS), specifically unstable angina or non-ST segment elevation myocardial infarction (UA/NSTEMI) and ST-segment elevation myocardial infarction (STEMI), while in the U.S. an approvable letter was received for this indication. Currently, the drug is in clinical development at GlaxoSmithKline for the treatment of venous limb superficial thrombosis.

Fondaparinux Molecule

GlaxoSmithKline had filed a regulatory application in the E.U. seeking approval of fondaparinux sodium for the prevention of venous thromboembolic events (VTE), however; in 2008, the application was withdrawn for commercial reasons. Commercial launch in Japan for the product for the prevention of venous thromboembolism in high risk patients undergoing surgery in the abdomen took place in 2008.

In 2010, the EMA approved a regulatory application filed by GlaxoSmithKline seeking approval of a once-daily formulation of fondaparinux sodium for the treatment of adults with acute symptomatic spontaneous superficial-vein thrombosis (SVT) of the lower limbs without concomitant DVT. Product launch took place in the U.K. for this indication the same year.

The antithrombotic activity of fondaparinux is the result of antithrombin III (ATIII)-mediated selective inhibition of Factor Xa. By selectively binding to ATIII, the drug potentiates (about 300 times) the innate neutralization of Factor Xa by ATIII. Neutralization of Factor Xa, in turn, interrupts the blood coagulation cascade and thus inhibits thrombin formation and thrombus development. Fondaparinux does not inactivate thrombin (activated Factor II) and has no known effect on platelet function. At the recommended dose, no effects have been demonstrated on fibrinolytic activity or bleeding time.

Originally developed by Organon and Sanofi (formerly known as sanofi-aventis), fondaparinux sodium is currently available in approximately 30 countries. In 2004, Organon transferred its rights to the drug to Sanofi in exchange for revenues based on future sales from jointly developed antithrombotic products and in early 2005, GlaxoSmithKline also acquired the antithrombotic.

At the beginning of 2005, GlaxoSmithKline signed a two-year agreement with Adolor (acquired by Cubist in 2011) for the copromotion of fondaparinux sodium in the U.S. In Sepetember 2013, Aspen Pharmacare acquired Arixtra global rights (excluding China, India and Pakistan) from GlaxoSmithKline for the treatment of thrombosis with GlaxoSmithKline commercializing the product in Indonesia under licence from Aspen.

Chemical structure

Abbreviations

• GlcNS6S = 2-deoxy-6-O-sulfo-2-(sulfoamino)-α-D-glucopyranoside
• GlcA = β-D-glucopyranuronoside
• GlcNS3,6S = 2-deoxy-3,6-di-O-sulfo-2-(sulfoamino)-α-D-glucopyranosyl
• IdoA2S = 2-O-sulfo-α-L-idopyranuronoside
• GlcNS6SOMe = methyl-O-2-deoxy-6-O-sulfo-2-(sulfoamino)-α-D-glucopyranoside

The sequence of monosaccharides is D-GlcNS6S-α-(1,4)-D-GlcA-β-(1,4)-D-GlcNS3,6S-α-(1,4)-L-IdoA2S-α-(1,4)-D-GlcNS6S-OMe, as shown in the following structure:

ARIXTRA (fondaparinux sodium) Injection is a sterile solution containing fondaparinux sodium. It is a synthetic and specific inhibitor of activatedFactor X (Xa). Fondaparinux sodium is methyl O-2-deoxy-6-O-sulfo-2-(sulfoamino)-α-D-glucopyranosyl-(1→4)-O-β-D-glucopyranuronosyl-( 1→4)-O-2-deoxy-3,6-di-O-sulfo-2-(sulfoamino)-α-D-glucopyranosyl-(1→4)-O-2-Osulfo-α-L-idopyranuronosyl-(1→4)-2-deoxy-6-O-sulfo-2-(sulfoamino)-α-D-glucopyranoside, decasodium salt.

The molecular formula of fondaparinux sodium is C₃₁H₄₃N₃Na₁₀O₄₉S₈ and its molecular weight is 1728. The structural formula is provided below:

ARIXTRA is supplied as a sterile, preservative-free injectable solution for subcutaneous use.

Each single-dose, prefilled syringe of ARIXTRA, affixed with an automatic needle protection system, contains 2.5 mg of fondaparinux sodium in 0.5 mL, 5.0 mg of fondaparinux sodium in 0.4 mL, 7.5 mg of fondaparinux sodium in 0.6 mL, or 10.0 mg of fondaparinux sodium in 0.8 mL of an isotonic solutionof sodium chloride and water for injection. The final drug product is a clear and colorless to slightly yellow liquid with a pH between 5.0 and 8.0.

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INTRODUCTION

In U.S. Patent No. 7,468,358, Fondaparinux sodium is described as the “only anticoagulant thought to be completely free of risk from HIT-2 induction.” The biochemical and pharmacologic rationale for the development of a heparin pentasaccharide in Thromb. Res., 86(1), 1-36, 1997 by Walenga et al. cited the recently approved synthetic pentasaccharide Factor Xa inhibitor Fondaparinux sodium. Fondaparinux has also been described in Walenga et al., Expert Opin. Investig. Drugs, Vol. 11, 397-407, 2002 and Bauer, Best Practice & Research Clinical Hematology, Vol. 17, No. 1, 89-104, 2004.

Fondaparinux sodium is a linear octasulfated pentasaccharide (oligosaccharide with five monosaccharide units ) molecule having five sulfate esters on oxygen (O-sulfated moieties) and three sulfates on a nitrogen (N- sulfated moieties). In addition, Fondaparinux contains five hydroxyl groups in the molecule that are not sulfated and two sodium carboxylates. Out of five saccharides, there are three glucosamine derivatives and one glucuronic and one L-iduronic acid. The five saccharides are connected to each other in alternate α and β glycosylated linkages (see Figure 1).

Figure 1 Fondaparinux Sodium

Monosaccharide E Monosaccharide D Monosaccharide C Monosaccharide B Monosaccharide A derived from derived from derived from derived from derived from

Monomer E Monomer D Monomer C Monomer B1 Monomer A2

Fondaparinux Sodium

Fondaparinux sodium is a chemically synthesized methoxy derivative of the natural pentasaccharide sequence, which is the active site of heparin that mediates the interaction with antithrombin (Casu et al., J. Biochem., 197, 59, 1981). It has a challenging pattern of O- and N- sulfates, specific glycosidic stereochemistry, and repeating units of glucosamines and uronic acids (Petitou et al, Progress in the Chemistry of Organic Natural Product, 60, 144-209, 1992).

The monosaccharide units comprising the Fondaparinux molecule are labeled as per the convention in Figure 1, with the glucosamine unit on the right referred to as monosaccharide A and the next, an uronic acid unit to its left as B and subsequent units, C, D and E respectively. The chemical synthesis of Fondaparinux starts with monosaccharides of defined structures that are themselves referred to as Monomers A2, Bl, C, D and E, for differentiation and convenience, and they become the corresponding monosaccharides in fondaparinux sodium.

Due to this complex mixture of free and sulfated hydroxyl groups, and the presence of N- sulfated moieties, the design of a synthetic route to Fondaparinux requires a careful strategy of protection and de-protection of reactive functional groups during synthesis of the molecule. Previously described syntheses of Fondaparinux all adopted a similar strategy to complete the synthesis of this molecule. This strategy can be envisioned as having four stages.

The strategy in the first stage requires selective de-protection of five out of ten hydroxyl groups. During the second stage these five hydroxyls are selectively sulfonated. The third stage of the process involves the de -protection of the remaining five hydroxyl groups. The fourth stage of the process is the selective sulfonation of the 3 amino groups, in the presence of five hydroxyl groups that are not sulfated in the final molecule. This strategy can be envisioned from the following fully protected pentasaccharide, also referred to as the late-stage intermediate.

In this strategy, all of the hydroxyl groups that are to be sulfated are protected with an acyl protective group, for example, as acetates (R = CH₃) or benzoates (R = aryl) (Stages 1 and 2) All of the hydroxyl groups that are to remain as such are protected with benzyl group as benzyl ethers (Stage 3). The amino group, which is subsequently sulfonated, is masked as an azide (N₃) moiety (Stage 4). R¹ and R² are typically sodium in the active pharmaceutical compound (e.g., Fondaparinux sodium).

This strategy allows the final product to be prepared by following the synthetic operations as outlined below: a) Treatment of the late- stage intermediate with base to hydrolyze (deprotect) the acyl ester groups to reveal the five hydroxyl groups. The two R¹ and R² ester groups are hydrolyzed in this step as well.

b) Sulfonation of the newly revealed hydroxyl groups.

c) Hydrogenation of the O-sulfated pentasaccharide to de-benzylate the five benzyl- protected hydroxyls, and at the same time, unmask the three azides to the corresponding amino groups.

d) On the last step of the operation, the amino groups are sulfated selectively at a high pH, in the presence of the five free hydroxyls to give Fondaparinux (Figure 1). While the above strategy has been shown to be viable, it is not without major drawbacks. One drawback lies in the procedure leading to the fully protected pentasaccharide (late stage intermediate), especially during the coupling of the D-glucuronic acid to the next adjacent glucose ring (the D-monomer to C-monomer in the EDCBA nomenclature shown in Figure 1). Sugar oligomers or oligosaccharides, such as Fondaparinux, are assembled using coupling reactions, also known as glycosylation reactions, to “link” sugar monomers together. The difficulty of this linking step arises because of the required stereochemical relationship between the D-sugar and the C-sugar, as shown below:

The stereochemical arrangement illustrated above in Figure 2 is described as having a β- configuration at the anomeric carbon of the D-sugar (denoted by the arrow). The linkage between the D and C units in Fondaparinux has this specific stereochemistry. There are, however, competing β- and α-glycosylation reactions.

The difficulties of the glycosylation reaction in the synthesis of Fondaparinux is well known. In 1991 Sanofi reported a preparation of a disaccharide intermediate in 51% yield having a 12/1 ratio of β/α stereochemistry at the anomeric position (Duchaussoy et al., Bioorg. & Med. Chem. Lett., 1(2), 99-102, 1991).

In another publication (Sinay et al, Carbohydrate Research, 132, C5-C9, 1984) yields on the order of 50% with coupling times on the order of 6- days are reported. U.S. Patent No. 4,818,816 {see e.g., column 31, lines 50-56) discloses a 50% yield for the β-glycosylation.

Alchemia’s U.S. Patent No. 7,541,445 is even less specific as to the details of the synthesis of this late-stage Fondaparinux synthetic intermediate. The ’445 Patent discloses several strategies for the assembly of the pentasaccharide (1+4, 3+2 or 2+3) using a 2-acylated D-sugar (specifically 2-allyloxycarbonyl) for the glycosylation coupling reactions. However, Alchemia’s strategy involves late-stage pentasaccharides that all incorporate a 2-benzylated D- sugar.

The transformation of acyl to benzyl is performed either under acidic or basic conditions. Furthermore, these transformations, using benzyl bromide or benzyl trichloroacetimidate, typically result in extensive decomposition and the procedure suffers from poor yields. Thus, such transformations (at a disaccharide, trisaccharide, and pentasaccharide level) are typically not acceptable for industrial scale production.

Examples of fully protected pentasaccharides are described in Duchaussoy et al, Bioorg. Med. Chem. Lett., 1 (2), 99-102, 1991; Petitou et al, Carbohydr. Res., 167, 67-75, 1987; Sinay et al, Carbohydr. Res., 132, C5-C9, 1984; Petitou et al., Carbohydr. Res., 1147, 221-236, 1986; Lei et al., Bioorg. Med. Chem., 6, 1337-1346, 1998; Ichikawa et al., Tet. Lett., 27(5), 611-614, 1986; Kovensky et al, Bioorg. Med. Chem., 1999, 7, 1567-1580, 1999.

These fully protected pentasaccharides may be converted to the O- and N-sulfated pentasaccharides using the four steps (described earlier) of: a) saponification with LiOHZH₂CVNaOH, b) O-sulfation by an Et₃N- SO₃ complex; c) de-benzylation and azide reduction via H₂/Pd hydrogenation; and d) N-sulfation with a pyridine-SO₃ complex.

Even though many diverse analogs of the fully protected pentasaccharide have been prepared, none use any protective group at the 2-position of the D unit other than a benzyl group. Furthermore, none of the fully protected pentasaccharide analogs offer a practical, scaleable and economical method for re-introduction of the benzyl moiety at the 2-position of the D unit after removal of any participating group that promotes β-glycosylation.

Furthermore, the coupling of benzyl protected sugars proves to be a sluggish, low yielding and problematic process, typically resulting in substantial decomposition of the pentasaccharide (prepared over 50 synthetic steps), thus making it unsuitable for a large [kilogram] scale production process.

Ref. 1. Sinay et al, Carbohydr. Res., 132, C5-C9, 1984.

Ref. 2. Petitou et al., Carbohydr. Res., 147, 221-236. 1986

It has been a general strategy for carbohydrate chemists to use base-labile ester-protecting group at 2-position of the D unit to build an efficient and stereoselective β-glycosidic linkage. To construct the β-linkage carbohydrate chemists have previously acetate and benzoate ester groups, as described, for example, in the review by Poletti et al., Eur. J. Chem., 2999-3024, 2003.

The ester group at the 2-position of D needs to be differentiated from the acetate and benzoates at other positions in the pentasaccharide. These ester groups are hydrolyzed and sulfated later in the process and, unlike these ester groups, the 2-hydroxyl group of the D unit needs to remain as the hydroxyl group in the final product, Fondaparinux sodium.

Some of the current ester choices for the synthetic chemists in the field include methyl chloro acetyl and chloro methyl acetate [MCA or CMA] . The mild procedures for the selective removal of theses groups in the presence of acetates and benzoates makes them ideal candidates. However, MCA/CMA groups have been shown to produce unwanted and serious side products during the glycosylation and therefore have not been favored in the synthesis of Fondaparinux sodium and its analogs. For by-product formation observed in acetate derivatives see Seeberger et al., J. Org. Chem., 2004, 69, 4081-93.

Similar by-product formation is also observed using chloroacetate derivatives. See Orgueira et al., Eur. J. Chem., 9(1), 140-169, 2003.

The levulinyl group can be rapidly and almost quantitatively removed by treatment with hydrazine hydrate as the deprotection reagent as illustrated in the example below. Under the same reaction conditions primary and secondary acetate and benzoate esters are hardly affected by hydrazine hydrate. See, e.g., Seeberger et al, J. Org. Chem., 69, 4081-4093, 2004.

The syntheses of Fondaparinux sodium described herein takes advantage of the levulinyl group in efficient construction of the trisaccharide EDC with improved β- selectivity for the coupling under milder conditions and increased yields.

Substitution of the benzyl protecting group with a THP moiety provides its enhanced ability to be incorporated quantitatively in position-2 of the unit D of the pentasaccharide. Also, the THP group behaves in a similar manner to a benzyl ether in terms of function and stability. In the processes described herein, the THP group is incorporated at the 2-position of the D unit at this late stage of the synthesis (i.e., after the D and C units have been coupled through a 1,2-trans glycosidic (β-) linkage). The THP protective group typically does not promote an efficient β- glycosylation and therefore is preferably incorporated in the molecule after the construction of the β-linkage.

Fondaparinux and sodium salt thereof can be prepared from pure compound of Formula II by following the teachings from Bioorganic and Medicinal Chemistry Letters, 1(2), p. 95-98 (1991). A second aspect of the present invention provides a process for the preparation of 4-0- -D-glucopyranosyl-l,6-anhydro- -D-glucopyranose, represented by STR BELOW

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SYNTHESIS

EP2464668A2   AND US8288515

The scheme below exemplifies some of the processes of the present invention disclosed herein.

The tetrahydropyranyl (THP) protective group and the benzyl ether protective group are suitable hydroxyl protective groups and can survive the last four synthetic steps (described above) in the synthesis of Fondaparinux sodium, even under harsh reaction conditions. Certain other protecting groups do not survive the last four synthetic steps in high yield.

Synthesis of Fondaparinux

Fondaparinux was prepared using the following procedure:

Synthesis of Fondaparinux

Fondaparinux was prepared using the following procedure:

The ester moieties in EDCBA Pentamer were hydrolyzed with sodium and lithium hydroxide in the presence of hydrogen peroxide in dioxane mixing at room temperature for 16 hours to give the pentasaccharide intermediate API1. The five hydroxyl moieties in API1 were sulfated using a pyridine-sulfur trioxide complex in dimethylformamide, mixing at 60° C. for 2 hours and then purified using column chromatography (CG-161), to give the pentasulfated pentasaccharide API2. The intermediate API2 was then hydrogenated to reduce the three azides on sugars E, C and A to amines and the reductive deprotection of the five benzyl ethers to their corresponding hydroxyl groups to form the intermediate API3. This transformation occurs by reacting API2 with 10% palladium/carbon catalyst with hydrogen gas for 72 hours. The three amines on API3 were then sulfated using the pyridine-sulfur trioxide complex in sodium hydroxide and ammonium acetate, allowing the reaction to proceed for 12 hours. The acidic work-up procedure of the reaction removes the THP group to provide crude fondaparinux which is purified and is subsequently converted to its salt form. The crude mixture was purified using an ion-exchange chromatographic column (HiQ resin) followed by desalting using a size exclusion resin or gel filtration (Biorad Sephadex G25) to give the final API, fondaparinux sodium

Experimental Procedures Preparation of IntD1 Bromination of Glucose Pentaacetate

To a 500 ml flask was added 50 g of glucose pentaacetate (C₆H₂₂O₁₁) and 80 ml of methylene chloride. The mixture was stirred at ice-water bath for 20 min HBr in HOAc (33%, 50 ml) was added to the reaction mixture. After stirring for 2.5 hr another 5 ml of HBr was added to the mixture. After another 30 min, the mixture was added 600 ml of methylene chloride. The organic mixture was washed with cold water (200 ml×2), Saturated NaHCO₃(200 ml×2), water (200 ml) and brine (200 ml×2). The organic layer was dried over Na₂SO₄ and the mixture was evaporated at RT to give white solid as final product, bromide derivative, IntD1 (˜95% yield). C₁₄H₁₉BrO₉, TLC R_f=0.49, SiO₂, 40% ethyl acetate/60% hexanes; Exact Mass 410.02.

Preparation of IntD2 by Reductive Cyclization

To a stirring mixture of bromide IntD1 (105 g), tetrabutylammonium iodide (60 g, 162 mmol) and activated 3 Å molecular sieves in anhydrous acetonitrile (2 L), solid NaBH₄ (30 g, 793 mmol) was added. The reaction was heated at 40° C. overnight. The mixture was then diluted with dichloromethane (2 L) and filtered through Celite®. After evaporation, the residue was dissolved in 500 ml ethyl acetate. The white solid (Bu₄NI or Bu₄NBr) was filtered. The ethyl acetate solution was evaporated and purified by chromatography on silica gel using ethyl acetate and hexane as eluent to give the acetal-triacetate IntD2 (˜60-70% yield). TLC R_f=0.36, SiO₂ in 40% ethyl acetate/60% hexanes.

Preparation of IntD3 by De-Acetylation

To a 1000 ml flask was added triacetate IntD2 (55 g) and 500 ml of methanol. After stirring 30 min, the reagent NaOMe (2.7 g, 0.3 eq) was added and the reaction was stirred overnight. Additional NaOMe (0.9 g) was added to the reaction mixture and heated to 50° C. for 3 hr. The mixture was neutralized with Dowex 50Wx8 cation resin, filtered and evaporated. The residue was purified by silica gel column to give 24 g of trihydroxy-acetal IntD3. TLC R_f=0.36 in SiO₂, 10% methanol/90% ethyl acetate.

Preparation of IntD4 by Benzylidene Formation

To a 1000 ml flask was added trihydroxy compound IntD3 (76 g) and benzaldehyde dimethyl acetate (73 g, 1.3 eq). The mixture was stirred for 10 min, after which D(+)-camphorsulfonic acid (8.5 g, CSA) was added. The mixture was heated at 50° C. for two hours. The reaction mixture was then transferred to separatory funnel containing ethyl acetate (1.8 L) and sodium bicarbonate solution (600 ml). After separation, the organic layer was washed with a second sodium bicarbonate solution (300 ml) and brine (800 ml). The two sodium carbonate solutions were combined and extracted with ethyl acetate (600 ml×2). The organic mixture was evaporated and purified by silica gel column to give the benzylidene product IntD4 (77 g, 71% yield). TLC R_f=0.47, SiO₂ in 40% ethyl acetate/60% hexanes.

Preparation of IntD5 by Benzylation

To a 500 ml flask was added benzylidene acetal compound IntD4 (21 g,) in 70 ml THF. To another flask (1000 ml) was added NaH (2 eq). The solution of IntD4 was then transferred to the NaH solution at 0° C. The reaction mixture was stirred for 30 min, then benzyl bromide (16.1 ml, 1.9 eq) in 30 ml THF was added. After stirring for 30 min, DMF (90 ml) was added to the reaction mixture. Excess NaH was neutralized by careful addition of acetic acid (8 ml). The mixture was evaporated and purified by silica gel column to give the benzyl derivative IntD5. (23 g) TLC R_f=0.69, SiO₂ in 40% ethyl acetate/60% hexanes.

Preparation of IntD6 by Deprotection of Benzylidene

To a 500 ml flask was added the benzylidene-acetal compound IntD5 (20 g) and 250 ml of dichloromethane, the reaction mixture was cooled to 0° C. using an ice-water-salt bath. Aqueous TFA (80%, 34 ml) was added to the mixture and stirred over night. The mixture was evaporated and purified by silica gel column to give the dihydroxy derivative IntD6. (8 g, 52%). TLC R_f=0.79, SiO₂ in 10% methanol/90% ethyl acetate.

Preparation of IntD7 by Oxidation of 6-Hydroxyl

To a 5 L flask was added dihydroxy compound IntD6 (60 g), TEMPO (1.08 g), sodium bromide (4.2 g), tetrabutylammonium chloride (5.35 g), saturated NaHCO₃ (794 ml) and EtOAc (1338 ml). The mixture was stirred over an ice-water bath for 30 min To another flask was added a solution of NaOCl (677 ml), saturated NaHCO₃ (485 ml) and brine (794 ml). The second mixture was added slowly to the first mixture (over about two hrs). The resulting mixture was then stirred overnight. The mixture was separated, and the inorganic layer was extracted with EtOAc (800 ml×2). The combined organic layers were washed with brine (800 ml). Evaporation of the organic layer gave 64 g crude carboxylic acid product IntD7 which was used in the next step use without purification. TLC R_f=0.04, SiO₂ in 10% methanol/90% ethyl acetate.

Preparation of Monomer D by Benzylation of the Carboxylic Acid

To a solution of carboxylic acid derivative IntD7 (64 g) in 600 ml of dichloromethane, was added benzyl alcohol (30 g) and N-hydroxybenzotriazole (80 g, HOBt). After stirring for 10 min triethylamine (60.2 g) was added slowly. After stirring another 10 min, dicyclohexylcarbodiimide, (60.8 g, DCC) was added slowly and the mixture was stirred overnight. The reaction mixture was filtered and the solvent was removed under reduced pressure followed by chromatography on silica gel to provide 60.8 g (75%, over two steps) of product, Monomer D. TLC R_f=0.51, SiO₂ in 40% ethyl acetate/60% hexanes.

Synthesis of the BA Dimer

Step 1. Preparation of BMod1, Levulination of Monomer B1

A 100 L reactor was charged with 7.207 Kg of Monomer B1 (21.3 moles, 1 equiv), 20 L of dry tetrahydrofuran (THF) and agitated to dissolve. When clear, it was purged with nitrogen and 260 g of dimethylamino pyridine (DMAP, 2.13 moles, 0.1 equiv) and 11.05 L of diisopropylethylamine (DIPEA, 8.275 kg, 63.9 moles, 3 equiv) was charged into the reactor. The reactor was chilled to 10-15° C. and 13.7 kg levulinic anhydride (63.9 mol, 3 equiv) was transferred into the reactor. When the addition was complete, the reaction was warmed to ambient temperature and stirred overnight or 12-16 hours. Completeness of the reaction was monitored by TLC (40:60 ethyl acetate/hexane) and HPLC. When the reaction was complete, 20 L of 10% citric acid, 10 L of water and 25 L of ethyl acetate were transferred into the reactor. The mixture was stirred for 30 min and the layers were separated. The organic layer (EtOAc layer) was extracted with 20 L of water, 20 L 5% sodium bicarbonate and 20 L 25% brine solutions. The ethyl acetate solution was dried in 4-6 Kg of anhydrous sodium sulfate. The solution was evaporated to a syrup (bath temp. 40° C.) and dried overnight. The yield of the isolated syrup of BMod1 was 100%.

Synthesis of the BA Dimer

Step 2. Preparation of BMod2, TFA Hydrolysis of BMod1

A 100 L reactor was charged with 9296 Kg of 4-Lev Monomer B1 (BMod1) (21.3 mol, 1 equiv). The reactor chiller was turned to <5° C. and stirring was begun, after which 17.6 L of 90% TFA solution (TFA, 213 mole, 10 equiv) was transferred into the reactor. When the addition was complete, the reaction was monitored by TLC and HPLC. The reaction took approximately 2-3 hours to reach completion. When the reaction was complete, the reactor was chilled and 26.72 L of triethylamine (TEA, 19.4 Kg, 191.7 mole, 0.9 equiv) was transferred into the reactor. An additional 20 L of water and 20 L ethyl acetate were transferred into the reactor. This was stirred for 30 min and the layers were separated. The organic layer was extracted (EtOAc layer) with 20 L 5% sodium bicarbonate and 20 L 25% brine solutions. The ethyl acetate solution was dried in 4-6 Kg of anhydrous sodium sulfate. The solution was evaporated to a syrup (bath temp. 40° C.). The crude product was purified in a 200 L silica column using 140-200 L each of the following gradient profiles: 50:50, 80:20 (EtOAc/heptane), 100% EtOAc, 5:95, 10:90 (MeOH/EtOAc). The pure fractions were pooled and evaporated to a syrup. The yield of the isolated syrup, BMod2 was 90%.

Synthesis of the BA Dimer

Step 3. Preparation of BMod3, Silylation of BMod2

A 100 L reactor was charged with 6.755 Kg 4-Lev-1,2-DiOH Monomer B1 (BMod2) (17.04 mol, 1 equiv), 2328 g of imidazole (34.2 mol, 2 equiv) and 30 L of dichloromethane. The reactor was purged with nitrogen and chilled to −20° C., then 5.22 L tert-butyldiphenylchloro-silane (TBDPS-Cl, 5.607 Kg, 20.4 mol, 1.2 equiv) was transferred into the reactor. When addition was complete, the chiller was turned off and the reaction was allowed to warm to ambient temperature. The reaction was monitored by TLC (40% ethyl acetate/hexane) and HPLC. The reaction took approximately 3 hours to reach completion. When the reaction was complete, 20 L of water and 10 L of DCM were transferred into the reactor and stirred for 30 min, after which the layers were separated. The organic layer (DCM layer) was extracted with 20 L water and 20 L 25% brine solutions. Dichloromethane solution was dried in 4-6 Kg of anhydrous sodium sulfate. The solution was evaporated to a syrup (bath temp. 40° C.). The yield of BMod3 was about 80%.

Synthesis of the BA Dimer

Step 4. Preparation of BMod4, Benzoylation

A 100 L reactor was charged with 8.113 Kg of 4-Lev-1-Si-2-OH Monomer B1 (BMod3) (12.78 mol, 1 equiv), 9 L of pyridine and 30 L of dichloromethane. The reactor was purged with nitrogen and chilled to −20° C., after which 1.78 L of benzoyl chloride (2155 g, 15.34 mol, 1.2 equiv) was transferred into the reactor. When addition was complete, the reaction was allowed to warm to ambient temperature. The reaction was monitored by TLC (40% ethyl acetate/heptane) and HPLC. The reaction took approximately 3 hours to reach completion. When the reaction was complete, 20 L of water and 10 L of DCM were transferred into the reactor and stirred for 30 min, after which the layers were separated. The organic layer (DCM layer) was extracted with 20 L water and 20 L 25% brine solutions. The DCM solution was dried in 4-6 Kg of anhydrous sodium sulfate. The solution was evaporated to a syrup (bath temp. 40° C.). Isolated syrup BMod4 was obtained in 91% yield.

Synthesis of the BA Dimer

Step 5. Preparation of BMod5, Desilylation

A 100 L reactor was charged with 8.601 Kg of 4-Lev-1-Si-2-Bz Monomer B1 (BMod4) (11.64 mol, 1 equiv) in 30 L terahydrofuran. The reactor was purged with nitrogen and chilled to 0° C., after which 5.49 Kg of tetrabutylammonium fluoride (TBAF, 17.4 mol, 1.5 equiv) and 996 mL (1045 g, 17.4 mol, 1.5 equiv) of glacial acetic acid were transferred into the reactor. When the addition was complete, the reaction was stirred at ambient temperature. The reaction was monitored by TLC (40:60 ethyl acetate/hexane) and HPLC. The reaction took approximately 6 hours to reach completion. When the reaction was complete, 20 L of water and 10 L of DCM were transferred into the reactor and stirred for 30 min, after which the layers were separated. The organic layer (DCM layer) was extracted with 20 L water and 20 L 25% brine solutions. The dichloromethane solution was dried in 4-6 Kg of anhydrous sodium sulfate. The solution was evaporated to a syrup (bath temp. 40° C.). The crude product was purified in a 200 L silica column using 140-200 L each of the following gradient profiles: 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20 (EtOAc/heptane) and 200 L 100% EtOAc. Pure fractions were pooled and evaporated to a syrup. The intermediate BMod5 was isolated as a syrup in 91% yield.

Synthesis of the BA Dimer

Step 6: Preparation of BMod6, TCA Formation

A 100 L reactor was charged with 5.238 Kg of 4-Lev-1-OH-2-Bz Monomer B1 (BMod5) (10.44 mol, 1 equiv) in 30 L of DCM. The reactor was purged with nitrogen and chilled to 10-15° C., after which 780 mL of diazabicyclo undecene (DBU, 795 g, 5.22 mol, 0.5 equiv) and 10.47 L of trichloroacetonitrile (TCA, 15.08 Kg, 104.4 mol, 10 equiv) were transferred into the reactor. Stirring was continued and the reaction was kept under a nitrogen atmosphere. After reagent addition, the reaction was allowed to warm to ambient temperature. The reaction was monitored by HPLC and TLC (40:60 ethyl acetate/heptane). The reaction took approximately 2 hours to reach completion. When the reaction was complete, 20 L of water and 10 L of dichloromethane were transferred into the reactor. This was stirred for 30 min and the layers were separated. The organic layer (DCM layer) was separated with 20 L water and 20 L 25% brine solutions. The dichloromethane solution was dried in 4-6 Kg of anhydrous sodium sulfate. The solution was evaporated to a syrup (bath temp. 40° C.). The crude product was purified in a 200 L silica column using 140-200 L each of the following gradient profiles: 10:90, 20:80, 30:70, 40:60 and 50:50 (EtOAc/Heptane). Pure fractions were pooled and evaporated to a syrup. The isolated yield of BMod6 was 73%.

Synthesis of the BA Dimer

Step 7. Preparation of AMod1, Acetylation of Monomer A2

A 100 L reactor was charged with 6.772 Kg of Monomer A2 (17.04 mole, 1 eq.), 32.2 L (34.8 Kg, 340.8 moles, 20 eq.) of acetic anhydride and 32 L of dichloromethane. The reactor was purged with nitrogen and chilled to −20° C. When the temperature reached −20° C., 3.24 L (3.63 Kg, 25.68 mol, 1.5 equiv) of boron trifluoride etherate (BF₃.Et₂O) was transferred into the reactor. After complete addition of boron trifluoride etherate, the reaction was allowed to warm to room temperature. The completeness of the reaction was monitored by HPLC and TLC (30:70 ethyl acetate/heptane). The reaction took approximately 3-5 hours for completion. When the reaction was complete, extraction was performed with 3×15 L of 10% sodium bicarbonate and 20 L of water. The organic phase (DCM) was evaporated to a syrup (bath temp. 40° C.) and allowed to dry overnight. The syrup was purified in a 200 L silica column using 140 L each of the following gradient profiles: 5:95, 10:90, 20:80, 30:70, 40:60 and 50:50 (EtOAc/heptane). Pure fractions were pooled and evaporated to a syrup. The isolated yield of AMod1 was 83%.

Synthesis of the BA Dimer

Step 8. Preparation of AMod3,1-Methylation of AMod1

A 100 L reactor was charged with 5891 g of acetyl Monomer A2 (AMod1) (13.98 mole, 1 eq.) in 32 L of dichloromethane. The reactor was purged with nitrogen and was chilled to 0° C., after which 2598 mL of trimethylsilyl iodide (TMSI, 3636 g, 18 mol, 1.3 equiv) was transferred into the reactor. When addition was complete, the reaction was allowed to warm to room temperature. The completeness of the reaction was monitored by HPLC and TLC (30:70 ethyl acetate/heptane). The reaction took approximately 2-4 hours to reach completion. When the reaction was complete, the mixture was diluted with 20 L of toluene. The solution was evaporated to a syrup and was co-evaporated with 3×6 L of toluene. The reactor was charged with 36 L of dichloromethane (DCM), 3.2 Kg of dry 4 Å Molecular Sieves, 15505 g (42 mol, 3 equiv) of tetrabutyl ammonium iodide (TBAI) and 9 L of dry methanol. This was stirred until the TBAI was completely dissolved, after which 3630 mL of diisopropyl-ethylamine (DIPEA, 2712 g, 21 moles, 1.5 equiv) was transferred into the reactor in one portion. The completion of the reaction was monitored by HPLC and TLC (30:70 ethyl acetate/heptane). The reaction took approximately 16 hours for completion. When the reaction was complete, the molecular sieves were removed by filtration. Added were 20 L EtOAc and extracted with 4×20 L of 25% sodium thiosulfate and 20 L 10% NaCl solutions. The organic layer was separated and dried with 8-12 Kg of anhydrous sodium sulfate. The solution was evaporated to a syrup (bath temp. 40° C.). The crude product was purified in a 200 L silica column using 140-200 L each of the following gradient profiles: 5:95, 10:90, 20:80, 30:70 and 40:60 (EtOAc/heptane). The pure fractions were pooled and evaporated to give intermediate AMod3 as a syrup. The isolated yield was 75%.

Synthesis of the BA Dimer

Step 9. Preparation of AMod4, DeAcetylation of AMod3

A 100 L reactor was charged with 4128 g of 1-Methyl 4,6-Diacetyl Monomer A2 (AMod3) (10.5 mol, 1 equiv) and 18 L of dry methanol and dissolved, after which 113.4 g (2.1 mol, 0.2 equiv) of sodium methoxide was transferred into the reactor. The reaction was stirred at room temperature and monitored by TLC (40% ethyl acetate/hexane) and HPLC. The reaction took approximately 2-4 hours for completion. When the reaction was complete, Dowex 50Wx8 cation resin was added in small portions until the pH reached 6-8. The Dowex 50Wx8 resin was filtered and the solution was evaporated to a syrup (bath temp. 40° C.). The syrup was diluted with 10 L of ethyl acetate and extracted with 20 L brine and 20 L water. The ethyl acetate solution was dried in 4-6 Kg of anhydrous sodium sulfate. The solution was evaporated to a syrup (bath temp. 40° C.) and dried overnight at the same temperature. The isolated yield of the syrup AMod4 was about 88%.

Synthesis of the BA Dimer

Step 10. Preparation of AMod5,6-Benzoylation

A 100 L reactor was charged with 2858 g of Methyl 4,6-diOH Monomer A2 (AMod4) (9.24 mol, 1 equiv) and co-evaporated with 3×10 L of pyridine. When evaporation was complete, 15 L of dichloromethane, 6 L of pyridine were transferred into the reactor and dissolved. The reactor was purged with nitrogen and chilled to −40° C. The reactor was charged with 1044 mL (1299 g, 9.24 mol, 1 equiv) of benzoyl chloride. When the addition was complete, the reaction was allowed to warm to −10° C. over a period of 2 hours. The reaction was monitored by TLC (60% ethyl acetate/hexane). When the reaction was completed, the solution was evaporated to a syrup (bath temp. 40° C.). This was co-evaporated with 3×15 L of toluene. The syrup was diluted with 40 L ethyl acetate. Extraction was carried out with 20 L of water and 20 L of brine solution. The Ethyl acetate solution was dried in 4-6 Kg of anhydrous sodium sulfate. The solution was evaporated to a syrup (bath temp. 40° C.). The crude product was purified in a 200 L silica column using 140-200 L each of the following gradient profiles: 5:95, 10:90, 20:80, 25:70 and 30:60 (EtOAc/heptane). The pure fractions were pooled and evaporated to a syrup. The isolated yield of the intermediate AMod5 was 84%.

Synthesis of the BA Dimer

Step 11. Preparation of BA1, Coupling of Amod5 with BMod6

A 100 L reactor was charged with 3054 g of methyl 4-Hydroxy-Monomer A2 (AMod5) from Step 10 (7.38 mol, 1 equiv) and 4764 g of 4-Lev-1-TCA-Monomer B1 (BMod6) from Step 6 (7.38 mol, 1 equiv). The combined monomers were dissolved in 20 L of toluene and co-evaporated at 40° C. Co evaporation was repeated with an additional 2×20 L of toluene, after which 30 L of dichloromethane (DCM) was transferred into the reactor and dissolved. The reactor was purged with nitrogen and was chilled to below −20° C. When the temperature was between −20° C. and −40° C., 1572 g (1404 mL, 11.12 moles, 1.5 equiv) of boron trifluoride etherate (BF₃.Et₂O) were transferred into the reactor. After complete addition of boron trifluoride etherate, the reaction was allowed to warm to 0° C. and stirring was continued. The completeness of the reaction was monitored by HPLC and TLC (40:70 ethyl acetate/heptane). The reaction required 3-4 hours to reach completion. When the reaction was complete, 926 mL (672 g, 6.64 mol, 0.9 equiv) of triethylamine (TEA) was transferred into the mixture and stirred for an additional 30 minutes, after which 20 L of water and 10 L of dichloromethane were transferred into the reactor. The solution was stirred for 30 min and the layers were separated. The organic layer (DCM layer) was separated with 2×20 L water and 20 L 25% 4:1 sodium chloride/sodium bicarbonate solution. The dichloromethane solution was dried in 4-6 Kg of anhydrous sodium sulfate. The solution was evaporated to a syrup (bath temp. 40° C.) and used in the next step. The isolated yield of the disaccharide BA1 was about 72%.

Synthesis of the BA Dimer

Step 12, Removal of Levulinate Methyl [(methyl 2-O-benzoyl-3-O-benzyl-α-L-Idopyranosyluronate)-(1→4)-2-azido-6-O-benzoyl-3-O-benzyl]-2-deoxy-α-D-glucopyranoside

A 100 L reactor was charged with 4.104 Kg of 4-Lev BA Dimer (BA1) (4.56 mol, 1 equiv) in 20 L of THF. The reactor was purged with nitrogen and chilled to −20 to −25° C., after which 896 mL of hydrazine hydrate (923 g, 18.24 mol, 4 equiv) was transferred into the reactor. Stirring was continued and the reaction was monitored by TLC (40% ethyl acetate/heptane) and HPLC. The reaction took approximately 2-3 hour for the completion, after which 20 L of 10% citric acid, 10 L of water and 25 L of ethyl acetate were transferred into the reactor. This was stirred for 30 min and the layers were separated. The organic layer (ETOAc layer) was extracted with 20 L 25% brine solutions. The ethyl acetate solution was dried in 4-6 Kg of anhydrous sodium sulfate. The solution was evaporated to a syrup (bath temp. 40° C.). The crude product was purified in a 200 L silica column using 140-200 L each of the following gradient profiles: 10:90, 20:80, 30:70, 40:60 and 50:50 (EtOAc/heptane). The pure fractions were pooled and evaporated to dryness. The isolated yield of the BA Dimer was 82%. Formula: C₄₂H₄₃N₃O₁₃; Mol. Wt. 797.80.

Synthesis of the EDC Trimer

Step 1. Preparation of EMod1, Acetylation

A 100 L reactor was charged with 16533 g of Monomer E (45 mole, 1 eq.), 21.25 L acetic anhydride (225 mole, 5 eq.) and 60 L of dichloromethane. The reactor was purged with nitrogen and was chilled to −10° C. When the temperature was at −10° C., 1.14 L (1277 g) of boron trifluoride etherate (BF₃.Et₂O, 9.0 moles, 0.2 eq) were transferred into the reactor. After the complete addition of boron trifluoride etherate, the reaction was allowed to warm to room temperature. The completeness of the reaction was monitored by TLC (30:70 ethyl acetate/heptane) and HPLC. The reaction took approximately 3-6 hours to reach completion. When the reaction was completed, the mixture was extracted with 3×50 L of 10% sodium bicarbonate and SOL of water. The organic phase (DCM) was evaporated to a syrup (bath temp. 40° C.) and allowed to dry overnight. The isolated yield of EMod1 was 97%.

Synthesis of the EDC Trimer

Step 2. Preparation of EMod2, De-Acetylation of Azidoglucose

A 100 L reactor was charged with 21016 g of 1,6-Diacetyl Monomer E (EMod1) (45 mole, 1 eq.), 5434 g of hydrazine acetate (NH₂NH₂.HOAc, 24.75 mole, 0.55 eq.) and 50 L of DMF (dimethyl formamide). The solution was stirred at room temperature and the reaction was monitored by TLC (30% ethyl acetate/hexane) and HPLC. The reaction took approximately 2-4 hours for completion. When the reaction was completed, 50 L of dichloromethane and 40 L of water were transferred into the reactor. This was stirred for 30 minutes and the layers were separated. This was extracted with an additional 40 L of water and the organic phase was dried in 6-8 Kg of anhydrous sodium sulfate. The solution was evaporated to a syrup (bath temp. 40° C.) and dried overnight at the same temperature. The syrup was purified in a 200 L silica column using 140-200 L each of the following gradient profiles: 20:80, 30:70, 40:60 and 50:50 (EtOAc/heptane). Pure fractions were pooled and evaporated to a syrup. The isolated yield of intermediate EMod2 was 100%.

Synthesis of the EDC Trimer

Step 3. Preparation of EMod3, Formation of 1-TCA

A 100 L reactor was charged with 12752 g of 1-Hydroxy Monomer E (EMod2) (30 mole, 1 eq.) in 40 L of dichloromethane. The reactor was purged with nitrogen and stirring was started, after which 2.25 L of DBU (15 moles, 0.5 eq.) and 15.13 L of trichloroacetonitrile (150.9 moles, 5.03 eq) were transferred into the reactor. Stirring was continued and the reaction was kept under nitrogen. After the reagent addition, the reaction was allowed to warm to ambient temperature. The reaction was monitored by TLC (30:70 ethyl acetate/Heptane) and HPLC. The reaction took approximately 2-3 hours to reach completion. When the reaction was complete, 40 L of water and 20 L of DCM were charged into the reactor. This was stirred for 30 min and the layers were separated. The organic layer (DCM layer) was extracted with 40 L water and the DCM solution was dried in 6-8 Kg of anhydrous sodium sulfate. The solution was evaporated to a syrup (bath temp. 40° C.). The crude product was purified in a 200 L silica column using 140-200 L each of the following gradient profiles: 10:90 (DCM/EtOAc/heptane), 20:5:75 (DCM/EtOAc/heptane) and 20:10:70 DCM/EtOAc/heptane). Pure fractions were pooled and evaporated to give Intermediate EMod3 as a syrup. Isolated yield was 53%.

Synthesis of the EDC Trimer

Step 4. Preparation of ED Dimer, Coupling of E-TCA with Monomer D

A 100 L reactor was charged with 10471 g of 6-Acetyl-1-TCA Monomer E (EMod3) (18.3 mole, 1 eq., FW: 571.8) and 6594 g of Monomer D (16.47 mole, 0.9 eq, FW: 400.4). The combined monomers were dissolved in 20 L toluene and co-evaporated at 40° C. This was repeated with co-evaporation with an additional 2×20 L of toluene, after which 60 L of dichloromethane (DCM) were transferred into the reactor and dissolved. The reactor was purged with nitrogen and was chilled to −40° C. When the temperature was between −30° C. and −40° C., 2423 g (2071 mL, 9.17 moles, 0.5 eq) of TES Triflate were transferred into the reactor. After complete addition of TES Triflate the reaction was allowed to warm and stirring was continued. The completeness of the reaction was monitored by HPLC and TLC (35:65 ethyl acetate/Heptane). The reaction required 2-3 hours to reach completion. When the reaction was completed, 2040 mL of triethylamine (TEA, 1481 g, 0.8 eq.) were transferred into the reactor and stirred for an additional 30 minutes. The organic layer (DCM layer) was extracted with 2×20 L 25% 4:1 sodium chloride/sodium bicarbonate solution. The dichloromethane solution was dried in 6-8 Kg of anhydrous sodium sulfate. The syrup was purified in a 200 L silica column using 140-200 L each of the following gradient profiles: 15:85, 20:80, 25:75, 30:70 and 35:65 (EtOAc/heptane). Pure fractions were pooled and evaporated to a syrup. The ED Dimer was obtained in 81% isolated yield.

Synthesis of the EDC Trimer

Step 5. Preparation of ED1 TFA, Hydrolysis of ED Dimer

A 100 L reactor was charged with 7.5 Kg of ED Dimer (9.26 mol, 1 equiv). The reactor was chilled to <5° C. and 30.66 L of 90% TFA solution (TFA, 370.4 mol, 40 equiv) were transferred into the reactor. When the addition was completed the reaction was allowed to warm to room temperature. The reaction was monitored by TLC (40:60 ethyl acetate/hexanes) and HPLC. The reaction took approximately 3-4 hours to reach completion. When the reaction was completed, was chilled and 51.6 L of triethylamine (TEA, 37.5 Kg, 370.4 mole) were transferred into the reactor, after which 20 L of water & 20 L ethyl acetate were transferred into the reactor. This was stirred for 30 min and the layers were separated. The organic layer (EtOAc layer) was extracted with 20 L 5% sodium bicarbonate and 20 L 25% brine solutions. Ethyl acetate solution was dried in 4-6 Kg of anhydrous sodium sulfate. The solution was evaporated to a syrup (bath temp. 40° C.). The crude product was purified in a 200 L silica column using 140-200 L each of the following gradient profiles: 20:80, 30:70, 40:60, 50:50, 60:40 (EtOAc/heptane). The pure fractions were pooled and evaporated to a syrup. Isolated yield of ED1 was about 70%.

Synthesis of the EDC Trimer

Step 6. Preparation of ED2, Silylation of ED1

A 100 L reactor was charged with 11000 g of 1,2-diOH ED Dimer (ED1) (14.03 mol, 1 equiv), 1910.5 g of imidazole (28.06 mol, 2 equiv) and 30 L of dichloromethane. The reactor was purged with nitrogen and chilled to −20° C., after which 3.53 L butyldiphenylchloro-silane (TBDPS-Cl, 4.628 Kg, 16.835 mol, 1.2 equiv) was charged into the reactor. When the addition was complete, the chiller was turned off and the reaction was allowed to warm to ambient temperature. The reaction was monitored by TLC (50% ethyl acetate/hexane) and HPLC. The reaction required 4-6 hours to reach completion. When the reaction was completed, 20 L of water and 10 L of dichloromethane were transferred into the reactor and stirred for 30 min and the layers were separated. The organic layer (DCM layer) was extracted with 20 L water and 20 L 25% brine solutions. Dichloromethane solution was dried in 4-6 Kg of anhydrous sodium sulfate. The solution was evaporated to a syrup (bath temp. 40° C.). Intermediate ED2 was obtained in 75% isolated yield.

Synthesis of the EDC Trimer

Step 7. Preparation of ED3, D-Levulination

A 100 L reactor was charged with 19800 g of 1-Silyl ED Dimer (ED2) (19.37 moles, 1 equiv) and 40 L of dry tetrahydrofuran (THF) and agitated to dissolve. The reactor was purged with nitrogen and 237 g of dimethylaminopyridine (DMAP, 1.937 moles, 0.1 equiv) and 10.05 L of diisopropylethylamine (DIPEA, 63.9 moles, 3 equiv) were transferred into the reactor. The reactor was chilled to 10-15° C. and kept under a nitrogen atmosphere, after which 12.46 Kg of levulinic anhydride (58.11 moles, 3 eq) was charged into the reactor. When the addition was complete, the reaction was warmed to ambient temperature and stirred overnight or 12-16 hours. The completeness of the reaction was monitored by TLC (40:60 ethyl acetate/hexane) and by HPLC. 20 L of 10% citric acid, 10 L of water and 25 L of ethyl acetate were transferred into the reactor. This was stirred for 30 min and the layers were separated. The organic layer (EtOAc layer) was extracted with 20 L of water, 20 L 5% sodium bicarbonate and 20 L 25% brine solutions. The ethyl acetate solution was dried in 6-8 Kg of anhydrous sodium sulfate. The solution was evaporated to a syrup (bath temp. 40° C.). The ED3 yield was 95%.

Synthesis of the EDC Trimer

Step 8. Preparation of ED4, Desilylation of ED3

A 100 L reactor was charged with 19720 g of 1-Silyl-2-Lev ED Dimer (ED3) (17.6 mol, 1 equiv) in 40 L of THF. The reactor was chilled to 0° C., after which 6903 g of tetrabutylammonium fluoride trihydrate (TBAF, 26.4 mol, 1.5 equiv) and 1511 mL (26.4 mol, 1.5 equiv) of glacial acetic acid were transferred into the reactor. When the addition was complete, the reaction was stirred and allowed to warm to ambient temperature. The reaction was monitored by TLC (40:60 ethyl acetate/hexane) and HPLC. The reaction required 3 hours to reach completion. When the reaction was completed, 20 L of water and 10 L of dichloromethane were transferred into the reactor and stirred for 30 min and the layers were separated. The organic layer (DCM layer) was extracted with 20 L water and 20 L 25% brine solutions. The dichloromethane solution was dried in 6-8 Kg of anhydrous sodium sulfate. The solution was evaporated to a syrup (bath temp. 40° C.). The crude product was purified using a 200 L silica column using 140-200 L each of the following gradient profiles: 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20 (EtOAc/heptane) and 200 L 100% EtOAc. The pure fractions were pooled and evaporated to a syrup and used in the next step. The isolated yield of ED4 was about 92%.

Synthesis of the EDC Trimer

Step 9. Preparation of ED5, TCA Formation

A 100 L reactor was charged with 14420 g of 1-OH-2-Lev ED Dimer (ED4) (16.35 mol, 1 equiv) in 30 L of dichloromethane. The reactor was purged with nitrogen and stirring was begun, after which 1222 mL of diazabicycloundecene (DBU, 8.175 mol, 0.5 equiv) and 23.61 Kg of trichloroacetonitrile (TCA, 163.5 mol, 10 equiv) were transferred into the reactor. Stirring was continued and the reaction was kept under nitrogen. After reagent addition, the reaction was allowed to warm to ambient temperature. The reaction was monitored by HPLC and TLC (40:60 ethyl acetate/heptane). The reaction took approximately 2 hours for reaction completion. When the reaction was completed, 20 L of water and 10 L of DCM were transferred into the reactor and stirred for 30 min and the layers were separated. The organic layer (DCM layer) was extracted with 20 L water and 20 L 25% brine solutions. The dichloromethane solution was dried in 6-8 Kg of anhydrous sodium sulfate. The solution was evaporated to a syrup (bath temp. 40° C.). The crude product was purified using a 200 L silica column using 140-200 L each of the following gradient profiles: 10:90, 20:80, 30:70, 40:60 and 50:50 (EtOAc/heptane). The pure fractions were pooled and evaporated to a syrup and used in the next step. The isolated yield of intermediate ED5 was about 70%.

Synthesis of the EDC Trimer

Step 10.

Preparation of EDC Trimer, Coupling of ED5 with Monomer C 6-O-acetyl-2-azido-3,4-di-O-benzyl-2-deoxy-α-D-glucopyranosyl-(1→4)-benzyl (3-O-benzyl-2-O-levulinoyl)-β-D-glucopyranosyluronate-(1→4)-(3-O-acetyl-1,6-anhydro-2-azido)-2-deoxy-β-D-glucopyranose

A 100 L reactor was charged with 12780 g of 2-Lev 1-TCA ED Dimer (ED5) (7.38 mole, 1 eq., FW) and 4764 g of Monomer C (7.38 mole, 1 eq). The combined monomers were dissolved in 20 L toluene and co-evaporated at 40° C. Repeated was co-evaporation with an additional 2×20 L of toluene, after which 60 L of dichloromethane (DCM) was transferred into the reactor and dissolved. The reactor was purged with nitrogen and chilled to −20° C. When the temperature was between −20 and −10° C., 2962 g (11.2 moles, 0.9 eq) of TES Triflate were transferred into the reactor. After complete addition of TES Triflate the reaction was allowed to warm to 5° C. and stirring was continued. Completeness of the reaction was monitored by HPLC and TLC (35:65 ethyl acetate/Heptane). The reaction required 2-3 hours to reach completion. When the reaction was completed, 1133 g of triethylamine (TEA, 0.9 eq.) were transferred into the reactor and stirred for an additional 30 minutes. The organic layer (DCM layer) was extracted with 2×20 L 25% 4:1 sodium chloride/sodium bicarbonate solution. Dichloromethane solution was dried in 6-8 Kg of anhydrous sodium sulfate. The syrup was purified in a 200 L silica column using 140-200 L each of the following gradient profiles: 15:85, 20:80, 25:75, 30:70 and 35:65 (EtOAc/heptane). Pure fractions were pooled and evaporated to a syrup. The isolated yield of EDC Trimer was 48%. Formula: C₅₅H₆₀N₆O₁₈; Mol. Wt. 1093.09. The ¹H NMR spectrum (d6-acetone) of the EDC trimer is shown in FIG. 3.

Preparation of EDC1

Step 1:

Anhydro Ring Opening & Acetylation 6-O-acetyl-2-azido-2-deoxy-3,4-di-O-benzyl-α-D-glucopyranosyl-(1→4)-O-[benzyl 3-O-benzyl-2-O-levulinoyl-β-D-glucopyranosyluronate]-(1→4)-O-2-azido-2-deoxy-1,3,6-tri-O-acetyl-β-D-glucopyranose

7.0 Kg (6.44 mol) of EDC Trimer was dissolved in 18 L anhydrous Dichloromethane. 6.57 Kg (64.4 mol, 10 eq) of Acetic anhydride was added. The solution was cooled to −45 to −35° C. and 1.82 Kg (12.9 mol, 2 eq) of Boron Trifluoride etherate was added slowly. Upon completion of addition, the mixture was warmed to 0-10° C. and kept at this temperature for 3 hours until reaction was complete by TLC and HPLC. The reaction was cooled to −20° C. and cautiously quenched and extracted with saturated solution of sodium bicarbonate (3×20 L) while maintaining the mixture temperature below 5° C. The organic layer was extracted with brine (1×20 L), dried over anhydrous sodium sulfate, and concentrated under vacuum to a syrup. The resulting syrup of EDC1 (6.74 Kg) was used for step 2 without further purification. The ¹H NMR spectrum (d6-acetone) of the EDC-1 trimer is shown in FIG. 4.

Preparation of EDC2

Step 2:

Deacetylation 6-O-acetyl-2-azido-2-deoxy-3,4-di-O-benzyl-α-D-glucopyranosyl-(1→4)-O-[benzyl 3-O-benzyl-2-O-levulinoyl-β-D-glucopyranosyluronate]-(1→4)-O-2-azido-2-deoxy-3,6-di-O-acetyl-β-D-glucopyranose

The crude EDC1 product obtained from step 1 was dissolved in 27 L of Tetrahydrofuran and chilled to 15-20° C., after which 6 Kg (55.8 mol) of benzylamine was added slowly while maintaining the reaction temperature below 25° C. The reaction mixture was stirred for 5-6 hours at 10-15° C. Upon completion, the mixture was diluted with ethyl acetate and extracted and quenched with 10% citric acid solution (2×20 L) while maintaining the temperature below 25° C. The organic layer was extracted with 10% NaCl/1% sodium bicarbonate (1×20 L). The extraction was repeated with water (1×10 L), dried over anhydrous sodium sulfate and evaporated under vacuum to a syrup. Column chromatographic separation using silica gel yielded 4.21 Kg (57% yield over 2 steps) of EDC2[ also referred to as 1-Hydroxy-6-Acetyl EDC Trimer]. The ¹H NMR spectrum (d6-acetone) of the EDC-2 trimer is shown in FIG. 5.

Preparation of EDC3

Step 3:

Formation of TCA Derivative 6-O-acetyl-2-azido-2-deoxy-3,4-di-O-benzyl-α-D-glucopyranosyl-(1→4)-O-[benzyl 3-O-benzyl-2-O-levulinoyl-β-D-glucopyranosyluronate]-(1→4)-O-2-azido-2-deoxy-3,6-di-O-acetyl-1-O-trichloroacetimidoyl-β-D-glucopyranose

4.54 Kg (3.94 mol) of EDC2 was dissolved in 20 L of Dichloromethane. 11.4 Kg (78.8 mol, 20 eq) of Trichloroacetonitrile was added. The solution was cooled to −15 to −20° C. and 300 g (1.97 mol, 0.5 eq) of Diazabicycloundecene was added. The reaction was allowed to warm to 0-10° C. and stirred for 2 hours or until reaction was complete. Upon completion, water (20 L) was added and the reaction was extracted with an additional 10 L of DCM. The organic layer was extracted with brine (1×20 L), dried over anhydrous sodium sulfate, and concentrated under vacuum to a syrup. Column chromatographic separation using silica gel and 20-60% ethyl acetate/heptane gradient yielded 3.67 Kg (72% yield) of 1-TCA derivative, EDC3. The ¹H NMR spectrum (d6-acetone) of the EDC-3 trimer is shown in FIG. 6.

Preparation of EDCBA1

Step 4:

Coupling of EDC3 with BA Dimer Methyl O-6-O-acetyl-2-azido-2-deoxy-3,4-di-O-benzyl-α-D-glucopyranosyl)-(1→4)-O-[benzyl 3-O-benzyl-2-O-levulinoyl-β-D-glucopyranosyluronate]-(1→4)-O-2-azido-2-deoxy-3,6-di-O-acetyl-α-D-glucopyranosyl-(1→4)-O-[methyl 2-O-benzoyl-3-O-benzyl-α-L-Idopyranosyluronate]-(1→4)-2-azido-6-O-benzoyl-3-O-benzyl-2-deoxy-α-D-glucopyranoside

3.67 Kg (2.83 mol) of EDC3 and 3.16 Kg (3.96 mol, 1.4 eq) of BA Dimer was dissolved in 7-10 L of Toluene and evaporated to dryness. The resulting syrup was coevaporated with Toluene (2×15 L) to remove water. The dried syrup was dissolved in 20 L of anhydrous Dichloromethane, transferred to the reaction flask, and cooled to −15 to −20° C. 898 g (3.4 mol, 1.2 eq) of triethylsilyl triflate was added while maintaining the temperature below −5° C. When the addition was complete, the reaction was immediately warmed to −5 to 0° C. and stirred for 3 hours. The reaction was quenched by slowly adding 344 g (3.4 mol, 1.2 eq) of Triethylamine. Water (15 L) was added and the reaction was extracted with an additional 10 L of DCM. The organic layer was extracted with a 25% 4:1 Sodium Chloride/Sodium Bicarbonate solution (2×20 L), dried over anhydrous sodium sulfate, and evaporated under vacuum to a syrup. The resulting syrup of the pentasaccharide, EDCBA1 was used for step 5 without further purification. The ¹H NMR spectrum (d6-acetone) of the EDCBA-1 pentamer is shown in FIG. 7.

Preparation of EDCBA2

Step 5:

Hydrolysis of Levulinyl moiety Methyl O-6-O-acetyl-2-azido-2-deoxy-3,4-di-O-benzyl-α-D-glucopyranosyl)-(1→4)—O-[benzyl 3-O-benzyl-β-D-glucopyranosyluronate]-(1→4)-O-2-azido-2-deoxy-3,6-di-O-acetyl-α-D-glucopyranosyl)-(1→4)-O-[methyl 2-O-benzoyl-3-O-benzyl-α-L-Idopyranosyluronate]-(1→4)-2-azido-6-O-benzoyl-3-O-benzyl-2-deoxy-α-D-glucopyranoside

The crude EDCBA1 from step 4 was dissolved in 15 L of Tetrahydrofuran and chilled to −20 to −25° C. A solution containing 679 g (13.6 mol) of Hydrazine monohydrate and 171 g (1.94 mol) of Hydrazine Acetate in 7 L of Methanol was added slowly while maintaining the temperature below −20° C. When the addition was complete, the reaction mixture was allowed to warm to 0-10° C. and stirred for several hours until the reaction is complete, after which 20 L of Ethyl acetate was added and the reaction was extracted with 10% citric acid (2×12 L). The organic layer was washed with water (1×12 L), dried over anhydrous sodium sulfate, and evaporated under vacuum to a syrup. Column chromatographic separation using silica gel and 10-45% ethyl acetate/heptane gradient yielded 2.47 Kg (47.5% yield over 2 steps) of EDCBA2. The ¹H NMR spectrum (d6-acetone) of the EDCBA-2 pentamer is shown in FIG. 8.

Preparation of EDCBA Pentamer

Step 6:

THP Formation Methyl O-6-O-acetyl-2-azido-2-deoxy-3,4-di-O-benzyl-α-D-glucopyranosyl-(1→4)-O-[benzyl 3-O-benzyl-2-O-tetrahydropyranyl-β-D-glucopyranosyluronate]-(1→4)-O-2-azido-2-deoxy-3,6-di-O-acetyl-α-D-glucopyranosyl-(1→4)-O-[methyl 2-O-benzoyl-3-O-benzyl-α-L-Idopyranosyluronate]-(1→4)-2-azido-6-O-benzoyl-3-O-benzyl-2-deoxy-α-D-glucopyranoside

2.47 Kg (1.35 mol) of EDCBA2 was dissolved in 23 L Dichloroethane and chilled to 10-15° C., after which 1.13 Kg (13.5 mol, 10 eq) of Dihydropyran and 31.3 g (0.135 mol, 0.1 eq) of Camphorsulfonic acid were added. The reaction was allowed warm to 20-25° C. and stirred for 4-6 hours until reaction was complete. Water (15 L) was added and the reaction was extracted with an additional 10 L of DCE. The organic layer was extracted with a 25% 4:1 Sodium Chloride/Sodium Bicarbonate solution (2×20 L), dried over anhydrous sodium sulfate, and evaporated under vacuum to a syrup. Column chromatographic separation using silica gel and 10-35% ethyl acetate/heptane gradient yielded 2.28 Kg (88.5% yield) of fully protected EDCBA Pentamer. The ¹H NMR spectrum (d6-acetone) of the EDCBA pentamer is shown in FIG. 9.

Preparation of API1

Step 1:

Saponification Methyl O-2-azido-2-deoxy-3,4-di-O-benzyl-α-D-glucopyranosyl-(1→4)-O-3-O-benzyl-2-O-tetrahydropyranyl-β-D-glucopyranosyluronosyl-(1→4)-O-2-azido-2-deoxy-α-D-glucopyranosyl-(1→4)-O-3-O-benzyl-α-L-Idopyranosyluronosyl-(1→4)-2-azido-3-O-benzyl-2-deoxy-α-D-glucopyranoside disodium salt

To a solution of 2.28 Kg (1.19 mol) of EDCBA Pentamer in 27 L of Dioxane and 41 L of Tetrahydrofuran was added 45.5 L of 0.7 M (31.88 mol, 27 eq) Lithium hydroxide solution followed by 5.33 L of 30% Hydrogen peroxide. The reaction mixture was stirred for 10-20 hours to remove the acetyl groups. Then, 10 L of 4 N (40 mol, 34 eq) sodium hydroxide solution was added. The reaction was allowed to stir for an additional 24-48 hours to hydrolyze the benzyl and methyl esters completely. The reaction was then extracted with ethyl acetate. The organic layer was extracted with brine solution and dried with anhydrous sodium sulfate. Evaporation of the solvent under vacuum gave a syrup of API1 [also referred to as EDCBA(OH)₅] which was used for the next step without further purification.

Preparation of API2

Step 2:

O-Sulfonation Methyl O-2-azido-2-deoxy-3,4-di-O-benzyl-6-O-sulfo-α-D-glucopyranosyl-(1→4)-O-3-O-benzyl-2-O-tetrahydropyranyl-β-D-glucopyranosyluronosyl-(1→4)-O-2-azido-2-deoxy-3,6-di-O-sulfo-α-D-glucopyranosyl-(1→4)-O-3-O-benzyl-2-O-sulfo-α-L-idopyranuronosyl-(1→4)-2-azido-2-deoxy-6-O-sulfo-α-D-glucopyranoside, heptasodium salt

The crude product of API1 [aka EDCBA(OH)₅] obtained in step 1 was dissolved in 10 L Dimethylformamide. To this was added a previously prepared solution containing 10.5 Kg (66 moles) of sulfur trioxide-pyridine complex in 10 L of Pyridine and 25 L of Dimethylformamide. The reaction mixture was heated to 50° C. over a period of 45 min. After stiffing at 1.5 hours at 50° C., the reaction was cooled to 20° C. and was quenched into 60 L of 8% sodium bicarbonate solution that was kept at 10° C. The pH of the quench mixture was maintained at pH 7-9 by addition of sodium bicarbonate solution. When all the reaction mixture has been transferred, the quench mixture was stirred for an additional 2 hours and pH was maintained at pH 7 or greater. When the pH of quench has stabilized, it was diluted with water and the resulting mixture was purified using a preparative HPLC column packed with Amberchrom CG161-M and eluted with 90%-10% Sodium Bicarbonate (5%) solution/Methanol over 180 min. The pure fractions were concentrated under vacuum and was then desalted using a size exclusion resin or gel filtration (Biorad) G25 to give 1581 g (65.5% yield over 2 steps) of API2 [also referred to as EDCBA(OSO₃)₅]. The ¹H NMR spectrum (d6-acetone) of API-2 pentamer is shown in FIG. 10.

Preparation of API3

Step 3:

Hydrogenation Methyl O-2-amino-2-deoxy-6-O-sulfo-α-D-glucopyranosyl-(1→4)-O-2-O-tetrahydropyranyl-β-D-glucopyranosyluronosyl-(1→4)-O-2-amino-2-deoxy-3,6-di-O-sulfo-α-D-glucopyranosyl-(1→4)-O-2-O-sulfo-α-L-idopyranuronosyl-(1→4)-2-amino-2-deoxy-6-O-sulfo-α-D-glucopyranoside, heptasodium salt

A solution of 1581 g (0.78 mol) of O-Sulfated pentasaccharide API2 in 38 L of Methanol and 32 L of water was treated with 30 wt % of Palladium in Activated carbon under 100 psi of Hydrogen pressure at 60-65° C. for 60 hours or until completion of reaction. The mixture was then filtered through 1.0μ and 0.2μ filter cartridges and the solvent evaporated under vacuum to give 942 g (80% yield) of API3 [also referred to as EDCBA(OSO₃)₅(NH₂)₃]. The ¹H NMR spectrum (d6-acetone) of API-3 pentamer is shown in FIG. 11.

Preparation of Fondaparinux Sodium

Step 4:

N-Sulfation & Removal of THP Methyl O-2-deoxy-6-O-sulfo-2-(sulfoamino)-α-D-glucopyranosyl-(1→4)—O-β-D-glucopyranuronosyl-(1→4)-O-2-deoxy-3,6-di-O-sulfo-2-(sulfoamino)-α-D-glucopyranosyl-(1→4)-O-2-O-sulfo-α-L-idopyranuronosyl-(1→4)-2-deoxy-6-O-sulfo-2-(sulfoamino)-α-D-glucopyranoside, decasodium salt

To a solution of 942 g (0.63 mol) of API3 in 46 L of water was slowly added 3.25 Kg (20.4 mol, 32 eq) of Sulfur trioxide-pyridine complex, maintaining the pH of the reaction mixture at pH 9-9.5 during the addition using 2 N sodium hydroxide solution. The reaction was allowed to stir for 4-6 hours at pH 9.0-9.5. When reaction was complete, the pH was adjusted to pH 7.0 using 50 mM solution of Ammonium acetate at pH 3.5. The resulting N-sulfated EDCBA(OSO₃)₅(NHSO₃)₃ mixture was purified using Ion-Exchange Chromatographic Column (Varian Preparative 15 cm HiQ Column) followed by desalting using a size exclusion resin or gel filtration (Biorad G25). The resulting mixture was then treated with activated charcoal and the purification by ion-exchange and desalting were repeated to give 516 g (47.6% yield) of the purified Fondaparinux Sodium form.

Analysis of the Fondaparinux sodium identified the presence of P1, P2, P3, and P4 in the fondaparinux. P1, P2, P3, and P4 were identified by standard analytical methods.

INTERMEDIATES

The monomers used in the processes described herein may be prepared as described in the art, or can be prepared using the methods described herein.

The synthesis of Monomer A-2 (CAS Registry Number 134221-42-4) has been described in the following references: Arndt et al., Organic Letters, 5(22), 4179-4182, 2003; Sakairi et al., Bulletin of the Chemical Society of Japan, 67(6), 1756-8, 1994; and Sakairi et al., Journal of the Chemical Society, Chemical Communications, (5), 289-90, 1991, and the references cited therein, which are hereby incorporated by reference in their entireties.

Monomer C(CAS Registry Number 87326-68-9) can be synthesized using the methods described in the following references: Ganguli et al., Tetrahedron: Asymmetry, 16(2), 411-424, 2005; Izumi et al., Journal of Organic Chemistry, 62(4), 992-998, 1997; Van Boeckel et al., Recueil: Journal of the Royal Netherlands Chemical Society, 102(9), 415-16, 1983; Wessel et al.,Helvetica Chimica Acta, 72(6), 1268-77, 1989; Petitou et al., U.S. Pat. No. 4,818,816 and references cited therein, which are hereby incorporated by reference in their entireties.

Monomer E (CAS Registry Number 55682-48-9) can be synthesized using the methods described in the following literature references: Hawley et al., European Journal of Organic Chemistry, (12), 1925-1936, 2002; Dondoni et al., Journal of Organic Chemistry, 67(13), 4475-4486, 2002; Van der Klein et al., Tetrahedron, 48(22), 4649-58, 1992; Hori et al., Journal of Organic Chemistry, 54(6), 1346-53, 1989; Sakairi et al., Bulletin of the Chemical Society of Japan, 67(6), 1756-8, 1994; Tailler et al.,Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry, (23), 3163-4, (1972-1999) (1992); Paulsen et al., Chemische Berichte, 111(6), 2334-47, 1978; Dasgupta et al., Synthesis, (8), 626-8, 1988; Paulsen et al., Angewandte Chemie, 87(15), 547-8, 1975; and references cited therein, which are hereby incorporated by reference in their entireties.

Monomer B-1 (CAS Registry Number 444118-44-9) can be synthesized using the methods described in the following literature references: Lohman et al., Journal of Organic Chemistry, 68(19), 7559-7561, 2003; Orgueira et al., Chemistry—A European Journal, 9(1), 140-169, 2003; Manabe et al., Journal of the American Chemical Society, 128(33), 10666-10667, 2006; Orgueira et al., Angewandte Chemie, International Edition, 41(12), 2128-2131, 2002; and references cited therein, which are hereby incorporated by reference in their entireties.
Synthesis of Monomer D
Monomer D was prepared in 8 synthetic steps from glucose pentaacetate using the following procedure:

Pentaacetate SM-B was brominated at the anomeric carbon using HBr in acetic acid to give bromide derivative IntD1. This step was carried out using the reactants SM-B, 33% hydrogen bromide, acetic acid and dichloromethane, stirring in an ice water bath for about 3 hours and evaporating at room temperature. IntD1 was reductively cyclized with sodium borohydride and tetrabutylammonium iodide in acetonitrile using 3 Å molecular sieves as dehydrating agent and stirring at 40° C. for 16 hours to give the acetal derivative, IntD2. The three acetyl groups in IntD2 were hydrolyzed by heating with sodium methoxide in methanol at 50° C. for 3 hours and the reaction mixture was neutralized using Dowex 50WX8-100 resin (Aldrich) in the acid form to give the trihydroxy acetal derivative IntD3.

The C4 and C6 hydroxyls of IntD3 were protected by mixing with benzaldehyde dimethyl acetate and camphor sulphonic acid at 50° C. for 2 hours to give the benzylidene-acetal derivative IntD4. The free hydroxyl at the C3 position of IntD4 was deprotonated with sodium hydride in THF as solvent at 0° C. and alkylated with benzyl bromide in THF, and allowing the reaction mixture to warm to room temperature with stirring to give the benzyl ether IntD5. The benzylidene moiety of IntD5 was deprotected by adding trifluoroacetic acid in dichloromethane at 0° C. and allowing it to warm to room temperature for 16 hours to give IntD6 with a primary hydroxyl group. IntD6 was then oxidized with TEMPO (2,2,6,6-tetramethyl-1-piperidine-N-oxide) in the presence of tetrabutylammonium chloride, sodium bromide, ethyl acetate, sodium chlorate and sodium bicarbonate, with stirring at room temperature for 16 hours to form the carboxylic acid derivative IntD7. The acid IntD7 was esterified with benzyl alcohol and dicyclohexylcarbodiimide (other reactants being hydroxybenzotriazole and triethylamine) with stirring at room temperature for 16 hours to give Monomer D.

Synthesis of the BA Dimer

The BA Dimer was prepared in 12 synthetic steps from Monomer B1 and Monomer A2 using the following procedure:

The C4-hydroxyl of Monomer B-1 was levulinated using levulinic anhydride and diisopropylethylamine (DIPEA) with mixing at room temperature for 16 hours to give the levulinate ester BMod1, which was followed by hydrolysis of the acetonide with 90% trifluoroacetic acid and mixing at room temperature for 4 hours to give the diol BMod2. The C1 hydroxyl of the diol BMod2 was silylated with tert-butyldiphenylsilylchloride by mixing at room temperature for 3 hours to give silyl derivative BMod3. The C2-hydroxyl was then benzoylated with benzoyl chloride in pyridine, and mixed at room temperature for 3 hours to give compound BMod4. The silyl group on BMod4 was then deprotected with tert-butyl ammonium fluoride and mixing at room temperature for 3 hours to give the C1-hydroyl BMod5. The C1-hydroxyl is then allowed to react with trichloroacetonitrile in the presence of diazobicycloundecane (DBU) and mixing at room temperature for 2 hours to give the trichloroacetamidate (TCA) derivative BMod6, which suitable for coupling, for example with Monomer A-2.

Monomer A-2 was prepared for coupling by opening the anhydro moiety with BF₃.Et₂O followed by acetylation of the resulting hydroxyl groups to give the triacetate derivative AMod1.

Monomer A2 was prepared for the coupling reaction by opening the anhydro moiety and acetylation of the resulting hydroxyl groups to give the triacetate derivative AMod1. This transformation occurs using boron trifluoride etherate, acetic anhydride and dichloromethane, between −20° C. and room temperature for 3 hours. The C1-Acetate of AMod1 was then hydrolyzed and methylated in two steps to give the diacetate AMod3. That is, first AMod1 was reacted with trimethylsilyl iodide and mixed at room temperature for 2 hours, then reacted with and tetrabutyl ammonium iodide. This mixture was reacted with diisoproylethylamine and methanol and stirred for 16 hours at room temperature, thus forming AMod3. The C4 and C6 acetates of AMod3 are hydrolyzed with sodium methoxide to give the diol Amod4. The AMod3 mixture was also subjected to mixing at room temperature for 3 hours with Dowex 50 Wx4x8-100 resin in the acid form for neutralization. This formed Amod4. The C6-hydroxyl of AMod4 is then benzoylated by treating with benzoyl chloride in pyridine at −40° C. and then allowing it to warm up to −10° C. over 2 hours to give AMod5.

Coupling of monomer AMod5 with the free C4-hydroxyl group of BMod6 was performed in the presence of BF₃.Et₂O and dichloromethane with mixing between −20° C. and room temperature for 3 hours to provide disaccharide BA1. The C4-levulinyl moiety of the disaccharide was then hydrolyzed with hydrazine to give the BA Dimer, which is suitable for subsequent coupling reactions.

Synthesis of EDC Trimer

The EDC Trimer was prepared in 10 synthetic steps from Monomer E, Monomer D and Monomer C using the following procedure:

Monomer E was prepared for coupling by opening the anhydro moiety with BF₃.Et₂O followed by acetylation of the resulting hydroxyl groups to give diacetate EMod1. This occurs by the addition of Monomer E with boron trifluoride etherate, acetic anhydride and dichloromethane at −10° C., and allowing the reaction to warm to room temperature with stirring for 3 hours. The C1-Acetate of EMod1 is then hydrolyzed to give the alcohol, EMod2. This occurs by reacting Emod1 with hydrazine acetate and dimethylformamide and mixing at room temperature for 3 hours. The C1-hydroxyl of Emod2 is then reacted with trichloroacetonitrile to give the trichloro acetamidate (TCA) derivative EMod3 suitable for coupling, which reaction also employs diazabicycloundecane and dichloromethane and mixing at room temperature for 2 hours.

Monomer D, having a free C4-hydroxyl group, was coupled with monomer EMod3 in the presence of triethylsilyl triflate with mixing at −40° C. for 2 hours to give the disaccharide ED Dimer. The acetal on ring sugar D of the ED Dimer is hydrolyzed to give the C1,C2-diol ED1. This occurs by reacting the ED Dimer with 90% trifluoro acetic acid and mixing at room temperature for 4 hours. The C1-hydroxyl moiety of ED1 was then silylated with tert-butyldiphenylsilyl chloride to give the silyl derivative ED2. The C2-hydroxyl of ED2 was then allowed to react with levulinic anhydride in the presence of dimethylaminopyridine (DMAP) and diethylisopropylamine for approximately 16 hours to give the levulinate ester ED3. The TBDPS moiety is then deprotected by removal with tert-butylammonium fluoride in acetic acid with mixing at room temperature for 3 hours to give ED4 having a C1-hydroxyl. The C1-hydroxyl moiety of ED4 was then allowed to react with trichloroacetonitrile to give the TCA derivative ED5, which is suitable for coupling.

The C1-hydroxyl moiety of ED4 is then allowed to react with trichloroacetonitrile to give the TCA derivative ED5 suitable for coupling using diazabicycloundecane and dichloromethane, and mixing at room temperature for 2 hours. Monomer C, havinga free C4-hydroxyl group, was then coupled with the disaccharide ED5 in the presence of triethylsilyl triflate and mixed at −20° C. for 2 hours to give the trisaccharide EDC Trimer.

Synthesis of the EDCBA Pentamer

The EDCBA Pentamer was prepared using the following procedure:

The preparation of EDCBA Pentamer is accomplished in two parts as follows. In part 1, the EDC Trimer, a diacetate intermediate, is prepared for the coupling reaction with Dimer BA by initially opening the anhydro moiety and acetylation of the resulting hydroxyl groups to give the tetraacetate derivative EDC1. This occurs by reacting the EDC Trimer with boron trifluoride etherate, acetic anhydride and dichlormethane and stirring between −10° C. and room temperature for 3 hours. The C1-Acetate of EDC1 is then hydrolyzed to give the alcohol, EDC2, by reacting EDC1 with benzylamine [BnNH₂] and tetrahydrofuran and mixing at −10° C. for 3 hours. The C1-hydroxyl of EDC2 is then reacted with trichloroacetonitrile and diazabicycloundecane, with mixing at room temperature for 2 hours, to give the trichloro acetamidate (TCA) derivative EDC3 suitable for coupling.

In Part 2 of the EDCBA Pentameter synthesis, the Dimer BA, having a free C4-hydroxyl group, is coupled with trisaccharide EDC3 in the presence of triethylsilyltriflate at −30° C. mixing for 2 hours to give the pentasaccharide EDCBA1. The levulinyl ester on C2 of sugar D in EDCBA1 is hydrolyzed with a mixture of deprotecting agents, hydrazine hydrate and hydrazine acetate and stiffing at room temperature for 3 hours to give the C2-hydroxyl containing intermediate EDCBA2. The C2-hydroxyl moiety on sugar D of EDCBA2 is then alkylated with dihydropyran (DHP) in the presence of camphor sulfonic acid (CSA) and tetrahydrofuran with mixing at room temperature for 3 hours to give the tetrahydropyranyl ether (THP) derivative, EDCBA Pentamer.

…………………………

A fast and effective hydrogenation process of protected pentasaccharide: A key step in the synthesis of fondaparinux sodium, Org Process Res Dev 2013, 17: 869, http://pubs.acs.org/doi/full/10.1021/op300367c

An improved method for the simultaneous removal of O-benzyl and N-carboxybenzyl groups as well as reducing azide groups to amines in protected heparin-like pentasaccharides, a key process in fondaparinux sodium synthesis, is reported. Under catalytic transfer hydrogenation conditions, using readily available and inexpensive ammonium formate, the hydrogenolysis is done in less than an hour in good yield and purity. This procedure represents a major advantage over the previously published procedures, the latter of which involve several hours/days of hydrogenation reaction under catalytic reduction using gaseous hydrogen.

Synthesis of Compound 1 (FONDAPARINUX)

………………

SYNTHESIS

WO2013003001A1

US20130005954

In the synthesis of Fondaparinux sodium, the monomers XII, XVIII, XXVII, XXXVIII, XXXXI and dimers XIX, XX, XL described herein may be made either by processes described in the art or, by a process as described herein. The XII and XVIII monomers may then linked to form a disaccharide XX, XXXIX and XXVII monomers may then linked to form a disaccharide XL, XLIII and XX dimers may then linked to form a tetrasaccharide, XLVII tetramer and XLV monomer may be linked to form a pentasaccharide (XLVIII) pentamer. The XLVIII pentamer is an intermediate that may be converted through a series of reactions to fondaparinux sodium. This strategy described herein provides an efficient method for multi-kilogram preparation of fondaparinux in high yields and highly stereoselective purity.

Fondaparinux sodium (LIII) was prepared in 3 synthetic steps from O – S pentasaccharide (L) using the following procedure:

Fondaparinux Sodium (LIII)

Preparation of Fondaparinux sodium (LIII)—

N- sulfonation of Deprotected Pentasaccharide (LI) methyl 0-2-deoxy-3,6-di-0- sulfo-2-(sulfoamino)-a-D-glucopyranosyl-(l— >4)-0-2-0-sulfo-a-L- idopyranurosyl-( 1— >4)-2-deoxy-6-0-sulfo-2-(sulfoamino)-a-D-glucopyranoside,decasodium salt

A solution of deprotected pentasaccharide (LI) (145 gm) in water (2.54 V) was adjusted to a pH of 9.5 – 10.5 with 1 N NaOH solution. S03-pyridine complex (156 gm) was added into 3 lots every 15 min, the pH being maintained at 9.5-10.5 by automatic addition of 1 N NaOH. The mixture was stirred for 2 hrs at RT, during this aqueous NaOH (IN solution) was added to maintain pH at 9.5 – 10.5. After neutralization to pH 7 – 7.5 by addition of HC1 solution, the mixture was evaporated using vacuum. The residue was dissolved in water (1.6 L) at RT, to this solution was added acetone (1.6 L) at RT. The reaction mass was cooled to 5°C – 1 0 °C and stirred for 1 hr. The solid was filtered and washed with cold acetone: water (1 :1). The clear filtrate was distilled off completely under vacuum below 55°C. The residue was dissolved in water (1.6 L) at RT, and to this solution was added acetone(1.6 L) at RT. The mixture was cooled to 5 to 10°C and stirred for 1 hr. The solid was filtered and washed with cold acetone/water (1 :1). The clear filtrate was distilled off completely under vacuum below 55°C. The residue was dissolved in water (0.7 L) and charcoal (40 gm) was added at RT. The mixture was stirred for 30 min at RT then filtered. To the filtrate was added charcoal (40 gm) at RT. The mixture was stirred for 30 min at RT then filtered. To the filtrate was added charcoal (40 gm) at RT. The mixture was stirred for 30 min at RT then filtered. The pH of the clear filtrate was adjusted to 8.0 – 8.5 with IN NaOH solution and distilled off completely under vacuum below 55 °C. The residue was dissolved in 0.5 M NaCl solution and layered onto a column of Dowex^® 1×2 -400 resins using a gradient of NaCl solution (0.5 to 10M). The product fractions were combined and distilled off under vacuum below 55 °C up to 1 – 2 L volume. The solid was filtered off and the clear filtrate was distilled off under vacuum below 55 °C up to slurry stage and subjected to azeotropic distillation with methanol two times. The solid residue was stirred with methanol (2.13 L) at RT for 1 hr and the solid was filtered off and washed with methanol. The wet solid was again stirred with methanol (2.13 L) at RT for 1 hr and the solid was filtered off and washed with methanol. The wet solid was again stirred with methanol (2.13 L) at RT for 1 hr and the solid was filtered off and washed with methanol. The above solid was dissolved in water and the pH adjusted to 4 – 4.5 with IN HC1 solution and charcoalized three times with 26 gm of charcoal at RT for 15-30 minutes and filtered off. To the clear filtrate was added 0.39 kg of NaCl, then methanol was added (35 volume) at RT and the mixture was stirred for 15-30 minutes. The solution was decanted and the sticky mass was stirred with methanol (0.65 L) at RT for 15-30 minutes. The solid was filtered off and dissolved in water, and the pH adjusted to 8 – 8.5 with IN NaOH solution. The solution was filtered through 0.45 micron paper & distilled off completely under vacuum below 55°C. The solution was subjected to azeotropic distillation with methanol to give highly pure fondaparinux sodium (97.17 gm) (HPLC purity 99.7%).

SOR Results

Three batches of product made in accordance with the present processes provided the following stereoisomeric optical rotation results:

Specification: Between +50.0° and +60.0°.

Batch- 1 = +55.1°

Batch-2 = +55.7° Batch-3 = +55.4°.

INTERMEDIATES

Synthetic Procedures

The following abbreviations are used herein: Ac is acetyl; MS is molecular sieve; DMF is dimethyl formamide; Bn is benzyl; MDC is dichloromethane; THF is tetrahydrofuran; TFA is trifluoro acetic acid; MeOH is methanol; RT is room temperature; Ac₂O is acetic anhydride; HBr is hydrogen bromide; EtOAc is ethyl acetate; Cbz is benzyloxycarbonyl; CADS is chloro acetyl disaccharide; HDS is hydroxy disaccharide; NMP is N-methylpyrrolidone.

Methyl 3-O-benzyl-4-O-monochloro acetyl-β-L-idopyranuronate

Route of Synthesis for α-Methyl-6-o-acetyl-3-o-benzyl-2-(benzyloxy carbonyl)amino-2-deoxy-α-D-glucopyranoside

Methyl 6-O-acetyl-3-O-benzyl-2-(benzyloxy carbonyl)amino-2-deoxy-4-O-(methyl-2-O acetyl-3-O-benzyl-α-L-idopyranosyluronate)-glucopyranoside

Route of Synthesis for 1,6-Anhydro-2-azido-3-O-acetyl-2-deoxy-beta-D-glucopyranose

Route of synthesis for Methyl 2,3-di-O-benzyl-4-O-chloroacetyl-beta-D-glucopyranuronate

Route of synthesis for 3-O-Acetyl-1,6-anhydro-2-azido-4-O-2,3-di-O-benzyl-4-O-chloroacetyl-beta-D-glucopyranosyl methyluronate-beta-D-glucopyranose

(or)

3-O-Acetyl-1,6-anhydro-2-azido-2-deoxy-4-O-(methyl 2,3-di-O-benzyl-4-O-chloroacetyl-beta-D-glucopyranosyluronate)-beta-D-glucopyranose

Route of Synthesis for 1,6-Anhydro-2-azido-3,4-di-O-benzyl-2-deoxy-beta-D-glucopyranose

Synthesis of Disaccharide XLIII

Disaccharide XLIII was prepared in 2 synthetic steps from CADS sugar (XL) using the following procedure:

CADS sugar XL was acetylated at the anomeric carbon using AC₂O and TFA to give acetyl derivative XLII. This step was carried out using the reactants CADS, AC₂O and TFA, stirring in an ice water bath for about 5-24 hours, preferably 20 hours, and evaporating to residue under vacuum. Residue was recrystallized in ether. Acetyl CADS (XLII) was brominated at the anomeric carbon using titanium tetra bromide in MDC andethylacetate and stirring at 20° C.-50° C. for 6-16 hours, preferably 6 hours, to give the bromo derivative, (XLIII) after work-up and recrystallization from solvent/alcohol.

Synthesis of the Monosaccharide (XLV)

The monosaccharide (XLV) was prepared in 2 synthetic steps from monomer (XLI) using the following procedure:

Mono sugar (XLI) was acetylated at the anomeric carbon using AC₂O and TFA to give acetyl derivative (XLIV). This step was carried out using the reactants Mono sugar (XLI), AC₂O and TFA, stirring in an ice water bath for about 5-24 hours, preferably 24 hours, and evaporating to residue under vacuum. Residue was recrystallized in ether. Acetyl Mono sugar (XLIV) was brominated at the anomeric carbon using titanium tetra bromide in MDC and ethyl acetate and stirring at 20° C.-50° C. for 6-20 hours, preferably 16 hours, to give the bromo derivative, (XLV) after work-up and recrystallization from ether.

Synthesis of the Hydroxy Tetrasaccharide (XLVII)

The hydroxy tetrasaccharide (XLVII) was prepared in 2 synthetic steps from disaccharide (XLIII) and HDS (XX) using the following procedure:

Disaccharide (XLIII), was coupled with disaccharide (XX) in the presence of silver carbonate, silver per chlorate and 4 A° MS in MDC and stirred at ambient temperature for 5-12 hrs, preferably 4-6 hours, in the dark followed by work-up and purification in water/methanol to give the tetrasaccharide (XLVI). The d echloroacetylation of tetrasaccharide (XLVI) was carried out in THF, ethanol and pyridine in the presence of thiourea at reflux for 6 to 20 hrs, preferably 12 hours, to give the hydroxy tetrasaccharide (XLVIII).

Synthesis of the Pentasaccharide (XLVIII)

The pentasaccharide (XLVIII) was prepared in 2 synthetic steps from monosaccharide (XLV) and tetrasaccharide (XLVII) using the following procedure:

Monosaccharide (XLV), was coupled with tetrasaccharide (XLVII) in the presence of 2,4,6-collidine, silver triflate and 4 A° MS in MDC and stirred at −10° C. to −20° C. for 1 hr in the dark followed by work-up and purification by column chromatography to give the pentasaccharide (XLVIII).

Synthesis of OS Pentasaccharide (L)

The OS pentasaccharide (L) was prepared in 2 synthetic steps from pentasaccharide (XLVIII) using the following procedure:

Pentasaccharide (XLVIII) was deacetylated in the presence of NaOH in mixture of solvents of MDC, methanol and water at 0° C. to 35° C., for 1-2 hrs followed by work-up and distillation to obtain deacetylated pentasaccharide (XLIX) which was subjected to O-sulfonation in DMF in the presence of SO₃-trimethylamine (TMA) at 50° C. to 100° C., preferably 50° C.-55° C., for 6-24 hrs, preferably 12 hours, followed by salt removal through Sephadex® resin and column chromatography purification, then pH adjustment by dilute NaOH to give OS pentasaccharide (L).

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INTERMEDIATE

WO2013011460A1

highly pure 4-Ο-β-ϋ- glucopyranosyl- 1 ,6-anhydro- -D-glucopyranose

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SYNTHESIS

WO2013115817A1

Synthesis of Fondaparinux

Fondaparinux was prepared using the following procedure:

Conversion of FPP (also referred to a Fully Protected Pentamer) to FondaparinuxSodium:

Reagents: 1. NaOH, H₂0₂, LiOH, Dioxane, RT, 24-48 h; 2. Py.S0₃, DMF, 60°C, 2h, CG-161 purification; 3. 10% Pd/C, H₂, 72h; 4. (a) Py.S0₃, NaOH, NH₄OAc, 12h, (b) HiQ NH₄OAc/ NaCl ion-exchange, Sephadex Desalt and (c) HiQ NaCl ion-exchange, Sephadex Desalt. The ester moieties in EDCBA Pentamer-CB were hydrolyzed with sodium and lithium hydroxide in the presence of hydrogen peroxide in dioxane mixing at room temperature for 24- 48 hours to give the pentasaccharide intermediate API1-CB. The five hydroxyl moieties in API1-CB were sulfated using a pyridine-sulfur trioxide complex in dimethylformamide, mixing at 60°C for 2 hours and then purified using column chromatography (CG-161), to give the pentasulfated pentasaccharide API2-CB. The intermediate API2-CB was then hydrogenated to reduce the three azides on sugars E, C and A to amines and the reductive deprotection of the six benzyl ethers to their corresponding hydroxyl groups to form the intermediate API3-CB. This transformation occurs by reacting API2-CB with 10% palladium/carbon catalyst with hydrogen gas for 72 hours. The three amines on API3-CB were then sulfated using the pyridine-sulfur trioxide complex in sodium hydroxide and ammonium acetate, allowing the reaction to proceed for 12 hours . The crude fondaparinux is purified and is subsequently converted to its salt form. The crude mixture was purified using an ion-exchange chromatographic column (HiQ resin) followed by desalting using a size exclusion resin or gel filtration (Biorad Sephadex G25) to give the final product, fondaparinux sodium.

Preparation of Fondaparinux Sodium – Step 4: N-Sulfation of API-3-CB:

Methyl 0-2-deoxy-6-0-sulfo-2-(sulfoamino)-a-D-glucopyranosyl-(l→4)-0^-D- glucopyranuronosyl-(l→4)-0-2-deoxy-3,6-di-0-sulfo-2-(sulfoamino)-a-D-glucopyranosyl- (l→4)-0-2-0-sulfo-a-L-idopyranuronosyl-(l→4)-2-deoxy-6-0-sulfo-2-(sulfoamino)-a-D- glucopyranoside, decasodium salt

To a solution of 25.4 gram (16.80 mmol, leq) of API-3-CB in 847 mL of water was slowly added 66.85 gram (446.88 mmol, 25eq) of sulfur trioxide-pyridine complex, maintaining the pH of the reaction mixture at pH 9-9.5 during the addition using 2N sodium hydroxide solution. The reaction was allowed to stir for 4 hours at pH 9.0 – 9.5. When reaction was completed, the pH was adjusted 7.0 by using 70 mL of 50 mmol Ammonium acetate solution pH -3.5. The resulting N-Sulfated Cellobiose mixture was purified using Ion-Exchange

Chromatographic Column followed by desalting using size exclusion resin to gave gram ( %) of the purified Fondaparinux Sodium form.

To a solution of 942 g (0.63 mol) of API3 in 46 L of water was slowly added 3.25 Kg (20.4 mol, 32 eq) of Sulfur trioxide-pyridine complex, maintaining the pH of the reaction mixture at pH 9-9.5 during the addition using 2 N sodium hydroxide solution. The reaction was allowed to stir for 4-6 hours at pH 9.0-9.5. When reaction was complete, the pH was adjusted to pH 7.0 using 50 mM solution of Ammonium acetate at pH 3.5. The resulting N- sulfated EDCBA(OS0₃)5(NHS0₃)3 mixture was purified using Ion-Exchange Chromatographic Column (Varian Preparative 15 cm HiQ Column) followed by desalting using a size exclusion resin or gel filtration (Biorad G25). The resulting mixture was then treated with activated charcoal and the purification by ion-exchange and desalting were repeated to give 516 g (47.6% yield) of the purified Fondaparinux sodium form.

INT

SCHEME 1 – Synthesis of Monomer A-2 & AMod5 fBuildinq Block Al

Reagents: 1. NaOMe, MeOH, RT, 2hr, 50wx resin; 2. (Bu₃Sn)₂0 (0.8equiv), ACN, MS, reflux, 3h; 3.l₂ (1.5 equiv), 5°C to RT, 2h; 4. NaH (2 equiv), DMF, p-MeOC₆H₄CH₂Br (PMB-Br, 2.5 equiv), -20°C to RT, 2h; 5. NaN₃, DMF, 120°C, 12h; 6. NaH, DMF, BnBr, 0°C to RT, 3h.; 7. BF₃.Et₂0, Ac₂0, DCM, -20°C to RT, 3h; 8. (a) TMS-I, TBAI, RT, 2h; (b) DIPEA, MeOH, 16h, RT; 9. NaOMe, Dowex 50WX8-100 resin H+ form, RT, 3h; 10. Pyridine, Bz-CI, -40°C to -10°C, 2h;

Scheme 2 – Synthesis of Monomer B-1 and BMod6 fBuildinq Block B1

Reagents: 1. NaH, BnBr, THF, DMF, 0° to 65°C, 3h; 2. 66% Acetic Acid/H₂0, 40 °C, 16h; 3. Nal0₄, (Bu)₄NBr, DCM, H₂0, Dark, 3h; 4. (PhS)₃CH, n-BuLi, THF, -78 °C, 3h; 5. CuCI₂/CuO, MeOH, H₂0, 3h; 6. 90% TFA/H₂0, DCM, RT, 2h; 7. DMF, CSA 2-methoxypropene, 0° to RT, 16hrs; MeOH, TEA. 8. Lev₂0, DIPEA, RT, 16h; 9. 90% TFA, RT, 4h; 10. Imidazole, TBDPSi-CI, RT, 3h; 11. Pyridine, BzCI, RT, 3h; 12. TBAF, RT, 3h; 13. TCA, DBU, RT, 2h; Also see, e.g., Bonnaffe et al., Tetrahedron Lett., 41, 307-311, 2000; Bonnaffe et al., Carbohydr. Res., 2003, 338, 681-686, 2003; and Seeberger et al., J. Org. Chem., 2003, 68, 7559- 7561, 2003.

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Carbohydrate Research, 2012 ,  vol. 361, p. 155 – 161

¹H NMR (D₂O) δ: 5.68 (d, J = 3.8 Hz, 1H, H-1D), 5.56 (d, J = 3.4 Hz, 1H, H-1F), 5.24 (d, J = 3.8 Hz, 1H, H-1G), 5.07 (d, J = 3.5 Hz, 1H, H-1H), 4.68 (d, J = 7.9 Hz, 1H, H-5G), 4.54 (dd, J = 11.4, 2.2 Hz, 1H, H-1E), 4.48-4.34 (m, 6H, H-6F, 6H, 6′H, 6D, 3E, 2G), 4.33-4.30 (m, 1H, H-6′F), 4.25-4.17 (m, 4H, H-4G, 3G, 6′D, 5F), 4.06-3.98 (m, 2H, H-4F, 5H), 3.94 (dd, J = 9.7, 2.2 Hz, 1H, H-5D), 3.92-3.86 (m, 2H,H-3E, H-4E), 3.85-3.80 (m, 2H, H-5E, 4H), 3.73-3.60 (m, 3H, H-3H, 3D, 4D), 3.53-3.44 (m, 2H, H-2F, H-2E), 3.47 (s, 3H, OMe), 3.34 (dd, J = 10.2, 3.7 Hz, 1H, H-2H), 3.31(dd, J = 10.2, 3.7 Hz, 1H, H-2D)

FONDAPARINUX

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Synthesis of intermediates

US8288515

Synthetic Procedures

The following abbreviations are used herein: Ac is acetyl; ACN is acetonitrile; MS is molecular sieves; DMF is dimethyl formamide; PMB is p-methoxybenzyl; Bn is benzyl; DCM is dichloromethane; THF is tetrahydrofuran; TFA is trifluoro acetic acid; CSA is camphor sulfonic acid; TEA is triethylamine; MeOH is methanol; DMAP is dimethylaminopyridine; RT is room temperature; CAN is ceric ammonium nitrate; Ac₂O is acetic anhydride; HBr is hydrogen bromide; TEMPO is tetramethylpiperidine-N-oxide; TBACl is tetrabutyl ammonium chloride; EtOAc is ethyl acetate; HOBT is hydroxybenzotriazole; DCC is dicyclohexylcarbodiimide; Lev is levunlinyl; TBDPS is tertiary-butyl diphenylsilyl; TCA is trichloroacetonitrile; O-TCA is O-trichloroacetimidate; Lev₂O is levulinic anhydride; DIPEA is diisopropylethylamine; Bz is benzoyl; TBAF is tetrabutylammonium fluoride; DBU is diazabicycloundecane; BF₃.Et₂O is boron trifluoride etherate; TMSI is trimethylsilyl iodide; TBAI is tetrabutylammonium iodide; TES-Tf is triethylsilyl trifluoromethanesulfonate (triethylsilyl triflate); DHP is dihydropyran; PTS is p-toluenesulfonic acid.

The monomers used in the processes described herein may be prepared as described in the art, or can be prepared using the methods described herein.

The synthesis of Monomer A-2 (CAS Registry Number 134221-42-4) has been described in the following references: Arndt et al., Organic Letters, 5(22), 4179-4182, 2003; Sakairi et al., Bulletin of the Chemical Society of Japan, 67(6), 1756-8, 1994; and Sakairi et al., Journal of the Chemical Society, Chemical Communications, (5), 289-90, 1991, and the references cited therein, which are hereby incorporated by reference in their entireties.

Monomer C(CAS Registry Number 87326-68-9) can be synthesized using the methods described in the following references: Ganguli et al., Tetrahedron: Asymmetry, 16(2), 411-424, 2005; Izumi et al., Journal of Organic Chemistry, 62(4), 992-998, 1997; Van Boeckel et al., Recueil: Journal of the Royal Netherlands Chemical Society, 102(9), 415-16, 1983; Wessel et al.,Helvetica Chimica Acta, 72(6), 1268-77, 1989; Petitou et al., U.S. Pat. No. 4,818,816 and references cited therein, which are hereby incorporated by reference in their entireties.

Monomer E (CAS Registry Number 55682-48-9) can be synthesized using the methods described in the following literature references: Hawley et al., European Journal of Organic Chemistry, (12), 1925-1936, 2002; Dondoni et al., Journal of Organic Chemistry, 67(13), 4475-4486, 2002; Van der Klein et al., Tetrahedron, 48(22), 4649-58, 1992; Hori et al., Journal of Organic Chemistry, 54(6), 1346-53, 1989; Sakairi et al., Bulletin of the Chemical Society of Japan, 67(6), 1756-8, 1994; Tailler et al.,Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry, (23), 3163-4, (1972-1999) (1992); Paulsen et al., Chemische Berichte, 111(6), 2334-47, 1978; Dasgupta et al., Synthesis, (8), 626-8, 1988; Paulsen et al., Angewandte Chemie, 87(15), 547-8, 1975; and references cited therein, which are hereby incorporated by reference in their entireties.

Monomer B-1 (CAS Registry Number 444118-44-9) can be synthesized using the methods described in the following literature references: Lohman et al., Journal of Organic Chemistry, 68(19), 7559-7561, 2003; Orgueira et al., Chemistry—A European Journal, 9(1), 140-169, 2003; Manabe et al., Journal of the American Chemical Society, 128(33), 10666-10667, 2006; Orgueira et al., Angewandte Chemie, International Edition, 41(12), 2128-2131, 2002; and references cited therein, which are hereby incorporated by reference in their entireties.
Synthesis of Monomer D
Monomer D was prepared in 8 synthetic steps from glucose pentaacetate using the following procedure:

Pentaacetate SM-B was brominated at the anomeric carbon using HBr in acetic acid to give bromide derivative IntD1. This step was carried out using the reactants SM-B, 33% hydrogen bromide, acetic acid and dichloromethane, stirring in an ice water bath for about 3 hours and evaporating at room temperature. IntD1 was reductively cyclized with sodium borohydride and tetrabutylammonium iodide in acetonitrile using 3 Å molecular sieves as dehydrating agent and stirring at 40° C. for 16 hours to give the acetal derivative, IntD2. The three acetyl groups in IntD2 were hydrolyzed by heating with sodium methoxide in methanol at 50° C. for 3 hours and the reaction mixture was neutralized using Dowex 50WX8-100 resin (Aldrich) in the acid form to give the trihydroxy acetal derivative IntD3.

The C4 and C6 hydroxyls of IntD3 were protected by mixing with benzaldehyde dimethyl acetate and camphor sulphonic acid at 50° C. for 2 hours to give the benzylidene-acetal derivative IntD4. The free hydroxyl at the C3 position of IntD4 was deprotonated with sodium hydride in THF as solvent at 0° C. and alkylated with benzyl bromide in THF, and allowing the reaction mixture to warm to room temperature with stirring to give the benzyl ether IntD5. The benzylidene moiety of IntD5 was deprotected by adding trifluoroacetic acid in dichloromethane at 0° C. and allowing it to warm to room temperature for 16 hours to give IntD6 with a primary hydroxyl group. IntD6 was then oxidized with TEMPO (2,2,6,6-tetramethyl-1-piperidine-N-oxide) in the presence of tetrabutylammonium chloride, sodium bromide, ethyl acetate, sodium chlorate and sodium bicarbonate, with stirring at room temperature for 16 hours to form the carboxylic acid derivative IntD7. The acid IntD7 was esterified with benzyl alcohol and dicyclohexylcarbodiimide (other reactants being hydroxybenzotriazole and triethylamine) with stirring at room temperature for 16 hours to give Monomer D.

Synthesis of the BA Dimer

The BA Dimer was prepared in 12 synthetic steps from Monomer B1 and Monomer A2 using the following procedure:

The C4-hydroxyl of Monomer B-1 was levulinated using levulinic anhydride and diisopropylethylamine (DIPEA) with mixing at room temperature for 16 hours to give the levulinate ester BMod1, which was followed by hydrolysis of the acetonide with 90% trifluoroacetic acid and mixing at room temperature for 4 hours to give the diol BMod2. The C1 hydroxyl of the diol BMod2 was silylated with tert-butyldiphenylsilylchloride by mixing at room temperature for 3 hours to give silyl derivative BMod3. The C2-hydroxyl was then benzoylated with benzoyl chloride in pyridine, and mixed at room temperature for 3 hours to give compound BMod4. The silyl group on BMod4 was then deprotected with tert-butyl ammonium fluoride and mixing at room temperature for 3 hours to give the C1-hydroyl BMod5. The C1-hydroxyl is then allowed to react with trichloroacetonitrile in the presence of diazobicycloundecane (DBU) and mixing at room temperature for 2 hours to give the trichloroacetamidate (TCA) derivative BMod6, which suitable for coupling, for example with Monomer A-2.

Monomer A-2 was prepared for coupling by opening the anhydro moiety with BF₃.Et₂O followed by acetylation of the resulting hydroxyl groups to give the triacetate derivative AMod1.

Monomer A2 was prepared for the coupling reaction by opening the anhydro moiety and acetylation of the resulting hydroxyl groups to give the triacetate derivative AMod1. This transformation occurs using boron trifluoride etherate, acetic anhydride and dichloromethane, between −20° C. and room temperature for 3 hours. The C1-Acetate of AMod1 was then hydrolyzed and methylated in two steps to give the diacetate AMod3. That is, first AMod1 was reacted with trimethylsilyl iodide and mixed at room temperature for 2 hours, then reacted with and tetrabutyl ammonium iodide. This mixture was reacted with diisoproylethylamine and methanol and stirred for 16 hours at room temperature, thus forming AMod3. The C4 and C6 acetates of AMod3 are hydrolyzed with sodium methoxide to give the diol Amod4. The AMod3 mixture was also subjected to mixing at room temperature for 3 hours with Dowex 50 Wx4x8-100 resin in the acid form for neutralization. This formed Amod4. The C6-hydroxyl of AMod4 is then benzoylated by treating with benzoyl chloride in pyridine at −40° C. and then allowing it to warm up to −10° C. over 2 hours to give AMod5.

Coupling of monomer AMod5 with the free C4-hydroxyl group of BMod6 was performed in the presence of BF₃.Et₂O and dichloromethane with mixing between −20° C. and room temperature for 3 hours to provide disaccharide BA1. The C4-levulinyl moiety of the disaccharide was then hydrolyzed with hydrazine to give the BA Dimer, which is suitable for subsequent coupling reactions.

Synthesis of EDC Trimer

The EDC Trimer was prepared in 10 synthetic steps from Monomer E, Monomer D and Monomer C using the following procedure:

Monomer E was prepared for coupling by opening the anhydro moiety with BF₃.Et₂O followed by acetylation of the resulting hydroxyl groups to give diacetate EMod1. This occurs by the addition of Monomer E with boron trifluoride etherate, acetic anhydride and dichloromethane at −10° C., and allowing the reaction to warm to room temperature with stirring for 3 hours. The C1-Acetate of EMod1 is then hydrolyzed to give the alcohol, EMod2. This occurs by reacting Emod1 with hydrazine acetate and dimethylformamide and mixing at room temperature for 3 hours. The C1-hydroxyl of Emod2 is then reacted with trichloroacetonitrile to give the trichloro acetamidate (TCA) derivative EMod3 suitable for coupling, which reaction also employs diazabicycloundecane and dichloromethane and mixing at room temperature for 2 hours.

Monomer D, having a free C4-hydroxyl group, was coupled with monomer EMod3 in the presence of triethylsilyl triflate with mixing at −40° C. for 2 hours to give the disaccharide ED Dimer. The acetal on ring sugar D of the ED Dimer is hydrolyzed to give the C1,C2-diol ED1. This occurs by reacting the ED Dimer with 90% trifluoro acetic acid and mixing at room temperature for 4 hours. The C1-hydroxyl moiety of ED1 was then silylated with tert-butyldiphenylsilyl chloride to give the silyl derivative ED2. The C2-hydroxyl of ED2 was then allowed to react with levulinic anhydride in the presence of dimethylaminopyridine (DMAP) and diethylisopropylamine for approximately 16 hours to give the levulinate ester ED3. The TBDPS moiety is then deprotected by removal with tert-butylammonium fluoride in acetic acid with mixing at room temperature for 3 hours to give ED4 having a C1-hydroxyl. The C1-hydroxyl moiety of ED4 was then allowed to react with trichloroacetonitrile to give the TCA derivative ED5, which is suitable for coupling.

The C1-hydroxyl moiety of ED4 is then allowed to react with trichloroacetonitrile to give the TCA derivative ED5 suitable for coupling using diazabicycloundecane and dichloromethane, and mixing at room temperature for 2 hours. Monomer C, having a free C4-hydroxyl group, was then coupled with the disaccharide ED5 in the presence of triethylsilyl triflate and mixed at −20° C. for 2 hours to give the trisaccharide EDC Trimer.

Synthesis of the EDCBA Pentamer

The EDCBA Pentamer was prepared using the following procedure:

The preparation of EDCBA Pentamer is accomplished in two parts as follows. In part 1, the EDC Trimer, a diacetate intermediate, is prepared for the coupling reaction with Dimer BA by initially opening the anhydro moiety and acetylation of the resulting hydroxyl groups to give the tetraacetate derivative EDC1. This occurs by reacting the EDC Trimer with boron trifluoride etherate, acetic anhydride and dichlormethane and stirring between −10° C. and room temperature for 3 hours. The C1-Acetate of EDC1 is then hydrolyzed to give the alcohol, EDC2, by reacting EDC1 with benzylamine [BnNH₂] and tetrahydrofuran and mixing at −10° C. for 3 hours. The C1-hydroxyl of EDC2 is then reacted with trichloroacetonitrile and diazabicycloundecane, with mixing at room temperature for 2 hours, to give the trichloro acetamidate (TCA) derivative EDC3 suitable for coupling.

In Part 2 of the EDCBA Pentameter synthesis, the Dimer BA, having a free C4-hydroxyl group, is coupled with trisaccharide EDC3 in the presence of triethylsilyltriflate at −30° C. mixing for 2 hours to give the pentasaccharide EDCBA1. The levulinyl ester on C2 of sugar D in EDCBA1 is hydrolyzed with a mixture of deprotecting agents, hydrazine hydrate and hydrazine acetate and stiffing at room temperature for 3 hours to give the C2-hydroxyl containing intermediate EDCBA2. The C2-hydroxyl moiety on sugar D of EDCBA2 is then alkylated with dihydropyran (DHP) in the presence of camphor sulfonic acid (CSA) and tetrahydrofuran with mixing at room temperature for 3 hours to give the tetrahydropyranyl ether (THP) derivative, EDCBA Pentamer.

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Intermediates

Fondaparinux sodium Intermediates

Fondaparinux sodium N-4

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Fondaparinux sodium N-3

114903-05-8

a-D-Glucopyranoside, Methyl O-2-azido-2-deoxy-3,4-bis-O-(phenylMethyl)-a-D-glucopyranosyl-(14) -O-2,3-bis-O-(phenylMethyl)-b-D-glucopyranuronosyl-(14)-O-2-azido- 2-deoxy-a-D-glucopyranosyl-(14)-O-3-O-(phenylMethyl)-a-L-idopyranu ronosyl-(14)-2-deoxy-2

FSC

114903-05-8

Chemical Name: O-[methyl2,3-di-O-benzyl-4-O-chloroacetyl-beta-Dglucopyranosyluronate]-( 1-4)-3-O-acetyl-1,6-anhydro-2-azido-2-deoxy-beta-D-glucopyranose

Description

CAS number 87907-02-6 Synonym O-[methyl2,3-di-O-benzyl-4-O-chloroacetyl-beta-Dglucopyranosyluronate]-(1-4)-3-O-acetyl-1,6-anhydro-2-azido-2-deoxy-beta-D-glucopyranose Molecular Formula C31H34ClN3O12 Molecular Weight 676.07

Chemical Name: 1,6-anhydro-2-azido-3,4-di-O-benzyl-2-deoxy-ß-D-glucopyranose

Description

CAS number 443916-61-8 Synonym 1,6-anhydro-2-azido-3,4-di-O-benzyl-2-deoxy-ß-D-glucopyranose Molecular Formula C20H21N3O4 Molecular Weight 367.4

Chemical Name: Methyl-6-O-acetyl-3-O-benzyl-2(benzyloxycarbonyl) amino-2-deoxy-4-O-(methyl2-O-acetyl-3-O-benzyl-alfa-L-idopyranosyl uronate)-alfa-D-glucopyranoside

Description

CAS number 114869-97-5 Synonym Methyl-6-O-acetyl-3-O-benzyl-2(benzyloxycarbonyl) amino-2-deoxy-4-O-(methyl2-O-acetyl-3-O-benzyl-alfa-L-idopyranosyl uronate)-alfa-D-glucopyranoside Molecular Formula C40H47NO15 Molecular Weight 781.8

Chemical Name: Benzyl-6-O-acetyl-3-O-benzyl-2-(benzyloxycarbonyl)amino-2-deoxy-4-O-(methyl2-Oacetyl-3-O-benzyl-alfa-L-idopyranosyluronate)-alfa-D-glucopyranoside

Description

CAS number 87907-11-7 Synonym Benzyl-6-O-acetyl-3-O-benzyl-2-(benzyloxycarbonyl)amino-2-deoxy-4-O-(methyl2-Oacetyl-3-O-benzyl-alfa-L-idopyranosyluronate)-alfa-D-glucopyranoside Molecular Formula C46H51NO15 Molecular Weight 857.33

Chemical Name: 3-O-Benzyl-1,2-O-isopropylidene-alpha-D-Glucofurasone

Description

CAS number 22529-61-9 Synonym 3-O-Benzyl-1,2-O-isopropylidene-alpha-D-Glucofurasone Molecular Formula C16H22O6

Chemical Name: Tetrasaccharide, ( Please refer Synonym )

Description

CAS number N-A Synonym Methyl-O-6-methyl-2,3-di-O-benzyl-beta-D-glucopyranouronosyl-(1->4)-3’6di-O’acetyl-2-azido-2-dexoy-alfa-D-glucopyranosyl-(1->4)-2-O-acetyl-3-O-benzyl-6-methyl-alfa-L-idopyranourinosyl-(1->4)-6-O-acetyl3-O-be nzyI-2-(benzyIoxycarbo n yl)amino-2-deoxy-alfa-D-gIucopyranoside Molecular Formula C71H82N4027 Molecular Weight 1423.42

Chemical Name: Fondaparinux Sodium N-3 Intermediate

Description

CAS number 114903-05-8 Synonym MethylO-(2-azido-3,4-di-O-benzyl-2-deoxy-a-D-glucopyranosyl)-(1-4)-O-(2,3-di-Obenzyl-ß-D-glucopyranosyluronicacid)-(1-4)-O-(2-azido-2-deoxy-a-D-glucopyranosyl)-(1-4)-O-(3-O-benzyl-a-L-idopyranosyluronic acid)-(1-4)-3-O-benzyl-2-benzyloxycarbonylamino-2-deoxy-a-D-glucopyranoside,N-3 Intermediate, Fondaparinux Molecular Formula C81H91N7O27 Molecular Weight 1593.60

References

FONDAPARINUX

• Arixtra home page
• Alchemia home page

The three specialties available in the United States – dalteparin (Fragmin, Pfizer), enoxaparin (Lovenox, Sanofi-Aventis) and tinzaparin (Innohep, Bristol-Myers Squibb) – the first two are found in Brazil, enoxaparin under the names Lovenox, Cutenox and Dripanina.

www.simplesharebuttons.comShare:

This is the basic structure of capreomycin. The table below identifies the various naturally occuring analogues^{12, 14}.

	R1	R2
Capreomycin IA	OH	b-Lys
Capreomycin IB	H	b-Lys
Capreomycin IIA	OH	NH2
Capreomycin IIB	H	NH2

Introduction

Capreomycin is a metabolite of Streptomyces capreolus, it is an antimycobacterial agent – and a potent tuberlostatic antibiotic. Capreomycin is effective against a number of Gram-positive and Gram-negative organisms, but is primarily active against mycobacteria. It has been used in the treatment of certain resistant strains of Mycobacterium tuberculosis. The drug was first described in 1960 be Herr, and was subsequently found to contain two components (I and II) and later to be comprised of four (IA, IB, IIA, IIB) as shown on thestructure page.

Tuberculosis

Tuberculosis is a disease of the respiratory system, and is airbourne. The bacilli implant themselves in areas such as the lungs, renal cortex and reticuloendothelial system where there is a high partial pressure of oxygen. This is the Primary infection and does not normally affect the person whilst their immune system is intact as the bacteria lie dormant. When the immune system is depressed, the secondary reactivation occurs, and effects of the disease are seen.

This infectious disease has been known since about 1000B.C., and it stills remains the ‘leading cause of death from a single infectious disease agent’⁷. It is estimated that around eight million people contract TB every year, of which 95% are in developing countries. Deaths from the disease is estimated at 3 million people per year by the World Health Organisation. The occurance of the disease is related directly to the economic state of the country. This is because the spread of the disease is greatly assisted by poor public and personal hygiene and by overcrowding. New drugs were develoed about forty years ago allowing tuberculosis to be regarded as a curable disease. This is no longer the case, as many multidrug-resistant strains of the disease have emerged. This is where capreomycin has it uses.

There are three groups of drugs used to treat TB, which vary in their effectiveness and potential side effects.

First line drugs include: isoniazid, rifampicin and pyrazinamide. These are most effective and have the fewest potential side effects.

Second line drugs include: ethambutol, streptomycin and p-amino salicyclic acid. These are less effective and have more toxic effects.

Third line drugs include: Capreomycin, cycloserine, viomycin, kanamycin and amikacin. These are least effective and have the most toxic effects.

The third line drugs have to be used for infections with tubercle bacilli, likely to be resistant to first and second line drugs or when first and second line drugs have been abandoned because of unwanted reactions. To decrease the possibility of resistant organisms from emerging, ‘Compound Drug Therapy’ is used where a concoction of several drugs is administered.

General Physical Data

Molecular Weight	653.70
Molecular Formula	C25H43N13O8
CAS Registry number	61394-77-2
Beilstein Registry number	876587
Chemical Name	L-3,6-diamino-hexanoyl->-cyclo-[L-2,3-diamino-propionyl->-L-seryl->-L-alanyl->-2-amino-3-ureido -acryloyl->-(S)-amino-((R)-2-amino-1(3),4,5,6-tetrahydro-pyrimidin-4-yl)-acetyl-(1->N%3&)]
Auto name	3,6-diamino-hexanoic acid [12-hydroxymethyl-3-(2-imino-hexahydro-pyrimidin-4-yl)-9-methyl- 2,5,8,11,14-pentaoxo-6-ureidomethylene-1,4,7,10,13-pentaaza-cyclohexadec-15-yl]-amide

 

		Cpm IA10	Cpm IB10	Cpm IIA14	Cpm IIB14
m.p. / oC		240-5	250-3	250	252
[a]D / o		-22.0	-42.5	+9.3	-24.9
UV / nm	0.1 M HCl	269 (e 23, 400)	268 (22, 000)
	H2O	268 (23, 200)	268 (21, 900)
	0.1 M NaOH	288 (15, 800)	290 (13, 100)

According to the literature⁹the following applies to naturally occuring capreomycin:
Ratio of IA to IB    = 1.16
Capreomycin II      = 1.5%

¹³C NMR Data of Cpm IA

Carbon Number	d /  ppm
1	51.92
2	40.28
4	172.76
10	176.29
11	54.15
5, 14	55.66
	56.23
7	168.0
8	105.90
13	172.00
16	176.6
17	135.79
19	155.32
20	18.86
21	68.33
22	49.20
23	23.53
24	49.83
26	157.0 (b)
1′	172.0
2′	36.93
3′	49.26
4′	23.59
5′	29.77
6′	39.77

 

 

 

 

The included NMR data is taken from tables in the literature^{8, 14}

The ¹³C NMR data is that of Capreomycin IA only, and the carbons are numbered accordingly in red on the structure shown above.

Below are ¹H NMR tables for the four different naturally occurring forms of capreomycin, the NH protons and CH protons are given in different tables. The NH protons are again numbered on the Cpm IA structure above, but this time in blue. The CH protons are numbered according to their postion in the amino acid residue. These are also numbered in pink on the above diagram.

Chemical Shifts of CH protons in Capreomycin Analogues

Position of Amino Acid Residue		Cpm IA	Cpm IB	Cpm IIA	Cpm IIB
1	a-CH2	2.63 (dd)	2.5 (dd)
		2.85 (dd)	2.81 (dd)
	b-CH2	3.8 (m)	3.7 (m)
	g-CH2	1.8 (m)	1.8 (m)
	d-CH2	1.8 (m)	1.8 (m)
	e-CH2	3.10 (m)	3.08 (m)
2	a-CH	4.3-3.5 (m)	4.2-4.5 (m)	4.3-4.6 (m)	4.3-4.6 (m)
	b-CH2	3.3 (m)	3.3 (m)	3.3 (m)	3.3 (m)
		3.8 (m)	3.8 (m)	4.1 (m)	4.1 (m)
3	a-CH	4.86 (t)	4.67 (q)	4.84 (t)	4.68 (q)
	b-CH2	3.84 (d)		3.95 (d)
	b-CH3		1.43 (d)		1.45 (d)
4	a-CH	4.3-4.5(m)	4.2-4.5 (m)	4.3-4.5 (m)	4.3-4.5 (m)
	b-CH2	3.7-4.2 (m)	3.7-4.2 (m)	3.7-4.2 (m)	3.79 (dd)
					3.8-4.2 (m)
5	b-CH	8.04 (s)	8.03 (s)	8.05 (s)	8.04 (s)
6	a-CH	5.01 (d)	4.96 (d)	5.01 (d)	4.95 (d)
	b-CH	4.5 (m)	4.5 (m)	4.5 (m)	4.5 (m)
	g-CH2	1.6-2.3 (m)	1.6-2.3 (m)	1.6-2.3 (m)	1.6-2.3 (m)
	d-CH2	3.3 (m)	3.3 (m)	3.3 (m)	3.3 (m)

 

Chemical Shifts of NH Protons of Capreomycin Analogues

	Cpm IA	Cpm IB	Cpm IIA	Cpm IIB
1	9.33 (d)	9.72(d)	9.60 (d)	9.50 (d)
2	9.24 (d)	9.24 (d)	9.33 (d)	9.30 (d)
3	8.82 (s)	8.76 (s)	9.10 (s)	9.10 (s)
4	8.64 (d)	8.68(d)	8.73 (d)	8.73 (d)
6	8.22 (t)	8.15 (t)
7	8.10 (t)	8.15 (t)	8.19 (t)	8.08 (t)
8	7.61 (d)	7.62 (d)	7.50 (d)	7.49 (d)
9	7.46 (s)	7.42 (s)	7.44 (s)	7.44 (s)
10	7.46 (s)	7.42 s)	7.31 (s)	7.18 (s)
11	6.48 (s)	6.49 (s)	6.43 (s)	6.34 (s)
12	6.29 (s)	6.34 (s)	6.29 (s)	6.27 (s)

Using the program gNMR I attempted to plot the above data. However, this was not successful as this program can only cope with molecules with up to 23 protons. As this molecule has Capreomycin IA has 43 hydogens, the generated ¹H NMR was lacking many essential peaks, and hence was not included.

IR Spectrum of Capreomycin IA

The same process could have done for any of the other three Capreomycin anlogues. The very broad band around 2000 cm^-1 upwards is due to the presence of so many nitrogen and carbonyl groups and hence hydrogen bonding.

Cyclo[3-[[(3S)-3,6-diamino-1-oxohexyl]amino]-L-alanyl-(2Z)-3-[(aminocarbonyl)amino]-2,3-didehydroalanyl-(2S)-2-[(4R)-2-amino-3,4,5,6-tetrahydro-4-pyrimidinyl]glycyl-(2S)-2-amino-b-alanyl-L-seryl]

capreomycinIA;Cyclo[3-[[(3S)-3,6-diamino-1-oxohexyl]amino]-L-alanyl-(2Z)-3-[(aminocarbonyl)amino]-2,3-didehydroalanyl-(2S)-2-[(4R)-2-amino-1,4,5,6-tetrahydro-4-pyrimidinyl]glycyl-(2S)-2-amino-b-alanyl-L-seryl] (9CI);1,4,7,10,13-Pentaazacyclohexadecane, cyclic peptide deriv.

37280-35-6

Formula:	C25H44 N14 O8
Molecular Weight:	668.83

Properties:Crystals. Mp: 246–248^°C.
Synonyms:capreomycin IA;Cyclo[A2pr*-Ser-N3-[(3S)-3,6-diamino-1-oxohexyl]A2pr-2-[(Z)-aminocarbonylaminomethylene]Gly-2-[(4R)-2-iminohexahydropyrimidine-4-yl]Gly-]SynthesisBelow is the peptide synthesis of capreomycin IA and IB. This was taken directly from the literature¹⁰.

 

 

No chemical synthesis of capreomycin could be found in any of the literature references. However, below is a synthesis devised from the peptide synthesis shown above. This is colour coded depending on the various amino residues. Each of the amino groups is added to the molecule in sequence linked by a peptide bond to eventually form the cyclo-structure. This was designed with some help from general references^1,2,3. 

  

 

This synthesis would be identical for capreomycin IB other than the Serine-Bzl is replaced by Alanine and the synthesis works in exactly the same way.

Capreomycin 

The individual components of the capreomycin were colour coded as follows:

Red	DEA / UDA	b, b � diethoxyalanine / b - ureidodehydroalanine
Green	A2pr	a, b � diaminopropionic acid
Turquoise	Ser	Serine
Blue	Cpd	Capreomycidine
Pink	b-Lys	b-Lysine

 

The black components of the synthesis were the various protecting groups involved:

Boc	tert � butoxycarbonyl
Z	Benzyloxycarbonyl
ONSu	N-hydroxysuccinimide
Nps	o-Nitrophenylsulphenyl
NO2	Nitro	NO2
Bzl	Benzene

 

Abbreviation	Chemical Name
NMM	N-Methylmorpholine
DCC	N,N�-Dicyclohexylcarbodiimine
HOBt	l-Hydroxybenztriazole
HONSu	N-Hydroxysuccinimide
THF	Tetrahydrofuran

 

This is the synthesis of capreomycin IA. The IB form is produced in an identical fashion except that Ser � Bzl , is replaced with Ala. 

……………………..

US8044186

 

 

Capastat Sulfate (capreomycin for injection) is a polypeptide antibiotic isolated from Streptomyces capreolus. It is a complex of 4 microbiologically active components which have been characterized in part; however, complete structural determination of all the components has not been established.

Capreomycin is supplied as the disulfate salt and is soluble in water. In complete solution, it is almost colorless.

Each vial contains the equivalent of 1 g capreomycin activity.

The structural formula is as follows:

Biological Action

Capreomycin is part of a group of drugs called aminoglycosides. These act to inhibit bacterial protein synthesis. The oxygen-dependent active transport by a polyamine carrier system affects the penetration of the aminoglycosides through the cell membrane of the bacterium. Minimal action on anaerobic organisms is observed. The effect of the aminoglycosides is bactericidal and is enhanced by agents that interfere with cell wall synthesis.

Very little is known about the mechanism of action of capreomycin specifically, but it is thought to inhibit protein synthesis by binding to the 70s ribosomal unit. Other sources⁶support this theory by suggesting that capreomycin “prevents protein biosynthesis by inhibiting group I intron splicing of RNA as well as blocking translation on the bacterial ribosome via inhibition of ribosomal subunits.” It has been reported¹⁴ that the b-amino group of the A₂pr residue promotes biological potency, and that its location within the molecule is of importance.

Side Effects

This powerful antimycobacterial agent can give rise to several side effects, some of which are listed below:

The following Nephrotoxic effects are reversible once treatment is stopped, but capreomycin is not recommended for people with kidney disorders.

• Polyuria (excess urination)
• Haematuria (red blood cells in the urine)
• Proteinuria (protein in the urine)
• Nitrogen metabolism
• Electrolyte disturbances
• Anorexia
• Anaemia
• Thirst

 

Capreomycin is also Ototoxic giving the following side effects. The nerve damage is permanent.

• Deafness
• Loss of vestibular function
• Damage to the cranial nerve 8

• References:1. An Introduction to Peptide Chemistry – P.D. Bailey
  2. Organic Chemistry – Vollhardt and Schore
  3. Peptide Synthesis – M. Bodanszky, Y. Klausner and M. Ondetti
  4. Pharmacology – H.P. Rand, M.M. Dale and J.M. Ritter
  5. http://www.aidsinfonyc.org/network/access/drugs/capr.html
  6. http://rwingo1.chm.colostate.edu/group/duane/duane.html
  7. http://www.hucmlrc.howard.edu/Pharmacology/handouts/TBRCLSIS.html
  8. J. Org.Chem.,1977, 42, 8 – McGahren, Morton, Kunstmann, Ellestad
  9. Bull.W.H.O., 1972, 47(3), 343-56 – Lightbrown et al.
  10. Tetrahedron, 1978, 34(7), 912-7 – Nomoto, Teshima, Wakamiya, Shiba
  11. Tetrahedron Letters, 1976, 43, 3907-10 – Shiba, Nomoto, Teshima, Wakamiya
  12. J.Org.Chem., 1992, 57, 5214-5217 – Gould and Minott
  13. Tetrahedron Letters, 1969, 30, 2549-41 – Bycroft, Cameron, Hassanali-Walji and Johnson
  14. Bull.Chem.Soc.Jpn, 1979, 52(6), 1709-15 – Nomoto and Shiba
  15. Experimentia – 1976, 32(9), 1109-11 – Nomoto and Wakamiya
  16. Pharmazie – 1970, 25(8), 471-2 – Voigt and Maa Bared
  17. Antimicrobial Agents Chemotherapy, 1964, 522-9 – Black, Griffith and Brickler
  18. Antimicrobial Agents Chemotherapy, 1962, 201-12 – Herr
  19. www2.chemie.uni-erlangen.de/services/telespec
• 20 ”Capreomycin binds across the ribosomal subunit interface using tlyA-encoded 2′-O-methylations in 16S and 23S rRNAs”. Mol. Cell 23 (2): 173–82. July 2006. doi:10.1016/j.molcel.2006.05.044. PMID 16857584
• 21   http://www.toku-e.com/Assets/MIC/Capreomycin%20sulfate.pdf
• CAPREOMYCIN wiki

Systematic (IUPAC) name
(3S)-3,6-diamino-N-[[(2S,5S,8E,11S,15S)-15-amino-11-[(4R)-2-amino-3,4,5,6-tetrahydropyrimidin-4-yl]-8-[(carbamoylamino)methylidene]-2-(hydroxymethyl)-3,6,9,12,16-pentaoxo-1,4,7,10,13-pentazacyclohexadec-5-yl]methyl]hexanamide; (3S)-3,6-diamino-N-[[(2S,5S,8E,11S,15S)-15-amino-11-[(4R)-2-amino-3,4,5,6-tetrahydropyrimidin-4-yl]-8-[(carbamoylamino)methylidene]-2-methyl-3,6,9,12,16-pentaoxo-1,4,7,10,13-pentazacyclohexadec-5-yl]methyl]hexanamide
Clinical data
AHFS/Drugs.com	monograph
MedlinePlus	a682860
Identifiers
CAS number	11003-38-6
Chemical data
Formula	C25H44N14O8
Mol. mass	668.706 g/mol

 

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US 8,007,830, US 5,565,473*PED, MERCK

MK-0476 (Montelukast, L-706631)

MONTELUKAST (Singulair® Oral Granules) helps to reduce asthma symptoms (coughing, wheezing, shortness of breath, or chest tightness) and control your asthma. It does not provide instant relief and cannot be used to treat a sudden asthma attack. It works only when used on a regular basis to help reduce inflammation and prevent asthma attacks. This drug is also helpful in improving seasonal allergies, like hay fever. Montelukast is effective in adults and children

Amongst the US approvals, tentative FDA approvals have been identified for generic Montelukast sodium, awarded to Endo, Glenmark, Mylan, Roxane, Sandoz, Teva and Torrent. The large number of generic authorisations awaiting launch in the UK is indicative of the likely competition the Singulair product will face across Europe upon SPC expiry

EP Pat. No. 480,717 discloses Montelukast sodium along with other related compounds and the methods for their preparation. The reported method of synthesis proceeds through corresponding methyl ester namely, Methyl 2-[(3S)-[3-[(2E)-(7-chloroquinolin - 2yl) ethenyl] phenyl] – 3 – hydroxypropyl] benzoate and involves coupling methyl 1- (mercaptomethyi) cyclopropaneacetate with a mesylate generated in-situ. The methyl ester of Montelukast is hydrolyzed to free acids and the latter converted directly to Montelukast Sodium salt (Scheme -1). The process is not particularly suitable for large – scale production because it requires tedious chromatographic purification of the methyl ester intermediate and / or the final product and the product yield is low.

Scheme -1

U.S. Pat. No. 5,614632 disclosed a process for the preparation of crystalline Montelukast sodium, which comprises of the following steps (Scheme – 2):

■ Reaction of methyl 2-[3(S)-[3-[2-(7-chloroquinolin -2-yl) ethenyl] phenyl] -3- hydroxypropyl benzoate (I) with Grignard reagent, methyl magnesium chloride in presence of cerium chloride to give Diol (II) ■ Reaction of Diol (II) with methane sulfonyl chloride to afford 2-[2-[3 (s)-[3- (2-(7-chloro quinolin-2yl) ethenyl] phenyl]- 3 – methane sulfonyloxy propyl] phenyl] -2-propanol (III)

^■ Condensation of 2-[2-[3(s)-[3-(2-(7-chloro quinolin - 2-yl) ethenyl] phenyl] -

3 – methane sulfonyloxypropyl] phenyl] – 2- propanol (III) with dilithium anion of 1-mercaptomethyl) cyclopropaneacetic acid, which has been generated by the reaction of l-(mercaptomethyl)cyclopropaneacetic acid (IV)with n-Butyl lithium

^■ Isolation of the condensed product, Montelukast as solid Montelukast dicyclohexylamine salt

■ Purification and conversion of Montelukast dicyclohexylamine salt into Montelukast sodium

■ Crystallization of Montelukast sodium from a mixture of toluene and acetonitrile

The process disclosed in U.S Pat. No. 5,614,632 further involved the reaction of Diol (II) with methane sulfonyl chloride involves the reaction temperature of about – 25°C and the storage condition of the intermediate, 2-[2-[3(s)-[3-(2-(7-chloro quinolin - 2-yl) ethenyl] pheny] -3 -methane sulfonyloxy propyl] phenyl] -2-propanol (III) at temperature below – 15⁰C for having the stability. The process further involves the reaction, formation of dilithium anion of l-(mercaptomethyl) cyclopropaneacetic acid which requires the usage of n-Butyl lithium, a highly flammable and hazardous reagent and the reaction is at temperature below -5°C further requires anhydrous conditions. Scheme – 2

Montelukast (trade names Singulair, Montelo-10, and Monteflo and Lukotas in India) is a leukotriene receptor antagonist(LTRA) used for the maintenance treatment of asthma and to relieve symptoms of seasonal allergies.^[1][2] It is usually administered orally once a day. Montelukast is a CysLT₁ antagonist; it blocks the action of leukotriene D4 (and secondary ligands LTC4 and LTE4) on the cysteinyl leukotriene receptor CysLT₁ in the lungs and bronchial tubes by binding to it. This reduces the bronchoconstriction otherwise caused by the leukotriene and results in less inflammation.

Because of its method of operation, it is not useful for the treatment of acute asthma attacks. Again because of its very specificmechanism of action, it does not interact with other asthma medications such as theophylline.

Another leukotriene receptor antagonist is zafirlukast (Accolate), taken twice daily. Zileuton (Zyflo), an asthma drug taken four times per day, blocks leukotriene synthesis by inhibiting 5-lipoxygenase, an enzyme of the eicosanoid synthesis pathway.

The Mont in Montelukast stands for Montreal, the place where Merck developed the drug.^[3]

Singulair was covered by U.S. Patent No. 5,565,473^[9] which expired on August 3, 2012.^[10] The same day, the FDA approved several generic versions of montelukast.^[11]

On May 28, 2009, the United States Patent and Trademark Office announced their decision to launch a reexamination of the patent covering Singulair. The decision to reexamine was driven by the discovery of references that were not included in the original patent application process. The references were submitted through Article One Partners, an online research community focused on finding literature relating to existing patents. The references included a scientific article produced by a Merck employee around the key ingredient of Singulair, and a previously filed patent in the same technology area.^[12]

On December 17, 2009, the U.S. Patent and Trademark Office determined that the patent in question was valid based on the initial reexamination and new information provided.^[13]

Montelukast is currently available in film coated tablet and orodispersible tablet formulations for once-daily administration, and also available as an oral granule formulation which is specifically designed for administration to paediatric patients.

Patent family US17493193A claims crystalline Montelukast sodium and processes for its preparation . Patents within this family are not considered to be a constraint to generic competition because the protected technology may possibly be circumvented by the synthesis and use of different molecular forms and/or salts. Patent family US33954901P relates to the specific marketed oral granule formulation of Montelukast.

The chemical name of montelukast sodium is: Sodium 1-[[[(1R)-1-[3-[(1E)-2-(7-chloro-2-quinolinyl)ethenyl]phenyl]-3-[2-(1-hydroxy-1-methylethyl)phenyl]propyl]thio]methyl]cyclopropaneacetic acid and its structure is represented as follows:

• Montelukast is apparently a selective, orally active leukotriene receptor antagonist that inhibits the cysteinyl leukotriene CysLT₁ receptor.

• The chemical name for montelukast sodium is [R-(E)]-1-[[[1-[3-[2-(7-chloro-2-quinolinyl)ethenyl]phenyl]-3-[2-(1-hydroxy-1-methylethyl)phenyl]propyl]thio]methyl] cyclopropaneacetic acid, monosodium salt. Montelukast sodium salt is understood to be represented by the following structural formula:
• U.S. patent No. 5,565,473 (“’473 patent”) is listed in the FDA’s Orange Book for montelukast sodium. The ’473 patent recites a broad class of leulcotriene antagonists as “anti-asthmatic, anti-allergic, anti-inflammatory, and cycloprotective agents” represented by a generic chemical formula. ’473 patent, col. 2,1. 3 to col. 4,1. 4. Montelukast is among the many compounds represented by that formula. The ’473 patent also refers to pharmaceutical compositions of the class of leukotriene antagonists of that formula with pharmaceutically acceptable carriers. Id. at col. 10,11. 42-46.
• Montelukast sodium is currently marketed by Merck in the form of film coated tablets and chewable tablets under the trade name Singular^®. The film coated tablets reportedly contain montelukast sodium and the following inactive ingredients: microcrystalline cellulose, lactose monohydrate, croscarmellose sodium, hydroxypropylcellulose, magnesium stearate, titanium dioxide, red ferric oxide, yellow ferric oxide, and carnauba wax. The chewable tablets reportedly containmontelukast sodium and the following inactive ingredients: mannitol, microcrystalline cellulose, hydroxypropylcellulose, red ferric oxide, croscarmellose sodium, cherry flavor, aspartame, and magnesium stearate. Physicians’ Desk Reference, 59th ed. (2005), p. 2141.
• However, there is a need in the art to improve the stability of compositions of montelukast and particularly those of the sodium salt.

Montelukast sodium is a leukotriene antagonist and inhibits the leukotriene biosynthesis. It is a white to off-white powder that is freely soluble in methanol, ethanol, and water and practically insoluble in acetonitrile.

A montelukast sodium salt is a substance which exhibits efficacy of Singulair (available from Korean MSD) generally used for the treatment of asthma as well as for the symptoms associated with allergic rhinitis, which is pharmaceutically known as a leukotriene receptor antagonist. Leukotrienes produced in vivo by metabolic action of arachidonic acid include LTB4, LTC4, LTD4 and LTE4. Of these, LTC4, LTD4 and LTE4 are cysteinyl leukotrienes (CysLTs), which are clinically essential in that they exhibit pharmaceutical effects such as contraction of airway muscles and smooth muscles and promotion of secretion of bronchial mucus.

Montelukast sodium salt is a white and off-white powder which has physical and chemical properties that it is well soluble in ethanol, methanol and water and is practically insoluble in acetonitrile.

A conventionally known method for preparing a montelukast sodium salt is disclosed in EP Patent No. 480,717. However, the method in accordance with the EP Patent requires processes for introducing and then removing a tetrahydropyranyl (THP) protecting group and purification by chromatography, thus being disadvantageously unsuitable for mass-production. In addition, the method disadvantageously requires investment in high-cost equipment, for example, to obtain amorphous final compounds by lyophilization.

Meanwhile, U.S. Pat. No. 5,614,632 discloses an improved method for preparing a montelukast sodium salt by directly reacting a methanesulfonyl compound (2) with 1-(lithium mercaptomethyl)cyclopropaneacetic acid lithium salt, without using the tetrahydropyranyl protecting group used in EP Patent No. 480,717, purifying in the form of a dicyclohexylamine salt by adding dicyclohexylamine to the reaction solution, and converting the salt into a montelukast sodium salt (1).

However, the method in accordance with the US patent should use n-butyl lithium as a base in the process of preparing the 1-(lithium mercaptomethyl)cyclopropaneacetic acid lithium salt and thus requires an improved process due to drawbacks that n-butyl lithium is dangerous upon handling and is an expensive reagent.

PCT International Patent Laid-open No. WO 2005/105751 discloses a method for preparing a montelukast sodium salt, comprising coupling methyl 1-(mercaptomethyl)cyclopropane acetate (3) used in step 10 shown in Example 146 of EP Patent 480,717 with a methanesulfonyl compound (2) in the presence of a solvent/cosolvent/base, performing hydrolysis, recrystallizing the resultingmontelukast acid (4) in the presence of a variety of solvents to obtain highly puremontelukast acid (4), and converting the same into a montelukast sodium salt (1).

In addition, WO 2005/105751 claims that, in the coupling reaction, one is selected from tetrahydrofurane and dimethylcarbonate as a solvent, a highly polar solvent is selected from dimethylformamide, dimethylacetamide and N-methylpyrrolidone as a cosolvent, and one is selected from sodium hydroxide, lithium hydroxide, sodium hydride, sodium methoxide, potassium tert-butoxide, lithium diisopropylamine and quaternary ammonium salts, as a base.

However, WO 2005/105751 discloses that, since the coupling reaction requires use of a mixed solvent and the mixed solvent is different from the solvent used for hydrolysis, a process for removing the cosolvent through distillation under reduced pressure or extraction is further required prior to hydrolysis.

Further, in accordance with the method of WO 2005/105751, recrystallization is performed in the presence of a variety of solvents in order to obtain a highly puremontelukast acid (4) and the resulting recrystallization yield is varied in a range of 30 to 80%, depending on the solvent. In the case where desired purity is not obtained, recrystallization is repeated until montelukast acid (4) with a desired purity can be obtained. Disadvantageously, the method causes deterioration in overall yield.

European Patent No. 480,717 discloses montelukast sodium and its preparation starting with the hydrolysis of its ester derivative to the crude sodium salt, acidification of the crude to montelukast acid, and purification of the crude acid by column chromatography to give montelukast acid as an oil. The resulting crude oil in ethanol was converted to montelukast sodiumby the treatment with an equal molar aqueous sodium hydroxide solution. After removal of the ethanol, the montelukastsodium was dissolved in water and then freeze dried. The montelukast sodium thus obtained is of a hydrated amorphous form as depicted in FIG. 2.

The reported syntheses of montelukast sodium, as pointed out by the inventor in EP 737,186, are not suitable for large-scale production, and the product yields are low. Furthermore, the final products, as the sodium salts, were obtained as amorphous solid which are often not ideal for pharmaceutical formulation. Therefore, they discloses an efficient synthesis of montelukastsodium by the use of 2-(2-(3-(S)-(3-(7-chloro-2-quinolinyl)ethenyl)phenyl)-3-methanesulfonyloxypropyl)phenyl)-2-propanol to couple with the dilithium salt of 1-(mercaptomethyl)cyclopropaneacetic acid. The montelukast acid thus obtained is converted to the corresponding dicyclohexylamine salt and recrystallized from a mixture of toluene and acetonitrile to obtain crystallinemontelukast sodium. This process provides improved overall product yield, ease of scale-up, and the product sodium salt in crystalline form.

According to the process described in EP 737,186, the chemical as well as optical purities of montelukast sodium depends very much on the reaction conditions for the mesylation of the quinolinyl diol with methanesulfonyl chloride. For instance, the reaction temperature determinates the chemical purity of the resulting coupling product montelukast lithium, due to the fact that an increase in the reaction temperature resulted in decreased selectivity of mesylation toward the secondary alcohol. Mesylation of the tertiary alcohol occurred at higher temperature will produce, especially under acidic condition, the undesired elimination product, the styrene derivative. This styrene impurity is difficult to remove by the purification procedure using DCHA salt formation; while excess base, butyl lithium in this case, present in the reaction mixture causes the formation of a cyclization by-product, which will eventually reduce the product yield.

PCT WO 2005/105751 discloses an alternative process for preparing montelukast sodium by the coupling of the same mesylate as disclosed in ’186 patent with 1-(mercaptomethyl)cyclopropane alkyl ester in the presence of a base. In this patent, the base butyl lithium, a dangerous and expensive reagent, is replaced with other milder organic or inorganic base. However, the problem concerning the formation of the styrene impurity is still not resolved.

CA 2649189 A1

https://www.google.co.in/patents/CA2649189A1?cl=en&dq=montelukast+sodium&hl=en&sa=X&ei=MMFwUvOrKsztkgXCsoD4Cg&ved=0CFUQ6AEwBA

Process for the manufacture of 1-[[[(1R)-1-[3-[(1E)-2-(7-chloro-2-quinolinyl)ethenyl]phenyl]-3-[2-(1-hydroxy-1-methylethyl)phenyl]propyl]thio]methyl]cyclopropane acetic acid, sodium salt [montelukast sodium (I)] consisting of: i. Converting methyl 1-(mercaptomethyl)-cyclopropaneacetate to a metal salt (X) using a metal hydroxide, ii. Subjecting the metal salt (X) to monometallation to provide a dimetallide (XI). iii. Converting a diol of formula (II) to a mesylate of formula (III) and reacting (III) in situ with (XI) affordin the metal salt of 1-[[[(1R)-1-[3-[(1E)-2-(7-chloro-2-quinolinyl)ethenyl]phenyl]-3-[2-(1-hydroxy-1-methylethyl)phenyl]propyl]thio]methyl]cyclopropane acetic acid. iv. Reacting the metal salt in-situ with a base and purifying to afford an amine salt (XII). v. Treating (XII) with a sodium base and precipitating out montelukast sodium (I).

 more info

European Patent No. 480,717 disclose the montelukast and its preparation method first be hydrolyzed to the crude ester derivatives sodium, then this crude product was acidified to montelukast acid (montelukastacid), Finally, column chromatography purification of this crude acid into oily montelukast acid. This oilMontelukast acid in ethanol, by equimolar amounts of sodium hydroxide solution and converted to montelukast sodium. The ethanol was removed aftermontelukast sodium dissolved in water, followed by freeze-drying. Finally obtainedmontelukast shown in Figure 2 is amorphous hydrated.

The invention, in European Patent No. 737,186 points out, thismontelukast synthesis method is not suitable for mass production, and the low yield. Moreover, the resulting amorphous solid salt, are generally not used in pharmaceutical formulations. Therefore, they disclose the synthesis of an effective method of montelukast sodium, which uses 2 – (2 – (3 – (S) – (3 – (7 – chloro-2 – quinolinyl) ethenyl) phenyl) -3 – methylsulfonyl) phenyl) -2 – propanol and 1 – (methylthio alcohol) cyclopropane coupling the lithium salt of acetic acid, the resulting Montelukast acid is converted into a corresponding bicyclic hexyl amine salt, and from a mixture of toluene and acetonitrile recrystallization to prepare crystalline montelukast. This method greatly improves the productivity, ease of mass production, and the product is crystalline sodium salt.

According to European Patent No. 737,186 described method for preparingmontelukast chemical purity and optical purity depends largely quinoline diol with methanesulfonyl chloride in the reaction between the mesylated condition. For example, the reaction temperature resulted in an increase of the secondary alcohols methanesulfonyl selective reduction, the reaction temperature determines the coupling product (montelukast lithium) chemical purity. Occurs at a higher temperature mesylation tertiary alcohols, in particular under acidic conditions, will produce impurities, such as styrene derivatives. This impurity is difficult styrene generated by using the DCHA salt (DCHA salt formation) in the purification process to remove; present in the reaction mixture and excess base, butyl lithium cyclized by-products resulting in the formation will eventually reduce the yield of the product.

W02005/105751 disclose another preparation method of montelukast sodium, which is the methanesulfonic acid (European Patent No. 737,186 is the same) in an alkaline state where 1_ (methyl mercaptan yl) cyclopropyl alkyl ester and coupling thereof. In this patent, the dangerous and expensive alkaline-butyl lithium reagent, is replaced by other more moderate organic or inorganic base. However, the formation of styrene impurity problem is still not resolved

1.  Lipkowitz, Myron A. and Navarra, Tova (2001) The Encyclopedia of Allergies (2nd ed.) Facts on File, New York, p. 178, ISBN 0-8160-4404-X
2.  “Asthma / Allergy “. Mascothealth.com. Retrieved 9 April 2011.
3.  http://www.merckfrosst.ca/mfcl/en/corporate/research/accomplishments/singulair.html
4.  “Montelukast Sodium”. The American Society of Health-System Pharmacists. Retrieved 3 April 2011.
5.  FDA Investigates Merck Drug-Suicide Link
6.  Updated Information on Leukotriene Inhibitors: Montelukast (marketed as Singulair), Zafirlukast (marketed as Accolate), and Zileuton (marketed as Zyflo and Zyflo CR). Food and Drug Administration. Published June 12, 2009. Accessed June 13, 2009.
7.  Rubenstein, Sarah (April 28, 2008). “FDA Sneezes at Claritin-Singulair Combo Pill”. The Wall Street Journal.
8.  Schering-Plough press release – Schering-Plough/MERCK Pharmaceuticals Receives Not-Approvable Letter from FDA for Loratadine/Montelukast
9.  5,565,473
10.  Singular patent details
11.  “FDA approves first generic versions of Singulair to treat asthma, allergies”. 03 August 2012. Retrieved 15 August 2012.
12.  “U.S. Reexamines Merck’s Singulair Patent”. Thompson Reuters. May 28, 2009.
13.  “Merck Says U.S. Agency Upholds Singulair Patent”. Thompson Reuters. December 17, 2009.

GENERAL METHOD1

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https://data.epo.org/publication-server/rest/v1.0/publication-dates/20110302/patents/EP1812394NWB1/document.html

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http://file.scirp.org/Html/8-2200440_26971.htm

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Improved Process for the Preparation of Montelukast: Development of an Efficient Synthesis, Identification of Critical Impurities and Degradants

(a) Ray, U. K.;Boju, S.; Pathuri, S. R.; Meenakshisunderam, S. (Aurobindo Pharma Limited, India). PCT Patent Application WO/2008/001213, 2008.

(b) Wang, Y.; Wang, Y.; Brand, M.; Kaspi, J. (Chemagis Ltd., Israel). PCT Patent Application WO/2007/088545, 2007.

(c) Turchetta, S.;Tuozzi, A.; Ullucci, E.; de Ferra, L. (Chemi S.P.A.; Italy). European Patent Application EA 1,693,368, 2008.

(d) Srinivas, P. L.; Rao, D. R.; Kankan, R. N.; Relekar, J. P. (Cipla Limited, India). PCT Patent Application WO/2006/064269, 2006.

(e) Reguri, B. R.; Bollikonda, S.;Bulusu, V. V. N. C. S.; Kasturi, R. K.; Aavula, S. K. (Dr. Reddy’s Laboratory, India). U.S. Patent Application U.S.2005/0107612, 2005.

(f) Coppi, L.; Bartra Sanmarti, M.; Gasanz Guillen, Y.; Monsalvatje Llagostera, M.; Talavera Escasany, P. (Esteve Quimica, S.A., Spain). PCT Patent Application WO/2007/051828, 2007.

(g) Hung, J. T.; Wei, C. P. (Formosa Laboratories, Inc., Taiwan). U.S. Patent Application U.S.2008/0097104, 2008.

(h) McGarrity, J.; Bappert, E.; Belser, E. (Lonza A.G., Switzerland). PCT Patent Application WO/2008/131932, 2008.

(i) Suri, S.; Sarin, G. S.; Mahendru, M. (Morepen Laboratories Limited, India). PCT Patent Application WO/2006/021974, 2006.

(j) Avdagic, A.; Mohar, B.;Sterk, D.; Stephan, M. (Pliva-Istrazivanje Razvoj D.O.O., Croatia). PCT Patent Application WO/2006/000856, 2006.

(k) Overman, A.; Gieling, R. G.; Zhu, J.; Thijs, L. (Synthon B.V., Holland). PCT Patent Application WO/2005/105479, 2005.

(l) Shapiro, E.; Yahomoli, R.;Niddam-Hildesheim, V.; Sterimbaum, G.; Chen, K. (Teva Pharmaceuticals Industries Ltd., Israel). PCT Patent Application WO/2005/105751, 2005.

(m) Achmatowicz, O.; Wisniewski,K.; Ramza, J.; Szelejewski, W.; Szechner, B. (Zaklady Farmaceutyczne Polpharma, S.A., Poland). PCT Patent Application WO/2006/043846, 2006.

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J. Liang*, J. Lalonde, B. Borup, V. Mitchell, E. Mundorff, N. Trinh, D. A. Kochrekar, R. N. Cherat, G. G. Pai
Codexis, Inc., Redwood City, USA and Arch PharmaLabs Limited, Mumbai, India
Development of a Biocatalytic Process as an Alternative to the (-)-DIP-Cl-Mediated Asymmetric Reduction of a Key Intermediate of Montelukast
Org. Process Res. Dev.  2010,  14:  193-198

Montelukast sodium (Singulair®) is a leukotriene receptor antagonist prescribed for the treatment of asthma and allergies. Workers at Codexis used directed evolution and high-throughput screening to engineer a robust and efficient ketoreductase enzyme (CDX-026) that accomplished the asymmetric reduction of ketone A, which is essentially water insoluble, at a loading of 100 g/L in the presence of ca. 70% organic solvents at 45 ˚C. The (S)-alcohol B was obtained in >95% yield in >99.9% ee and in >98.5% purity on a >500 mol scale.

The enzymatic reduction entails the reversible transfer of a hydride from isopropanol to the ketone A with concomitant formation of acetone. The reaction is driven to completion by the fortuitous crystallization of the monohydrate B. The four-step conversion of B into montelukast sodium is described in the Merck process patent (M. Bhupathy, D. R. Sidler, J. M. McNamara, R. P. Volante, J. J. Bergan US 6320052, 2001). This biocatalytic reduction is superior to the reduction of A with (-)-DIPCl previously used in the manufacture of montelukast

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TEVETEN® (eprosartan mesylate) is a non-biphenyl non-tetrazole angiotensin II receptor (AT1) antagonist. A selective non-peptide molecule, TEVETEN® is chemically described as the monomethanesulfonate of (E)-2-butyl-1 -(p-carboxybenzyl)-α-2-thienylmethylimid-azole-5 -acrylic acid.

Its empirical formula is C23H24N2O4S•CH4O3S and molecular weight is 520.625. Its structural formula is:

EPROSARTAN MESYLATE

tevetenEprosartan mesilate, SK&F-108566-J(?, SK&F-108566, Teveten SB, Navixen, Regulaten, Tevetenz, Teveten

US 5656650

exp Aug 12, 2014

Eprosartan is an angiotensin II receptor antagonist used for the treatment of high blood pressure. It is marketed as Teveten byAbbott Laboratories in the United States.It is marketed as Eprozar by INTAS Pharmaceuticals in India and by Abbott Laboratorieselsewhere. It is sometimes paired with hydrochlorothiazide, marketed in the US as Teveten HCT and elsewhere as TevetenPlus.

The drug acts on the renin-angiotensin system in two ways to decrease total peripheral resistance. First, it blocks the binding ofangiotensin II to AT₁ receptors in vascular smooth muscle, causing vascular dilatation. Second, it inhibits sympatheticnorepinephrine production, further reducing blood pressure.

As with other angiotensin II receptor antagonists, eprosartan is generally better tolerated than enalapril (an ACE inhibitor), especially among the elderly.^[1]

^{Eprosartan is an angiotensin II receptor antagonist used for the treatment of high blood pressure. It acts on the renin-angiotensin system in two ways to decrease total peripheral resistance. First, it blocks the binding of angiotensin II to AT1 receptors in vascular smooth muscle, causing vascular dilatation. Second, it inhibits sympathetic norepinephrine production, further reducing blood pressure.}

1.  Ruilope L, Jäger B, Prichard B (2001). “Eprosartan versus enalapril in elderly patients with hypertension: a double-blind, randomized trial”. Blood Press. 10 (4): 223–9. doi:10.1080/08037050152669747. PMID 11800061.

• Teveten website

PAT            APR                EXP

J Med Chem1991,34,(4):1514-7

J Med Chem1993,36,(13):1880-92

Synth Commun1993,23,(22):3231-48

AU 9056901, EP 403159, JP 91115278, US 5185351.

Drugs Fut1997,22,(10):1079

Eprosartan mesylate was developed successfully by SmithKline Beecham Corporation in 1997, and marketed in Germany in 1998 under the trade-name Teveten and in the United States later in 1999. Eprosartan mesylate, as an angiotensin II receptor blocker, is an antihypertensive drug of the latest generation. Eprosartan mesylate is potent to lower systolic and diastolic pressures in mild, moderate and severe hypertensive patients, and is safe and tolerable. Eprosartan mesylate is rapidly absorbed when administrated orally, with a bioavailability of 13% and a protein binding rate of 98%. The blood peak concentration and AUC (Area Under Curve) can be elevated by about 50% in patients with liver and kidney dysfunction, or fullness after administration, and can be elevated by 2 to 3 folds in elderly patients. Eprosartan mesylate has a structure shown as follows:

U.S. Pat. No. 5,185,351 discloses a method for preparing eprosartan mesylate using Eprosartan and methanesulfonic acid in isopropanol (U.S. Pat. No. 5,185,351, Example 41 (ii)). However, it is found when following this method for preparing eprosartan mesylate in industry, an esterification reaction can occur between eprosartan and isopropanol and the following two impurities can be generated:

In addition to the above two esterification impurities, the salifying method provided by the above patent is prone to produce isopropyl mesylate. Considering currently known potential risk of gene toxicity of methylsulfonic acid ester on human as well as the stringent requirements of methylsulfonic acid ester from the Europe and the America authorities, it is important to produce eprosartan mesylate in a non-alcohol solvent during the process of producing eprosartan mesylate, since it avoids the formation of methylsulfonic acid ester and the residue thereof in the final product. Since the dosage of eprosartan mesylate is high, it is particularly important to strictly control methylsulfonic acid ester in eprosartan mesylate.

In addition, for the above salifying method, solid eprosartan is suspended in propanol at a low temperature, then methanesulfonic acid is added, about ten seconds later a great deal of eprosartan mesylate precipitate is obtained. Therefore, solid eprosartan may be embedded by the precipitated eprosartan mesylate. Since isopropyl alcohol has a high viscosity at low temperature, a heavy filtering operation burden is needed to obtain solid from isopropanol, and the obtained solid contains quite an amount of isopropanol.

Eprosartan has been obtained by several different ways: 1) The iodination of 2-butylimidazole (I) with I2 and Na2CO3 in dioxane/water gives 2-butyl-4,5-diiodoimidazole (II), which is treated with benzyl chloromethyl ether (III) and K2CO3 in DMF yielding the imidazole derivative (IV). The condensation of (IV) with N-methyl-N-(2-pyridyl)formamide (V) by means of butyllithium in THF affords 1-(benzyloxymethyl)-2-butyl-4-iodoimidazole-5-carbaldehyde (VI), which is deprotected with concentrated HCl ethanol to give 2-butyl-4-iodoimidazole-5-carbaldehyde (VII). The acylation of (VII) with methyl 4-(bromomethyl)benzoate (VIII) by means of K2CO3 in hot DMF yields 4-(2-butyl-5-formyl-4-iodoimidazol-1 ylmethyl)benzoic acid methyl ester (IX), which is deiodinated by hydrogenation with H2 over Pd/C in methanol affording compound (X). The condensation of (X) with methyl 3-(2-thienyl)propionate (XI) by means of lithium diisopropylamide (LDA) in THF gives (XII), which is acylated with acetic anhydride and dimethylaminopyridine (DMAP) in dichloromethane yielding the corresponding acetate (XIII). Elimination of acetic acid from (XIII) with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in hot toluene affords the expected propenoic ester (XIV), which is finally saponified with NaOH or KOH in ethanol/water.

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WO 1998035962 A1

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TAMOXIFEN

10540-29-1 CAS

READ ABOUT TITLE AT……….http://www.rsc.org/chemistryworld/sites/default/files/CIIE_Tamoxifen.mp3

Molecular Formula: C₂₆H₂₉NO•C₆H₈O₇
CAS Number: 54965-24-1
Brands: Nolvadex, TAMOXIFEN CITRATE

Chemically, NOLVADEX (tamoxifen citrate) is the trans-isomer of a triphenylethylene derivative. The chemical name is (Z)2-[4-(1,2-diphenyl-1-butenyl) phenoxy]-N, N-dimethylethanamine 2 hydroxy-1,2,3- propanetricarboxylate (1:1). The structural and empirical formulas are:

Tamoxifen citrate has a molecular weight of 563.62, the pKa’ is 8.85, the equilibrium solubility in water at 37°C is 0.5 mg/mL and in 0.02 N HCl at 37°C, it is 0.2 mg/mL.

NDA021807 APPR2005-10-29 DARA BIOSCIENCES,

US PATENT  6,127,425

Tamoxifen is an antagonist of the estrogen receptor in breast tissue via its active metabolite, hydroxytamoxifen. In other tissues such as the endometrium, it behaves as an agonist, and thus may be characterized as a mixed agonist/antagonist. Tamoxifen is the usual endocrine (anti-estrogen) therapy for hormone receptor-positive breast cancer in pre-menopausal women, and is also a standard in post-menopausal women although aromatase inhibitors are also frequently used in that setting.

Some breast cancer cells require estrogen to grow. Estrogen binds to and activates the estrogen receptor in these cells. Tamoxifen is metabolized into compounds that also bind to the estrogen receptor but do not activate it. Because of this competitive antagonism, tamoxifen acts like a key broken off in the lock that prevents any other key from being inserted, preventing estrogen from binding to its receptor. Hence breast cancer cell growth is blocked.

Tamoxifen was discovered by pharmaceutical company Imperial Chemical Industries (now AstraZeneca) and is sold under the trade names Nolvadex, Istubal, and Valodex. However, the drug, even before its patent expiration, was and still is widely referred to by its generic name “tamoxifen.

Breast cancer

Tamoxifen is currently used for the treatment of both early and advanced ER+ (estrogen receptor positive) breast cancer in pre- and post-menopausal women.Additionally, it is the most common hormone treatment for male breast cancer. It is also approved by the FDA for the prevention of breast cancer in women at high risk of developing the disease. It has been further approved for the reduction of contralateral (in the opposite breast) cancer.

In 2006, the large STAR clinical study concluded that raloxifene is equally effective in reducing the incidence of breast cancer, but after an average 4-year follow-up there were 36% fewer uterine cancers and 29% fewer blood clots in women taking raloxifene than in women taking tamoxifen, although the difference is not statistically significant.

Nolvadex (tamoxifen) 20 mg tablets

In 2005, the ATAC trial showed that after average 68 months following a 5 year adjuvant treatment, the group that received anastrozole (Arimidex) had significantly better results than the tamoxifen group in measures like disease free survival, but no overall mortality benefit. Data from the trial suggest that anastrozole should be the preferred medication for postmenopausal women with localized breast cancer that is estrogen receptor (ER) positive.Another study found that the risk of recurrence was reduced 40% (with some risk of bone fracture) and that ER negative patients also benefited from switching to anastrozole.

Crystallographic structure of 4-hydroxy-tamoxifen (carbon = white, oxygen = red, nitrogen = blue) complexed with ligand binding domain of estrogen receptor alpha (cyan ribbon)

Tamoxifen

Adequate patent protection is required to develop an innovation in a timely manner. In 1962, ICI Pharmaceuticals Division filed a broad patent in the United Kingdom (UK) (Application number GB19620034989 19620913). The application stated, “The alkene derivatives of the invention are useful for the modification of the endocrine status in man and animals and they may be useful for the control of hormone-dependent tumours or for the management of the sexual cycle and aberrations thereof. They also have useful hypocholesterolaemic activity”.

This was published in 1965 as UK Patent GB1013907, which described the innovation that different geometric isomers of substituted triphenylethylenes had either oestrogenic or anti-oestrogenic properties. Indeed, this observation was significant, because when scientists at Merrell subsequently described the biological activity of the separated isomers of their drug clomiphene, they inadvertently reversed the naming. This was subsequently rectified.

Although tamoxifen was approved for the treatment of advanced breast cancer in post-menopausal women in 1977 in the United States (the year before ICI Pharmaceuticals Division received the Queen’s Award for Technological Achievement in the UK), the patent situation was unclear. ICI Pharmaceuticals Division was repeatedly denied patent protection in the US until the 1980s because of the perceived primacy of the earlier Merrell patents and because no advance (that is, a safer, more specific drug) was recognized by the patent office in the United States. In other words, the clinical development advanced steadily for more than a decade in the United States without the assurance of exclusivity. This situation also illustrates how unlikely the usefulness of tamoxifen was considered to be by the medical advisors to the pharmaceutical industry in general. Remarkably, when tamoxifen was hailed as the adjuvant endocrine treatment of choice for breast cancer by the National Cancer Institute in 1984, the patent application, initially denied in 1984, was awarded through the court of appeals in 1985. This was granted with precedence to the patent dating back to 1965! So, at a time when world-wide patent protection was being lost, the patent protecting tamoxifen started a 17 year life in the United States. The unique and unusual legal situation did not go uncontested by generic companies, but AstraZeneca (as the ICI Pharmaceuticals Division is now called) rightly retained patent protection for their pioneering product, most notably, from the Smalkin Decision in Baltimore, 1996. (Zeneca, Ltd. vs. Novopharm, Ltd. Civil Action No S95-163 United States District Court, D. Maryland, Northern Division, March 14, 1996.)

 

Title: Tamoxifen

CAS Registry Number: 10540-29-1

CAS Name: (Z)-2-[4-(1,2-Diphenyl-1-butenyl)phenoxy]-N,N-dimethylethanamine

Additional Names: 1-p-b-dimethylaminoethoxyphenyl-trans-1,2-diphenylbut-1-ene

Molecular Formula: C26H29NO

Molecular Weight: 371.51

Percent Composition: C 84.06%, H 7.87%, N 3.77%, O 4.31%

Literature References: Nonsteroidal estrogen antagonist.

Prepn: BE 637389 (1964 to ICI). Identification and separation of isomers: G. R. Bedford, D. N. Richardson, Nature 212, 733 (1966); BE 678807; M. J. K. Harper et al., US 4536516 (1966, 1985 both to ICI). Stereospecific synthesis: R. B. Miller, M. I. Al-Hassan, J. Org. Chem. 50, 2121 (1985). Review of chemistry and pharmacology: B. J. A. Furr, V. C. Jordan, Pharmacol. Ther. 25, 127-205 (1984). Reviews of clinical experience in treatment and prevention of breast cancer: I. A. Jaiyesimi et al., J. Clin. Oncol. 13, 513-529 (1995); C. K. Osborne, N. Engl. J. Med. 339, 1609-1618 (1998).

Properties: Crystals from petr ether, mp 96-98°.

Melting point: mp 96-98°

Derivative Type: Citrate

CAS Registry Number: 54965-24-1

Manufacturers’ Codes: ICI-46474

Trademarks: Kessar (Pharmacia); Nolvadex (AstraZeneca); Tamofène (Aventis); Zemide (Alpharma); Zitazonium (Servier)

Molecular Formula: C26H29NO.C6H8O7

Molecular Weight: 563.64

Percent Composition: C 68.19%, H 6.62%, N 2.49%, O 22.71%

Properties: Fine, white, odorless crystalline powder, mp 140-142°. Slightly sol in water; sol in ethanol, methanol, acetone. Hygroscopic at high relative humidities. Sensitive to uv light. LD50 in mice, rats (mg/kg): 200, 600 i.p.; 62.5, 62.5 i.v.; 3000-6000, 1200-2500 orally (Furr, Jordan).

Melting point: mp 140-142°

Toxicity data: LD50 in mice, rats (mg/kg): 200, 600 i.p.; 62.5, 62.5 i.v.; 3000-6000, 1200-2500 orally (Furr, Jordan)

Derivative Type: (E)-Form

CAS Registry Number: 13002-65-8

Properties: mp 72-74° from methanol.

Melting point: mp 72-74° from methanol

Derivative Type: (E)-Form citrate

Manufacturers’ Codes: ICI-47699

Properties: mp 126-128°.

Melting point: mp 126-128°

CAUTION: Tamoxifen is listed as a known human carcinogen: Report on Carcinogens, Eleventh Edition (PB2005-104914, 2004) p III-239.

Therap-Cat: Antineoplastic (hormonal).

Keywords: Antineoplastic (Hormonal); Antiestrogens; Selective Estrogen Receptor Modulator (SERM).

Synthesis of the E and Z isomers of the antiestrogen Tamoxifen. David W.Robertson and John A. Katzenellenbogen. Journal of Organic Chemistry 1982 , 47, Pages 2387-2393. An early synthesis of Tamoxifen : Production of non stereo specific products. 

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 For easy of understanding the complete synthesis has been broken down into a number of steps.Step 1.  Step 1. This step shows use of a simple friedel-craft acylation involving Anisole(A) and Phenylacetic acid (B). The acylating agent in this process was a mixture of PCl5 / SnCl4. The ketone C was formed in a 78% yield.

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Step 2.

 

 

 

Step 2. 

Alkylation was promoted by treating the ketone C with Sodium hydride (NaH). This removed the acidic protons (located on the position alpha to the carbonyl group) to produce the enolate ion. This could be isolated as the sodium enolate of the ketone treatment of this with ethyl iodide resulted in the formation of compound (D) in a 94% yield. The Ethyl iodide was chosen as the acylating agent probably as it contains the iodide ion , which is an excellent leaving group. It can therefore facilitate an SN2 substitution reaction with relative easy. 

 

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Step 3.

 

 

 

Step 3.  The phenol was deprotected using Lithium ethanthiolate in DMF ( Dimethyl This facilitated the removal of the methyl group and replaced it with a H to form a hydroxl group. Thus forming compound (E) in a 96% yield.

 

This is a key step as it has left a chink in the armour of the molecule. This can then be used to build up a characteristic part of the Tamoxifen molecule. (eg the (diemthylamino)ethyl group can be added easily from here) 

 

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Step 4.

 

 

 

 

Step 4. 

Then product E can be alkylated by treatment with 2-(dimethylamino) ethy chloride. The most facile site of alklation is the OH group on the phenyl ring. This can be interpreted roughly by using HSAB theory. e.g Hard and Soft acid/base theory. The carbon adjacent to the chloride ion of the reactant 2-(dimethylamino)ethyl chloride is made slightly harder due to the process of symbiosis. This can rationalise the formation between the hard oxygen atom to the normally soft carbon atom. In this case the carbon atom has become slightly harder due to the presence of the hard chorine atom. Hence the interaction is favourable by HSAB theory. The above reaction gives product F via a SN2 substitution reaction in 70% yield. 

 

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Step 5.

 

 

Step5. 

F on treatment with PhMgBr forms the tertiary alcohol (G). 

Formation of the Grignard reagent can be achieved via reaction of PhBr + Mg —–> PhMgBr. The Grignard reagent has effectively formed a carbanion species eg C delta negative (-ve). This is due to the presence of the C-Mg bond. the fact that Magnesium is a more electropositive element thus making the Carbon atom the more electronegative element and hence acquiring a negative charge. As a result of the negative nature of the carbon atom it can now attack the delta positive (+ve) Carbon atom of the carbonyl group. 

 

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step 6.

 

 

 

 

Step 6.The dehydration of F was initiated by treatment of methanoic hydrogen chloride. this gives the required structure of Tamoxifen. However it gives a racemic mixture of both cis and trans isomers. 

The ratio of the Cis / Trans isomers was (1.3 / 1). These isomers of Tamoxifen can be separated by Silica gel thin layer chromatography with benzene / triethylamine (9:1) as the developing solvent. Analysis of this technique revealed that the Z (Trans) isomer was more mobile than the E (Cis) isomer.

Synthetic Route 2: A Stereospecific Approach.

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Stereospecific Synthesis of (Z) – Tamoxifen via carbometalation of Alkynylsilanes.

Studied for historical reasons rather than synthetic brilliance. This synthesis was the first stereo specific synthesis of (Z) Trans Tamoxifen. Comparison between this synthesis and the previous route I believe can illustrate the development of synthetic approaches to large molecules. In particular the quest for stereo specific reactions. So starting from an alkynylsilane (A) and through a series of reactions we can generate only the (Z) – Trans isomer of Tamoxifen.

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Again for ease of understanding the complete synthesis has been broken down into a number of steps.

Step1.

 

Step1.

 

 

This step contains the vital stereo specific step. Namely the carbometalation of the alkynylsilane.It is this step which establishes the stereochemistry about the double bond. The phenyl (trimethyl silyl) – acetylene was carbometalated with diethylaluminium chloride – titanocene dichloride reactant to produce an organometallic intermediate. This organometallic intermediate was then cleaved with N bromosucciniamide to produce the alkene (B) in 85% yield.

The stereochemistry was assigned as E (Cis) mechanistic evidence suggests that this is linked to some steric reasons.

(Earlier work dedicated to this reaction see : Miller, R.B. Al-Hassan.M.I J.Org.Chem. 1984, 49, 725)

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Step2.

Step 2.

The second step shows the stereo specific replacement of the Br group by a phenyl group. This was achieved by use of Palladium – catalysed coupling of compound (B) with phenyl zinc chloride to form (C) the vinylsilane in a 95% yield.

Step3.

 

Step3.

This step during the synthesis was reported to be tricky and several approaches were attempted before a successful technique was discovered.

 

The objective of this step was to replace the trimethyl Silyl group by a suitable halogen atom (e.g. Bromine or Iodine)

However a facile reaction was reported when (C) was treated with bromine – sodium methoxide at -78�C to produce the vinyl bromide (D) in a yield of 85%

 

Step 4.

 

Step 4.

The vinyl bromide (D) coupled well with a Zinc organometallic species to produce (E) the ethyl triaryl olefin in a yield of 84%.

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Step 5.

 

Step 5.

The formation of (F) Tamoxifen was achieved by demethylation with sodium ethylthoilate in refluxing dimethyl formamide. then reaction of the phenoxide ion with 2-( dimethylamino)ethyl chloride via a SN2 substitution.

Purification of the crude product was achieved via it’s hydrochloride salt ( via a reaction with HCl (g)) then F was regenerated by treatment with dilute base this produced the stereospecific (Z)- Trans isomer in an overall yield of 60%.

a synthesis

Palladium-Catalyzed Fluoride-Free Cross-Coupling of Intramolecularly ActivatedAlkenylsilanes and Alkenylgermanes: Synthesis of Tamoxifen as a Synthetic Application (pages 642–650)Kenji Matsumoto and Mitsuru ShindoArticle first published online: 23 FEB 2012 | DOI: 10.1002/adsc.201100627

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http://pubs.rsc.org/en/content/articlelanding/2011/cs/c0cs00129e#!divAbstract

 

 

 

 

EP 0883587 A1  WO1997026234A1)

 

Preparation of Z isomer of Tamoxifen

A solution of bromobenzene (3.92g, 25mmol) in ether (5ml) containing a crystal of iodine was added dropwise to a suspension of magnesium turnings (0.63g, 26mmol) in ether (5ml) at reflux, under nitrogen. After the addition was complete, the reaction mixture was cooled to room temperature and a solution of l- [ 4- ( 2- chloroethoxy)phenyl]-2-phenyl-l-butanone (3.75g, 12.4mmol) in ether (15ml) was added over 1 hour. The resulting mixture was refluxed for 16 hours, then poured into dilute hydrochloric acid (50ml) and extracted with ether (3x40ml) . The combined ether layers were concentrated, the residual oil was dissolved in ethanol (10ml) and refluxed with concentrated hydrochloric acid (5ml) for 4 hours. The organic phase was separated, dried (Na₂S0₄) and evaporated to dryness to give a yellow oil. Η NMR (see Figures 1 to 4 and discussion below) showed this to be a 2:1 mixture of the Z and E isomers. The oil was then dissolved in warm methanol (about 40°C) and allowed to cool to room temperature. The colourless crystals formed proved to be pure Z isomer of 2-chloroethoxy tamoxifen (4.12g, 11.4mmol, 92% yield) . M.p. 107-109°C, m/z 362/364 (chlorine atom present), <S_H 0.92 (3H, t, J = 7.33 Hz, CH₃) , 2.46 (2H, q, J = 7.33 Hz, CH₂CH₃) , 3.72 (2H, t, J = 5.86 Hz, 0CH₂CH₂C1) , 4.09 (2H, t, J = 5.86 Hz, 0CH₂CH₂C1) , 6.55 (2H, d, J = 8.79 Hz, aromatic protons ortho to 0CH₂CH₂C1) , 6.79 (2H, d, J = 8.79 Hz, aromatic protons meta to 0CH₂CH₂C1) , 7.10-7.38 (10H, m, the two remaining C₆H₅ ^,s) (see Figure 5) . The 2-chloroethoxy tamoxifen was reacted with dimethylamine in ethanol, under reflux, to produce the desired Z isomer of tamoxifen.

Analysis of Η NMR data

Figures 1 to 4 represent a mixture of the E- and Z- forms of compound XI described above.

The expansion of the region ό^* 0.80 to 1.05 shows two overlapping triplets corresponding to the CH₃ groups in the

Z- and E- derivatives respectively. The critical point is the ratio of the heights of the peaks at 0.92 (for the Z) and 0.94 (for the E) , which is approximately 2:1. The expansion of the 4.00 to 4.35 region reveals similar information where ratios are 10:6.4 and 5.56:3.43.

Similarly expansion of the region 3.6 to 3.9 shows the ratio to be 2.46:1. All of these measurements suggest an approximate 2:1 ratio.

Referring to Figure 5, this shows almost pure Z- isomer. It should be noted that there is 660 mg of this from an original mixture of a 2:1 ratio mixture of 780 mg which would contain only 520 mg of the Z-isomer.

 

 

 

Z isomer of tamoxifen and 4-hydroxytamoxi en include stereoselective syntheses (involving expensive catalysts) as described in J. Chem. Soc, Perkin Trans I 1987, 1101 and J. Org. Chem. 1990, 55, 6184 or chromatographic separation of an E/Z mixture of isomers as described in J. Chem. Res., 1985 (S) 116, (M) 1342, 1986 (S) 58, (M) 771.

(Z)-tamoxifen (1) as a white solid, mp: 95.8-96.3 ºC. ¹H-NMR (500 MHz, CDCl₃) d 0.92 (3H, t, J 7.3 Hz), 2.29 (6H, s), 2.45 (2H, q, J 7.3 Hz), 2.65 (2H, t, J 5.8 Hz), 3.93 (2H, t, J 5.8 Hz), 6.68 (2H, d, J 9.5 Hz), 6.78 (2H, d, J 9.5 Hz), 7.08-7.28 (10H, m).¹³C-NMR (125 MHz, CDCl₃) d 13.6 (CH₃), 29.0 (CH₂), 45.8 (CH₃), 58.2 (CH₂), 65.5 (CH₂), 113.4 (C), 126.0 (C), 126.5 (CH), 127.8 (CH), 128.1 (C), 129.7 (C), 131.8 (CH), 135.6 (CH), 138.2 (CH), 141.3 (CH), 142.4 (CH), 143.8 (C), 156.7 (C). IR (KBr film) n_max/cm^-1: 3055, 2979, 2925, 2813, 2769, 1606, 1509, 1240, 1035, 707. GC-MS (EI) m/z 371(5%), 58(100%).

 

(Z)-tamoxifen (1) and (E)-tamoxifen (2) in 52% yield. ¹H-NMR (300 MHz, CDCl₃) d 0.91 (Z isomer. 3H, t, J 7.3 Hz), 0.94 (E isomer. 3H, t, J 7.3 Hz), 2.28 (Z isomer. 6H, s), 2.34 (E isomer. 6H, s), 2.42-2.52 (Z and Eisomers. 4H, m), 2.63 (Z isomer. 2H, t, J 5.9 Hz), 2.74 (E isomer. 2H, t, J 5.9 Hz), 3.94 (Z isomer. 2H, t, J 5.9 Hz), 4.07 (E isomer. 2H, t, J 5.9 Hz), 6.68 (Z isomer. 2H, d, J 9.7 Hz), 6.76 (E isomer. 2H, d, J 9.3 Hz), 6.86-7.36 (Z and E isomers. 10H, m). IR (KBr film) n_max/cm^-1: 3081, 3056, 2974, 2826, 2770, 1611, 1509, 1238, 1044. GC-MS (EI) m/z: Z isomer, 371(4%), 72 (24%), 58(100%); E isomer, 371(3%), 72 (24%), 58(100%). (the diastereoisomeric ratio was determined by capillary GC analysis and the configuration of the major diastereoisomer established by comparison of the NMR data of the synthetic mixture with an authentic sample of (Z)-tamoxifen (1).

 

 

nmr

 

 

ir

FTIR

shows the typical spectra’s of pure tamoxifen citrate, PCL, a physical mixture of tamoxifen citrate and PCL and drug-loaded implants. The spectrum of tamoxifen citrate shows characteristic absorption bands at 3027 cm⁻¹ (=C-H stretching), 1507 and 1477 (C=C ring stretching) and 3180 cm ^-1 (-NH2). PCL displays a characteristic absorption band at strong bands such as the carbonyl stretching mode around 1727 cm⁻¹ (C=O), asymmetric stretching 2949 cm⁻¹ (CH ₂ ) symmetric stretching 2865 cm⁻¹ (CH ₂ ). No changes in the spectrum of the physical mixture and drug-loaded microspheres were evident by FTIR spectroscopy. The strong bands such as the carbonyl peak were clear at all points.

Figure 2: Transmission FTIR spectra of (a) tamoxifen-loaded implant, (b) physical mixture of drug+PCL, (c) pure PCL, (d) pure tamoxifen citrate

enlarged view

 

FTIR spectra of A) tamoxifen citrate; B) PLGA; C) mixture of drug and excipients; D) freshly prepared nanoparticles in the formulation (BS-3HS).

Mentions: The pure drug tamoxifen citrate, PLGA-85:15, PVA, a mixture of PLGA and PVA, and a mixture of tamoxifen citrate, PLGA, and PVA; and a freshly prepared formulation were mixed separately with IR grade KBr in the ratio of 1:100 and corresponding pellets were prepared by applying 5.5 metric ton pressure with a hydraulic press. The pellets were scanned in an inert atmosphere over a wave number range of 4000–400 cm−1 in Magna IR 750 series II, FTIR instrument (Nicolet, Madison, WI, USA).

 

dsc

 

DSC thermograms of pure tamoxifen (a), pure PCL (b), physical mixture of drug+PCL (c) and (d) drug-loaded implant. The experiment was carried with crimped aluminum pans and a heating rate of 10ºC/min

 

 

xrd

X-ray diffraction studies of pure drug (a), pure PCL (b), physical mixture of drug+PCL (c) and (d) drug-loaded implant

 

synthesis

J.Chem. Research,1985(S) 116, (M) 1342 and 1986 (S) 58, (M) 0771.