WO 2016012539, Tadalafil , New patent, KRKA, D.D., NOVO MESTO

WO 2016012539,  A PROCESS FOR THE PREPARATION OF CGMP-PHOSPHODIESTERASE INHIBITOR AND ORAL PHARMACEUTICAL FORMULATION COMPRISING TADALAFIL CO-PRECIPITATES

KRKA, D.D., NOVO MESTO [SI/SI]; Smarjeska cesta 6 8000 Novo mesto (SI)

BARIC, Matej; (SI).
BENKIC, Primoz; (SI).
BOMBEK, Sergeja; (SI).
KRASOVEC, Dusan; (SI).
SKRABANJA, Vida; (SI).
VRECER, Franc; (SI).
BUKOVEC, Polona; (SI).
HUDOVORNIK, Grega; (SI).
KROSELJ, Vesna; (SI)

The present Invention relates to an improved process for preparation of tadalafil and crystallization and/or purification thereof, wherein the processes are conducted at increased pressure. The invention relates also to a process for preparation of tadalafil co-precipitates and to a solid pharmaceutical composition comprising tadalafil co-precipitates and at least one water soluble diluent and/or water insoluble non-swellable diluent, wherein the composition is substantially free of water insoluble swellable diluents

The present invention relates to a process for the preparation of CGMP-phosphodiesterase inhibitor, particularly tadalafil, a method for production co-precipitate thereof and to solid oral pharmaceutical formulations comprising tadalafil co-precipitate.

Tadalafil, chemically known as (6R-trans)-6-(1,3-benzodioxol-5-il)-2,3,6,7,12,12a-hexahydro-2-methyl-pyrazino.1′, 2′:1,6]pyrido[3,4-b]indole-1,4-dione, is a potent and selective inhibitor of the cyclic guanosine monophosphate (cGMP) – specific phosphodiesterase enzyme PDE5. It is shown below as structural formula I:

Tadalafil is marketed under the tradename CIALIS* and is used for the treatment of erectile dysfunction. The product is available as a film-coated tablet for oral administration containing 2.5, 5, 10 and 20 mg of active ingredient and the following inactive ingredients: lactose monohydrate, hydroxypropylcellulose, sodium lauryl sulfate, croscarmellose sodium, microcrystaliine cellulose, magnesium stearate, hypromellose, triacetin, titanium dioxide (E171), iron oxide (E172) and talc.

Tadalafil is practically insoluble in water and very slightly soluble in organic solvent such as ethanol, methanol and acetone.

Problems associated with low solubility of tadalafil in ethanol and most of other organic solvents resulted in the need of large quantities of solvents required to perform synthesis and crystallization of tadalafil at industrial scale, which have unwanted technological, environmental and economical impact.

US Patent No. 5 859 006 describes the synthesis of the tadalafil and its intermediate (A) which involves reacting D-tryptophan methyl ester with a piperonal in the presence of dichloromethane and trifluoroacetic acid which provides a mixture of desired cis and undesired trans isomer of intermediate A with poor selectivity. The isomers are further separated by column chromatography. The cis isomer is further reacted with chloroacetyl chloride in chloroform, providing another intermediate of tadalafil (B) which reacted with methylamine to give tadalafil of formula (1) in methanol slurry requiring an additional purification step by flash chromatography.

An improved process in the synthesis of tadalafil via modified Pictet-Spengler reaction is described in WO 04/011463 in which D-tryptophan methyl ester hydrochloride and piperonal are condensed in anhydrous isopropyl alcohol to provide hydrochloride of intermediate A. After isolation of desirable cis isomer, the product is further reacted with chloroacetyl chloride and then with methylamine in THF to give tadalafil.

Therefore there still exists a need for an improved process for a synthesis and purification of tadalafil, which would overcome the disadvantages of the prior art processes.

Low solubility of tadalafil in aqueous solutions is further disadvantageous because in vivo absorption is typically dissolution rate-limited which may result in poor bioavailability of the drug. Different approaches in the processes of preparation of pharmaceutical compositions have been applied to overcome the poor solubility.

For example, EP 1 200 092 Bl describes a pharmaceutical composition of free drug particulate form of tadalafil wherein at least 90% of the particles have a particle size of less than about 40 μm as well as composition comprising tadalafil, wherein the compound is present as solid particles not embedded in polymeric co-precipitate. Apparently, preferably at least 90% of the particles have a particle size of less than 10 μm. The technological drawback of such small particles is possible chargeability and secondary agglomeration due to increased surface energy which can cause problems during the micronization and further processing.

WO 2008/134557 describes another approach to overcome the low-solubility problem by pharmaceutical composition comprising starch and tadalafil characterized by particle size having d(90) greater than 40 μm wherein the weight ratio of starch to tadalafil is 4.5 to 1 or greater. Apparently, the preferred ratio is at least 15 to 1.

Yet another approach to overcome the low-solubility problem is to use a “co-precipitate” of tadalafil and a carrier or excipient. For example, EP 828 479 Bl describes a solvent based process wherein tadalafil and a carrier are co-precipitated with a medium in which the tadalafil and carrier are substantially insoluble. EP 828 479 describes a solvent based process wherein tadalafil and hydroxypropyl methylcellulose phthalate are co-precipitated in weakly acidic medium from a combination of non-aqueous water miscible solvent and water. However, pharmaceutical composition prepared according to EP 828479 exhibit deviations in release rate of tadalafil which was due to poor reproducibility of a process for preparation of co-precipitate. It was found that precipitation in acidic media causes unwanted degradation of hydroxypropyl methylcellulose phthalate and that precipitation at higher temperatures does not produce desired product.

WO 2008/005039 also describes a solid composite including tadalafil being in intimate contact with a carrier. The carriers include hydrophilic polymers such as povidone, cellulose derivatives, polyethylene glycol and polymethacrylates. The compositions are prepared by combining tadalafil with hydrophilic polymer and removal of the solvent by evaporation.

WO 2010/115886 describes an adsorbate comprising poorly soluble active ingredient with a particulate and/or porous carrier wherein the adsorbate is prepared by using non-polar solvent. Apparently, the solvents used are selected from the group of chlorinated hydrocarbon (dichloromethane or trichloromethane), diisopropylether and hexane, which is also the main drawback of this solution.

Co-precipitates of phosphodiesterase-5-inhibitor and copolymer of different acrylic acid derivatives are described in WO 2011/012217. The procedures described involve the use of tetrahydrofurane.

Poor solubility can also be solved with co-crystals. WO 2010/099323 discloses crystalline molecular complexes of tadalafil with co-former selected from the group of a short to medium chain organic acids, alcohols and amines.

WO 2012/107541 and WO 2012/107092 disclose co-granulate of tadalafil with cyclodextrines.

WO 2014/003677 discloses a pharmaceutical composition comprising solid dispersion particles containing tadalafil and a dispersing component, which composition further comprises a solubilizer.

Based on the above, there is still a need for an improved dosage form containing tadalafil and improved technological process for the preparation thereof.

The process for preparing tadalafil according to a preferred embodiment of the present invention is disclosed in Scheme 1.

Scheme 1

Example 1: Synthesis of tadalafil intermediate B via intermediate A

D-tryptophan methyl ester hydrochloride (9g) and piperonai (6g) was suspended in acetonitrile (60mL). The reaction mixture was stirred and heated at about 105*C for three to five hours in an autoclave. The reaction suspension was cooled to ambient temperature and aqueous solution (60m L) of sodium carbonate (4.1g) was added. The mixture was then cooled in an ice bath and the solution of chloroacetyl chloride (5.1mL) in acetonitrile was slowly added to the reaction mixture. A solid was obtained, filtered and washed twice with aqueous solution of acetonitrile. The crude product was dried, and intermediate B (13.4g) with a purity of 97% (HPLC area%) was obtained.

Example 1A:

D-tryptophan methyl ester hydrochloride (8.2kg) and piperonai (5.1kg) was suspended in acetonitrile (55L). The reaction mixture was stirred and heated at about to 105″C for three hours in the reactor vessel. The reaction suspension was cooled to ambient temperature and aqueous solution (55L) of sodium carbonate (4.8kg) was added. The mixture was then cooled in an ice bath and the solution of chloroacetyl chloride (5.2L) was slowly added to the reaction mixture at 5-10°C. A solid was obtained, centrifuged and washed twice with aqueous solution of acetonitrile (2x 121). The crude product was dried at temperature up to 50″C, and intermediate B (12.3kg) with a purity of 98% (HPLC area%) was obtained.

Comparative example 1:

D-tryptophan methyl ester hydrochloride (9.0g) and piperonai (5.84g) was suspended in acetonitrile (60mL). The reaction mixture was stirred and heated at about to 80-85’C for 15-20 hours in the reactor vessel. The reaction suspension was cooled to 0-10°C. The Intermediate A was then isolated on centrifuge and was dried at temperature up to 60°C.

The isolated dried Intermediate A (12,8g) was charged into reactor and suspended with ethyl acetate. The aqueous solution (60mL) of sodium carbonate (5.3g) was added to precooied suspension of Intermediate A. The chloroacetyl chloride (3.4mL) was slowly added to the above reaction mixture. The solid was obtained, centrifuge and washed twice with water (2x 10mL). The crude product was dried at temperature up to 70°C, and intermediate B (11.8g) with a purity of 99% (HPLC area%) was obtained.

Example 2: Synthesis oftadalafil

Intermediate B (4g) obtained in Example 1 and 40% aqueous methylamine solution (1.6mL) were dissolved in 70% aqueous solution of 2-propanol (120mL) while heating in a closed reaction vessel above the reflux temperature (110-120°C) for two to five hours. The solution was hot filtered and cooled on an ice bath. The precipitated product was filtered and dried. The purity of the product was 99.9% (HPLC area%) and the particle distribution of the product was D(90) of about 144 microns.

Example 2A: Synthesis of tadalaf il

Intermediate B (12.3kg) obtained in Example 1A and 40% aqueous methylamine solution (4.76L) were dissolved in 70% aqueous solution of 2-propanol (402L) while heating in a closed reaction vessel above the reflux temperature (110-120°C) for three hours. The solution was hot filtered and cooled on an ice bath. The precipitated product was filtered and dried. The final product (9.8kg) with a purity of more than 99.99% (HPLC area%) and the particle distribution of the product was D(90) of about 155 microns was obtained.

Comparative example 2:

Intermediate B (10g) obtained in the above comparative example 1 and 31% ethanolic methylamine solution (12.3mL) were suspended in absolute ethanol (150mL). The suspension

was heated up to 55°C for 3 – 6 hours. The suspension was cooled on an ice bath. The product was filtered and dried. The crude product (8.22g) with a purity of more than 99.9% (HPLC area%) was obtained and crystallized from hot DMSO solution. The product Is crystallized with addition of water.

Example 3: Recrystallization of tadalaf il

Tadalafil (700g) (99% purity) was suspended in 70% aqueous solution of 2-propanol (24.6L) and suspension was heated to about 110°C in an autoclave at pressure of 0.31MPa until the material was dissolved. The obtained solution was then hot filtrated and cooled to about 10°C. The isolated tadalafil (660g) has a purity of 99.95% (HPLC area%) and the particle distribution D(90) of about 144 microns.

Example 3A: Recrystallization of tadalafil

Tadalafil (5g) (99% purity) was suspended in 70% aqueous solution of acetone (lOOmL) and suspension was heated to about 90°C in an autoclave at pressure of 0.28MPa until the material was dissolved. The obtained solution was then hot filtrated and cooled to about 10°C. The isolated tadalafil (4.44g) has a purity of 99.99% (HPLC area%).

Example 3B: Recrystallization of tadalafil

Tadalafil (4g) (99% purity) was suspended in 70% aqueous solution of acetonitrile (lOOmL) and suspension was heated to about 85°C in an autoclave at pressure of 0.2MPa until the material was dissolved. The obtained solution was then hot filtrated and cooled to about 10°C. The isolated tadalafil (3g) has a purity of 99.99% (HPLC area%).

Example 3C: Recrystallization of tadalafil

Tadalafil (5g) (99% purity) was suspended in 70% aqueous solution of tetrahydrofuran (60mL) and suspension was heated to about 120″C in an autoclave at pressure of 0.3MPa until the material was dissolved. The obtained solution was then hot filtrated and cooled to about 10°C. The isolated tadalafil has a purity of 99.99% (HPLC area%).

Comparative example 3:

Tadalafil (lg) (99% purity) was suspended in 2-propanol (200mL) and suspension was heated up to reflux temperature until the material was dissolved. The obtained solution was then hot filtrated and cooled to about lO’C. The crystallized tadalafil was centrifuged and dried in an oven at temperature up to 70°C.

Comparative Example 4: Preparation of tadalafil co-precipitate with HPMCP HP-50, Precipitation at higher temperature

Tadalafil (100 g) and hydroxypropyl methylcellulose phthalate (100 g) were dissolved in a mixture of acetone (2430m L) and water (270mL) at reflux temperature. Solution was hot filtered and added to 0.25 M HCI in water (4150mL) at 65°C. Precipitate was collected by vacuum filtration, washed with water and dried in vacuum tray dryer up to 70°C. Dry material was milled by a pin mill. HPLC assay of tadalafil was 48.5 %; average particle size of co-precipitate was 53 μm, specific surface area 2.5 m2/g-

Example 5: Preparation of tadalafil co-precipitate with HPMCP HP-50

Tadalafil (1 kg) and hydroxypropyl methylcellulose phthalate (1 kg) were dissolved in mixture of acetone (20L) and water (3 L) at 54°C and under pressure O.lMPa. Solution was hot filtered and added to water (42 L) at 2°C. Suspension was heated up to reflux and acetone was distilled off. Tadalafil co-precipitate was collected by pressure filtration and dried in vacuum dryer. Dry material was milled by a pin mill. HPLC assay of tadalafil was 53.5%.

Example 6: Preparation of tadalafil co-precipitate with HPMCP HP-50

Tadalafil (1 kg) and hydroxypropyl methylcellulose phthalate (1 kg) were dissolved in mixture of acetone (20 L) and water (3 L) at 54°C and under pressure O.lMPa. Solution was hot filtered and added to water (42 L) at 2°C. Suspension was heated up to reflux and acetone was distilled off. Tadalafil co-precipitate was collected by centrifuge and dried in a fluid bed dryer. Dry material was milled by a pin mill. HPLC assay of tadalafil was 52.5 %.

3

Example 7: Preparation of tadalafil co-precipitate with HPMCP HP-50

Tadalafil (0.786 kg) and hydroxypropyl methylcellulose phthaiate (1.140 kg) were dissolved in a mixture of acetone (24L) and water (2.3 L) at 54°C and under pressure 0.1MPa. Solution was filtered hot and added to water (42 L) at 2°C. Suspension was collected by centrifuge and dried in a vacuum tray dryer up to 70°C. Dry material was milled by a pin mill. HPLC assay of tadalafil was 43.5 %, average particle size of co-precipitate was 49 μm, specific surface area 31.0 m2/g-

Example 8: Preparation of tadalafil co-precipitate with HPMCP HP-50

Tadalafil (2 g) and hydroxypropyl methylcellulose phthaiate HP 50 (2 g) were dissolved in a mixture of acetone (48.5mL) and water (5.5mL) at reflux temperature. To obtained solution crospovidone (lg) was added. Obtained suspension was co-precipitated in water (83mL) at 2°C. Obtained material was collected with a vacuum filter and dried in vacuum dryer up to 90°C. HPLC assay of tadalafil 39.9%. Yield was 90%.

Example 9: Preparation of tadalafil co-precipitate with HPMCP HP-50

Tadalafil (2 g) and hydroxypropyl methylcellulose phthaiate HP 50 (2 g) were dissolved in a mixture of acetone (54mL) and methanol (19mL) at reflux temperature. To obtained solution crospovidone (lg) was added. Obtained suspension was co-precipitated in heptane (83mL) at 0°C. Obtained material was collected with a vacuum filter and dried in vacuum dryer up to 50°C. HPLC assay of tadalafil was 36.1 %. Yield was 90%.

Example 10: Preparation of tadalafil co-precipitate with HPMCP HP-50

Tadalafil (2 g) and hydroxypropyl methylcellulose phthaiate HP 50 (2 g) were dissolved in a mixture of aceton (54mL) and methanol (19mL) at reflux temperature. Obtained solution was co-precipitated in heptane (83mL) at 0°C. Obtained material was collected with a vacuum filter and dried in vacuum dryer up to 50°C. HPLC assay of tadalafil was 36.1 %. Yield was 90%.

Example 11: Preparation of tadalafil co-precipitate with HPMCP HP-50

Tadaiafil (1.3 kg) and hydroxypropyl methylcellulose phthalate {1.53 kg) were dissolved in mixture of acetone (32 L) and water (4 L) at 54°C and 1000 mbar. Solution was hot filtered and added to water (54 L) at 2°C. Tadalafil co-precipitate was collected by decanter centrifuge and dried in a vacuum drier. Dry material (2.4kg) was milled in a pin mill. HPLC assay of tadalafil was 48.8 %; average particle size of co-precipitate was 54 μm and specific surface area 26.1 m2/g<

Example 12: Preparation of tadalafil co-precipitate with hydroxypropyl cellulose

Tadalafil (3g) and Klucel ELF (3g) was dissolved in a mixture of acetone (73mL) and water (8mL) at 50°C. Solution was hot filtered and added to 125mL water at 90°C. After that acetone was distilled off at 65°C and suspension was stirred for additional hour. Precipitated material was filtered using preheated filter funnel and dried at 80°C. Yield 3.8 g, HPLC assay was 50.0%.

Example 13: Preparation of tadalafil co-precipitate with hydroxypropyl cellulose

Tadaiafil (3g) and Klucel ELF (3g) was dissolved in a mixture of acetone (73mL) and water (8m L) at 50°C. Solution was hot filtered and added to 125m L water at 90°C with dissolved lactose (14g) at 90°C. After that acetone was distilled off at 65°C and suspension was stirred for additional hour. Precipitated material was filtered using preheated filter funnel and dried at 80°C. Yield 5 g, HPLC assay was 48.8%.

Examples of tablets prepared according to the present Invention

Example Fl: Tablets containing tadalafil co-precipitate with HPMCP HP-50 prepared in accordance with Example 11 with water soluble mannitol and without swellable water insoluble diluents

Tadalafil co-precipitate with HPMCP HP-50 was homogeneously mixed with mannitol, croscarmellose sodium and sodium lauryl sulphate. The magnesium stearate was added and mixed. The resultant blend was compressed into tablets. Dissolution profile of the example is shown in Figure 1.

Example F2: Tablets containing tadalafil co-precipitate with HPC prepared in accordance with Example 13 with water soluble mannitol and without swellable water insoluble diluents

Tadalafil co-precipitate with HPC was homogeneously mixed with mannitol, croscarmellose sodium and sodium lauryl sulphate. The magnesium stearate was added and mixed. The resultant blend was compressed into tablets. Dissolution profile of the example is shown in Figure 1.

Example F3: Tablets containing tadalafil co-precipitate with HPMCP with water soluble spray-dried lactose and without swellable water insoluble diluents

Tadaiafil co-precipitate with HPMCP was homogeneously mixed with spray-dried lactose, starch 1500 and sodium lauryi sulphate. The magnesium stearate was added and mixed. The resultant blend was compressed into tablets.

Example F4: Tablets containing tadalafil co-precipitate with HPMCP with water insoluble non-swellable anhydrous dibasic calcium phosphate and without swellable water insoluble diluents

Tadalafil co-precipitate with HPMCP was homogeneously mixed with calcium phosphate, croscarmellose sodium and sodium lauryi sulphate. The magnesium stearate was added and mixed. The resultant blend was compressed into tablets.

Comparative examples of tablets containing microcrvstalline cellulose

Comparative example F5: Tablets containing tadalafil co-precipitate with HPMCP HP-50 with water soluble mannitol and water insoluble swellable microcrvstalline cellulose as diluent 

Tadalafil co-precipitate with HPMCP HP-50 was homogeneously mixed with mannitol, microcrystalline cellulose, croscarmellose sodium and sodium lauryl sulphate. The magnesium stearate was added and mixed. The resultant blend was compressed into tablets. Dissolution profile of the example is shown in Figure 1.

Comparative example F6: Tablets containing tadalafil co-precipitate with HPMCP HP-50 with water soluble lactose anhydrous and water insoluble swellable microcrystalline cellulose as diluent

Tadalafil co-precipitate with HPMCP HP-50 was homogeneously mixed with lactose anhydrous, microcrystalline cellulose, croscarmellose sodium and sodium lauryl sulphate. The magnesium stearate was added and mixed. The resultant blend was compressed into tablets. Dissolution profile of the example is shown in Figure 1.

Comparative example F7: Tablets containing tadalafil co-precipitate with HPMCP HP-50 with water soluble lactose monohydrate and spray dried lactose and water insoluble swellable microcrystalline cellulose as diluent

Tadalafil co-precipitate with HPMCP HP-50 was homogeneously mixed with lactose monohydrate, spray dried lactose, microcrystalline cellulose, croscarmeilose sodium and sodium lauryl sulphate. The magnesium stearate was added and mixed. The resultant blend was compressed into tablets. Dissolution profile of the example is shown in Figure 1.

Comparative example F8: Tablets containing tadalafil co-precipitate with HPMCP HP-50 with water insoluble non-swellable calcium phosphate and water insoluble swellable microcrystalline cellulose as diluent

Tadalafil co-precipitate with HPMCP HP-50 was homogeneously mixed with calcium phosphate, microcrystalline cellulose, croscarmellose sodium and sodium lauryl sulphate. The magnesium stearate was added and mixed. The resultant blend was compressed into tablets. Dissolution profile of the example is shown in Figure 1.

Comparative example F9: Tablets containing tadalafil co-precipitate with HPMCP HP-50 with only water insoluble swellable microcrystalline cellulose as diluent

Tadalafil co-precipitate with HPMCP HP-50 was homogeneously mixed with microcrystalline cellulose, croscarmellose sodium and sodium lauryl sulphate. The magnesium stearate was added and mixed. The resultant blend was compressed into tablets. Dissolution profile of the example is shown in Figure 1.

Comparative example F10: Tablets containing tadalafil co-precipitate with HPMCP HP-50 with water insoluble swellable microcrystalline cellulose and cellactose as diluents

Tadalafil co-precipitate with HPMCP HP-50 was homogeneously mixed with microcrystalline cellulose, cellactose, croscarmellose sodium and sodium lauryl sulphate. The magnesium stearate was added and mixed. The resultant blend was compressed into tablets. Dissolution profile of the example F10 is shown in Figure 2, together with dissolution profiles of the same sample, taken after two months at 22°C and 60% RH.

In comparison, dissolution profile of composition according to invention is unaffected by storage at 40°C/75% for one month (Figure 2).

The aforementioned tablet formulations were film-coated with a film-coating dispersion containing:

Figures 1 and 2 show dissolution profiles of tablet formulations comprising tadalafil co-precipitates prepared according to listed examples. Dissolution conditions comprise: basket apparatus (USP I), 100 RPM, 0.1M HCI + 0.2% SDS, 900 mL

Krka, tovarna zdravil, d.d., Novo mesto  

Raziskovalna in razvojna dejavnost na drugih področjih naravoslovja in tehnologije

 

Address: Šmarješka cesta 6, 8501 Novo mesto, Slovenia

/////////WO 2016012539, KRKA, D.D., NOVO MESTO, tadalafil, new patent

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WO 2016011767, New patent, Clopidogrel, SHENZHEN SALUBRIS/ HUIZHOU SALUBRIS

WO 2016011767

SHENZHEN SALUBRIS PHARMACEUTICALS CO.,LTD [CN/CN]; 37F Main Tower, Lvjing plaza, Che Gong Miao, No. 6009 Shennan Road, Futian District Shenzhen, Guangdong 518040 (CN).
HUIZHOU SALUBRIS PHARMACEUTICALS CO.,LTD. [CN/CN]; No.42, West petrochemical Avenue, West District，Huizhou DayaBay Huizhou, Guangdong 516083 (CN)

LI, Haidong; (CN).
TAN, Duanming; (CN).
WANG, Hai; (CN)

Provided is a preparation method for high purity clopidogrel and salt thereof. In the present method, inorganic acid solution is used to wash an organic phase containing clopidogrel till a specific pH value range is reached; during the post-processing stage, impurities including TTP can be removed from the clopidogrel product. The ensuing refining step can be avoided, thereby simplifying production techniques and ensuring the quality of the clopidogrel product.

Clopidogrel, molecular formula: C ₁₆ H ₁₆ ClNO ₂ S, it is an inhibitor of induced platelet aggregation by inhibiting platelet aggregation reduces the chance of arterial obstruction, to prevent stroke and heart attack efficacy, and can effectively treatment and prevention of atherosclerosis. Clopidogrel clinical use for right-handed body, clinical sulfate administered in the form of finished products on the domestic market clopidogrel main Plavix (Plavix) and Techno.

Currently it reported a variety of synthetic methods clopidogrel or a salt thereof, may be optically active or racemic α- substituted-o-chlorophenyl-acetate as a raw material, and 4,5,6,7-tetrahydro-thieno [3, 2-c] pyridine or a salt thereof under basic conditions to afford the optically active or racemic clopidogrel or a salt thereof, and further in line with the preparation of pharmaceutically acceptable Clopidogrel sulfate API standards.

Chinese Patent CN200810142388.3 using α- dextrose substituted benzenesulfonic substituted-o-chlorophenyl-acetate prepared above dextrorotatory clopidogrel free base, the process with ethyl acetate as the reaction solvent, followed by treatment using the organic phase washed with water The method of removing impurities.

Chinese Patent CN201310167933.5 prepared using the above racemic Clopidogrel hydrochloride, the method with dichloromethane as the solvent, after the reaction was washed with water and the organic layer was evaporated to dryness, the salt in ethyl acetate to give the product.

If the above process synthesis optically active or racemic clopidogrel or a salt thereof, the reaction system there is usually residual starting material 4,5,6,7-tetrahydro-thieno [3,2-c] pyridine (referred to as "TTP ") or a salt thereof, according to the method disclosed in the prior art, after the treatment of the synthesis process commonly used water extraction - water / weak alkaline solution washed - salt-forming method, since the same TTP and clopidogrel alkaline organics neutral or alkaline solution solubility difference, and is in an acidic solution with a salt, and therefore only the wash water or weak alkaline solution generally can not be divisible TTP, usually larger residues.

 

Due to the special nature of clopidogrel API, making it even within the scope of quality control requirements of the quality standards, there are still unstable phenomenon. In the standard range of high impurity content on the one hand it can significantly affect the stability of the product, on the other hand will increase the side effects of the subsequent steps. Thus, the prior art is usually removed after the reaction by purification methods such as recrystallization include TTP including impurities, but it will increase the preparation process, in addition to loss of product due to some of the products will remain in the mother liquor caused.

From the above, in a more convenient way to remove impurities, higher purity, better stability of clopidogrel and its salts are existing technology is not yet resolved. The present invention is a departure from the deficiencies of the prior art, provides a method for preparing high purity clopidogrel and its salts, which can be removed after the treatment stage the majority of clopidogrel impurities in the product, avoiding the subsequent refining step In simplifying the production process, while ensuring the quality of clopidogrel products.

Example 1 (racemic clopidogrel hydrochloride monohydrate) Example

China Patent CN201310167933.5 using the method disclosed in Example 19 preparation of racemic clopidogrel. In TTP and α- bromo-o-chlorophenyl acetate The reaction was refluxed for 4h after the organic phase was separated, the methylene chloride solution of racemic clopidogrel. With stirring was added 5% hydrochloric acid (pH approximately 0), the aqueous phase until the pH stabilized around 4. The phases were separated and the organic phase the solvent was evaporated under reduced pressure, 75ml of ethyl acetate was added to dissolve, added dropwise with stirring 6.6g 36% hydrochloric acid to precipitate crystals. 2h After filtration, the filter cake washed with ethyl acetate. After drying in vacuo to give 17.2g white crystals. Using the same test conditions and CN201310167933.5 testing product purity of 99.8% containing impurities TTP 0.011% (area normalization method).

Example 2 (racemic clopidogrel hydrochloride monohydrate)

China Patent CN201310167933.5 using the method disclosed in Example 19 preparation of racemic clopidogrel. In TTP with α- bromo-o-chlorophenyl acetate reflux 4h reaction after the separation of the organic phase. The organic phase the solvent was evaporated under reduced pressure, 75ml of ethyl acetate was added to dissolve. 5% hydrochloric acid was added with stirring, until the aqueous phase pH stabilized around 3. Phase, the organic phase was added dropwise with stirring to 6.6g 36% hydrochloric acid to crystallize. 2h After filtration, the filter cake washed with ethyl acetate. After drying under vacuum to give 17.0g white crystals. Product purity was 99.7% containing impurities, TTP 0.014% (detecting method as in Example 1).

Example 3 (right-handed clopidogrel hydrogen sulfate)

The TTP hydrochloride 26.4g (0.15mol), ethyl acetate 50ml, 80ml mixing water and potassium carbonate 22g, stirred for 20 minutes. Joined by R-α- methyl tosylate Chloromandelic 34.1g (0.1mol) mixture of ethyl acetate and 50ml solution. The reaction temperature was raised to 45 ℃ 4h, then the reaction was heated to 60 ℃ to R-α- methyl tosylate Chloromandelic completely consumed (about 3h). Cooled to room temperature phase.

The organic phase was added with stirring to a 5% aqueous sulfuric acid until the pH of the aqueous phase is stable at around 3. After stirring 10min static phase separation. Then dried over anhydrous magnesium sulfate, and evaporated to dryness to give 30.6g dextrose clopidogrel hydrogen sulfate. Purity 98.6% by HPLC, spectrum display free of impurities TTP.

 

 

//////WO 2016011767, New patent,Clopidogrel, SHENZHEN SALUBRIS,  HUIZHOU SALUBRIS

WO 2015031595, A PROCESS FOR PREPARATION OF SAXAGLIPTIN AND ITS HYDROCHLORIDE SALT, AMNEAL

WO2015031595,  A PROCESS FOR PREPARATION OF SAXAGLIPTIN AND ITS HYDROCHLORIDE SALT 
https://patentscope.wipo.int/search/en/detail.jsf?docId=WO2015031595

AMNEAL PHARMACEUTICALS LLC





KUMAR, Agarwal Virendra; (IN).
BADRULHUSAN, Siddiqui Arif; (IN).
KESHAV, Kataria Lalit; (IN).
SUBODHBHAI, Maheta Abhay; (IN).
CHANGANBHAI, Butani Pankaj; (IN).
PRABHAKARRAO, Patil Shashikant; (IN).
YASHWANT, Patil Tushar; (IN).
SURYAKANT, Deore Ganesh; (IN).
JAHYANTIBHAI, Pansuriya Ketan; (IN).
SURESHBHAI, Patel Hitesh; (IN).
BADHABHAI, Sondharava Lalit; (IN)

Described is an improved and industrially feasible process for the preparation of Saxagliptin or its hydrochloride salt. Also described are the novel intermediates and their use in the preparation of Saxagliptin or its hydrochloride salt.

Dipepeptidyl peptidase IV inhibitors (DPP-IV inhibitors) are a class of oral hypoglycemic agents that block the enzyme DPP-rV and have been used to treat diabetes mellitus type 2. Saxagliptin has the chemical names (l_lS',3_lS^,,5_lS^,)-2-[2(_lS^,)-2-amino-2-(3-hydroxy-adamantan- l-yl)acetyl]-2-azabicyclo[3.1.0]hexane-3-carbonitrile or (lS,3S,5S)-2-[(2S)-2- 3 7

amino-2-(3-hydroxytricyclo[3.3.1.1 ' ]dec- l-yl)acetyl]-2-azabicyclo[3.1.0]hexane-3-carbonitrile and the structural formula [I] . It is an orally active reversible DPP-IV inhibitor that is the active ingredient in the form of its hydrochloride salt in the ONGLYZA® tablet products originally developed by Bristol-Myers S uibb, and now marketed by AstraZeneca.

 

Saxagliptin and its hydrochloride and trifluoroacetic acid salts are disclosed in U.S. Patent 6,395,767. U.S. Patent 7,420,079 and U.S. Patent 8,278,462 disclose a process for the preparation of saxagliptin, its hydrochloride salt, trifluoroacetate, and benzoate salts, and saxagliptin monohydrate. U.S. Patent 7,705,033 discloses a process for the preparation of saxagliptin monohydrate. U.S. Patent 7,214,702 discloses a process for the preparation of saxagliptin or its hydrochloride salt.

The above documents disclose a process for the preparation of saxagliptin, which involves condensation of 2-aza-bicyclo[3.1.0]hexane-3-carboxylic acid amide with adamantan-1-yl-tert-butoxycarbonylamino acetic acid.

U.S. Patent 7,186,846 discloses a process for the preparation of saxagliptin which involves reacting 2-aza-bicyclo[3.1.0]hexane-3-carbonitrile with trifhioroacetic acid 3-[carboxy-(2,2,2-trifluoroacetylamino)-methyl]adamantan-l-yl ester, followed by reductive cleavage of protected saxagliptin.

Hiroshi Fukushima et al., "Synthesis and Structure- Activity Relationships of Potent 1- (2-Substituted-aminoacetyl)-4-fluoro-2-cyanopyrrolidine Dipeptidyl Peptidase IV Inhibitors," Chemical and Pharmaceutical Bulletin, Vol. 56(8), pages 1110-1117 (2008), reports the instability of 2-cyanofluoropyrrolidine derivatives at pH 6-8, due to intramolecular cyclization of basic nitrogen to a cyano group, leading to the formation of cyclic amidine which further transforms to diketopiperazine derivatives. Saxagliptin, being a 2-cyanopyrrolidine derivative, may undergo intramolecular cyclization to form a cyclic amidine.

The above reported processes suffer from the drawback that the tert-butyloxy carbonyl ("BOC") group is too sensitive in acidic conditions, which exist during the condensation of 2-aza-bicyclo[3.1.0]hexane-3-carboxylic acid amide with adamantan-l-yl-tert-butoxycarbonylamino acetic acid, which leads to formation of unwanted impurities. Further, deprotection of BOC requires harsh and more acidic conditions. Moreover, using BOC as a protecting group makes the reaction monitoring difficult using thin layer chromatography ("TLC" ) and tedious since it is less sensitive to ultraviolet ("UV"). BOC also is relatively expensive, making the process not viable industrially.

Indian Application 2065/CHE/2012 discloses a process for the preparation of saxagliptin which involves the use of the benzyloxy carbonyl group ("CBZ") for protection of the amino group. However, CBZ deprotection would eventually lead to saxagliptin, which by itself is unstable and prone to intramolecular cyclization. Moreover, CBZ is difficult to handle on an industrial scale because of its liquid state and lacrimating properties.

Scheme-I

 

In yet another aspect, the present invention provides a process for preparation of saxagliptin hydrochloride as depicted in the scheme-II below.

Scheme-II

 

Potassium Carbonate

 

The following examples are provided only for the purpose of illustrating certain specific aspects and embodiments of the present invention and should not be considered as limiting the scope or spirit of the invention in any manner.

Example 1

Preparation of (lS)-a-amino-3-hydroxyadamantane-acetic acid hydrochloride

A solution of (lS)-l-[[(l,l-Dimethylethoxy)carbonyl]amino]-3-hydroxyadamantane-l-acetic acid (1.0 g) in dichloromethane (10 ml) at 10-20°C was mixed with 20-25% isopropanol-HCl (2 ml) and stirred at 25-35°C for 8 hours. Solvent was evaporated from the reaction mixture to give the product (lS)-a-amino-3-hydroxyadamantane-acetic acid hydrochloride as a solid (0.72 g). (Yield: 90.0%)

Example 2

Preparation of (lS)-l-[triphenylmethyl amino]-3-hydroxyadamantane-l-acetic acid

A solution of (lS)-a-amino-3-hydroxyadamantane-acetic acid (1.0 g) in dichloromethane (10 ml) at 15-25°C was mixed with triethylamine (1.18 ml) and triphenylmethyl chloride (1.2 g). The reaction mixture was stirred at 25-35°C for 4 hours. Solvent was evaporated from the reaction mixture to give the product (lS)-l-[triphenylmethyl amino] -3-hydroxyadamantane-l-acetic acid (1.24 g). (Yield: 70.0%)

Example 3

Preparation of methanesulfonic acid salt of (lS,3S,5S)-2-azabicyclo[3.1.0]hexane-3-carboxamide

Tert-butyl (lS,3S,5S)-3-carbamoyl-2-azabicyclo[3.1.0]hexane-2-carboxylate (100 g, 0.442 mole) was combined with isopropyl alcohol (600 ml), with stirring at 25-30°C. The mixture was heated to 60-70°C and methanesulfonic acid (55.2 g, 0.575 mole) was added in small amounts over 60 minutes. The mixture was stirred for 4 hours at 60-70°C. Completion of the reaction was confirmed using TLC. The mixture was cooled to 5-15°C and stirred for 1 hour.

The mixture was filtered and the solid was washed with chilled isopropyl alcohol (2x50 ml). The filtrate was dried under vacuum to obtain the methanesulfonic acid salt of (lS,3S,5S)-2-azabicyclo[3.1.0]hexane-3-carboxamide. (Yield=96.7%; HPLC purity= 96%)

Mass: 434 [M+H]⁺

1H-NMR (CDCI₃) δ: 6.96 (1 H, s), 5.68 (1 H, s), 5.39-5.42 (1 H, d), 4.88-4.91 (1 H, dd), 4.52-4.54 (1 H, d), 3.67-3.70 (1 H, m), 2.50-2.53 (1 H, dd), 2.22 (2 H, s), 2.03 (1 H, s), 1.47-1.75 (15 H, m), 1.41 (9 H, s), 1.24 (1 H, s), 0.81-0.95 (2 H, m)

Example 4

Preparation of (lS,3S,5S)-2-[(2S)-2-triphenylmethylamino-2-(3-hydroxyadamantan-l-yl)acetyl]-2-azabicyclo[3.1.0]hexane-3-carboxamide

A solution of (lS)-l-[triphenylmethyl amino] -3-hydroxyadamantane-l -acetic acid (1.0 g), (1S,3S, 5S)-2-azabicyclo [3.1.0]-hexane-3-carboxamide methanesulphonate (0.47 g), 1-hydroxybenzotriazole monohydrate (HOBt^»H20) (0.08 g), dichloromethane (5 ml), and triethyl amine (0.4 ml) at 5-15°C was combined with triethylamine (0.65 ml) and l-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC.HC1) (0.5 g) and stirred at ambient temperature (25-35°C) for 12 hours. Completion of the reaction was verified using TLC. The reaction mixture was successively washed with water (5 ml), IN HC1 (5 ml), 5% aqueous sodium bicarbonate solution (3x5 ml), and then with brine (5 ml). The solvent from the organic phase was evaporated to give a residue. To the residue was added toluene (5 ml) and water (5 ml) and the mixture was heated to 45-55°C and maintained for 1 hour. The mixture was cooled to 25°C, stirred for 2 hours and filtered. The solid was washed with toluene (2 ml) and dried at 50-60°C in an oven to give the title compound (0.984 g). (Yield: 80.0%)

Example 5

Preparation of (lS,3S,5S)-2-[(2S)-2-(tritylamino)-2-(3-hydroxyadamantan-l-yl)acetyl]-2-azabicyclo[3.1.0]hexane-3-carboxamide

l-Ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC.HC1) (1.2 eq., 12.3 g) was added in portions to a solution of 3-hydroxyadamantane-l-yl (lS)-tritylamino-acetic acid

(25.0 g) in tetrahydrofuran (175 ml) and stirred for 15 minutes. 1 -Hydroxybenzotriazole monohydrate (HOBt^»H20) (1.0 eq., 8.2 g) and (1S,3S, 5S)-2-azabicyclo [3.1.0]-hexane-3-carboxamide methanesulphonate (1.0 eq., 11.88 g) were added to the mixture in portions.

Triethyl amine (3.2 eq., 17.28 g) was added dropwise to the reaction mixture over 20 minutes. The reaction mixture was stirred at 25°C for 5 hours. Completion of the reaction was verified using TLC. The solvent was distilled from the reaction mixture to give a residue.

Dichloromethane (250 ml) and water (100 ml) were mixed with the residue and the organic

phase was separated. The organic phase was washed with aqueous dilute HC1 (100 ml), aqueous 10% sodium bicarbonate solution (100 ml), and then with brine (100 ml). The organic phase was dried over sodium sulfate and the solvent evaporated to give a residue, which was dried under high vacuum at 30-40°C for 2 hours to obtain (lS,3S,5S)-2-[(2S)-2-(tritylamino)-2-(3-hydroxyadamantan-l-yl)acetyl]-2-azabicyclo[3.1.0]hexane-3-carboxamide (18.0 g). (Yield: 59%)

Example 6

Preparation of (lS,3S,5S)-2-[(2S)-2-tritylamino-2-(3-hydroxyadamantan-l-yl)acetyl]-2-azabicyclo[3.1.0]hexane-3-carboxamide

Tert-butoxycarbonylamino-(3-hydroxy-adamantan-l-yl)-acetic acid (100 g; 0.307 mole) was added to dichloromethane (500 ml) with stirring. The methanesulfonic acid salt of (1S,3S,5S)-2-azabicyclo[3.1.0]hexane-3-carboxamide (64.8 g; 0.292 mole) was added, and the reaction mixture was stirred for 15 minutes at 25-35°C. In a separate flask, 1-hydroxybenzotriazole monohydrate (11.8 g; 0.077 mole) and triethylamine (34.2 g) were added to dichloromethane (500 ml) and stirred to form a solution. This solution was added to the reaction mixture gradually over 30 minutes at 25-30°C. The reaction mixture was then cooled to 5-15°C, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC.HC1) (70.6 g) was added, and the mixture was stirred for 15 minutes at 5-15°C. Triethylamine (65.2 g) was added to the reaction mixture and stirred for 30 minutes. Temperature of the reaction mixture was raised to 25-35°C and stirred continuously for 12 hours. Reaction completion was confirmed by HPLC. Water (500 ml) was added, the mixture was stirred, and the organic layer was separated. The organic layer was washed with dilute hydrochloric acid solution (500 ml, prepared by adding concentrated hydrochloric acid (60 ml) to water (440 ml)), and further washed with sodium bicarbonate solution (3 times), followed by washing with sodium chloride solution. Hydrogen chloride in isopropanol (14.2% w/w, 315.6 g) was added over 60 minutes, and the mixture was stirred for 4 hours. Completion of the reaction was confirmed by HPLC. The mixture was distilled under vacuum to remove dichloromethane. Toluene was added to the residue and distilled under vacuum. Acetonitrile (400 ml) was added to the residue followed by addition of triethylamine (79.2 g) over 15 minutes with stirring. The reaction mixture was cooled to 10-20°C, and trityl chloride (72.7 g) was added gradually, followed by stirring for 2 hours. Completion of the reaction was confirmed by HPLC. The mixture was distilled under vacuum to remove acetonitrile. Toluene was added to the residue and distilled under vacuum. Toluene (500 ml) followed by water (500 ml) were added to the residue, the mixture was heated at 45-55°C and filtered and dried to obtain the product. (Yield=60.3%; HPLC purity=94%)

Mass: 576 [M+H]⁺

1H-NMR (CD₃OD) δ: 7.43-7.45 (5 H, d), 7.06-7.17 (10 H, m), 4.50 (1 H, s), 3.84-3.87 (1 H, dd), 3.42 (1 H, s), 3.09-3.13 (1 H, m), 2.87-2.91 (1 H, m), 2.15-2.23 (1 H, m), 2.09 (1 H, s), 1.90-1.92 (1 H, d), 1.42-1.77 (13 H, m), 1.19-1.22 (1 H, t), 0.72-0.76 (1 H, m), 0.50-0.55 (1H, m)

Example 7

Preparation of (lS,3S,5S)-2-[(2S)-2-tritylamino-2-(3-hydroxyadamantan-l-yl)acetyl]-2-azabicyclo[3.1.0]hexane-3-carbonitrile

A solution of (lS,3S,5S)-2-[(2S)-2-tritylamino-2-(3-hydroxyadamantan-l-yl)acetyl]-2-azabicyclo[3.1.0]hexane-3-carboxamide (15.0 g) in tetrahydrofuran (150 ml) was mixed with pyridine (12.3 g) and cooled to 0-10°C. Trifluoroacetic anhydride (19.1 g) was added to the reaction mixture slowly over 30 minutes. The reaction mixture was stirred at 0-10°C for 3 hours. Completion of the reaction was confirmed by HPLC. Aqueous potassium carbonate solution (20%, 240 ml) was added to the reaction mixture over 30 minutes to obtain pH 10-11. Methanol (50 ml) was added, and the reaction mixture was stirred at 25°C for 3 hours. Completion of the reaction was verified using TLC. The reaction mixture was cooled to 0°C and stirred for 30 minutes. The solid was filtered and washed with water (2x15 ml). The solid was dried under vacuum at 50-60°C for 8 hours to give the title compound (10.0 g). (Yield=79%; HPLC purity=99%)

Mass: 558 [M+H]⁺

1H-NMR (DMSO d₆) δ: 7.47-7.49 (6 H, d), 7.24-7.28 (6 H, t), 7.16-7.19 (3 H, t), 4.46 (1 H, s), 4.05-4.08 (1 H, dd), 3.10-3.13 (1 H, m), 2.95-2.98 (1 H, d), 2.20-2.26 (1 H, m), 2.12-2.18 (2 H, m), 1.88-1.95 (3 H, m), 1.38-1.75 (1 H, m), 0.75-0.80 (1 H, q), 0.42-0.46 (1 H, m)

Example 8

Preparation of saxagliptin hydrochloride

A mixture of aqueous hydrochloric acid (34.5% w/w) (2.3 g) and methanol (20 ml) was added to a mixture of (lS,3S,5S)-2-[(2S)-2-tritylamino-2-(3-hydroxyadamantan-l-yl)acetyl]-2-

azabicyclo[3.1.0]hexane-3-carbonitrile (10.0 g) in methanol (80 ml), and the mass was stirred at 25°C for 3 hours. Completion of the reaction was verified by HPLC. Solvent was distilled from the reaction mixture to give a residue. Ethyl acetate (100 ml) was mixed with the residue for 30 minutes at ambient temperature. The solid was filtered and washed with ethyl acetate (2x5 ml). The solid was dried under vacuum at 50-60°C for 8 hours to give the title product (6.0 g). (Yield=90 ; HPLC purity=99.5 )

Mass: 316 [M+H]⁺

1H-NMR (DMSO d₆) δ: 8.29 (3 H, s), 5.21-5.24 (1 H, dd), 4.63 (1 H, s), 4.23 (1 H, s), 4.09-4.12 (1 H, m), 2.54-2.57 (1 H, m), 2.23-2.27 (1 H, dd), 2.15 (1 H, s), 1.93-1.98 (1 H, m), 1.40-1.67 (12 H, m), 1.00-1.05 (1 H, m), 0.73-0.77 (1 H, m)

Amneal Pharmaceuticals' co-CEO Chirag Patel to be honored by the New Jersey City University Foundation - Community - The American Bazaar



Chirag Patel (c), president of Bridgewater, N.J.-based Amneal Pharmaceuticals.

///

WO 2016012927, ANAGLIPTIN HYDROCHLORIDE , NEW PATENT, LUPIN

https://patentscope.wipo.int/search/en/detail.jsf?docId=WO2016012927&redirectedID=true

WO 2016012927,  ANAGLIPTIN HYDROCHLORIDE , NEW PATENT, LUPIN

A PROCESS FOR PREPARATION OF ANAGLIPTIN HYDROCHLORIDE 



ANSARI, Shahid, Akhtar; (IN).
YADAV, Ashok, Keshavlal; (IN).
PATIL, Tushar, Yashwant; (IN).
PATHAK, Dharmendrakumar, Shripati; (IN).
BARIA, Reenaben, Ratansing; (IN).
PATIL, Shashikant, Prabhakar; (IN)


The present invention relates to process for preparing dipeptidyl peptidase IV inhibitor Anagliptin free base or its hydrochloride salt by using novel methane sulfonic acid salt of (2S)-1-{[(1-Amino-2-methylpropan-2-yl) amino] acetyl} pyrrolidine-2-carbonitrile (formula IIa). Anagliptin is used for the treatment of diabetes.

The present invention relates to process for preparing dipeptidyl peptidase IV inhibitor Anagliptin free base or its hydrochloride salt by using novel methane sulfonic acid salt of (2S)-l-{ [(l-Amino-2-methylpropan-2-yl) amino] acetyl} pyrrolidine-2-carbonitrile.

Anagliptin is used for the treatment of diabetes.

Background of the Invention:

Glucagon-like peptide- 1 (GLP-1), a thirty-amino acid peptide hormone, is secreted by intestinal L-cells in response to food ingestion and stimulates insulin secretion from b-cells in a glucose-dependent manner. GLP-1 is also known to have multiple actions such as suppression of glucagon secretion, inhibition of gastric emptying and induction of satiety. Based on these findings, GLP-1 has been considered to be an attractive target for the therapy of type 2 diabetes mellitus (T2DM). However, GLP-1 is rapidly degraded into inactive GLP-1 by a serine protease, dipeptidyl peptidase IV (DPP-IV), which fueled the development of biologically stable GLP-1 analogs. Therefore, inhibitors of DPP-IV capable of increasing the circulating concentration of active GLP- 1 have now emerged as promising treatments for T2DM. In addition, it was demonstrated in a clinical study of diabetic patients receiving active GLP- 1 infusion that a 24-h infusion of active GLP- 1 resulted in a more marked improvement in glycemic control than a 16-h infusion, and based on accumulating clinical studies, greater than 2-fold enhancement of circulating levels of active GLP-1 is known to result from inhibition of 80% or more of the plasma DPP-IV activity. Consequently, optimal glycemic control requires continuous high-level exposure to DPP-IV inhibitors.

US Patent 7,345, 180 B2 relates to one such DPP-IV inhibitor, Anagliptin Hydrochloride (Formula I). US Patent ' 180 also discloses process and intermediates for preparation of Anagliptin Hydrochloride.

Object of the invention

The object of the present invention is to provide a novel salt of methane sulfonic acid (Ila) of (2S)-l-{ [(l-Amino-2-methylpropan-2-yl) amino] acetyl} pyrrolidine-2-carbonitrile (Formula II).

Another object of the present invention is to provide a process for preparation of novel salt (Ila) of (2S)-l-{ [(l-Amino-2-methylpropan-2-yl) amino] acetyl} pyrrolidine-2-carbonitrile (Formula II).

Further object of the present invention is use of novel salt of methane sulfonic acid (Ila) of (2S)-l-{ [(l-Amino-2-methylpropan-2-yl) amino] acetyl} pyrrolidine-2-carbonitrile (Formula II) in preparation of Anagliptin free base or its hydrochloride salt.

Example 1

(2S)-l-{[(l-Amino-2-methylpropan-2-yl) amino] acetyl} pyrrolidine-2-carbonitrile methane sulfonate salt

Titled compound was prepared by adding t-butyl (S)-{2-[(2-cyanopyrrolidine-l-yl)-2-oxoethylamino]-2-methyl-l -propyl} carbamate (25. Og) to acetonitrile (150 ml) followed by drop-wise addition of methane sulfonic acid (10 g). The reaction mass was heated to 50-55 °C for 2 hours. Completion of reaction was monitored by TLC. After completion of reaction, the reaction mass was cooled to 0-5°C and stirred for 1 hour at same temperature. Obtained solid was filtered and washed with chilled acetonitrile (15ml). The obtained solid is less hydroscopic, crystalline as compared with hydrochloric salt , Wet-cake was dried under vacuum till a constant weight was obtained (22.6g, yield 91.58% purity 99.93%).

Example 2 (2S)-l-{[(l-Amino-2-methylpropan-2-yl) amino] acetyl} pyrrolidine-2-carbonitrile methane sulfonate salt

Titled compound was prepared by adding t-butyl (S)-{2-[(2-cyanopyrrolidine-l-yl)-2-oxoethylamino]-2-methyl-l -propyl} carb-amate (lOg, 0.0277) to Toluene (60ml, 6 volumes) at 25-30°C, followed by drop-wise addition of methane sulfonic acid (4.0g, 0.0416 moles) at 25-30°C. The reaction mass was heated to50-55°C for 2 hours. Completion of reaction was monitored by TLC. After completion of reaction, the reaction mass was cooled to 0-5 °C and stirred for 1 hour at same temperature. The obtained solid was filtered and washed with chilled toluene (15ml). The obtained solid is less hydroscopic, crystalline as compared with hydrochloric salt. The Wet-cake was dried under vacuum till a constant weight.

Example 3 Anagliptin free base

2-methylpyrazolo [1, 5-a] pyrimidine-6-carboxylic acid was coupled with (2S)-1-{ [(1-Amino-2-methylpropan-2-yl) amino] acetyl} pyrrolidine-2-carbonitrile methane sulfonate salt in presence of EDC.HC1, HOBT, TEA. The reaction was carried out in DCM (yield 69.3%, purity 99.73%).

Anagliptin free base could be converted to Anagliptin hydrochloride by processes as disclosed in the literature

WO 2016014324, New Patent, Omarigliptin, MERCK SHARP & DOHME CORP

Omarigliptin , MK-3102

WO2016014324, PROCESS FOR PREPARING CHIRAL DIPEPTIDYL PEPTIDASE-IV INHIBITORS

MERCK SHARP & DOHME CORP. [US/US]; 126 East Lincoln Avenue Rahway, New Jersey 07065-0907 (US).

CHUNG, John, Y. L.; (US).
PENG, Feng; (US).
CHEN, Yonggang; (US).
KASSIM, Amude Mahmoud; (US).
CHEN, Cheng-yi; (US).
MAUST, Mathew; (US).
MCLAUGHLIN, Mark; (US).
ZACUTO, Michael, J.; (US).
CHEN, Qinghao; (US).
TAN, Lushi; (US).
SONG, Zhiguo Jake; (US).
CAO, Yang; (US).
XU, Feng; (US)

A process for preparing a compound of structural Formula Ia: comprising Boc deprotection with TFA of, reductive amination of:.

The present invention is directed to a novel process for the preparation of omarigliptin, (2R,35^,,5R)-2-(2,5-difluorophenyl)-5-[2-(methylsulfonyl)-2,6-dihydropyrrolo[3,4-c]pyrazol-5(4H)-yl]tetrahydro-2H-pyran-3 -amine, a dipeptidyl peptidase-IV (DPP-4) inhibitor, for the treatment of Type 2 diabetes, and related intermediates.

BACKGROUND OF THE INVENTION

Syntheses of omarigliptin have previously been described in PCT international patent applications numbers WO 2010/056708 and WO2013/003250. The process described in WO 2010/056708 does not result in a favorable yield of the compound of structural Formula la, as it results in a racemic mixture. WO2013/003250 describes the following scheme to make the compound of structural Formula la, an intermediate for synthesizing omarigliptin:

In WO2013/003250, synthesis of the compound of structural Formula la involves using benzenesulfonic acid (BSA) to remove the Boc protecting group of the compound of structural Formula 1, by first forming a BSA salt of the compound of structural Formula la. The BSA salt is then isolated and undergoes reductive amination with Boc -ketone of the compound of structural Formula 7, to produce the compound of structural Formula la, as a 19: 1 diastereomeric mixture. The BSA mediated Boc deprotection requires up to 72 h to reach full conversion.

An alternative process which eliminates the need to isolate the BSA salt of the compound of Formula la and reduces the overall reaction time of the process is desired. The inventors have now discovered a process for making the compound of structural Formula la which eliminates the step of isolating a salt of the compound of structural Formula la and reduces the overall reaction time. The present process also produces an end-of reaction homogeneous solution via reductive amination, which facilitates crystallization of the compound of structural Formula la. The described process also improves the diastereoselectivity, overall yield, cost and cycle time over the process described in WO2013/003250.

WO2013/003250 also describes the Boc deprotection of the compound of Formula la to produce omarigliptin (Formula I) shown below. As described in WO2013/003250, the Boc deprotection of the compound of Formula la involves aging the substrate in aqueous sulfuric acid in DMAc at 30 °C for 15-20 h, then working up with ammonium hydroxide. This work up produces large amounts of poorly soluble ammonium sulfate which co-crystallizes with the desired product. As a result, isolation of the desired product requires a long cycle time for filtration, washing and drying.

Formula I (omarigliptin)

Because the processes described herein use trifluoroacetic acid with or without a co-solvent for the transformation of the compound of Formula la to omarigliptin, which offers good solubility for the compound of Formula la, omarigliptin is achieved with fast reaction kinetics and good purity profiles.

the compound of structural Formula 1 is prepared by the following processes:

reagents

and,

or alternatively

10 R = Ms

X=OAc

SCHEME 3: Synthesis of the Boc Ketone

16 17 18 19

IPA, H₂Q ,

¹⁾⁹⁵⁶

Step 1 : As

A round bottom flask was charged with ligand L (0.829 g), Cu(II) propionate

monohydrate (0.402 g) (or Cu(II) acetate (0.31 g) or CuCl or CuCl₂) and EtOH (350 ml) and agitated at room temperature for lh. 2,4-Difluorobenzaldehyde (100.0 g) was added followed by DABCO (2.368 g) (or 2,4-dimethylpiperizine) and the mixture was cooled to -5 - -15 °C. Cold (0°C) nitromethane (190 ml or 215 g) was added slowly to the cold solution and the solution was aged at -5 to -15 °C for 20-24 h and at 0 °C for 2-4h. 5 wt% EDTA^»2Na (500 ml) followed by

water (200 mL) and MTBE (1.0 L) was added to the cold solution, and the temperature was raised to 20°C. The layers were separated and the organic layer was washed with additional 5 wt% EDTA^»2Na (500 ml), followed by water (50 mL) and brine (250 mL). The organic layer, containing Compound 17, was concentrated to remove nitromethane, then the solvent was switched to THF.

Step 2: Michael-Lactolization - Nitro lactol

To Compound 17 in 2 volumes of THF (258 mL) from Step 1 under 2 and cooling at 0 °C, 1 equivalent of Hunig's base was added. 1.15 equivalents of acrolein was added over 1 h via syringe pump at 0-5 °C. The reaction was stirred at -10-0 °C overnight. The resulting mixture was used directly in the next step.

Alternatively, the mixture was concentrated at 0-5 °C to remove excess acrolein, then the residue was flushed with acetonitrile until Hunig's base and water are mostly removed. The residue was taken up in 8 volumes of acetonitrile and used directly in the next step.

Alternatively, at the end of the reaction the mixture was worked up by diluting with MTBE and washing with aqueous citric acid solution, and aqueous NaHCC solution, and the solvent was switched to acetonitrile. Alternatively, the end reaction mixture was taken forward directly to the next step.

Step 3: Dehydration - Nitro dihydropyrans

1.1 Equivalents of TEA was added to the acetonitrile solution of lactol 18 from Step 2 followed by 1.2 equivalents of mesyl chloride and 1.2 equivalents of S-collidine under < +10 °C . The reaction was aged at 10°C for 0.5-1 h. Alternatively, the end of the reaction mixture from Step 2 was cooled to between -20 °C to 0 °C. Two equivalents of S-collidine and 1.4 equivalents of mesyl chloride were then added. The mixture was heated to 36 °C and aged overnight. The mixture was cooled to room temperature. 15 volumes of MTBE was added and the solution was

washed with 3 volumes 10 wt% citric acid and 6 volumes water, 10 volumes water, then 3 volumes of 5% aHC03 solution and 6 volumes water. The organic was concentrated with 20 volumes of MTBE using 10 volumes MTBE. The organic solution was stirred with 20-30 wt% AQUAGUARD for 2 hours at room temperature. The mixture was filtered and washed with 2 volumes of MTBE.

Step 4: Dynamic Kinetic Resolution (DKR) crystallization - rraws-nitro-dihydropyran (19t)

The organic MTBE solution of Step 3 was solvent switched to 2 volumes of IPA and the final volume was -300 mL. 10 Mol% of TEA (or DAB CO or morpholine or DMAP) was added. Then water (1 15 mL) was slowly added over 3 hours. The slurry was filtered, washed with 80/20 IP A/water (2x100 mL) and vacuum dried under N₂.

Step 5: Hydroboration/oxidation - Trans-nitro-pyranol

To a vessel charged with /raws-nitro-dihydropyran (10 g), MTBE (100 mL) was added under nitrogen. The mixture was stirred at room temperature to give a clear orange solution. The solution was cooled to +2 °C and borane dimethyl sulfide complex (9.55 ml) was added. The clear solution was aged for 2-5h until >99% conversion by HPLC analysis. The reaction was slowly quenched with water (7.25 ml) keeping at < +9 °C. After the solution was aged at 5°C for 5 min, water (78 mL) was added at < +13 °C. Solid sodium percarbonate (13.26 g, 84 mmol) was added. The suspension was stirred at 5 °C for 15h. The mixture was transferred to a separatory funnel with the aid of 60 mL MTBE and 20 mL water. The mixture was allowed to warm to room temperature. The aqueous phase was back-extracted with 40 mL MTBE. The combined organic phase was washed once with 30 mL half saturated sodium chloride solution, once with 15 mL brine and 15 mL 0.2N HC1, and once with 30 mL half-saturated sodium chloride solution. The organic layer was dried over a2S04. The organic was filtered, washed with 10 mL MTBE and concentrated to an oil. The oil was diluted to 200 mL for a 0.191M solution.

Step 6: Nitro Reduction/Boc protection - Pyranol

A 3 -neck jacketed round bottom flask equipped with overhead stirrier was charged with 0.191M (5R,6S)-5-nitro-pyran-3-ol (119 ml) (Compound 20) in ethanol and ethanol (32 ml). The solution was cooled to 1 1-12 °C. Cold 6N HC1 (19.55 ml, 1 17 mmol) was added at <

+17°C. Zinc dust (12.93 g) was added in five portions (5x2.59g) at < +26 °C. The mixture was stirred at 12 °C for 22 h. 1M K₂C0₃ (76 mL) was added in one portion. MTBE (59 mL) was added then EDTA 2K 2H₂0 (22.55 g) was added over 10 min at < +14 °C. To the solution 45 wt% KOH (4.86 mL) solution was added. The solution was cooled to 5 °C, and 1.1 equivalents of B0C2O (5.46 g) was added. The solution was rinsed with MTBE (10 mL) and stirred at 5 °C for 2h, then at 12 °C for 16h, and then at 24 °C for lOh until >99.5% conversion. The solution was transferred to a separatory funnel with the aid of MTBE (30 mL) and water (5 mL). The organic layer was filtered and washed with MTBE (20 mL). The organic filtrate was concentrated. MTBE (60 mL), water (30 mL) and saturated sodium chloride solution (15 mL) were added. The mixture was warmed in a 30 °C bath to dissolve solid, and then concentrated. The concentrate was flushed with toluene in a 60 °C bath, then concentrated. Toluene (8.4 mL) was added and the mixture was heated to 80 °C. Heptane (70.8 mL) was added over lh at 80 °C, then cooled slowly to room temperature. The mixture was filtered and washed with 1 :2 toluene/heptane (23.55 mL), filterated and vacuum dried under nitrogen until a constant weight.

The purity could be further upgraded by the following procedure: a round bottom flask was charged with the product of Step 6 (7.069 g) from above. EtOH (21 mL) was added and the mixture was heated to 45 °C. Water (31.5 mL) was slowly added over 1 h at 45 °C. The mixture was aged for lh. Water (31.5 mL) was added in one portion, then cooled slowly to room temperature and aged overnight. The slurry was filtered and washed with 1 :3.5 EtOH/water (23.56 mL). Crystals were vacuum dried under nitrogen until a constant weight.

Alternatively, Compound 20 was reduced with 100 psi hydrogen in 20 volume wet THF in the presence of 10-30 wt% Raney nickel at 50 °C. Then the reaction mixture was basified with 2 equivalent of K2CO₃ and a slight execess B0C2O to afford crude Compound 21 after aqueous work up.

Compound 7 was obtained from 21via oxidation as described in WO2013/003250.

S

Boc-mesyl-pyrazole solid 1 was added to 2.5 volumes of TFA at 0-2 °C, over 2-3 minutes under nitrogen, followed by 0.5 volume of TFA rinse. Conversion to TFA salt was complete within 0.5-lh at 1-2 °C. DMAc (14 vol) followed by triethylamine (5 equivalents or 2.3 volumes) were slowly added to the TFA reaction mixture at 0 °C maintaining < +20 °C. Boc-ketone 7 (0.89 equivalent) was then added at -15 °C followed by solid NaBH(OAc)₃ (1.4 equivalents) which was added in three portions over lh. The reaction solution was aged at -15 °C overnight. The solution was then warmed to 22 °C, and after aging for 2-5 h. Diastereomeric ratio was > 96.5:3.5.

The solution was seeded with Boc amine 1 wt% at 22 °C and stirred at 22-40 °C for 2-4 h. 0.36 volume 28% ammonium hydroxide was added over 2-4 h, then, 3.64 volumes 28% ammonium hydroxide was added over 4-10h at 22-60 °C. After cooling to 22 °C, the batch was filtered, washed with 5: 1 DMAc/water, then water. The wet cake was vacuum dried under nitrogen at ambient affording the product. Diastereoselectivity was > 30: 1.

Boc Deprotection of Formula la

A reactor was charged with 2.5 X (by volume) of trifluoroacetic acid. The batch was cooled to 5-10 °C. The reactor was then charged with 0.4 X (by volume) water. The batch was cooled to 0-5 °C. The reactor was then charged with 1 equivalent (1 kg) of the compound of Formula la over 0.5-lh while maintaining the temperature between 0 -5°C. The reactor was then charged with 0.5 X (by volume) trifluoroacetic acid to reactor while maintaining the temperature between 0-5°C. The batch was then heated between 15-20°C and aged for 2-2.5 h. The batch was then cooled to between 5-10°C. A crystallizer was charged with water 5.0 X (by volume) and 0.1 X (by volume) of ammonia water and adjusted to between 3-13°C. To generate a seed bed, Compound I seed (lwt% vs la) was added and the temperature as adjusted to between 3-13°C. A solution of ammonia water 3.8 X (by volume) and of the compound of Formula la was added simultaneously to the seed bed over 2.5 - 3.5 hours while maintaining temperature at 3-13°C and pH -9-10. The batch was aged for at least 30 minutes and then filtered. The resulting crystals were washed with 3. OX (by volume) water at 3 - 13°C twice and vacuum dried at < 50°C to afford the compound of formula I.

//////WO 2016014324, New Patent, Omarigliptin, MERCK SHARP & DOHME CORP, MK-3102