澳格列汀, SP2086, Retagliptin 1174122-54-3(Retagliptin), 1174038-86-8 (Retagliptin Hydrochloride), 1256756-88-3（Retagliptin Phosphate) (R)-7-[3-amino-4-(2,4,5-trifluoro-phenyl)-butyryl]-3-trifluoromethyl-5,6,7, 8-tetrahydro-imidazo[1,5-a]pyrazine-1-carboxylic acid methyl ester Methyl (R)-7-[3-amino-4-(2,4,5-trifluoro-phenyl)-butyryl]-3-trifluoromethyl-5,6,7,8-tetrahydro-imidazo [1,5-a]pyrazine-1-carboxylate, DPP-4 inhibitor Type II diabetes

  Nanjing Changao Pharmaceutical 澳格列汀 is a novel DPP-4 inhibitor (gliptin) for the treatment of type II diabetes. Because Shanghai Sun Sail Pharmaceutical, a wholly owned subsidiary of Nanjing Changao Pharmaceutical, has filed two patents to protect DPP-4 inhibitors (WO2011147207 and CN101786978), it is unknown which one covers this drug. Relevant data’s from WHO showed morbidity rate, disability rate, death rate of diabetes mellitus and overall health level of diabetes mellitus patients have already ranked the third place in non-infectious diseases, diabetes, together with tumors and cardiovascular diseases were the three main diseases which threats human health. Diabetes mellitus is usually classified into type 1 and type 2, there are more than 240 million diabetes patients, and 90% of them are suffering from type 2 diabetes, which also has a 1% growth rate every year, so, type 2 diabetes will be the main new growth point of diabetes drug market. The incidence of diabetes in China is about 5%, the number of patients of which ranks second place in the world just behind India. There are many antidiabetic drugs on the market, insulin injection, metformin, rosiglitazone, pioglitazone are representations of them. However, there is no drug alone can keep the HbA1c level of type 2 diabetes patients within the aimed range in a long term. Even though used in combination, the effect of the drugs will go down year by year after 3-4 years. Adverse reaction is one of the problems of many hypoglycemic drugs, wherein the fatal hypoglycemia is most worried by clinicians; secondly, many oral hypoglycemic drugs, such as sulfonylureas, α-glycosidase inhibitors and thiazolidinediones may all induce weight gain to patients, some of the drugs may also induce cardiovascular diseases. Therefore, developing new type hypoglycemic drugs with brand new mechanism of action, higher safety and effectiveness is an important task that should be completed quickly for the scientists. In the process of constantly finding new methods endocrine hormones were found to play an important role in the pathology and physiology of type 2 diabetes. Dipeptidyl peptidase-IV (DPP-IV) is an important enzyme related to diabetes, inhibiting the action of which to treat type 2 diabetes is a new method with good prospect. DPP-IV inhibitors can indirectly stimulate the secretion of insulin, the action of which is generated by inhibit DPP-IV to stabilize endocrine hormones such as incretin hormones, glucagons-like-peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP). GLP-1 is a production expressed by glucagon protogene after eating, and mainly secreted by intestinal mucosa L-cell, and it can stimulate the secretion of insulin by pancreatic β-cells, which plays a significant role in the stability of blood sugar. Experiments prove that GLP-1 has physiological functions as following: acting on pancreatic β-cells in a glucose-dependent manner, facilitating the transcription of insulin genes, increasing the biosynthesis and secretion of insulin, stimulating the proliferation and differentiation of β-cells, inhibiting the apoptosis of β-cells to increasing the number of pancreatic β-cells; inhibiting the secretion of glucagon; inhibiting the appetite and food intake; retarding the emptying of gastric contents, etc., all of these functions are helpful to reduce blood sugar after food intake and to keep blood sugar within constant level. In addition, it won’t cause the danger of severe hypoglycemia. GLP-1 well controlled the blood sugar of type 2 diabetes animal models and patients by multiple mechanisms. However, GLP-1 may lose biological activity through quick degradation by DPP-IV, and the half life of it is shorter than 2 minutes, which utterly limits the clinical use of GLP-1. It was found in researches that DPP-IV inhibitors can totally protect endogenous and even extraneous GLP-1 from inactivation by DPP-IV, improve activated GLP-llevel, and reduce the antagonistic effect of GLP-1 metabolites. Moreover, DPP-IV inhibitors can also delay the incidence of diabetes through stimulating the regeneration of pancreatic β-cells and the improving the glucose tolerance and insulin sensitivity. Dipeptidyl peptidase-IV (DPP-IV) inhibitors represent a novel class of agents that are being developed for the treatment or improvement in glycemic control in patients with Type 2 diabetes. For reviews on the application of DPP-IV inhibitors for the treatment of Type 2 diabetes, reference is made to the following publications: (1) H.-U.Demuth.et al. “Type 2 diabetes-Therapy with dipeptidyl peptidase IV inhibitors“, Biochim.Biophvs. Acta. 1751:33-44 (2005) and (2) K.Augustyns. et al. “Inhibitors of proline-specific dipeptidyl peptidases: DPP4 inhibitors as a novel approach for the treatment of Type 2 diabetes“, Expert Opin. Ther. Patents, 15:1387-1407 (2005). At present, some DPP-IV inhibitors have been disclosed ( US5462928 , US5543396 , WO9515309 ,WO2003004498 , WO2003082817 , WO2004032836 , WO2004085661 ), including MK-0431 as an DPP-IV inhibitor made by Merck which showed good inhibition activity and selectivity, and which has been on the market by 2006.

• sitagliptin

  (R)-7-[3-amino-4-(2,4,5-trifluoro-phenyl)-butyryl]-3-trifluoromethyl-5,6,7, 8-tetrahydro-imidazo[1,5-a]pyrazine-1-carboxylic acid methyl ester of the following formula is compound A, the code of which is SP2086.

  

courtesy yaopha see enlarged image at http://www.yaopha.com/2014/02/10/chemical-structure-and-synthesis-of-hengrui-medicines-diabetes-drug-retagliptin/ …………………………………………………………..

EP2436684A1

http://www.google.com/patents/EP2436684A1?cl=en

Example 1. Preparation of hydrochloride of compound A (SP2086-HCL)
(R)-7-[3-t-butoxycarbonylamino-4-(2,4,5-trifluoro-phenyl)-butyryl]-3-trifluoromethyl-5,6,7,8-tetrahydro-imidazo[1,5-a]pyrazine-1-carboxylic acid methyl ester (SM2086-15) (1.35kg, 2.40mol), HCL-ethyl acetate (greater than 2M) (12.3kg) were added into a 100L reaction kettle and stirred to dissolved. The mixture was reacted for more than 2 hours at normal temperature. Detected with TLC to reaction completely before evaporated and pumped to dryness with oil pump to give 1.15∼1.20kg of white to light yellow solid product with [α]

_D²⁰

-28.0∼-33.0° (C=1, methanol), yield 96.0∼100%. The product was hydrochloride of (R)-7-[3-amino-4-(2,4,5-trifluoro-phenyl)-butyryl]-3-trifluoromethyl-5,6,7, 8-tetrahydro-imidazo[1,5-a]pyrazine-1-carboxylic acid methyl ester (SP2086-HCL). (TLC detection: silica gel GF254plate; developing reagent: chloroform: methanol: ammonia= 40: 1: 0.1; raw material 15: Rf=0.80, product 1: Rf=0.50; ultraviolet visualization).

Example 2. Preparation of phosphate of compound A (SP2086-HPO4)

• SP2086-HCL(1.20kg, 2.40mol) was added into 100L reaction kettle, and dissolved in dichloromethane (15.2kg), then washed with saturated sodium bicarbonate solution (5.8kg). The aqueous layer was extracted once with dichloromethane ( 6.0 kg). The organic layers were combined and washed once with water (5kg), dried with anhydrous sodium sulphate. The mixture was filtrated and concentrated to dryness under reduced pressure at 40°C to give 1.12 kg of oil. The oil was stirred and dissolved with 30 times amount of isopropanol (26.0kg). A solution of 85% phosphoric acid (305.2g, 2.65mol) in isopropanol (1.22kg) was added immidiately after the oil completely dissolved. The solid was separated out, filtered after stirring for 2 hours and washed with cold isopropanol. The wet product was dried under reduced pressure at 40°C to give 1.16∼1.24kg of white to light yellow solid with a yield of 86.0∼92.0% (the wet product could be directly suspended in isopropanol without drying).

……………………………………… http://www.google.com/patents/EP2230241A1?cl=en Example 1(R)-7-[3-Amino-4-(2,4,5-trifluoro-phenyl)-butyryl]-3-trifluoromethyl-5,6,7,8-tetrahydro-imidazo[1,5-a]pyrazine-1-carboxylic acid methyl ester hydrochloride

Step 1

• 2,2-Dimethyl-5-[2-(2,4,5-trifluoro-phenyl)-acetyl]-[1,3]dioxane-4,6-dione 2,2-Dimethyl-[1,3]dioxane-4,6-dione (5.69 g, 39.5 mmol) was dissolved in 400 mL of dichloromethane under stirring, followed by addition of (2,4,5-trifluoro-phenyl)-acetic acid 1a (7.15 g, 37.6 mmol) and 4-dimethylaminopyridine (7.35 g, 60.2 mmol) in an ice-water bath. Then a suspension of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (8.28 g, 43.2 mmol) in 250 mL of dichloromethane was added dropwise slowly. After stirring at room temperature for 36 hours, the reaction mixture was washed with the solution of 5% potassium bisulfate (250 mL×7) and saturated brine (250 mL×2), dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to obtain the title compound 2,2-dimethyl-5-[2-(2,4,5-trifluoro-phenyl)-acetyl]-[1,3]dioxane-4,6-dione 1b (11.4 g, yield 96%) as a white solid. MS m/z (ESI): 315.5 [M-1]

Step 23-Oxo-4-(2,4,5-trifluoro-phenyl)-butyric acid ethyl ester

• 2,2-Dimethyl-5-[2-(2,4,5-trifluoro-phenyl)-acetyl]-[1,3]dioxane-4,6-dione 1b (15.72 g, 49.6 mmol) was dissolved in 280 mL of ethanol under stirring, then the reaction mixture was heated to 70 °C in an oil bath overnight. After cooling, the mixture was concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography to obtain the title compound 3-oxo-4-(2,4,5-trifluoro-phenyl)-butyric acid ethyl ester 1c (12 g, yield 88%) as a yellow oil. MS m/z (ESI): 259 [M-1]

Step 33-Amino-4-(2,4,5-trifluoro-phenyl)-but-2-enoic acid ethyl ester

• 3-Oxo-4-(2,4,5-trifluoro-phenyl)-butyric acid ethyl ester 1c (24.6 g, 94.5 mmol) was dissolved in 240 mL of methanol, and ammonium acetate (36.4 g, 473 mmol) was added to the solution. The reaction mixture was heated to reflux for 3 hours and monitored by thin layer chromatography until the disappearance of the starting materials. The reaction mixture was concentrated under reduced pressure, then 100 mL of water was added to the residue. The mixture was extracted with ethyl acetate (200 mL×3), and the combined organic phase was washed with 200 mL of saturated brine, dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to obtain a light yellow solid. The resulting solid was dissolved in 50 mL of ethyl acetate at 80 °C, then 50 mL of n-hexane and seed-crystal were added to the solution. The mixture was cooled to room temperature, half an hour later, 100 mL of n-hexane was added. The mixture was stored in refrigerator overnight and then filtered under reduced pressure to obtain the title compound 3-amino-4-(2,4,5-trifluoro-phenyl)-but-2-enoic acid ethyl ester 1d(19.5 g, yield 80%) as a white solid. MS m/z (ESI): 260.1 [M+1]Step 43-tert-Butoxycarbonylamino-4-(2,4,5-trifluoro-phenyl)-butyric acid ethyl ester

• 3-Amino-4-(2,4,5-trifluoro-phenyl)-but-2-enoic acid ethyl ester 1d (4.1 g, 15.8 mmol) was added into an autoclave, followed by addition of 70 mL of methanol, di-tert-butyl dicarbonate (3.8 g, 17.4 mmol), chloro(1, 5-cyclooctadiene)rhodium( I ) dimer (32 mg, 0.0632 mmol) and (R)-1-[(S)-2-(diphenyl phosphino)ferrocenyl]-ethyl-tert-butylphosphine (68 mg, 0.126 mmol). The reaction mixture was hydrogenated for 24 hours under 6.67 atmosphere at 30 °C. The mixture was filtered and the filtrate was concentrated under reduced pressure. Then 34 mL of methanol was added to the residue at 50 °C, followed by addition of 12 mL of water until all dissolved. After cooling to room temperature, the mixture was stored in the refrigeratory overnight and then filtered. The solid product was washed with the solvent mixture of methanol/water (v:v = 3:2), dried in vacuo to obtain the title compound 3-tert-butoxycarbonylamino-4-(2,4,5-trifluoro-phenyl)-butyric acid ethyl ester 1e (4 g, yield 70%) as a light yellow solid. MS m/z (ESI): 362.4 [M+1]Step 5(R)-3-tert-Butoxycarbonylamino-4-(2,4,5-trifluoro-phenyl)-butyric acid

• 3-tert-Butoxycarbonylamino-4-(2,4,5-trifluoro-phenyl)-butyric acid ethyl ester 1e (10 g, 27.7 mmol) and sodium hydroxide (3.32 g, 83.1 mmol) were dissolved in the solvent mixture of 100 mL of methanol and 50 mL of water under stirring. The reaction mixture was reacted at 40-45 °C for 1-1.5 hours, then part of the solution was evaporated under reduced pressure. The residue was added with some water, then pH was adjusted to 2-3 with 1 N hydrochloric acid in an ice-water bath. The mixture was extracted with ethyl acetate (200 mLx3), and the combined organic phase was washed with 200 mL of saturated brine, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure, and then recrystallized from ethyl acetate/n-hexane to obtain the title compound (R)-3-tert-butoxycarbonylamino-4-(2,4,5-trifluoro-phenyl)-butyric acid 1f (9.2 g) as a white solid, which was directly used in the next step. MS m/z (ESI): 332.3 [M-1] Reference: Tetrahedron Asymmetry, 2006, 17(2), 205-209

Step 6C-Pyrazin-2-yl-methylamine

• Pyrazine-2-carbonitrile 1g (10.5 g, 100 mmol) was dissolved in 150 mL of 1,4-dioxane under stirring, then Raney nickel (1.0 g) was added into a 250 mL autoclave. The reaction mixture was hydrogenated for 8 hours under 40 atmosphere at 60 °C, filtered and concentrated under reduced pressure to obtain the title compound C-pyrazin-2-yl-methylamine 1h (10.7 g, yield 98%) as a brown oil. MS m/z (ESI): 110 [M+1]

Step 72,2,2-Trifluoro-N-pyrazin-2-ylmethyl-acetamide

• C-Pyrazin-2-yl-methylamine 1h (10.9 g, 100 mmol) was added into a reaction flask, then 20 mL of trifluoroacetic anhydride was added dropwise slowly within an hour at 0 °C in an ice-water bath. The reaction mixture was reacted at room temperature for 2 hours and monitored by thin layer chromatography until the disappearance of the starting materials. Then it was concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography to obtain the title compound 2,2,2-trifluoro-N-pyrazin-2-ylmethyl-acetamide 1i (21.0 g) as a brown oil. MS m/z (ESI): 206.1 [M+1]

Step 83-Trifluoromethyl-imidazo[1,5-a]pyrazine

• 2,2,2-Trifluoro-N-pyrazin-2-ylmethyl-acetamide 1i (21.0 g, 100 mmol) was added into a reaction flask at room temperature, followed by addition of 100 mL of phosphorus oxychloride. After stirring at room temperature for 30 minutes, phosphorous pentoxide (17.8 g, 125 mmol) was added to the solution. The reaction mixture was heated to reflux for 5 hours and monitored by thin layer chromatography until the disappearance of the starting materials. Phosphorus oxychloride was removed, and the reaction system was quenched with deionized water. The mixture was adjusted to pH 5-6 with 20% sodium hydroxide solution in an ice-water bath. The mixture was extracted with ethyl acetate (250 mL×4), and the combined organic phase was dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography to obtain the title compound 3-trifluoromethyl-imidazo[1,5-a]pyrazine 1j (12.0 g, yield 65%) as a yellow solid. MS m/z (ESI): 188.0 [M+1] ¹H NMR (400 MHz, CDCl₃): δ 9.15 (s, 1H), 8.06 (d, 1H), 7.92 (s, 1H), 7.81 (d, 1H)

Step 93-Trifluoromethyl-5,6,7,8-tetrahydro-imidazo[1,5-a]pyrazine

• 3-Trifluoromethyl-imidazo[1,5-a]pyrazine 1j (12.0 g, 64.2 mmol) was dissolved in 150 mL of anhydrous ethanol under stirring, then 10% Pd/C (500 mg) was added to the solution. The reaction mixture was stirred at room temperature under a hydrogen atmosphere overnight. The reaction solution was filtered through a pad of coarse silica gel and concentrated under reduced pressure to obtain the title compound 3-trifluoromethyl-5,6,7,8-tetrahydro-imidazo[1,5-a]pyrazine 1k (12.2 g, yield 99%) as a brown solid. ¹H NMR (400 MHz, CDCl₃): δ 6.84 (s, 1H), 4.10 (m, 4H), 3.26 (m, 2H), 1.81 (s, 1H)

Step 10(R)-[3-Oxo-1-(2,4,5-trifluoro-benzyl)-3-(3-trifluoromethyl-5,6-dihydro-8H-imidazo [1,5-a]pyrazin-7-yl)-propyl]-carbamic acidtert-butyl ester

• Under a nitrogen atmosphere, 3-tert-butoxycarbonylamino-4-(2,4,5-trifluoro-phenyl)-butyric acid 1k (8.6 g, 45 mmol) and 9.4 mL of triethylamine were dissolved in 300 mL of dichloromethane under stirring. After stirring at room temperature for 5 minutes, 3-trifluoromethyl-5,6,7,8-tetrahydro-imidazo[1,5-a]pyrazine 1f (15.0 g, 45 mmol) and bis(2-oxo-3-oxazolidinyl)phosphonic chloride (17.1 g, 67.3 mmol) were added to the solution successively. The reaction mixture was reacted at room temperature for 2 hours and monitored by thin layer chromatography until the disappearance of the starting materials and then concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography to obtain the title compound (R)-[3-oxo-1-(2,4,5-trifluoro-benzyl)-3-(3-trifluoromethyl-5,6-dihydro-8H-imidazo[1,5-a]pyrazin-7-yl)-propyl]-carbamic acid tert-butyl ester 1l (20.0 g, yield 88%) as a white solid. ¹H NMR (400 MHz, CD₃OD): δ 7.25 (m, 1H), 7.11 (m, 1H), 7.032 (s, 1H), 4.93 (m, 2H), 4.35 (m, 3H), 4.05 (m, 2H), 2.99 (m, 2H), 2.73 (m, 2H), 1.34 (s, 9H)

Step 11(R)-[3-(1-Bromo-3-trifluoromethyl-5,6-dihydro-8H-imidazo[1,5-a]pyrazin-7-yl)-3-oxo-1-(2,4,5-trifluoro-benzyl)-propyl]-carbamic acidtert-butyl ester

• (R)-[3-Oxo-1-(2,4,5-trifluoro-benzyl)-3-(3-trifluoromethyl-5,6-dihydro-8H-imidazo[1,5-a]pyrazin-7-yl)-propyl]-carbamic acid tert-butyl ester 11 (20.0 g, 39.6 mmol) was dissolved in 300 mL of anhydrous ethanol under stirring, and 1-bromo-2,5-pyrolidinedione (14.1 g, 79.2 mmol) was then added to the solution at room temperature. After stirring for an hour, potassium carbonate (10.9 g, 79.2 mmol) and di-tert-butyl dicarbonate (8.6 g, 39.6 mmol) were added to the mixture, and the mixture was stirred for an hour and monitored by thin layer chromatography until the disappearance of the starting materials. The reaction mixture was filtered through a pad of coarse silica gel to remove potassium carbonate, and then concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography to obtain the title compound (R)-[3-oxo-1-(2,4,5-trifluoro-benzyl)-3-(1-bromo-3-trifluoromethyl-5,6-dihydro-8H-i midazo [1,5-a]pyrazin-7-yl)-propyl]-carbamic acid tert-butyl ester 1m (20.0 g, yield 86%) as a white solid. ¹H NMR (400 MHz, CDCl₃): δ 7.063 (m, 1H), 6.88 (m, 1H), 4.72 (s, 1H), 4.56 (s, 1H), 4.13 (m, 3H), 3.88 (m, 2H), 2.94 (m, 2H), 2.62 (m, 2H), 1.36 (s, 9H)

Step 12(R)-7-[3-tert-Butoxycarbonylamino-4-(2,4,5-trifluoro-phenyl)-butyryl]-3-trifluoromethyl-5,6,7,8-tetrahydro-imidazo[1,5-a]pyrazine-1-carboxylic acid methyl ester

• Octacarbonyldicobalt (4.02 g, 11.76 mmol), ethyl chloroacetate (0.71 g, 5.88 mmol), potassium carbonate (1.62 g, 11.76 mmol) and 50 mL of methanol were added into the reaction flask. After stirring for 5 minutes, (R)-[3-oxo-1-(2,4,5-trifluoro-benzyl)-3-(1-bromo-3-trifluoromethyl-5,6-dihydro-8H-imidazo[1,5-a]pyrazin-7-yl)-propyl]-carbamic acidtert-butyl ester 1m (2.3 g, 3.92 mmol) was added. The reaction mixture was reacted at 60 °C in an oil bath, and the colour of the reaction mixture turned from puce to purple. 2 hours later, Electro-Spray Ionization (ESI) mass spectrometry showed the starting material disappeared. The reaction mixture was concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography to obtain the title compound (R)-7-[3-tert-butoxycarbonylamino-4-(2,4,5-trifluoro-phenyl)-butyryl]-3-trifluoromethyl-5,6,7,8-tetrahydro-imidazo[1,5-a]pyrazine-1-carboxylic acid methyl ester 1n (1.1 g, yield 50%) as a white solid. MS m/z (ESI): 565.0 [M+1] Reference: Journal of Organometallic Chemistry, 1985, 285(1-3), 293-303

Step 13(R)-7-[3-Amino-4-(2,4,5-trifluoro-phenyl)-butyryl]-3-trifluoromethyl-5,6,7,8-tetrahydro-imidazo[1,5-a]pyrazine-1-carboxylic acid methyl ester hydrochloride

• [0064]
  (R)-7-[3-tert-Butoxycarbonylamino-4-(2,4,5-trifluoro-phenyl)-butyryl]-3-trifluoromethyl-5,6,7,8-tetrahydro-imidazo[1,5-a]pyrazine-1-carboxylic acid methyl ester 1n (0.12 g, 2.12 mmol) was added to a solution of 2.2 N hydrochloric acid in 5 mL of ethyl acetate. The reaction mixture was reacted at room temperature for 5 hours and monitored by thin layer chromatography until the disappearance of the starting materials. The reaction mixture was concentrated under reduced pressure to obtain the title compound (R)-7-[3-amino-4-(2,4,5-trifluoro-phenyl)-butyryl]-3-trifluoromethyl-5,6,7,8-tetrahydro-imidazo[1,5-a]pyrazine-1-carboxylic acid methyl ester hydrochloride 1 (0.12 g, yield 94.3%) as a light yellow solid. MS m/z (ESI): 465.2 [M+1] ¹H NMR (400 MHz, CD₃OD): δ 7.101-7.08 (m, 1H), 6.906-6.864 (m, 1H), 5.343-4.995 (m, 2H), 4.221-4.093 (m, 5H), 3.954 (s, 3H), 2.978-2.937 (m, 2H), 2.71-2.643 (m, 2H), 2.061 (s, 2H)