FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
Complete Specification [See Sections 10 and rule 13]
Title: Process for preparation of Anagliptin
Applicant: (a) INTAS Pharmaceuticals Limited (b) Nationality: Indian (c) 2nd Floor, Chinubhai Centre,
Ashram Road, Ahmedabad 380009. Gujarat. India.
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
The present invention relates to a novel process for preparation of (S)-N-(2-((2-(2-cyanopyrrolidin-l-yl)-2-oxoethy])amino)-2-methylpropyl)-2-rnethylpyrazolo[l,5-a] pyrimidine-6-carboxamide, commonly known as anagliptin of formula I.

The present invention further relates to polymorphic forms of anagliptin of formula I.
The present invention also relates to process for preparation of polymorphic forms of anagliptin of formula I.
BACKGROUND OF THE INVENTION
Anagliptin is an anti-diabetic agent which acts as dipeptyl peptidase-4 (DPP-4) inhibitor. There are only few reports available on synthesis of anagliptin in prior art. US 7,345.180 discloses compound of formula I (INN name Anagliptin) or pharmaceutical^ acceptable salts thereof, which has an excellent inhibitory effect on dipeptidyl peptidase TV (abbreviated hereinafter to DPP-IV) and is useful for treatment and prevention of type 2 diabetes, treatment or prevention of its related complications, or treatment of other pathologic condition associated with DPP-IV and processes for the preparation of anagliptin of formula I.
There is a need to develop cost effective and industrial scale process for the preparation of anagliptin of formula I.

Polymorph of a drug substance may display different hygroscopicity, stability, solubility and/or dissolution rate, crystallinity. crystal habits, bioavailability and formulation handling characteristics, which are among the numerous properties that need to be considered in preparing medicament that can be effectively administered.
Polymorphic forms of anagliptin are not reported in prior art.
Accordingly, there is a need to prepare polymorphic forms of anagliptin of formula I.
OBJECTS OF THE INVENTION
The main object of the present invention is to provide a process for preparation of anagliptin comprising a step of reacting tert-butyI(2-amino-2-methylpropyl)carbamate of formula II with (S)-l-(2-chloroacetyl)pyrrolidine-2-carbonitrile of formula III to give (S)-l-(2-((l-amino-2-methylpropan-2-yl)amino)acetyl)pyrrolidine-2-carbonitrile dihydrochloride of formula IV or salts thereof.
Yet another object of the present invention is to provide amorphous form of anagliptin of formula I.
Yet another object of the present invention is to provide a process for the preparation of amorphous form of anagliptin of formula I by crystallization,
Yet another object of the present invention is to provide crystalline form of anagliptin of formula I.

Yet another object of the present invention is to provide process for the preparation of crystalline form of anagliptin of formula I.
Yet another object of the present invention is to provide a process for the purification of crystalline anagliptin of formula I.
SUMMARY OF THE INVENTION
The present invention provides a process for the preparation of anagliptin comprising a step of reacting tert-butyl (2-amino-2-methylpropyl)carbamate of formula II with (S)-l-(2-chloroacetyl)pyrrolidine-2-carbonitrile of formula III in the presence of sodium iodide, potassium carbonate and acetone to give (S)-l-(2-((l-amino-2-methylpropan-2-yl)amino)acetyI)pyrrolidine-2-carbonitrile (in situ), which on reaction with IPA-HC1 in presence of dichloromethane gives (S)-l-(2-((l-amino-2-methylpropan-2-yl)amino)acetyl)pyrrolidine-2-carbonitrile dihydrochloride of formula IV. This reaction can be summarized as below:


Another aspect of the invention provides a process for preparation of anagliptin comprising converting compound of formula IIIa


to compound of formula IV and converting compound of formula IV to anagliptin. In another aspect the present invention provides amorphous anagliptin.
In an embodiment the present invention provides process to prepare amorphous anagliptin.
According to the present invention the process to prepare amorphous anagliptin includes treating anagliptin hydrochloride with a base and solvent.
In another embodiment the process to prepare amorphous anagliptin can include treating anagliptin with solvent.
In an aspect the present invention provides crystalline anagliptin.
The present invention also provides process to prepare crystalline anagliptin.
In an embodiment the process to prepare crystalline anagliptin includes treating anagliptin hydrochloride with base and solvent.
Further the process to prepare crystalline anagliptin may include treating anagliptin with solvent.

Yet another aspect of the present invention is to provide a process for the purification of anagliptin.
BRIEF DESCRIPTION OF DRAWINGS
Fig. 1 is X-ray diffrac to gram (XRD) of amorphous form of anagliptin
Fig. 2 is X-ray diffractogram (XRD) of crystalline form of anagliptin
Fig. 3 is Differential Scanning Calorimetry (DSC) of crystalline form of anagliptin
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides a process for preparation of anagliptin comprising reaction of tert-butyl (2-amino-2-methylpropyl)carbamate of formula II with (S)-l-(2-chloroacetyl)pyrrolidine-2-carbonitrile of formula III to give (S)-l-(2-((l-amino-2-methy|propan-2-yl)amino)acetyl)pyrrolidine-2-carbonitrile of formula IIIa, which on reaction with alcoholic-HCl to give (S)-l-(2-((l-amino-2-methylpropan-2-yl)amino)acetyl)pyrrolidine-2-carbonitrile dihydrochloride of formula IV. This reaction can be summarized as below:


The reaction of compounds of formula II and III can be carried out in presence of a base and solvent. The base can be selected from any suitable base such as alkali or alkaline earth metal salts or halides or mixture thereof. The solvent can be selected form any suitable solvent preferably organic solvent such as alkanol. ketone. aromatic hydrocarbon, ester, nitrile, halogenated solvents or like. The reaction can be carried out at room temperature or also at higher temperature.
After completion of the reaction, the obtained product i.e. compound of formula Ilia can be isolated from the reaction mixture or it can be taken for further reaction without isolation.

Compound of formula IIIa is treated with alcoholic-HCl to get compound of formula IV. Alcoholic-HCl used for this reaction can be selected form isopropanolic-HCl, methanolic-HCl, ethanolic-HCl. pentanolic-HCl or like. The conversion of compound of formula IIIa to compound of formula IV can be carried out in presence of solvent selected from organic solvent such as alkanol, ketone, nitrile, halogenated solvent or any other solvent suitable for the reaction. Preferably the reaction is carried out in presence of isopropanolic-HCl or methanolic-HCl and a solvent selected form dichloromethane.
The reaction can be carried out at a temperature in the range of room temperature to reflux. Preferably the reaction is carried out at 20-40°C. The compound of formula IV thus prepared can be isolated form reaction mixture by any suitable method such as filtration.
Compound of formula IV can be converted to anagliptin by conventional process or the process described in the examples of present application,
In an embodiment, the present invention provides an amorphous form of anagliptin.
The amorphous form of anagliptin is characterized by the X-ray powder diffractogram as provided in figure I.
In another embodiment, the present invention provides a process for the preparation of an amorphous form of anagliptin.
Amorphous form of anagliptin can be prepared by treating anagliptin with solvent or treating anagliptin hydrochloride with a base and solvent. Anagliptin hydrochloride is treated with a base preferably an inorganic base followed by treatment with a solvent

to give amorphous form of anagliptin. The inorganic base can be selected from alkali or alkaline metal containing base or like. Preferably the solvent used for this reaction is selected from chlorinated solvents such as dichloromethane.
In another embodiment, the present invention provides crystalline form of anagliptin.
The crystalline form of anagliptin is characterized by the position of the major peaks in the X-ray powder diffractogram, but may also be characterized by endotherm in DSC diagram.
The crystalline form of anagliptin can also be characterized by endotherm at 119.07° in a DSC.
The XRD pattern shows at least one characteristic peak at about 18.6, 17.4 and 9.9 ±0.26. More particularly the XRD shows characteristic peaks at 8.8, 9.9. 11.1, 12.9. 15.1, 16.4, 17.4, 18.6, 19.0, 19.2. 20.1. 25.2. 25.4 and 25.9 degree two-theta ±0.26,
Crystalline form of anagliptin can also be characterized by X-ray diffraction (XRD) pattern as set forth in figure 2.
The crystalline form of anagliptin can also be characterized by endotherm at 119.07° in a DSC.
The XRD main peaks with positions and relative intensities have been extracted from the diffractogram in Fig.2 are given below.

Angle 2-Theta° d value Angstrom Intensity %
8.8 9.98 42.1
9.9 8.89 66.3
11.1 7.9 40.4
12.9 6.81 30.6
17,4 5.06 85.3
18.6 4.74 100.0
19.2 4.60 41.9
20.1 4.40 30.3
25.2 3.52 39.8
25.4 3.50 37.2
25.9 3.43 40.2
In another embodiment, the present invention provides a process for the preparation of crystalline form of anagliptin comprising treatment of anagliptin in presence of a suitable solvent or anagliptin hydrochloride in presence of base and solvent.
Base used in this reaction can be selected from inorganic or organic base; preferably inorganic base is used for the purpose of present invention. Inorganic base includes but not limited to alkali metal carbonates, alkaline earth metal carbonates ammonia and the like.
Solvent is selected from chlorinated solvent and ester solvent. Chlorinated solvent includes dichloromethane. chloroform, carbon tetrachloride and the like. Preferably the ester solvent is ethyl acetate.

In another embodiment, the present invention provides a process for the purification of anagliptin. The process comprises treating crude anagliptin with suitable solvent. Preferred solvent is alcoholic solvent and most preferably isopropyl alcohol.
Identification of solids obtained by the present invention can be made by methods known in the art, such as X-Ray diffraction and differential scanning calorimetry (DSC). It should be understood that operator, instrument and other similar changes may result in some margin of error with respect to analytical characterization of the solid.
The XRD and DSC methods used for the identification and characterization of amorphous and crystalline form of anagliptin are described below:
a) XRPD method:
Analytical characterization of the compound of present invention was carried out by using X-ray powder diffraction using AD-429 D8 advance of Bruker make. The details of the same are given in Table No 1.
Table No 1

Instrument D8 Advance
Make Bruker AXS
Detector Lynx Eye
X-Ray Tube Copper K2A
Kβ Filter Ni
Wavelength 1.5406 A
Scan type Locked Coupled
Scan mode Continuous
Scan speed 0.2 sec

Scan step size 0.02°
Divergence Slit 0.3°
Antiscattering Slit Fixed
Rotation On
Voltage 40 KV
b) DSC method:
The DSC (Differential Scanning Calorimetry) analysis of the compound of present invention was recorded at a temperature range from 50°C-250°C. The details of the same are given in Table No 2.
Table No 2

Instrument name TA DSC
Instrument No. DSC Q 200 V24.10
Heating rate 5.00oC/min
Scanning range 50°C - 250°C
The following examples are given to illustrate the present invention. It should be understood that the invention is not to be limited to the specific conditions or details described in those examples.
Example 1: Preparation of methyl 2-methylpyrazolo[l,5-a] pyrimidine-6-carboxylate
Isopropyl alcohol {400 ml) and 3-methyl-l H-pyrazol-5-amine (100 gm) were charged in RBF at 30±5°C. Ethyl 2-formyl-3-oxopropanoate (151.0 gm) was added dropwise to reaction mass at 30±5°C. The temperature was maintained at 30±5°C for around

12 hours. After completion of reaction the reaction mixture is filtered and solid thus obtained was washed with isopropyl alcohol and dried to get 150 gm of title product.
Example 2: Preparation of 2-methylpyrazolo[l,5-a]pyrimidine-6-carboxylic acid
Methanol (1000 ml) and methyl 2-methylpyrazolo[1.5-a] pyrimidine-6-carboxylate (100 gm) obtained as per example 1 were charged in RBF at 30±5°C, The reaction mixture was stirred at 30±5°C for 15-20 minutes followed by addition of 20% sodium hydroxide solution at 30±5°C in 30-45 minutes. Reaction mass was maintained at 30±5°C for 1 hour. The reaction mass was filtered, to the filtrate solution of hydrochloric acid [dissolve hydrochloric acid (150 ml) in purified water (150 ml)] was added. Reaction mass was stirred at 30±5°C for I hour, filtered and the solid thus obtained was washed with methanol. Solid thus obtained was dried to get 70 gm of title compound.
Example 3: Preparation of tert-butyl (2-amino-2-methylpropyl)carbamate
Isopropyl alcohol (600 ml) and 2-methylpropane- 1.2-diamine (100 gm) were charged in RBF at 30±5°C. Reaction mass thus obtained was refluxed. Di-tert-butyl dicarbonate was added at 80±5°C and the reaction mass was maintained at the same temperature for 3-4 hours. After completion of reaction solvent was distilled off under vacuum at 50±5°C, the residue thus obtained was cooled to 30±5°C. Dichloromethane (300 ml) was added to the residue and the residue was cooled to 15±5°C. Solution of citric acid was added at 15±5°C, reaction mass was stirred at 15±5°C.The layers were separated and solvent was evaporated from organic layer. To the residue cyclohexane (200 ml) was added followed by distillation to obtain residue and the resultant reaction mass was heated to 75±5°C followed by cooling to 15±5°C,

the reaction mixture was filtered and the solid thus obtained was dried to get 150 gm of title compound.
Example 4: Preparation of (S)-l-(2-((l-amino-2-methylpropan-2-yI)amino)acety]) pyrrolidine-2-carbonitrile dihydrochloride of formula IV
(A) Preparation of (S)-tert-butyl(2-((2-(2-cyanopyrroIidin-l-yl)-2-
oxoethyl)amino-2-methyl propyl) carbamate
Acetone (700 ml) and tert-butyl (2-amino-2-methylpropyl)carbamate (100 g) obtained as per example 3 were charged in RBF at 30±5°C. Potassium iodide (5.0 gm) and potassium carbonate powder (96.0 gm) were charged in RBF at 30±5°C. Stirred the reaction mixture at 30±5°C for 45-60 minutes and added drop wise prepared solution of (S)-l-(2-chloroacetyl) pyrrolidine-2-carbonitri!e solution (400 ml) [(S)-l-(2-chloroacetyl) pyrrolidine-2-carbonitrile (96 gm) dissolved in acetone (300 ml)] to the reaction mixture at 15±5°C for 45-60 minutes. The reaction mass was maintained at 30±5°C for 7-8 hrs. The reaction mass was filtered out at 30±5°C. Water (1000 ml) was added to the reaction mass at 20±5°C, followed by addition of dichloromethane (1000 ml) to the reaction mass at 25±5°C and stirred the reaction mass at 25±5°C for 20-30 minutes. The lower dichloromethane layer was separated and dichloromethane was distilled out completely under vacuum at 40±5°C. Isopropyl acetate (100 ml) was added to the residue at 40±5°C and stirred the reaction mass at 40±5°C for 15-20 minutes. Thus obtained solid product washed with chilled [10±5°C] isopropyl acetate (100 m!) and dried the solid product in tray dryer at 45±5°C for 6 hours to get 110 gm of title compound.

B) Preparation of (S)-l-(2-((l-amino-2-methylpropan-2-yl)amino)acetyl) pyrrolidine-2-carbonitrile dihydrochloride of formula IV
Dichloromethane (800 ml) and (S)-tert-butyl(2-((2-(2-cyanopyrrolidin-l-yl)-2-oxoethyl)amino-2-methyl propyl) carbamate (100 g) were charged in RBF at 30±5°C. The obtained reaction mixture was cooled to 20±5°C. Isopropyl alcohol-HCI (300 ml) was added drop wise to the reaction mixture at 20±5°C for 60-90 minutes. The reaction mass was maintained at 30±5°C for 60-90 minutes. After completion of reaction, the reaction mass was filtered at 30±5°C under nitrogen atmosphere. The solid product thus obtained was washed with dichloromethane (200 ml) under nitrogen atmosphere and dried the solid product in vacuum tray dryer at 45±5°C for 6 hours to get 70 gm of title compound.
Example 5: Preparation of anagliptin hydrochloride
Dichloromethane (1200 ml) and 2-methylpyrazolo[l,5-a]pyrimidine-6-carboxylic acid (60 gm) obtained as per example 2 were charged in RBF at 30±5°C. The reaction mixture was stirred at 30±5°C for 15-20 minutes. N,N'-carbonyldiimidazole (82.0 gm) was charged to the reaction mixture at 30±5°C and the reaction mass maintained at 30±5°C for 3-4 hrs. [Part-A]
Dichloromethane (1000 ml) and (S)-l-(2-((l-amino-2-methylpropan-2-yl)amino) acetyl)pyrrolidine-2-carbonitrile dihydrochloride obtained as per example 4 were charged in RBF at 30±5°C. Sodium carbonate (299.0 gm) was charged to the reaction mixture at 30±5°C and the obtained reaction mass was stirred at 30±5°C for Vi hour. [Part-B]

The above prepared reaction mass [Part-B] was slowly added to the above prepared reaction mixture [Part-A] at 30±5°C during 1 hour. The reaction mixture was maintained at 30±5°C for 2-3 hours. Water (1000 ml) was added to the reaction mass at 30±5°C and stirred the reaction mass at 25±5°C for 20-30 minutes. The lower dichloromethane layer was separated and water (500 ml) was added to the dichloromethane layer at 25±5°C. The dichloromethane layer was dried over sodium sulfate (50 gm) and filtered. 20% isopropyl alcohol-HCl (92.0 ml) was added drop wise to the dichloromethane layer at 30±5°C for 45-60 minutes. The reaction mixture was stirred at 30±5°C for 1 hour. The reaction mass was filtered. The obtained solid product was washed with dichloromethane (100 ml) and dried the solid product in vacuum tray dryer at 45±5°C for 12 hours to get 150 gm of title compound.
Example 6: Preparation of amorphous form of anagliptin
Purified water (1000 ml) and Anagliptin hydrochloride (100 gm) obtained as per example 5 were charged in RBF at 30±5°C. The reaction mixture was stirred at the same temperature for 20-30 minutes. 6.0% of sodium bicarbonate (500 ml) solution was added dropwise to the reaction mass at 30±5°C for 30-45 minutes, followed by addition of dichloromethane (500 ml) to the reaction mass at 30±5°C. The reaction mass was stirred at 30±5°C for 20-30 minutes. The lower dichloromethane layer was separated; dried over sodium sulfate (50 gm) and filtered out. The obtained residue was degassed for 2-3 hours. Thus, obtained solid product was scratched and degassed again for 2-3 hours. The solid product obtained was dried in vacuum tray dryer at 45±5°C for 6 hours to get 75 gm of title compound.

Example 7: Preparation of crystalline form of anagliptin
Purified water (1000 ml) and Anagliptin hydrochloride (100 gm) obtained as per example 5 were charged in RBF at 30±5°C. The reaction mixture was stirred for 20-30 minutes. Dichloromethane (300 ml) was added to the reaction mass at 30±5°C and the reaction mixture was stirred at 30±5°C for 20-30 minutes. The obtained aqueous layer was charged to the RBF, followed by addition of drop wise prepared solution of 6.0 % sodium bicarbonate solution to the reaction mass at 30±5°C in 30-45 minutes. Dichloromethane layer was completely distilled out and ethyl acetate [200 ml] was added to the obtained residue. The reaction mixture was stirred followed by cooling up to 15±5°C. The obtained solid product was washed with chilled (5-10°C) ethyl acetate (50 ml) and dried to get 80 gm of title compound.
Example 8: Purification of crystalline form of anagliptin
Isopropyl alcohol (225 ml) and Anagliptin (100 gm) obtained from example 7 were charged in RBF at 30±5°C. The reaction mass was heated up to 75±5°C and stirred the reaction mass at 75±5°C for 20-30 minutes. The reaction mass was filtered and washed with hot isopropyl alcohol [75±5°C] (25 ml). Thus, obtained filtrate was charged in RBF and cooled the reaction mass up to 30±5°C. The reaction mass was stirred at 30±5°C for 2-3 hours. Thus, obtained solid product washed with chilled isopropyl alcohol [5-10°C] (50 ml) and dried to get 60 gm of crystalline form of Anagliptin.
Example 9: Preparation of crystalline form of anagliptin
Dichloromethane (1000 ml) and 2-methy1pyrazolo[1.5-a]pyrimidine-6-carboxylic acid (100 gm) prepared from example 2 were charged in RBF at 30±5°C. The reaction mixture was stirred at 30±5°C for 15-20 minutes followed by addition of N,N'-

carbonyldiimidazole (137.5 gm) to the reaction mixture at 30±5°C. The obtained reaction mass was maintained at 30±5°C for 3-4 hrs. Sodium carbonate (299.0 gm) and (S)-l-(2-((I-amino-2-methylpropan-2-yl) amino)acetyl) pyrrolidine-2-carbonitrile di hydrochloride (218.0 gm) obtained as per example 4 were charged to the reaction mass at 30±5°C. The reaction mixture was stirred at 30±5°C for 2-3 hours. After completion of the reaction the lower dichloromethane layer was separated. Prepared solution of hydrochloric acid (500 ml) [dissolve hydrochloric acid (172 ml) in purified water (500 ml)] was added dropwise to the dichloromethane layer at 25±5°C. Thus obtained reaction mass was stirred at 25±5°C for 20-30 minutes and lower dichloromethane layer was separated. The obtained aqueous layer was charged to the RBF at 30±5°C. Prepared sodium bicarbonate solution [dissolve sodium bicarbonate (142.3 ml) in purified water (1500 ml)] was added drop wise to the aqueous layer at 30±5°C in 45-60 minutes followed by addition of dichloromethane (1000 ml) to the aqueous layer at 30±5°C. The reaction mass was stirred at 25±5°C for 20-30 minutes. Dichloromethane layer was separated, dried over sodium sulfate (50 gm) and filtered out. The obtained residue was degassed and isopropyl alcohol (125 ml) was added to the residue in RBF at 30±5°C. The reaction mass was heated up to 70±5°C and stirred at the same temperature for 20-30 minutes followed by cooling of reaction mass up to 30±5°C, The obtained solid product was washed with chilled isopropyl alcohol [5-10°C] (50 ml) and dried to get 110 gm of title compound.

We claim:
1. A process for preparation of anagliptin of formula I

with alcoholic-HCI to give (S)-l-(2-((l-amino-2-methylpropan-2-yl)amino)acetyl)pyrrolidine-2-carbonitrile of formula IV or its salt

and optionally converting compound of formula IV to anagliptin of formula I.
2. A process as claimed in claim 1, wherein alcoholic-HCI is selected from isopropanolic-HCL methanolic-HCl, ethanolic-HCl, pentanolic-HCl or like.
3. A process for preparation of anagliptin wherein anagliptin hydrochloride is converted to anagliptin.
4. An amorphous form of anagliptin.

5. The amorphous form of anagliptin as claimed in claim 4. which is characterized by X-ray powder diffraction pattern (XRPD) as depicted in figure 1.
6. A process for preparation of an amorphous form of anagliptin wherein the process comprises reacting anagliptin hydrochloride with base and solvent.

7. A process as claimed in claim 6. wherein base is selected from the group consisting of alkali metal carbonates, alkaline earth metal carbonates, ammonia, triethylamine or mixture thereof.
8. A process as claimed in claim 6, wherein solvent is selected from group consisting of chlorinated solvent such as dichloromethane, chloroform and carbon tetrachloride.
9. A process for preparation of an amorphous form of anagliptin comprising treating anagliptin with chlorinated solvent.

10. A process as claimed in claim 9, wherein chlorinated solvent is dichloromethane.
11. A crystalline form of anagliptin.
12. The crystalline form of anagliptin as claimed in claim 11, which is characterized by X-ray powder diffraction pattern (XRPD) as depicted in figure 2.
13. The crystalline form of anagliptin as claimed in claim 11, which is characterized by Differential Scanning Calorimetry (DSC) as depicted in figure 3.
14. A crystalline form of anagliptin characterized by at least one characteristic peak at 18.6. 17.4 and 9.9 degree two-theta ±0.2θ.

15. The crystalline form of anagliptin as claimed in claim 14, further characterized by at least one characteristic peak at 8.8, 9.9, 11.1, 12.9, 15.1, 16.4, 17.4, 18.6, 19.0. 19.2, 20.1, 25.2, 25.4 and 25.9 degree two-theta ±0.2θ.
16. A process for preparation of crystalline form of anagliptin comprising reaction of anagliptin hydrochloride with base and solvent.
17. A process as claimed in claim 16. wherein base is inorganic or organic base.
18. A process as claimed in claim 17, wherein base is selected from the group consisting of alkali metal carbonates, alkaline earth metal carbonates, ammonia or triethyl amine.
19. A process as claimed in claim .16, wherein solvent is selected from group
consisting of chlorinated solvent, ester, alcohols or mixture thereof.
20. A process as claimed in claim 19, wherein solvent is selected from
dichloromethane, ethyl acetate, isopropanol or mixture thereof.
21. A process for the purification of anagliptin from organic solvent selected from group consisting of alcohols, esters, ketones, nitrile, ethers, polar aprotic solvent or mixture thereof.
22. A process as claimed in claim 21, wherein alcohol is isopropanol.