Abstract: An improved process for the crystallization of benazepril hydrochloride to obtain in at least 99.8% diastereomeric purity. The process comprises making a concentrated solution of benazepril hydrochloride in ethanol and adding the resulting solution to a non-solvent diisopropyl ether.

Abstract: A novel crystalline form of quinapril hydrochloride of formula (I) An amorphous form of quinapril hydrochloride substantially free of impurities, specially diketopiperazine compound, and conforming to pharmacopoeial specifications formed from the said novel crystalline form of quinapril hydrochloride of formula (I). The crystalline quinapril hydrochloride is in the form nitroalkane solvate in which the nitroalkane is nitromethane, nitroethane and nitropropanae. Each such nitroalkane solvate having particular characteristic X-ray diffraction patterns. A process for preparation of amorphous form of quinapril hydrochloride, substantially free of impurities, specially diketopiperazine compound, and conforming to pharmacopoeial specifications, using the novel crystalline quinapril hydrochloride as an intermediate. The process involves obtaining free base compound of formula (V) by adjusting the pH of a solution of the benzyl ester maleate salt of quinapril of formula (V) between 7.5-8.

Abstract: A process for preparation of crystalline perindopril erbumine of formula (II) which exhibits the X-ray (powder) diffraction pattern like that shown in FIG. 2 The process comprises reacting a solution of perindopril of formula (I), in a solvent selected from N,N-dimethylformamide, dimethyl acetals of lower aliphatic aldehydes, dimethyl ketals of lower aliphatic ketones and 1,2-dialkoxyethane with tertiary butylamine and crystallization of the erbumine salt thus obtained by heating the reaction mixture to reflux, filtering hot, cooling gradually to 20° C. to 30° C., and further cooling to 0° C. to 15° C. for 30 minutes to 1 hour and finally filtering off and drying the crystals.

Abstract: The present invention provides an improved process for preparation of highly pure trandolapril. The process comprises of the following steps: (i) crystallization of mixture of racemic benzyl trans-(2S, 3aR, 7aS)-octahydro-1H-indole carboxylate p-toluene sulphonic acid salt (IIa.p-TsOH) and benzyl trans-(2R, 3aS, 7aR)-octahydro-1H-indole carboxylate p-toluene sulphonic acid salt (IIb.p-TsOH) through appropriate selection of solvents to enrich the purity to >99% from a mixture containing the other diastereomers (IIc-h.

Abstract: The present invention relates to a novel method for obtaining (2S,3aS,6aS)-1-[(S)-2-[[(S)-1-(ethoxycarbonyl)-3-phenylpropyl]-amino]propanoyl]octahydro cyclopenta[b]pyrrole-2-carboxylic acid, viz. Ramipril(I) in high optical purity, free of other stereoisomers, and in high bulk density. The present invention also relates to a novel hydrated form of Ramipril(I) and a process for preparation thereof.

Abstract: A dicyclohexyamine salt of compound of formula I, namely perindopril, having an X-ray powder diffraction pattern with characteristic peaks (2?): 8.462, 10.624, 18.693, 9.424, 17.272, 14.177, 19.499, 20.765, 21.409, and 14.540. A process for preparation of the said salt of perindopril and its use in the purification of an impure perindopril and a process for purification of perindropril comprising formation of its salt with dicyclohexylamine. The present invention also relates to preparation of Perindopril tert-butyl amine salt directly from Perindopril dicyclohexylamine salt without isolating the free base.

Abstract: A multistep process for producing 8-chloro-6-(2-fluorophenyl)-1-methyl-4-H-imidazo?1,5a!?1,4!benzodiazepine (midazolam) comprises treating a compound of Formula II with a lower alkyl dithiol to produce a compound of Formula III, wherein n=2 or 3, converting the compound of Formula III to a compound of Formula VII, and then treating the compound of Formula VII with a deprotecting agent, thereby producing midazolam. Novel intermediate compounds are also disclosed.

Abstract: A multistep process for producing 8-chloro-6-(2-fluorophenyl)-1-methyl-4-H-imidazo?1,5a!?1,4! benzodiazepine (midazolam) comprises treating a compound of Formula II with a lower alkyl dithiol to produce a compound of Formula III, wherein n=2 or 3, converting the compound of Formula III to a compound of Formula VII, and then treating the compound of Formula VII with a deprotecting agent, thereby producing midazolam. Novel intermediate compounds are also disclosed.