Abstract: A process for preparing irbesartan comprises pentanoylation of cycloleucine in the presence of sodium hydroxide to form n-pentanoyl cycloleucine, condensing this product with 2-(4-aminomethyl phenyl) benzonitrile using dicyclohexyl carbodiimide and 1-hydroxy benzotriazole as a catalyst to form the 4-(&quest-N-pentanoyl amino) cyclopentamido methyl-2?-cyano biphenyl compound, and then cyclizing using trifluoroacetic acid in the presence of an aromatic solvent to form cyano irbesartan. Cyano irbesartan is converted to irbesartan by reaction with tributyltin chloride and sodium azide in the presence of an aromatic solvent.

Abstract: A process for the preparation of 3-[2-[4-(6-fluoro-1,2-benzisoxazol-3-yl)-1-piperidinyl]-ethyl]-6,7,8,9-tetrahydro-2-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, which is known as Risperidone of Formula (I). Risperidone of Formula (I) is represented by the following structure.

Abstract: The present invention relates to a novel amorphous form of 2-n-butyl-3-[[2?-(1H-tetrazol-5-yl)[1,1?-biphenyl]-4-yl]methyl]-1,3-diazaspiro[4.4]non-1-en-4-one and to a process for preparation thereof. Irbesartan (2-n-Butyl-3-[[2?-(1H-tetrazol-5-yl)[1,1?-biphenyl]-4-yl]methyl]-1,3-diazaspiro[4.4] non-1-en-4-one), represented by the following formula (I), is a non-peptide angiotensin—II antagonist. By inhibiting the action of angiotensin—II on its receptors, this compound prevents the increase in blood pressure produced by the hormone-receptor interactions and is hence used in the treatment of cardiovascular complaints such as hypertension and heart failure.