Abstract: A process for the preparation of Irbesartan of formula (I) using the step of, reacting biphenyl derivative of formula (VIa) wherein R represents a group selected from —CONH2 or compound of formula wherein X represents H or C1-4 alkyl, preferably methyl; or any other such group which can be converted to cyano group, with 1-veleramido cyclopentane carboxylic acid of formula (V) in the presence of an acid in an organic solvent to give biphenyl derivative of formula (VIIa) wherein R has the same meaning as mentioned hereinabove.

Abstract: A process for the preparation of Irbesartan of formula (I) using the steps of: (i) reacting 4? aminomethyl-2-cyano biphenyl of formula (VI) with 1-veleramido cyclopentane carboxylic acid of formula (V) in an organic solvent and in the presence of an acid, without activating the —COOH group of compound of formula (V) to give 1-(2?cyanobiphenyl-4-yl-methylaminocarbonyl)-1-pentanoylamino cyclopentane of formula (VII). converting the compound of formula (VII) obtained in step (i) to Irbesartan of formula (I) by reacting the compound of the formula (VII) with tributyl tin azide in o-xylene to give Irbesartan of formula (I).