Patent ID: 8981109
Filing Date: 2015-03-17
Classification: C07D

Abstract:
1. A process for the preparation of Valsartan of formula (I) substantially free from impurities of formulae (Ia), (Ib), and (Ic), which comprises: (i) condensing 2-(4′-bromomethylphenyl)benzonitrile of formula (II), (ii) treating the compound (VI) of step (i) with acid followed by treating with base to produce pure compound (VI) substantially free from dimeric impurity of formula (VIa); (iii) reacting the pure compound of formula (VI) with n-valeryl chloride in the presence of a base to produce pure N-valeryl-N-[(2′-cyanobiphenyl-4-yl)methyl]-(L)-valine methyl ester (VII) substantially free from alkene impurity of formula (VIIa); (iv) reacting the compound of formula (VII) with trialkyltin chloride and a metal azide in a solvent at a reflux temperature to produce N-(1-oxopentyl)-N-[[2′-(2-tributyltintetrazol-5-yl)-(1,1′-biphenyl)-4-yl]methyl]-(L)-valine methyl ester of formula (VIIIb) free from thermal degradation impurity (VIIIa); (v) hydrolyzing the compound of formula (VIIIb) in the presence of alkaline conditions to produce Valsartan (I).