Patent ID: 7923567

Claim:
A process for the preparation of (S)-N-(1-carboxy-2-methylprop-1-yl)-N-pentanoyl-N-[2′-(1H-tetrazol-5-yl)biphenyl-4-ylmethyl]amine (Valsartan) of formula I comprising: (a) reacting 4-halomethyl-2′-cyanobiphenyl of formula (II) wherein X represents halogen selected from Cl or Br, with L-valine ester derivative of formula (III) wherein R 1 represents C 1 -C 4 alkyl selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, 2-methylpropyl or benzyl; in presence of base and solvent, optionally in presence of catalyst; to form N-[(2′-cyanobiphenyl-4-yl)methyl]-(L)-valine ester derivative of formula (IVa) wherein R 1 represents C 1 -C 4 alkyl selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, or 2-methylpropyl or benzyl, (b) treating N-[(2′-cyanobiphenyl-4-yl)methyl]-(L)-valine ester derivative of formula (IVa) with organic acid to obtain compound of formula (IV) wherein R 1 represents C 1 -C 4 alkyl selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, 2-methylpropyl or benzyl; S represents organic acid selected from oxalic acid, acetic acid, formic acid, malic acid, maleic acid, malonic acid, succinic acid, furmaric acid, phthalic acid, terephthalic acid, citric acid, tartaric acid, methanesulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid, trifluoroacetic acid, ascorbic acid and the like, (c) acylating the compound of formula (IV) with valeroyl halide of formula (V) wherein X is halogen selected from Cl or Br; in the presence of base and water, optionally in organic solvent; to obtain compound of formula (VI) wherein R 1 represents C 1 -C 4 alkyl selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, 2-methylpropyl or benzyl, (d) converting the compound of formula (VI) to obtain compound formula (I).