Patent ID: 8492577

Claim:
A process for preparing N-[(2-cyano[1,1′-biphenyl]-4-yl)methyl]-L-valine benzyl ester of formula I or an acid addition salt substantially free of N,N-bis-[(2′-cyano[1,1′-biphenyl]-4-yl)methyl]-L-valine benzyl ester of formula III which process comprises: a) preparing a solution of L-valine benzyl ester in a solvent at about 40-140° C. in the presence of a base b) adding a solution of 4-Bromomethyl-2-cyanobiphenyl of formula II gradually at least for 1 hour 30 minutes to the solution prepared in step (a) maintaining the temperature at about 40-140° C. c) maintaining the reaction mass for at least 3 hours at about 40-140 deg C. d) isolating the N-[(2′-cyano[1,1′-biphenyl]-4-yl)methyl]-L-valine benzyl ester of formula I or converting the compound of formula I into an acid addition salt and isolating as the solid.