Patent ID: 7880015

Claim:
A process for the preparation of N-(1-oxopentyl)-N-[[2′-(1H-tetrazol-5-yl)[1,1′-bipheny]-4-yl]methyl]-L-valine of Formula I, which comprises: (i) treating N-[[2′-(1-triphenylmethyltetrazol-5-yl)biphenyl-4-yl]methyl]-L-valine methyl ester Formula (X) with oxalic acid or its hydrates in a solvent to produce N-[[2′-(1-triphenylmethyltetrazol-5-yl)biphenyl-4-yl]methyl]-L-valine methyl ester oxalate Formula (Xa), (ii) treating the compound of Formula (Xa) with a base in a solvent followed by reacting with valeryl chloride in presence of base in a solvent to produce N-[[2′-(1-triphenylmethyltetrazol-5-yl)[1,1′-biphenyl]-4-yl]methyl]-N-valeryl-L-valine methyl ester Formula (XI), (iii) deprotecting the compound of formula (XI) using acid reagent to produce N-(1-oxopentyl)-N-[[2′-(1H-tetrazol-5-yl)[1,1′-biphenyl]-4-yl]methyl-L-valine methyl ester Formula (V); (iv) treating the compound of formula (V) with base in a solvent to produce N-(1-oxopentyl)-N-[[2′-(1H-tetrazol-5-yl)[1,1′-biphenyl]-4-yl]methyl]-L-valine Formula (I).