NOVELTY - Producing N-pentanoyl-N-((2'-(1H-tetrazol-5-yl)(1,1'-biphenyl)-4-yl)methyl)-L-valine, comprises treating crude N-pentanoyl-N-((2'-(1H-tetrazol-5-yl)(1,1'-biphenyl)-4-yl)methyl)-L-valine with highly active carbon having pore volume of 0.8-1.8 cc/gm.    USE - The N-pentanoyl-N-((2'-(1H-tetrazol-5-yl)(1,1'-biphenyl)-4-yl)methyl)-L-valine is useful for treating high blood pressure and cardiac insufficiency. No biological data given.    ADVANTAGE - The improved process is economical, environmentally friendly, and industrially feasible.    DETAILED DESCRIPTION - Producing N-pentanoyl-N-((2'-(1H-tetrazol-5-yl)(1,1'-biphenyl)-4-yl)methyl)-L-valine comprises: either treating crude N-pentanoyl-N-((2'-(1H-tetrazol-5-yl)(1,1'-biphenyl)-4-yl)methyl)-L-valine with highly active carbon having pore volume of 0.8-1.8 cc/gm; or (a) reacting a 4-halomethyl-2'-cyanobiphenyl compound of formula (VIIIa) with a L-valine alkyl ester of formula (IIIb) or an acid addition salt of formula (IIIa) in presence of a base and solvent to obtain a N-(2'-cyanobiphenyl-4-yl-methyl) (L)-valine alkyl ester of formula (IVb) or its acid addition salt of formula (IVa), (b) reacting (IVb) or (IVa) with a valeroyl halide of formula (CH3-(CH2)3-C(=O)-X) (Va) in the presence of a base and organic solvent to obtain a N-(2'-cyanobiphenyl-4-yl-methyl) N-pentanoyl-L-valine alkyl ester of formula (VIa), (c) subjecting (VIa) to cyclo addition reaction with alkali metal azide and tri-n-butyl tin chloride in solvent to obtain a pentanoic acid propyl-(2'-(1H-tetrazol-5-yl)-biphenyl-4-ylmethyl)-amide compound of formula (VIIa) and quenching the reaction with a base to obtain crude N-pentanoyl-N-((2'-(1H-tetrazol-5-yl)(1,1'-biphenyl)-4-yl)methyl)-L-valine, and (d) treating crude N-pentanoyl-N-((2'-(1H-tetrazol-5-yl)(1,1'-biphenyl)-4-yl)methyl)-L-valine with highly active carbon to get pure N-pentanoyl-N-((2'-(1H-tetrazol-5-yl)(1,1'-biphenyl)-4-yl)methyl)-L-valine.    X = halo comprising Cl or Br; and    R1 = 1-4C alkyl comprising methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, 2-methyl propyl, or benzyl.