TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The inorganic base used in step (b) comprises hydroxide, carbonate or bicarbonate salt of alkali or alkaline earth metal, or ammonia. The alkali metal azide used in step (c) is sodium azide.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The highly active carbon has a pore volume of 1-1.3 cc/gm. The highly active carbon is grade perforated vent panel (PF-511) SPL. The highly active carbon has a surface area of 1200-1800 (preferably 1400-1600) m2/gm. The N-pentanoyl-N-((2'-(1H-tetrazol-5-yl)(1,1'-biphenyl)-4-yl)methyl)-L-valine has a tin content of equal to or less than 5 ppm, preferably equal to or less than 1 ppm. The acid addition salt comprises hydrochloride or hydrobromide salt. The base used in step (a) and (b) comprise organic base and inorganic base, where the organic base is an amine comprising triethylamine, ethylamine, di-isopropyl ethylamine, tributylamine, dicyclohexylamine or pyridine, and the inorganic base comprises hydroxide, hydride, carbonate, bicarbonate or alkoxide salt of alkali or alkaline earth metal. The solvent used in step (a) and (b) comprise amides, sulfoxides, nitriles, ketones, hydrocarbons, ethers, esters, and/or halogenated hydrocarbons. The base used in step (c) is hydroxide, carbonate or bicarbonate salt of alkali or alkaline earth metal. The solvent used in step (c) comprises amides, sulfoxides, and/or hydrocarbons. Preferred Process: The reaction temperature used in step (a) is 10-70 degrees C. The reaction temperature used in step (b) is 0-50 degrees C. The reaction temperature in step (c) is 80-180 degrees C. ACTIVITY - Hypotensive; Cardiant.    MECHANISM OF ACTION - None given.    EXAMPLE - N-((2'-cyanobiphenyl-4-yl)methyl)-(L)-valine methyl ester hydrochloride (100 g) was basified with sodium bicarbonate solution and extracted in dichloromethane. The organic layer was separated, washed with water. The organic layer was dried over anhydrous sodium sulfate. The organic layer containing free base was condensed with valeryl chloride (45 g) in the presence of triethylamine (36 g) at 0-5 degrees C and stirred at 0-5 degrees C for 1 hour. After completion of the reaction, the mixture was washed with dilute hydrochloric acid, dilute sodium bicarbonate and water. The organic layer was separated and concentrated completely and O-xylene was added. The O-xylene layer was washed with dilute hydrochloric acid, dilute sodium bicarbonate and water. The organic layer was separated, dried over anhydrous sodium sulfate to form N-valeryl-N-((2'-cyanobiphenyl-4-yl)methyl)-(L)-valine methyl ester. Tri-n-butyl tin chloride (170 g) and sodium azide (34 g) were added to the organic layer containing N-valeryl-N-((2'-cyanobiphenyl-4-yl)methyl)-(L)-valine methyl ester. The mixture was heated to 135-138 degrees C and stirred for 24 hours, and cooled to 10-15 degrees C, followed by adding a solution of aqueous sodium hydroxide solution (54 g), and heated to 55-60 degrees C for 2-2.5 hours. After completion of the reaction, the mass was cooled to 25-30 degrees C and separated into aqueous and organic layers. The aqueous layer was washed twice with o-xylene (100 ml). The aqueous layer was cooled to 15-20 degrees C and pH was adjusted to 2.5-3 by dilute hydrochloric acid and extracted with dichloromethane. The organic layer was washed with water and brine solution. The organic layer was concentrated to get (S) N-(oxopentyl)-N-((2'-(1H-tetrazol-5-yl)(1,1'-biphenyl)-4-yl)methyl)-L-valine.