A mixture of potassium carbonate (152.2 g) and de-mineralized water (300 ml) was stirred for 10 to 15 minutes to dissolve the solid. The temperature of the mixture was maintained at 30° to 35° C. and dichloromethane (300 ml) was added. L-Valine benzyl ester tosylate (153.3 g), tetrabutyl ammonium bromide (10.0 g) and 4-bromomethyl-2′-cyanobiphenyl (100 g) were added to the reaction mixture. The reaction mixture was stirred for 20 to 24 hours at 30° to 35° C. After completion of the reaction de-mineralized water (400 ml) was added and the mixture was stirred for 5 minutes. The two phases were separated and the aqueous layer was extracted with dichloromethane (200 ml). The combined organic layer was washed with de-mineralized water (300 ml) and concentrated at 40° to 45° C. Ethyl acetate (600 ml) was then added to the residue and stirred for 5 to 10 minutes to dissolve the residue. The reaction mixture was cooled to 0° to 5° C. and concentrated hydrochloric acid (50 ml) was added to the reaction mixture. The mixture was stirred for 1 hour. The precipitated solid was filtered, washed with ethyl acetate and dried to obtain the title compound.
