10 gms of 5-Benzyloxy-5-(4-fluoro-phenyl)-pentanoic acid was added to 30 ml of toluene at 20-25° C., followed by 5.6 gms of triethyl amine and 5.5 gms of Pivollyl chloride. Reaction mass was stirred for about 2 hours. To the obtained reaction mass 6.5 gms of Evan's auxiliary and 20 ml of dimethyl ammonium phosphate and 0.2 gms of dimethyl formamide were added. Heated the reaction mass at reflux temperature and maintained for about 6-8 hours. Cooled the reaction mass to 20-25° C. and 20 ml of water was added. Stirred the reaction mass and separated the organic layer and aqueous layer was extracted with toluene. Combined all organic layers and washed with brine solution. Separated the organic layer and dried over sodium sulphate and distilled the solvent completely under reduced pressure at 50-55° C. The obtained oily mass was taken in toluene and hexane was added and stirred for about 1-2 hours at 0-5° C. Filtered the compound, washed with hexane and dried at 40-45° C. to get 12 gms of 1-[5-Benzyloxy-5-(4-fluoro-phenyl)-pentanoyl]-5-phenyl-pyrrolidin-2-one.
