Patent ID: 8895772
Filing Date: 2014-11-25
Classification: C07C

Abstract:
1. A process of preparation of N-[4′-cyano-3′-(trifluoromethyl)phenyl]-3-[(4″-fluoro-phenyl)sulfonyl]-2-hydroxy-2-methylpropionamide (I)— comprising the steps of a. selectively oxidizing N-[4′-Cyano-3′-(trifluoromethyl)phenyl]-3-[(4″-fluoro phenyl)thio]-2-hydroxy-2-methyl propionamide of Formula (III) with 1% ortho tungstic acid and aqueous hydrogen peroxide in presence of an C1-C3 organic alcohol solvent; b. raising the temperature to about 50° C. or more; c. stirring until the content of compound of formula (III) achieved till less than about 1%; c. isolating the solid by cooling the reaction mass; d. adding mixture of water and water immiscible ester solvent (about 1:2); e. separate the organic ester solvent layer; f. optionally repeat the further extraction of aqueous layer with water immiscible ester solvent; g. optionally adding activated carbon followed by filtering the extracted organic layer; h. evaporating the water immiscible ester solvent; and i. isolating the pure compound of formula (I).