Synthesis of trifluoromethylated dihydro-1,4-oxathin-3-carboxanilides through polymer-bound activated ester

Abstract

A synthesis of new trifluoromethylated dihydro-1,4-oxathiin-3-carboxanilids (2) through polymer-bound activated ester is described. Chlorination of ethyl gamma,gamma,gamma-trifluoroacetoacetate (3) followed by treatment of 2-mercaptoethanol gave hydroxyoxathianes isomers (cis-10 and trans-11). Replacement of hydroxy to chlorine and then dehydrochlorination afforded trifluoromethyl dihydro-1,4-oxathiin ester (7). The polymer-bound trifluoromethylated dihydro-1,4-oxathiin-3-carboxylic acid, 4-hydroxy-3-nitrobenzophenone ester (16) was prepared through the reaction of polystyrene-bound 4-hydroxy-3-nitrobenzophenone (14) with the trifluoromethylated dihydro-1,4-oxathiin-3-carbonyl chloride (15). Refluxing of 16 with anilines in acetonitrile gave the corresponding carboxanilide (2). The reaction rate depended on the nucelophilicity of nitrogen in aniline.