In situ preparation of mixed anhydrides containing the trifluoroacetyl moiety. Application to the esterification of cholesterol and phenol

Abstract

This paper reports an easy characterization of carboxylic-trifluoroacetic mixed anhydrides by 1H and 13C NMR, and gives evidence that mixed anhydrides are produced instantaneously, at room temperature, from a carboxylic acid and trifluoroacetic anhydride and even from carboxylic anhydrides and trifluoroacetic acid. The esterification of phenol with the carboxylic-trifluoroacetic anhydrides is highly chemoselective, and affords pure products, in quantitative yields, and in the case of cholesterol, some cholesteryl trifluoroacetate is also produced. ©ARKAT.