Fe(BF4)2-Catalyzed Inter- and Intramolecular Carbonyl-Ene Reaction of Trifluoropyruvate

Abstract

Inter- and intramolecular carbonyl-ene reactions have been developed using 5 mol% Fe(BF4)2 as catalyst, affording homoallylic alcohols in 36–87% isolated yields. This catalyst, prepared from FeCl2 and AgBF4, is the first FeII Lewis acid reported for the carbonyl-ene reaction using ethyl trifluoropyruvate. The method was successfully applied to the reaction of various 1,1-disubstituted alkenes with ethyl trifluoropyruvate and to the cyclization of citronellal.