Silver or copper-catalyzed ring opening [3+2] annulation of 2-polyfluoroalkyl chromones/6-polyfluoroalkyl pyran-4H-ones with methylene isocyanides: regioselective synthesis of 3-polyfluoroalkyl pyrroles

Abstract

In this work, we present a synthetic protocol for the preparation of polysubstituted 3-trifluoromethyl(polyfluoroalkyl)pyrroles. The method is based on a metal-catalyzed formal [3+2] cycloaddition reaction of activated isocyanides, such as ethyl isocyanoacetate or benzyl isocyanide with 2-trifluoromethyl(polyfluoroalkyl)chromones or 6-trifluoromethyl(polyfluoroalkyl)pyran-4H-ones. This method is convenient and simple, with good substrate availability occurring under a wide substrate scope. Moreover, the reactions could be carried out with 90% yield and easily scaled to the gram scale.