Formal intermolecular [4+1] cycloaddition reaction of in situ generated ortho-quinomethanes with CF3-Imidoyl sulfoxonium ylides and dual double bond isomerization cascade: Synthesis of trifluoromethyl-containing benzofuran derivatives

Abstract

A straightforward strategy for the metal-free synthesis of trifluoromethyl-containing benzofuran derivatives has been developed using in situ generated ortho-quinomethanes and CF₃-imidoyl sulfoxonium ylides. This cascade transformation involves a formal intermolecular [4 + 1] cycloaddition, followed by an unexpected dual double bond isomerization. This methodology is characterized by mild reaction conditions, a broad substrate scope, and an operationally simple procedure, yielding benzofuran derivatives with excellent yields.