Pd(II)-catalyzed regioselective ring opening/[3+2] annulation reaction of enaminones with cyclopropenones: divergent synthesis of γ-butenolides and γ-lactams

A practical, effective, and regioselective palladium-catalyzed ring opening/[4+2] annulation of enaminones with cyclopropenones for the controllable synthesis of highly substituted γ-butenolides and γ-lactams has been described. This method for the first time reports the regio-selective annulation reaction on the carbon and amine groups of the enaminone structure. This reaction is characterized by its wide substrate scope, good functional group compatibility, moderate to good yields, scale-up synthesis, and versatile transformations, providing a versatile and general protocol to construct γ-butenolides and γ-lactams.