Palladium(II)-Catalyzed Three-Component Coupling Reaction Initiated by Acetoxypalladation of Alkynes:  An Efficient Route to γ,δ-Unsaturated Carbonyls

A divalent palladium-catalyzed coupling reaction of electron-deficient alkynes and acrolein or MVK (methyl vinyl ketone) was developed. The reaction provides an efficient method to synthesize γ,δ-unsaturated carbonyls. A mechanism involving acetoxypalladation of alkyne, followed by insertion of alkene and protonolysis of the C−Pd bond, is proposed. The protonolysis of the carbon−palladium bond with the assistance of bidentate nitrogen containing ligands is the key step in this tandem reaction.