Palladium(II)-catalyzed three-component coupling reaction initiated by acetoxypalladation of alkynes: an efficient route to gamma,delta-unsaturated carbonyls.

[formula: see text] 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 gamma,delta-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.