Palladium‐Catalyzed Cascade Carbonylation to α,β‐Unsaturated Piperidones via Selective Cleavage of Carbon–Carbon Triple Bonds

A direct and selective synthesis of α,β-unsaturated piperidones by a new palladium-catalyzed cascade carbonylation is described. In the presented protocol, easily available propargylic alcohols react with aliphatic amines to provide broad variety interesting heterocycles. Key success this transformation remarkable catalytic cleavage present carbon–carbon triple bond using specific catalyst 2-diphenylphosphinopyridine as ligand appropriate reaction conditions. Mechanistic studies control experiments revealed branched unsaturated acid 11 crucial intermediate.