Oxidative Cyclization-Dimerization Reaction of 2,3-Allenoic Acids and 1,2-Allenyl Ketones: An Efficient Synthesis of 4-(3′-Furanyl)butenolide Derivatives

The active PdII catalyst in the efficient oxidative cyclization/dimerization reaction between 2,3-allenoic acids 1 and 1,2-allenyl ketones 2 to give 4-(3′-furanyl)butenolide derivatives 3 may be regenerated from Pd0 after a cyclometalation/protonolysis step in the catalytic cycle.