New Methods for the Syntheses of α,β-Unsaturated Ketones, Aldehydes, and Nitriles by the Palladium-Catalyzed Reactions of Allyl β-Oxo Esters, Allyl 1-Alkenyl Carbonates, and Allyl α-Cyano Esters

Abstract

Allyl β-oxo esters, allyl 1-alkenyl carbonates, and allyl α-cyano esters are converted into α,β-unsaturated ketones, aldehydes, and nitriles by palladium-catalyzed intramolecular decarboxylation-dehydrogenation. Palladium-phosphine complexes such as Pd(OAc)2-PPh3, Pd(OAc)2-dppe, or Pd2(dba)3 - CHCl3-PPh3 are effective catalysts. Yields depend on solvents and on the mole ratio of palladium to phosphine. The optimum Pd/P ratio for each substrate was determined Use of nitriles as solvents is essential for the dehydrogenation.