A Convenient Route to β,γ-Unsaturated Esters without Formation of the α,β-Isomers. Palladium-Catalyzed Alkoxycarbonylation of Allylic Halides under Alcohol–Potassium Carbonate Tow-Phase Conditions

Palladium-catalyzed, atmospheric pressure carbonylation of allylic halides under alcohol-potassium carbonate (liquid–solid) two-phase conditions affords β,γ-unsaturated esters without formation of the α,β-isomers. Phosphine-free palladium compounds such as Pd(OAc)2 (1) and Na2[PdCl4] (2) are a convenient catalyst for this reaction. Presence of triphenylphosphine retards the carbonylation. A mixture of Pd(OAc)2-PPh3 or [PdCl2(PPh3)2] (3) catalyzes the carbonylation under pressure.