Allyl-Palladium-Catalyzed α,β-Dehydrogenation of Carboxylic Acids via Enediolates.

A highly practical and step-economic α,β-dehydrogenation of carboxylic acids via enediolates is reported through the use of allyl-palladium catalysis. Dianions underwent smooth dehydrogenation when generated using Zn(TMP)2 ⋅2 LiCl as a base in the presence of excess ZnCl2 , thus avoiding the typical decarboxylation pathway of these substrates. Direct access to 2-enoic acids allows derivatization by numerous approaches.