Palladium-Catalyzed Decarbonylative Dehydration for the Synthesis of α-Vinyl Carbonyl Compounds and Total Synthesis of (-)-Aspewentins A, B, and C

The direct alpha-vinylation of carbonyl compounds to form a quaternary stereocenter is a challenging transformation. It was discovered that delta-oxocarboxylic acids can serve as masked vinyl compounds and be unveiled by palladium-catalyzed decarbonylative dehydration. The carboxylic acids are readily available through enantioselective acrylate addition or asymmetric allylic alkylation. A variety of alpha-vinyl quaternary carbonyl compounds are obtained in good yields, and an application in the first enantioselective total synthesis of (-)-aspewentins A, B, and C is demonstrated.