Stereoselective Synthesis of alpha-Alkylidene beta-Oxo Amides by Palladium-Catalyzed Carbonylation

A direct method to obtain -alkylidene -oxo amides by the palladium-catalyzed carbonylation of -chloro ketones in the presence of aromatic imines has been described. The methodology can be applied to a variety of C-aryl imines bearing N-aryl or N-alkyl substituents. The entire process is highly stereoselective and affords the -alkylidene -oxo amides only as (Z) isomers. A mechanistic hypothesis involving an acyl--lactam intermediate has also been proposed.