Palladium-Catalyzed Decarboxylative Generation and Propargylation of 2-Azaallyl Anions

A palladium-catalyzed decarboxylative propargylation (DcPg) of propargyl 2,2-diphenylglycinate imines was developed. In this process, the nature of the propargyl ester and aryl imine components, as well as the catalyst system and solvent, had a significant impact on the ratio of desired propargylated products vs. allene and/or diene side products that arise via different modes of C-C bond formation. The resulting propargylated products can be transformed readily into useful (Z)-homoallylic amines. Moreover, the regioisomeric diene products could be converted to pharmaceutically-relevant diarylmethyl imines via a two-step Diels-Alder/oxidation process.