Skeletal Editing of α-Oxoketene-N,S-Acetals into Amides via Cooperative Base-Promoted/Copper-Catalyzed Amidation.

A practical and efficient method for the direct synthesis of various secondary amides via skeletal editing and 1,3-arylamine migration of readily accessible α-oxoketene-N,S-acetals under copper catalysis has been devised. The reaction proceeds by base-mediated elimination of MeSH to generate a ketenimine intermediate, which undergoes hydration to form an α-enolic amide. Thus, the α-enolic amide formed coordinates with Cu(OAc)2, followed by skeletal modification to give amide, highlighting the ability of copper catalysis to control selective bond reorganization. DFT calculations were employed to elucidate the proposed domino pathway.