CuH-Catalyzed Selective N‑Methylation of Amines Using Paraformaldehyde as a C1 Source

Copper hydride (CuH) complexes have been proposed as key intermediates in synthesis and catalysis. Herein, we developed a highly efficient strategy for CuH-catalyzed N-methylation of aromatic and aliphatic amines using paraformaldehyde and polymethylhydrosiloxane (PMHS) under mild reaction conditions. The reaction proceeded smoothly without additives to furnish the corresponding N-methylated products using cyclic­(alkyl)­(amino)­carbene (CAAC)­CuH as a reaction intermediate, which results from a reaction between PMHS and (CAAC)­CuCl.