Geometry-Constrained N,N,O-Nickel Catalyzed alpha-Alkylation of Unactivated Amides via a Borrowing Hydrogen Strategy

Reported herein is a well-defined geometry-constrained tridentate N,N,O-nickel complex for selective alpha-alkylation of unactivated amides using readily available alcohols as the alkylating reagents. The newly developed transformation could accommodate a broad substrate scope including various substituted benzylic or aliphatic alcohols and tertiary/secondary acyclic amides or lactams. The tolerance of methanol and ethanol in this protocol provided a novel possibility of carbon chain homologation of amides. Mechanistic studies suggested that the reaction proceeds through a borrowing hydrogen pathway.