Transfer Hydrogenation of Ketones and Imines with Methanol under Base-Free Conditions Catalyzed by an Anionic Metal–Ligand Bifunctional Iridium Catalyst

An anionic iridium complex [Cp*Ir­(2,2′-bpyO)­(OH)]­[Na] was found to be a general and highly efficient catalyst for transfer hydrogenation of ketones and imines with methanol under base-free conditions. Readily reducible or labile substituents, such as nitro, cyano, and ester groups, were tolerated under present reaction conditions. Notably, this study exhibits the unique potential of anionic metal–ligand bifunctional iridium catalysts for transfer hydrogenation with methanol as a hydrogen source.