Imine Reductase‐Catalyzed Intermolecular Reductive Amination of Aldehydes and Ketones

Abstract Imine reductases (IREDs) have emerged as promising biocatalysts for the synthesis of chiral amines. In this study, the asymmetric imine reductase‐catalyzed intermolecular reductive amination with NADPH as the hydrogen source was investigated. A highly chemo‐ and stereoselective imine reductase was applied for the reductive amination by using a panel of carbonyls with different amine nucleophiles. Primary and secondary amine products were generated in moderate to high yields with high enantiomeric excess values. The formation of the imine intermediate was studied between carbonyl substrates and methylamine in aqueous solution in the pH range of 4.0 to 9.0 by 1 H NMR spectroscopy. We further measured the kinetics of the reductive amination of benzaldehyde with methylamine. This imine reductase‐catalyzed approach constitutes a powerful and direct method for the synthesis of valuable amines under mild reaction conditions.