Iridium-Catalyzed Asymmetric Hydrogenation of Simple Ketones with Tridentate PNN Ligands Bearing Unsymmetrical Vicinal Diamines.

An iridium catalytic system with a ferrocene-based phosphine ligand bearing a modular and tunable unsymmetrical vicinal diamine scaffold was developed for the asymmetric hydrogenation of aryl ketones. This approach provided a powerful tool for the enantioselective synthesis of diverse chiral alcohols with excellent reactivity and enantioselectivity (up to 99% yield, up to 99% ee, and up to 50,000 turnover number). The substituents and chirality of unsymmetrical diamines in ligands played an important role in the satisfactory results.