Iridium-catalyzed asymmetric transfer hydrogenation of aromatic ketones with a cinchona alkaloid derived NNP ligand

Abstract

An iridium complex generated in situ from [Ir(COD)Cl]₂ and a cinchona alkaloid derived NNP ligand has been developed for the asymmetric transfer hydrogenation of aromatic ketones. In this study, 30 aromatic ketones and heteroaryl ketones were hydrogenated to produce valuable chiral alcohols with up to 99% ee using i-PrOH as the hydrogen source and the solvent. The easily prepared Ir(L8)(COD)Cl also exhibited excellent activity and enantioselectivity in asymmetric transfer hydrogenation of aromatic ketones with a high S/C ratio (up to 2000).