Manganese catalyzed enantio- and regioselective hydrogenation of α,β-unsaturated ketones using an imidazole-based chiral PNN tridentate ligand

Abstract The enantioselective 1,2-reduction of α,β-unsaturated ketones has been achieved using a chiral pincer Mn catalyst. A series of PNN tridentate ligands containing benzimidazole groups were designed with ferrocene as the backbone, which coordinated with Mn to form the active catalyst. This mild process represents a general method to access chiral allyl alcohols with high catalytic activity (up to 9500 TON) and high enantioselectivity (66–86% ee). Furthermore, this catalytic system provides a novel synthesis of key pharmaceutical intermediates of cannabidiol.