Ruthenium-Catalysed Efficient Asymmetric Transfer Hydrogenation of Aromatic Ketones using Cinchona Alkaloids as Chiral Ligands

Abstract

Cinchona alkaloid derivatives were applied in asymmetric transfer hydrogenation of aromatic ketones in a ruthenium catalytic system using i-PrOH as the hydrogen source. A series of aromatic ketones could be transfer-hydrogenated to the corresponding alcohols with good to excellent conversion and enantioselectivity. The best results were achieved using 9-amino(9-deoxy) epiquinidine as the ligand; the enantioselectivity with acetophenone and 2′-(trifluoromethyl)acetophenone could reach 90% ee.