Enantioselective Reduction of Aromatic and Aliphatic Ketones Catalyzed by Ruthenium Complexes Attached to β‐Cyclodextrin

Water-soluble chiral Ru complexes with a β-cyclodextrin unit have been shown to catalyze the reduction of aliphatic ketones (see scheme) with up to 97 % ee and in good to excellent yields in the presence of sodium formate. The β-cyclodextrin unit is an essential component of the catalyst. It contributes to the unprecedented levels of enantioselectivity observed through the preorganization of the substrates in the hydrophobic cavity.