Electrochemically Driven Asymmetric Hydrogenation of Aromatic Ketones by Noyori–Ikariya Catalyst

The electrochemically driven asymmetric hydrogenation of 2,2,2-trifluoroacetophenone was performed using a Noyori–Ikariya catalyst, yielding a 97% product yield and a 47% enantiomeric excess (ee) with a charge input of only 0.5 F/mol. In comparison, the ethoxylate anion generated by the electroreduction of the solvent, EtOH, can efficiently drive the transfer hydrogenation of Ru catalysts more effectively than organic bases. After optimizing the electrolysis conditions, this method has been successfully extended to other aromatic ketones, including heterocyclic aromatic ketones and the base-sensitive substrate ethyl benzoylformate, with yields ranging from 71% to 97% and ee values ranging from 55% to 82%. A possible reaction mechanism was proposed.