Enantioface-differentiating hydrogenation of the CO double bond using a modified Raney nickel: Role of the carboxylic acid added to the reaction system

A tartaric acid—sodium bromide—modified Raney nickel (TANaBrMRNi) is a unique catalyst for the enantioface-differentiating hydrogenation of 2-alkanones and β-ketoesters. The addition of carboxylic acid to the reaction system results in improvement of the optical yield over this catalyst. In this study, the enantioface-differentiating hydrogenations of 2-octanone and methyl acetoacetate were carried out to clarify how the added carboxylic acids improve the efficiency of the enantio-differentiation of the substrates over TANaBrMRNi. The participation of the conjugate bases and protons generated from the added carboxylic acid during the hydrogenation of 2-alkanones and β-ketoesters is proposed.