Enantio-differentiating hydrogenation of methyl acetoacetate over modified Raney nickel catalysts prepared by two-step modifications

Two-step modifications of the Raney nickel were examined for the enantio-differentiating hydrogenation of methyl acetoacetate. Among the two-step modifications attempted in this study, the combination of ‘pre-modification with disodium tartrate and NaBr in water’ and ‘in-situ modification with tartaric acid’ resulted in the highest optical yield (84%). This modification process is a greener process than the conventional one carried out under weakly acidic conditions, because this process generated almost no Ni2+ ions. The pre-modification with the tartrate and NaBr preferentially eliminated Al3+ from the Raney nickel surface.