Patent ID: 7057064

Claim:
A continuous process for the enantioselective catalytic hydrogenation of β-ketoesters comprising: (a) providing a catalytic hydrogenation zone and maintaining it under conditions of temperature and pressure effective for the catalytic hydrogenation of β-ketoesters; (b) continuously supplying to the catalytic hydrogenation zone a substrate comprising a β-ketoester to be hydrogenated, a catalyst effective for enantioselective hydrogenation of the β-ketoester and hydrogen; (c) contacting the substrate, the catalyst and the hydrogen in the hydrogenation zone for a residence time effective for at least partial enantioselective catalytic hydrogenation of the β-ketoester, the substrate/catalyst molar ratio in the hydrogenation zone being at least about 15,000:1; (d) continuously withdrawing from the hydrogenation zone a reaction product mixture comprising enantioselectively hydrogenated β-ketoester, unreacted β-ketoester, catalyst and hydrogen; (e) supplying the reaction product mixture to a separation zone and separating at least some of the enantioselectively hydrogenated β-ketoester from the reaction product mixture; (f) withdrawing the separated enantioselectively hydrogenated β-ketoester as product; and (g) optionally supplying at least part of the remaining material from the separation zone to the hydrogenation zone.