Asymmetric hydrogenation of ethyl pyruvate: Relationship between conversion and enantioselectivity

The hydrogenation of ethyl pyruvate over cinchonidine-modified Pt exhibited intriguing transient behavior at the beginning of the reaction, and a period of rising rate and enantioselectivity was linked to conversion of substrate for a wide range of reaction temperatures and initial substrate concentrations. A ''reaction-driven equilibration'' of the surface environment for optimal enantioselective catalysis was proposed for these reactions carried out under conditions where moderate enantioselectivities are observed. (C) 1996 Academic Press, Inc.