Improvement in the enantioselective hydrogenation of methyl pyruvate over platinum clusters by addition of rare earth cations

The modification of some rare earth metal cations to polymer-stabilized Pt colloidal clusters leads to significant increase in both the ee and the act ivity in the homogeneous enantioselective hydrogenation of methyl pyruvate to (R)-(+)-methyl lactate. Compared to ee (72.5%) in the absence of rare ea rth cations, the highest ee (88.0%) in ethanol solvent is obtained by addin g a suitable amount of Yb3+ into the Pt colloidal cluster catalyst. The mod ification effect of rare earth cations is also effective in other alcohol a nd water solvents.