In the asymmetxic hydrogenation of ethyl pyruvate catalyzed by 0.5% Rh/PVP-TiO_2, the chiral modifier cinchonidine not only induces the enantioselectivity, but also accelerates the reaction rate greatly. A promotion effect of TiO_2 for the asymmetric hydrogenation is observed, when the modified rhodium nanoclusters are supported on TiO_2. The results show that TOF increase from 15.7 to 58.6 min~(-1) and e.e. values of R( + )-ethyl lactate increase from 42.2% to 60.0% in the hydrogenation of ethyl pyruvate. This suggests that TiO2 is favourable for the dispersion of Rh/PVP and its stabilization on the support surface. Under the optimum conditions: 298 K, p_(H_2) =6.0 MPa, 4. 3*10~(-3) mol/L cinchonidine in THF, ethyl pyruvate/rhodium = 942 (molar ratio), TOF and e.e. value are 58.6 min~(-1) and 61.9%, respectively.

Key words: ethyl pyruvate, HYDROGENATION, ASYMMETRY, cinchonidine, OXIDATION