Pt-based chiral organotin modified heterogeneous catalysts for the enantioselective hydrogenation of 3,4-hexanedione

Abstract

In this paper we have studied the liquid-phase enantioselective hydrogenation of 3,4-hexanedione using Pt-based catalysts, modified with chiral organotin compounds derived from the (−)-menthyl group: (−)-Pt-MenSnBu3 and (−)-Men3Sn-Sn-(−)-Men3. The organotin chiral modifiers were carefully synthesizedand characterized in order to obtain optically pure compounds. The catalysts were prepared through a controlled surface reaction between the supported transitionmetal and the organometallic compound, using techniques derived from Surface Organometallic Chemistry on Metals (SOMC/M). The organobimetallic catalytic systems were found to be active and enantioselective in the hydrogenation of 3,4-hexanedione, yielding an enantiomeric excess of 25–27% for 4-hydroxy-3-hexanone.