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

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 synthesized and characterized in order to obtain optically pure compounds.The catalysts were prepared through a controlled surface reaction between the supported transition metal 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.

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► Organotin compounds with the chiral carbon bonded to the Sn exert a chiral induction.
► PtSn catalysts were obtained by a surface reaction between Pt and menthyl compounds.
► PtSn systems have been active in the liquid phase hydrogenation of 3,4-hexanedione.
► PtSn catalysts have been enantioselective (ee% for 4-hydroxy-3-hexanone of 25%).
► An increase in the ee% with a decrease in the reaction temperature has been observed.