Heterogeneous enantioselective hydrogenation over cinchona alkaloid modified platinum: mechanistic insights into a complex reaction

Modification of a metal surface by a strongly adsorbed chiral organic molecule has proven to be an interesting strategy for heterogeneous chiral catalysis. Platinum chirally modified by cinchona alkaloids, successfully applied for the enantioselective hydrogenation of alpha-ketoesters, is probably the most prominent catalyst based on this concept. Despite considerable research efforts toward understanding of this complex catalytic system, the proposed mechanistic models are still debated. Here we discuss how enantiodifferentiation can be induced on a catalytically active surface and validate the models proposed for the platinum-cinchona system in the light of the existing molecular knowledge.