ABSTRACT
In this paper the role of substrate-modifier interactions in the control of diastereoand enantioselectivity is discussed. The discussions are based on results obtained in two reactions: (i) diastereoselective hydrogenations of D-fructose to D-mannitol in the presence of -B(OH)x moieties anchored to the catalyst support and (ii) enantioselective hydrogenations of ethyl pyruvate (EtPy) in the presence of cinchonidine added into the reactor during the racemic hydrogenation. Results indicate that substrate-modifier interactions, taking place either in the bulk liquid phase or in the boundary diffusion layer, are involved in the control of selectivity. It is proposed that the substrate-modifier interaction is responsible for rate acceleration in the enantioselective hydrogenation of EtPy.
