Abstract:

Owing to the recent environmental consideration and safety concerns,the uses of homogeneous and heterogeneous asymmetric methods for the synthesis of chiral product such as enantioselective hydrogenation are especially preferable.¹ Up to now, only a few homogeneous and heterogeneous enantioselective hydrogenation catalytic systems have been investigated in some detail. One of these is the enantioselective hydrogenation of activated carbonyl compounds over a-hydroxy acid modified Raney nickel catalyst.² Systematic variation of the modifier may prove as an efficient tool to shed light on the reaction mechanism. It has been proposed that tartaric acid adsorbs as a chelate to form binuclear Ni tartarate surface complex. However, the exact adsorption state of the modifier is unknown exactly and requires further attention. Direct investigation of the adsorption mode of the modifier over Raney nickel is not yet possible. Any indirect evidence for the adsorption mode is therefore of crucial importance for a better understanding of the reaction.³