ABSTRACT
The application of enantioselective catalysts in the pharmaceutical and agrichemical industries has increased rapidly. Only a very few heterogeneous enantioselective catalyst systems have been found, and they are usually substrate-specific. The prime example of commercial enantioselective catalysis is the Monsanto l-dopa process. The preparation of the enantioselective catalysts is an exercise in organometallic chemistry. Laboratory-scale preparation of enantioselective ruthenium hydrogenation catalysts using standard but specific synthesis techniques shows a wide variation in techniques. The preparation of enantioselective heterogeneous catalyst by the immobilization of an enantioselective organometallic complex on a solid substrate has been the subject of much research and discussion with limited success. Nickel catalysts modified with tartaric acid give enantioselective hydrogenations of prochiral ketones as ß-keto esters and ß-diketones. The enantioselective hydrogenation of a-keto esters has been investigated by Onto. A possible hydrid enantioselective hydrogen has been studied by Tungler.
