Chiral reactions in heterogeneous catalysis (1975-1999)

Abstract

The preparation of pure chemical compounds has been one of the most rapid growth areas in chemistry over the last decade with heterogeneous catalysis being recognised as providing new possibilities. A number of different strategies have been developed to obtain enantioselectivity through heterogeneous catalysis: the use of chiral species to modify the solid surface; the grafting of a chiral catalytic complex on a solid - the so called heterogenised homogeneous catalyst - and homogeneous formation of a chiral complex before reaction at the solid surface. Because the interaction between functional groups is complex, the influence the surface has on reaction mechanisms is, so far, not well developed.

Hydrogenation reactions have dominated the field with α- or β-ketoesters being the preferred substrates and nickel modified by tartaric acid and platinum modified by cinchona alkaloids as preferred catalytic systems with modified zeolites playing a crucial role. Some examples of the leading groups are in Switzerland (Blaser and Baiker), Japan (Nitta, Osawa, Izumi and Harada), USA (Sachtler, Augustine), United Kingdom (Webb, Wells, Thomas, Catlow, Hutchings and Whyman) and the Netherlands (Sheldon).In spite of the present hyper-activity the use of metal catalysts to effect asymmetric reactions is not new with Schwab in Germany and Lipkin and Stewart in the USA active in the 1930s. In 1995 at the ChiCat Symposium both Reisse and Ghosez suggested that those in catalysis should “not reinvent wheels that organic chemists had laboured over many years” and “that goals already achieved by organic chemists will not be easy to obtain through heterogeneous catalysis”. We await future developments with much anticipation!