Use of heterogenized metal complexes in hydrogenation reactions: comparison of hydrogenation and CTH reactions

In the fine chemicals industry the preference for heterogeneous over homogeneous catalysts is well known. However, the activity and selectivity of heterogeneous metal complexes are usually better than those of their homogeneous counterparts. There has, consequently, been an increasing demand for heterogenized metal complexes which combine the advantages of both types of catalyst. In the production of fine chemicals, selectivity is probably its most important property of a catalyst. Chemoselectivity, regioselectivity, and enantioselectivity are very important in the synthesis of fine chemicals. Several examples of hydrogenation with heterogenized metal complexes have been studied, with emphasis on selectivity. Catalytic transfer hydrogenation is also discussed, as an alternative to classical hydrogenation.