Enantioselective reactions, catalyzed by chiral

Abstract In general, asymmetric catalysts are based on the combination of a chiral organic ligand and a metal ion. Here we show that future research should also focus on complexes in which the chirality resides only at the metal center, as the result of a given topology of coordination of achiral ligands to the metal ion. Here we make a brief presentation of the methods available for preparing such compounds as well as the very few examples of enantioselective reactions catalyzed by chiral-at-metal complexes. 

There are many other enantioselective reactions catalyzed by chiral metal complexes. These include complexes of various chiral phosphines, tartrate ion, and others as ligands. Chiral cyclopentadienyl metal complexes (32) also are used. Chiral ligands are not limited to those containing an asjonmetric carbon. [RuCbinap)] " is a catalyst for enantioselective hydrogenation. In some cases such as [Rh(dipamp)] and [Rh(pnnp)] well defined complexes are used. In many cases the reaction is carried out in the presence of a chiral ligand and a metal compound. The reaction involving... 

Numerous investigations of highly enantioselective reactions catalyzed by chiral phosphoric acids (86) continue to be reported. The potential of this type of Bronsted acid in asymmetric catalysis has been demonstrated. The first asymmetric direct hetero Diels-Alder reaction catalyzed by a chiral Bronsted acid has been described. Thus chiral phosphoric acid (86) exhibited superior enantioselectivity, affording fairly good yields and enantioselectivities for reactions of aromatic aldimines with cyclohexenone (Scheme 21). ... 

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