Chiral-at-metal catalysts

Scheme 10.21 Olefin metathesis processes invert the absolute stereochemistry of chiral-at-metal catalysts.

With synthetic access to pure samples of both diastereomers of chiral-at-metal catalyst 11, the abihty of each diastereomer to selectively effect enantioselective... 

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. 

Fontecave M, Hamelin O, Menage S (2005) Chiral-at-Metal Complexes as Asymmetric Catalysts. 15 271-288 FraUe JM, Garcia JI, Mayoral JA (2005) Non-covalent Immobilization of Catalysts Based on Chiral Diazaligands. 15 149-190 Frenking G, see Deubel D (2005) 12 109-144 Fu GC, see Netherton M (2005) 14 85-108... 

Fontecave M, Hamelin O, Menage S (2005) Chiral-at-Metal Complexes as Asymmetric Catalysts. 15 271-288... 

The synthesis of chiral-at-metal complexes may lead to the development of more selective asymmetric catalysts see... 

What two steps are needed to convert A to L-dopa, an uncommon amino aoid that is effective in treating Parkinson s disease These two steps are the key reactions in the first oommercial asymmetrio synthesis using a chiral transition metal catalyst. This process was developed at Monsanto in 1974. 

With the most advanced streptavidin variants, the strategy in which a racemic catalyst is converted to a chiral-at-metal complex and then further assisted by residues in the chiral protein has led to the development of both R- and 5-selective synthetic enzymes for imine reduction. Extensive kinetic data has been obtained for these new synthetic enzymes, and computer modelling of the complex stmctures (which contain four interacting subunits) serves to support and understand the results. An induced lock and key where the host protein structure determines the catalyst structure and the reduction selectivity is proposed (Fig. 44) [141]. 

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