Chiral homogeneous metal complexe

Catalytic synthesis of pantolactone and other pharmaceuticals using chiral homogeneous metal complexes... 

Carmona D., Pilar Lamata M., Oro, L. A. Recent Advances in Homogeneous Enantioselective Diels-Alder Reactions Catalyzed by Chiral Transition-Metal Complexes Coord. Chem. Rev. 2000 200-202 717-772... 

The detailed design of chiral reaction spaces for asymmetric catalysis on surfaces is still a serious challenge [1, 26, 27]. The chemistry of homogeneous metal complexes in solution can not straightforwardly be transferred to chemistry on solid surfaces, and both catalytic activity and enantioselectivity in homogeneous systems often decrease upon simple immobilization of the homogeneous meal complexes on surfaces. 

BINOL and its derivatives have been utilized as versatile chiral sources for asymmetric catalysis, and efficient catalysts for their syntheses are, ultimately, required in many chemical fields [39-42]. The oxidative coupling of 2-naphthols is a direct synthesis of BINOL derivatives [43, 44], and some transition metals such as copper [45, 46], iron [46, 47] and manganese [48] are known as active metals for the reaction. However, few studies on homogeneous metal complexes have been reported for the asymmetric coupling of 2-naphthols [49-56]. The chiral self-dimerized V dimers on Si02 is the first heterogeneous catalyst for the asymmetric oxidative coupling of 2-naphthol. 

One of the most attractive fields of homogeneous catalysis is catalysis by chiral transition metal complexes, as the tool for preparing very valuable optically active products from prochiral reactants. 

Enantioselective homogeneous hydrogenation catalyzed by chiral transition metal complexes is one of the most well established transformations in asymmetric synthesis [1]. Excellent enantioselectivities have been achieved in the hydrogenation of a wide range of substrates, often with very low catalyst loadings. High reliability, mild reaction conditions, and perfect atom economy are further attractive attributes of this method. In particular complexes based on Ru or Rh have found broad application in industrial processes [1] and the impact of these catalysts has been recognized by the Nobel Prize awarded to Ryoji Noyori and William S. Knowles in 2001 [2]. 

The most prevalent catalysts are homogeneous metal complexes mostly with chiral diphosphine ligands, isolated enzymes and whole cell preparations, whereas... 

Among the various methods to selectively produce one single enantiomer of a chiral compound, enantioselective catalysis is arguably the most attractive method. At this time, homogeneous metal complexes with chiral ligands are the most widely used and versatile enantioselective catalysts [ 1 ]. From an industrial point of view, heterogeneous catalysts are of interest for a number of reasons, and... 

Compared to homogeneous chiral transition metal complexes, enantioselective hydrogenation of aromatic and heteroaromatic compounds over modified metal catalysts has the greater potential. 

This chapter summarizes some of the most characteristic results obtained with the use of mainly homogeneous metal complex eatalysts either in the industry or in processes recommended for practical use. These are large seale processes of asymmetric synthesis of the herbicide metolachlor, synthesis of optically pure menthol with the use of chiral iridium and rhodium phosphine complexes, consideration of the synthesis of ethyl 2-hydroxybutyrate as a monomer for the preparation of biodegradable polyesters with use of heterogeneous ehiral modified nickel catalyst, the manufacturing of (fJ)-pantolactone by means of a possible eata-IjTic systems for enantioselective hydrogenation of ketopantolactone, and catalytic systems for the preparation of other pharmaceuticals. 

Industrial interest in the application of enantioselective catalysts started in earnest in the mid-sixties when the first publications of successful enantioselective transformations using homogeneous metal complexes were published. Within a surprisingly short period, production processes for two small-scale products were developed and implemented by Monsanto and Sumitomo. For quite some time, it was not really clear whether these applications where mere curiosities or whether this would be the beginning of a new area of producing chiral compounds. One reason for this state of affairs was that both companies were very reluctant to disclose information on the new technology. 

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