Enantioselective heterogeneous catalysis catalysts

H. U. Blaser, B. Pugin, M. Studer, Enantioselective heterogeneous catalysis academic and industrial challenges, in D. E. de Vos, I. F. J. Vankelecom, P. A. Jacobs (Eds.), Chiral Catalyst Immobilization and Recycling, Wiley-VCFI, Weinheim, 2000, p. 1. 

Blaser H-U, Pugin B, Studer M (2000) Enantioselective heterogeneous catalysis academic and industrial challenges. In De Vos DE.Vankelecom IFJ, Jacobs PA (eds) Chiral catalyst immobilization and recycling. Wiley-VCH,Weinheim,p 1... 

An unusual ee-screening system for enantioselective transition metal catalysts is based on IR-thermo-graphy,55 which had previously been used in heterogeneous catalysis.36,81,82 Using an AIM-2562 IR... 

The enantioselective hydrogenation of prochiral substances bearing an activated group, such as an ester, an acid or an amide, is often an important step in the industrial synthesis of fine and pharmaceutical products. In addition to the hydrogenation of /5-ketoesters into optically pure products with Raney nickel modified by tartaric acid [117], the asymmetric reduction of a-ketoesters on heterogeneous platinum catalysts modified by cinchona alkaloids (cinchonidine and cinchonine) was reported for the first time by Orito and coworkers [118-121]. Asymmetric catalysis on solid surfaces remains a very important research area for a better mechanistic understanding of the interaction between the substrate, the modifier and the catalyst [122-125], although excellent results in terms of enantiomeric excesses (up to 97%) have been obtained in the reduction of ethyl pyruvate under optimum reaction conditions with these Pt/cinchona systems [126-128],... 

Despite the convenience of handling and separation in heterogeneous catalysis, many other parameters have a strong influence on the stereochemical outcome pressure temperature modifier purity of substrates high substrate specificity catalyst preparation, which includes type, texture, and porosity of the support dispersion impregnation reduction and pretreatment of the metal.22 Reproducibility of catalyst activities and enantioselectivities can often be a problem attributed to variations in catalyst preparations and purity of the substrate.5-22... 

In heterogeneous catalysis, transition metal nanoparticles are supported on different substrates and are utilized as catalysts for different reactions [57], such as hydrogenations and enantioselective synthesis of organic compounds [58], oxidations and epoxidations [59], and reduction and decomposition [57],... 

Pini, D., Petri, A., Mastantuono, A., Salvador , P. Heterogeneous enantioselective hydrogenation and dihydroxylation of carbon carbon double bond mediated by transition metal asymmetric catalysts. Chiral Reactions In Heterogeneous Catalysis, [Proceedings of the European Symposium on Chiral Reactions In Heterogeneous Catalysis], 1st, Brussels, Oct. 25-26, 1993 1995, 155-176. 

Scheme 9.9 Heterogeneous catalysis of enantioselective hydrogenations with self-supported MonoPhos/Rh catalysts.

The immobilized catalyst provided good enantioselectivity and activity in the heterogeneous catalysis of the oxidative kinetic resolution of secondary alcohols and can be recovered and recycled for four times without obvious loss of enantioselectivity and activity. Oxidative kinetic resolutions of meso-diols, hydroxyl esters, and primary alcohols were also studied using this catalytic system. 

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