Asymmetric catalysis chemical

Desimoni, G., Faita, G., Jorgensen, K.A. 2006. C-2-syminetric chiral bis(oxazoline) ligands in asymmetric catalysis. Chemical Reviews 106(9) 3561-3651. 

Industrial applications inclnde the production of petrochemicals, fine chemicals and pharmacenticals (particnlarly throngh asymmetric catalysis), hydrometallurgy, and waste-treatment processes. Many life processes are based on metallo-enzyme systems that catalyse redox and acid-base reactions. 

Bayer, T. (2004) 7-Aminocephalosporanic acid - chemical versus enzymatic production process, in Asymmetric Catalysis on Industrial Scale (2004), (eds H.-U. Blaser and E. Schmidt), Wiley-VCH Verlag GmbH, 117-130. 

Annual Volume 71 contains 30 checked and edited experimental procedures that illustrate important new synthetic methods or describe the preparation of particularly useful chemicals. This compilation begins with procedures exemplifying three important methods for preparing enantiomerically pure substances by asymmetric catalysis. The preparation of (R)-(-)-METHYL 3-HYDROXYBUTANOATE details the convenient preparation of a BINAP-ruthenium catalyst that is broadly useful for the asymmetric reduction of p-ketoesters. Catalysis of the carbonyl ene reaction by a chiral Lewis acid, in this case a binapthol-derived titanium catalyst, is illustrated in the preparation of METHYL (2R)-2-HYDROXY-4-PHENYL-4-PENTENOATE. The enantiomerically pure diamines, (1 R,2R)-(+)- AND (1S,2S)-(-)-1,2-DIPHENYL-1,2-ETHYLENEDIAMINE, are useful for a variety of asymmetric transformations hydrogenations, Michael additions, osmylations, epoxidations, allylations, aldol condensations and Diels-Alder reactions. Promotion of the Diels-Alder reaction with a diaminoalane derived from the (S,S)-diamine is demonstrated in the synthesis of (1S,endo)-3-(BICYCLO[2.2.1]HEPT-5-EN-2-YLCARBONYL)-2-OXAZOLIDINONE. 

Noyori, R. Asymmetric Catalysis in Organic Synthesis Wiley New York, 1994 Chapter 2. Ohkuma, T. Noyori, R. In Transition Metals for Organic Synthesis Building Blocks and Fine Chemicals, Beller, M., Bolm, C., Eds. Wiley-VCH Weinheim, 1998 Vol. 2, p 25. 

A detailed review of the literature of non-enzymic catalysts is given in Comprehensive Asymmetric Catalysis eds Jacobsen, E.N., Pfaltz, A. and Yamamoto, H. Springer-Verlag, Berlin/Heidelberg, 1999. As an introductory text for post-graduate students see Catalysis in Asymmetric Synthesis, Williams, J.MJ. Sheffield Academic Press, Sheffield, UK, 1999. A comparison of biocatalysis versus chemical catalysis has also been made by Averill, B.A., Laane, N.W.M., Straathof, A.JJ. and Tramper, J., in Catalysis An Integrated Approach (eds van Santen, R.A. van Leeuwen, P.W.N.M., Moulijn, J.A. and Averill, B.A.) Elsevier, The Netherlands, 1999, Chapter 7. 

The development of catalytic asymmetric reactions is one of the major areas of research in the field of organic chemistry. So far, a number of chiral catalysts have been reported, and some of them have exhibited a much higher catalytic efficiency than enzymes, which are natural catalysts.111 Most of the synthetic asymmetric catalysts, however, show limited activity in terms of either enantioselectivity or chemical yields. The major difference between synthetic asymmetric catalysts and enzymes is that the former activate only one side of the substrate in an intermolecular reaction, whereas the latter can not only activate both sides of the substrate but can also control the orientation of the substrate. If this kind of synergistic cooperation can be realized in synthetic asymmetric catalysis, the concept will open up a new field in asymmetric synthesis, and a wide range of applications may well ensure. In this review we would like to discuss two types of asymmetric two-center catalysis promoted by complexes showing Lewis acidity and Bronsted basicity and/or Lewis acidity and Lewis basicity.121... 

The field of asymmetric catalysis in synthesis is far from mature however. There are a considerable number of important chemical transformations that do not yet have a catalytic enantioselective variant, and few of the existing catalytic asymmetric reactions - perhaps none of them - are truly general. Some argue that there are no general methods, asymmetric or not several asymmetric variations of the same general transformation may therefore be needed. Furthermore, many of the applications that were discussed here were employed by researchers that also developed the asymmetric methods we have not reached a stage yet, when scientists not involved in the discovery and development of catalytic asymmetric reactions regularly utilize such protocols. It is hoped that this article... 

For an overview of the application of enantioselective catalysis in fine chemicals production, see (a) Blaser, H.U., Spindler, F. and Studer, M. (2002) Applied Catalysis A General, 221, 119 (b) Blaser, H.U. and Schmidt, E. (eds) (2003) Large-Scale Asymmetric Catalysis, Wiley-VCH Verlag GmbH, Weinheim, p. 1. 

H. (Eds.), Springer-Verlag, Heidelberg, 1999 (b) Catalytic Asymmetric Synthesis, 2nd ed., Ojima, I. (Ed.), Wiley, New York, 2000 (c) Methodologies in Asymmetric Catalysis, Malhotra, S. V. (Ed.), American Chemical Society, Washington, DC, 2004. 

New Frontiers in Asymmetric Catalysis provides readers with a comprehensive perspective on understanding the concepts and applications of asymmetric catalysis reactions. Despite the availability of excellent comprehensive multi volume treatises in this field, we felt that researchers in pharmaceutical and chemical companies as well as university faculty and graduate students would benefit from a selection of some of the most important recent advances in this ever-growing area. 

The majority of chemical methods for the asymmetric hydrogenation of unsaturated systems rely on the use of transition metal catalysts or stoichiometric amounts of metal hydride. The chemical importance of this transformation has led to the development of some of the most powerful and efficient methods in catalytic asymmetric synthesis. Routinely used on the milligram to multi-tonne scale, they represent one of the biggest success stories of asymmetric catalysis [120]. 

The commercialization in 1983 of the process illustrated in Eq. (1) is undoubtedly one of the most significant triumphs of asymmetric catalysis to date [2]. Takasago Chemical Company produced more than 22 000 tons of menthol by this route during the period 1983-1996, consuming only 125 kg of the chiral Hgand in the process. Rh(I)/Tol-BINAP-catalyzed isomerizations of allylic amines are beheved to proceed through the pathway outlined in Eq. (2) [3]. 

Implementation of the concept of combined acids in the field of asymmetric catalysis has been known for over 20 years. Several excellent reviews containing historical background and theoretical perspectives on this subject have appeared [93]. Fundamentally, a combined acid system involves the association of an acceptor atom A with a donor atom D that is chemically bonded to another... 

But there is still another point, not yet discussed but with considerable potential, which may also impact eventually on technical asymmetric catalysis. Even though biocatalysts are efficient, active, and selective, there still remains one big disadvantage At present, there is not yet an appropriate enzyme known or available for every given chemical reaction. It is estimated that about 25 000 enzymes exist in Nature, and 90% of these have still to be discovered [28, 29]. New biocatalysts are made available nowadays not only from screening known organism but also via screening metagenomic libraries and directed evolution techniques [30]. 

Chirality plays a central role in the chemical, biological, pharmaceutical and material sciences. Owing to the recent advances in asymmetric catalysis, catalytic enantioselective synthesis has become one of the most efficient methods for the preparation of enantiomer-ically enriched compounds. An increased amount of enantiomerically enriched product can be obtained from an asymmetric reaction using a small amount of an asymmetric catalyst. Studies on the enantioselective addition of dialkylzincs to aldehydes have attracted increasing interest. After the chiral amino alcohols were developed, highly enantioselective and reproducible —C bond forming reactions have become possible. 

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