Homogeneous catalysis asymmetric synthesis

Keywords Heterobimetallic catalysts, Lanthanoid complexes, Asymmetric synthesis, Homogenous catalysis... 

Noyori, R., Hasiguchi, S., Yamano, T. Asymmetric synthesis. In Applied Homogeneous Catalysis with Organic Compounds. Herrmann, B.C.W.A. 

Chaloner, P.A., Esteruelas, M.A., Joo, F., Oro, L.A., Homogeneous Hydrogenation, Kluwer, Dordrecht, 1994 Noyori, R., Asymmetric Catalysis in Organic Synthesis (especially Chapter 2), John Wiley Sons, Inc., New York, 1994 Ojima, I. (Ed.), Catalytic Asymmetric Synthesis,... 

Optically active aldehydes are important precursors for biologically active compounds, and much effort has been applied to their asymmetric synthesis. Asymmetric hydroformylation has attracted much attention as a potential route to enantiomerically pure aldehyde because this method starts from inexpensive olefins and synthesis gas (CO/H2). Although rhodium-catalyzed hydrogenation has been one of the most important applications of homogeneous catalysis in industry, rhodium-mediated hydroformylation has also been extensively studied as a route to aldehydes. 

Homogeneous Catalysis Parshall, G.W. and Ittel, S.D. (eds), 1992 (second edition), Wiley, New York, p 33 Takaya, H., Ohta, T. and Noyori, R. Catalytic Asymmetric Synthesis Chapter 1, VCH, Weinheim, 1993. 

For the production of chemicals, food additives and pharmaceutical products, homogeneous catalysis offers some attractive features such as a high selectivity and activity, e.g. in asymmetric synthesis. However, since most homogeneous catalysts are relatively expensive, their current industrial application is limited [3]. On the other hand, heterogeneous catalysts can easily be separated from the products and can be recycled efficiently. Membrane separations with emphasis on nanofil-tration and ultrafiltration will allow for a similar recyclability of homogeneous catalysts, which is important both from an environmental as well as a commercial... 

Such diene complexes can be used to prepare homogeneous hydrogenation catalysts in situ, especially where a variable tertiary phosphine/rhodium ratio is required3 or where an asymmetric tertiary phosphine is employed for asymmetric synthesis.4 The cyclooctadiene complex is also the starting point for the preparation a number of complexes of the type [Rh(l, 5-C8H12)L2]+ (L represents a variety of P— and N— donor ligands) of interest in homogeneous catalysis.s... 

In recent years the synthesis of chiral and achiral tripodal phosphines and their application in homogeneous catalysis has been studied in more detail [2]. Enantiomerically pure tripodal ligands were synthesized from the corresponding trichloro compounds and chiral, cyclic lithio-phosphanes, e.g. 17, (Scheme 6) [21,22], Using a rhodium(I) complex of ligand 18, an enantiomeric excess of 89 % was obtained in the asymmetric hydrogenation reaction of methyl acetami-docinnamate (19). 

Based in part on the article Asymmetric Synthesis by Homogeneous Catalysis by Brice Bosnich which appeared in the Encyclopedia of Inorganic Chemistry, First Edition. 

---