Catalysts asymmetric hydrogenation

Styrene, a-ethyl-asymmetric hydroformylation catalysts, platinum complexes, 6, 266 asymmetric hydrogenation catalysts, rhodium complexes, 6, 250 Styrene, a-methyl-asymmetric carbonylation catalysis by palladium complexes, 6, 293 carbonylation... 

Palmer and Wills in 1999 reviewed other ruthenium catalysts for the asymmetric transfer hydrogenation of ketones and imines [101]. Gladiali and Mestro-ni reviewed the use of such catalysts in organic synthesis up to 1998 [102]. Review articles that include the use of ruthenium asymmetric hydrogenation catalysts cover the literature from 1981 to 1994 [103, 104], the major contributions... 

Many attempts have been made to develop novel nonracemic ferrocenyl phosphine derivatives as asymmetric hydrogenation catalysts. Interested readers will find the design and synthesis of these chiral ferrocenyl phosphine ligands in a recent review by Richards and Locke.286... 

As recently recognized by the Nobel Chemistry award committee, the conceptualization, development, and commercial application of enantioselective, homogeneous hydrogenation of alkenes represents a landmark achievement in modem chemistry. Further elaboration of asymmetric hydrogenation catalysts by Noyori, Burk, and others has created a robust and technologically important set of catalytic asymmetric synthetic techniques. As frequently occurs in science, these new technologies have spawned new areas of fundamental research. Soon after the development of... 

Much like the enol systems discussed in Sect. 6.1, enamines are predictably difficult substrates for most iridium asymmetric hydrogenation catalysts. Both substrate and product contain basic functionahties which may act as inhibitors to the catalyst. Extended aromatic enamines such as indoles may be even more difficult substrates for asymmetric hydrogenation with an additional energetic barrier to overcome. Initial reports by Andersson indicated a very difficult reaction indeed (Table 14) [75]. Higher enantioselectivities were later reported by Baeza and Pfaltz (Table 14) [76]. 

Wilson, M.E. and Whitesides, G.M. (1978) Conversion of a protein to a homogeneous asymmetric hydrogenation catalyst by site-specific modification with a dipho-sphinerhodium(l) moiety. J. Am. Chem. Soc., 100, 306-307. 

NMR spectroscopy has been used to study the species formed in solution by interaction of cinnamic add derivatives with asymmetric hydrogenation catalysts.257,258 Such studies are necessarily limited to those spedes which accumulate in adequate concentration and have sufficiently long lifetimes for observation by NMR. In catalytic reactions as rapid as those described here, such complexes appear likely to be outside rather than in the operating catalytic cycle.91... 

Table 5 Some Other Highly Selective Asymmetric Hydrogenation Catalysts...

The two diphosphinites 40 and 41 obtained from D-glucose by standard procedures proved to be good asymmetric hydrogenation catalysts <2000CCL587>. 

One of the earliest examples of such catalysis was demonstrated in 1966 by the Japanese chemist Hitosi Nozaki, who reacted styrene and ethyl diazoacetate in the presence of a chiral Schiffbase-Cu11 complex [72-74], Although the initial enantios-electivity was modest (<10% ee), the principle was proven. Some years later, the companies Sumitomo and Merck used similar copper catalysts for asymmetric cyclopropanation on a multikilogram scale, in the production of various insecticides and antibiotics [75]. One of Nozaki s PhD students at that time was Rioji Noyori, who later developed the BINAP asymmetric hydrogenation catalysts for which he received the 2001 Nobel Prize in Chemistry [7[. 

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