Organometallic chiral rhodium catalyst

In conclusion, chiral heterogeneous catalysts are prepared from chiral Rhodium diphosphine complexes and Al-MCM-41. The bonding supposedly occurs via an ionic interaction of the cationic complex with the host. Also a slight reduction of weak acidic sites of Al-MCM-41 has been observed. These catalysts are suitable for the hydrogenation of functionalised olefins. The organometallic complexes remain stable within the mesopores of the carrier at reaction conditions. The catalyst can be recycled by filtration or centrifugation. 

Nishiyama H, Kondo M, Nakamura T, Itoh K (1991) Highly enantioselective hydrosilylation of ketones with chiral and c2-symmetrical bis(oxazolmyl)pyridine-rhodium catalysts. Organometallics 10 500-508... 

Nonorganic and organometallic catalysts are also used to channel the reactions toward the chiral synthesis pathway. The drug called levodopa, (5)-3,4-dihydroxyalanine, is an effective drug against Parkinson s disease. It is stereoselectively manufactured using catalysts such as rhodium or ruthenium complexes. 

Subsequent major events, up until the early 1980s, have been reviewed [2], with one of the major reactions involved being that of asymmetric hydrogenation, which is especially useful and efficient. This was first developed using rhodium complexes equipped with chiral mono- or diphosphines [3-6], though many other types of reaction (e.g., hydroformylation, Diels-Alder reaction) are now well controlled in the presence of chiral organometallic catalysts. Over the past few years there has been a clear renewal of interest for organocatalysis [7], and consequently this chapter will review the specific and unusual case of the catalytic enantioselective reduction of C=C, C=0, and C=N double bonds. 

Joo, E and Trocsanyi, E. (1982) Asymmetric hydrogenation of acetophenone with rhodium(I) complexes of new chiral phosphines derived from amiono acids. An usual modification of the catalyst system. Journal of Organometallic Chemistry, 231, 63-70. 

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