Tris triphenylphosphine chlororhodium I

Wilkinson catalyst, tris (triphenylphosphine) chlororhodium (I). With this in mind, it will be helpful to review briefly a few facts about [(C6H5)3P] 3RhCl before discussing the asymmetric rhodium catalysts in greater detail. 

Tris(triphenylphosphine)chlororhodium(I). The homogenous catalysis of the hydrogenation of ethylene and other olefins by RhCl( PPha) a, recently discovered by Wilkinson and co-workers (6J), probably involves a dihydride intermediate. A plausible mechanism for this reaction, involving steps of the type already described, is shown in Reaction 36. 

Tris(triphenylphosphine)chlororhodium (I) (Wilkinson s catalyst) has been the most widely studied homogeneous hydrogenation catalyst. Analogous polymeric catalysts have been prepared for use in hydrogenation. A variety of alkenes, cycloalkenes, dienes, and alkynes have been reduced by polymer-bound catalysts, indicating the wide scope of their use (Grubbs et al., 1977). 

A new polymer-supported rhodium(i) catalyst has been obtained by chloro-methylation of polystyrene beads containing 1.8% cross-linking of divinyl-benzene, converting to the diphenylphosphine, and then equilibrating with tris(triphenylphosphine)chlororhodium(i) (Scheme 22). This catalyst reduced... 

A different type of cyclizalion by means of the rhodium complex is observed in the case of a compound containing a I-al-6-ene system. Thus reaction of (-l-)-citTonellal (4) with I eq. of tris(triphenylphosphine)chlororhodium in freshly distilled chloroform at room temperature for 15 hr. results in the formation of (-t-)-neoisopulegol (5) and (—)-isopulegDl (6) in the ratio of 3 1. 

Tire reaction of carbon dioxide, hydrogen and methyloxirane Iras been desenbed by Koiiiunra (173, 174]. I, 2 Propanedtol formates were prepared in the presence of iri (triphenylphosphine)chlororhodium or tris (tripheny I phosphine) dichlororutheniunr as catalysts. No cocatalysl is required. 

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