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Wilkinson catalysts Subject

In Section 5.9, we saw that alkenes can be converted to alkanes by catalytic hydrogenation by a variety of catalysts, such as palladium and platinum. These are heterogeneous catalysts. We also noted that homogeneous catalytic hydrogenation can be carried out by Wilkinsons catalyst, Ru[(PPh3)3Cl. We now return to that subject to discuss the reaction mechanism. We will find that hydrogenation by Wilkinson s catalyst occurs in a catalytic cycle that is strikingly similar to the catalytic cycles of the reactions we have discussed thus far in this chapter. The transition metal in the Wilkinson catalyst, however, is ruthenium, not palladium. [Pg.580]

Transition-metal chemistry is currently one of the most rapidly developing research areas. The record of investigation for compounds with metal silicon bonds is closely comparable to that for silicones it was in 1941 when Hein discovered the first metal silicon complex, followed by Wilkinson in 1956. A milestone in the development of this chemistry was Speier s discovery of the catalytic activity of nobel metal complexes in hydrosilylation reactions in 1977. Hydrosilylation is widely used in modem organic syntheses as well as in the preparation of organo functionalized silicones. Detailed investigations of the reaction mechanisms of various catalysts continue to be subject of intense research efforts. [Pg.167]

Rhodium-catalyzed allylic substitution processes generally proceed in a stereospecific manner. After initial reports by Tsuji [107], extensive studies by Evans have resulted in the development of a reliable and general method for the stereoselective preparation of useful building blocks [39, 108-111]. With Wilkinson s catalyst in the presence of phosphites, Evans has showcased the rhodium-catalyzed allylation of numerous substrate classes. Thus, substitution of the carbonate in 125 with malonate 124 furnished 126 dr =26 1), which was subsequently subjected to decarboxylation and io-dolactonization reaction [112] to afford 127 (dr >30 1, Scheme 14.20) [109]. [Pg.473]


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Catalyst Subject

Wilkinson catalyst

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