Chlorotris rhodium Wilkinson

Chlorotris(triphenylphosphine)rhodium (Wilkinson s catalyst) is among the most efficient catalysts and permits hydrogenation in homogeneous solution. The Rh complex is readily prepared by heating rhodium chloride with excess triphenylphosphine in ethanol. 

Other catalysts, such as chlorotris(triphenylphosphane)rhodium (Wilkinson s catalyst) or di-carbonylbis(triphenylphosphane)nickel, also allow this type of cocyclotrimerization of diynes with alkynes35. 

Aldehydes, both aliphatic and aromatic, can be decarbonylated by heating with chlorotris(triphenylphosphine)rhodium or other catalysts such as palladium. The compound RhCl(Ph3P)3 is often called Wilkinson s catalyst.In an older reaction, aliphatic (but not aromatic) aldehydes are decarbonylated by heating with di-tert-peroxide or other peroxides, usually in a solution containing a hydrogen donor, such as a thiol. The reaction has also been initiated with light, and thermally (without an initiator) by heating at 500°C. 

The water-soluble Wilkinson-type catalyst chlorotris(diphenylphosphinoben-zene-m-sulfonate)rhodium(I), RhQfdpm) (19), acts as catalyst for H2-evolution [158], hydrogenation and hydroformylation [159]. In a photosystem composed of Ru(bpy)i+ as photosensitizer, ascorbic acid, HA, as electron donor and RhCl(dpm)3, hydrogen evolution proceeds with a quantum efficiency corresponding to (p = 0.033. In the presence of ethylene or acetylene, hydrogen evolution is blocked and hydrogenation of the unsaturated organic substrates predominates. Table 6 summarizes the quantum yields for H2-evolution and... 

The most important catalyst in this class is Wilkinson s Catalyst, chlorotris(triphenylphosphine)rhodium(I). The catalytic cycle of this complex is shown in Scheme 7. The basic catalytic cycle is very simple, but parasitic side reactions make its study more difficult. 

Enantiomerically pure carboxylic acids are routinely obtained from N-acylsultams by Hydrogen Peroxide assisted saponification with Lithium Hydroxide in aqueous THF. 4 Alternatively, transesterification can be effected under neutral conditions in allyl alcohol containing Titanium Tetraisopropoxide, giving the corresponding allyl esters which can be isomerized/hydrolyzed with Wilkinson s catalyst (Chlorotris(triphenylphosphine)rhodium(I)) in Et0H-H20. This provides a convenient route to carboxylic acids containing base-sensitive functionality. Primary alcohols are obtained by treatment with L-Selectride (Lithium Tri-s-butylborohydride) in THF at ambient temperature. ... 

Chlorotris(triphenylphosphine)rhodium(I), [RhCl(PPh3)3], was reported independently by three groups in 1965, " and its application to catalytic homogeneous hydrogenation has been studied intensively by Wilkinson s group. The Wilkinson catalyst is now the most widely used for hydrogenation of a variety of unsaturated substrates, and several extensive reviews of this catalyst have been published. ... 

Wilkinson s catalyst A homogeneous catalyst with the formula chlorotris(triphenylphosphine) rhodium. 

Similarly, intramolecular [4 4- 2] cycloaddition of unactivated dienynes is also catalyzed and dramatically accelerated by low-valent rhodium complexes, e.g., Wilkinson s catalyst [chloro-tris(triphenylphosphane)rhodium] and phosphite analogs, under mild conditions46. Thus, ( , )-l-(2-propynyloxy)-2,4-hexadiene (3, Z = O) and similar dienynes, with 5 mol% of chlorotris(tri-phenylphosphane)rhodium in 2,2,2-trifluoroethanol for 30 minutes at 55 C. give up to quantitative yield of the cycloadducts with excellent to complete diastereoselection. According to control... 

Similarly, reduction of the unsaturated lactone 4 by hydrogenation over palladium on carbon yielded only the tetrasubstituted monohydrogenated product. In this case Wilkinson s catalyst [chlorotris(triphenylphosphane)rhodium] is the catalyst of choice for the regio- and diastereose-lective reduction of the exocyclic double bond7. 

Wieland s. Barbier Wilkinson rhodium catalyst s. Chlorotris(triphenyl-phosphine)rhodium Wittig synthesis, intramolecular to... 

Detailed kinetic studies [17] have been done of oxidative addition of some hydrosilanes to an iridium(I) complex, which is isoelectronic with the Wilkinson s complex [chlorotris(triphenylphosphine)rhodium(I)] but ineffective as catalyst. Hydrosilanes Me (EtO)3 SiH were found to undergo a readily reversible oxidative addition to the complex. 

Since the intermediacy of a-siloxyalkyl rhodium complex III (see Scheme 4) is strongly suggested in the hydrosilylation of terpene ketones catalyzed by chlorotris-(triphenylphosphine)rhodium(I) (7), such an intermediate most likely plays a key role in the asymmetric induction of the present system. The fundamental premise is to assume a square-pyramidal structure of the a-siloxyalkyl-rhodium intermediate VI, as shown in equation (18), on the basis of the established structures of dihydrido [46] and of silylhydrido [14, 32c, 47] complexes derived from the Wilkinson s rhodium(I) complex. 

The influence of phosphine ligands, added salts, and the type of metal catalyst on the selectivity of the cyclization have been studied. With K2CO3 as base, Wilkinson s catalyst (chlorotris(triphenylphosphine) rhodium(I)) showed higher se-... 

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