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Wilkinson's catalyst (chloridotris(triphenylphosphine)rhodium(I)) is a coordination complex of rhodium with the formula [RhCl(PPh 3) 3], where 'Ph' denotes a phenyl group. It is a red-brown colored solid that is soluble in hydrocarbon solvents such as benzene, and more so in tetrahydrofuran or chlorinated solvents such as dichloromethane .
The Tsuji–Wilkinson decarbonylation proceeds under mild conditions and is highly stereospecific. In addition to aliphatic, aromatic, and α,β-unsaturated aldehydes, acyl nitriles and 1,2-diketones are also suitable substrates. Few methods exist for decarbonylation. One illustrative application is the synthesis of the core nucleus of FR ...
The difference in regioselectivity is more pronounced in the hydroboration of vinylarenes with HBcat. Wilkinson's catalyst or the cation Rh(COD) 2 (in the presence of PPh 3) produces the Markovnikov product. [12] [13] The anti-Markovnikov product is produced in the absence of a catalyst. [14]
Tetrakis(triphenylphosphine)palladium(0) is widely used to catalyse C-C coupling reactions in organic synthesis, see Heck reaction. Wilkinson's catalyst, RhCl(PPh 3) 3 is a square planar Rh(I) complex of historical significance used to catalyze the hydrogenation of alkenes.
An example of this is the Tsuji–Wilkinson decarbonylation reaction using Wilkinson's catalyst. (Strictly speaking, the noncatalytic version of this reaction results in the formation of a rhodium carbonyl complex rather than free carbon monoxide.)
Mechanism for the hydrogenation of a terminal alkene using Wilkinson's catalyst. Homogeneous catalysts are also used in asymmetric synthesis by the hydrogenation of prochiral substrates. An early demonstration of this approach was the Rh-catalyzed hydrogenation of enamides as precursors to the drug L-DOPA. [10]
The most prominent example is the Wilkinson catalyst (RhCl(PPh₃)₃), which oxidatively adds dihydrogen for the hydrogenation of olefins. [15] It is well established that the cleavage of dihydrogen results from the synergistic donation of H₂ σ-MO electrons to the metal's vacant d orbitals, as well as the back-donation of electrons from the ...
Knowles developed one of the first asymmetric hydrogenation catalysts by replacing the achiral triphenylphosphine ligands in Wilkinson's catalyst with chiral phosphine ligands. This experimental catalyst was effective for enantioselective synthesis, achieving a modest 15% enantiomeric excess.