Alkene and Alkyne Insertion

The kinetics have been measured for the insertion of acrylonitrile into the Pt—H bond of the 3-cyanopropyl hydrido-complex (12) (L=PPhg). The rate is first order 

The insertion-/9-elimination equilibrium between (16) and (17) is reported to be sufficiently rapid for n.m.r. line-broadening broad n.m.r. signals for Rh/f and are observed at room temperature which sharpen to the expected 

Although insertion into M—C bonds should occur intramolecularly this need not be so for M—H bonds. Alkynes react with [PdH(N03)(PR3)a] to give 

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Oppolzer, W. Transition Metal Allyl Complexes Intramolecular Alkene and Alkyne Insertions. In Comprehensive Organometallic Chemistry II Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds. Elsevier Oxford, 1995 Vol. 12, pp 905-921. 

Because of the donor atom lability, the solvato complexes behave as coordinatively unsaturated species to the extent that they facilitate reactions such as alkene and alkyne insertion reactions and cleavage of B—C bonds. 

The cation trans-[PtH(CH3OH)(PEt3)2]+ is obtained from trans-[PtHCl(PEt3)2] by the general method just outlined.2 Its normal alkene and alkyne insertion reactions with methyl acrylate,3 diphenylacetylene,4 and... 

Migratory insertion is the principal way of building up the chain of a ligand before elimination. The group to be inserted must be unsaturated in order to accommodate the additional bonds and common examples include carbon monoxide, alkenes, and alkynes producing metal-acyl, metal-alkyl, and metal-alkenyl complexes, respectively. In each case the insertion is driven by additional external ligands, which may be an increased pressure of carbon monoxide in the case of carbonylation or simply excess phosphine for alkene and alkyne insertions. In principle, the chain extension process can be repeated indefinitely to produce polymers by Ziegler-Natta polymerization, which is described in Chapter 52. 

Alkene and alkyne insertions followed by carbonylation are shown in Schemes j3 [io],[28]-[33] j4 [34] gjjjj j5 [2i],[35],[36] Interestingly, alkene insertion occurs faster than CO insertion. In several cases, the carbonylation was succeeded by hydrolysis to provide the corresponding acid or yet another carbon-carbon bond formation in the same operation. 

Examples of alkene and alkyne insertions followed by transmetallation with organotin compounds as well as boranates, and eventually reductive elimination are shown in Scheme 16.[ 0l.ns].[37]-[39] reactions do not only require that the transmetalla-... 

Many examples of alkene and alkyne insertion into metal-carbon bonds can also be found in the section on homogeneous catalysis. Other recent examples include the insertion of conjugated dienes into palladium-allyl bonds, olefin arylation in the presence of palladium acetate, and the reaction of ethylene with arylmagnesium halides in the presence of nickel chloride. Reaction of isocyanates with nickel-ethynyl compounds... 

Two or three further examples of alkene and alkyne insertion are mentioned in the section on cyclization and ring expansion at the end of this chapter. 

Guram AS, Jordan RF. Alkene and alkyne insertion reactions of cationic Cp2Zr (l] -pyridy])(L) complexes. Zirconium-mediated functionalization of pyridines. Organometallics. 1991 10 3470-3479. 

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