Metal groups alkynylation

Intermolecular alkynyl ligand transfer of transition metal complexes is more common than the aryl and alkyl ligand transfer. Alkynyl compounds of Cu(I) and Hg(II) transport the ligand to other transition metals, giving various alkynyl transition metal complexes. [Cu(C=CR)] [171], isolated or generated in situ from the reaction of alkyne, Cul, and base, was employed in preparation of a number of alkynyl complexes of group 5-10 transition metals. The alkynyl hgand transfer is depicted schematically in Eq. 5.46 [172-175]. 

Cubic NLO data for selected group 10 metal bis(alkynyl) complexes are listed in Table XVII. Hyperpolarizability decreases progressing down the group for phe-nylalkynyl examples, the same observation as with group 4 metal alkynyl complexes (see above). For these complexes is, in all cases, close to 3co, and a high-order intensity dependence was observed this is characteristic of multiphoton resonant enhancement, so it is possible that three-photon effects exist. 

The reactions described so far can be considered as alkylation, alkenylation, or alkynylation reactions. In principle all polar reactions in syntheses, which produce monofunctional carbon compounds, proceed in the same way a carbanion reacts with an electropositive carbon atom, and the activating groups (e.g. metals, boron, phosphorus) of the carbanion are lost in the work-up procedures. We now turn to reactions, in which the hetero atoms of both the acceptor and donor synthons are kept in a difunctional reaction produa. 

The formation of the indole moiety has found immense attention, since it exists in many bioactive compounds such as the indole alkaloids [302]. Whilst the Fischer indole synthesis remains the most important procedure, during the past few years several transition metal-catalyzed syntheses have been developed. Recently, a Cu11-catalyzed cyclization of anilines containing an ortho-alkynyl group was published by Hiroya and coworkers [303], which allows a double cyclization in domino fashion to provide annulated indoles. Thus, reaction of 6/4-92 in the presence of... 

The group R1 can be allyl, acyl, or alkynyl, and arynes can also act as the acceptors. The catalysts are usually Ni(cod)2, or ligated palladium. The mechanisms are not understood in detail, but a catalytic cycle involving the product of oxidative addition, Sn-M-R1, is thought to be involved. The stannylalkenes that are formed can then be subjected to reaction with electrophiles (e.g., AczO or RCH=0), or to coupling reactions in the presence of transition metals (e.g., the Stille reaction). 

Coupling ofa-Alkynyl Groups with Concomitant Aggregation of the Metal Fragments... 

Metal-promoted 1,2-migration of silyl groups in silylalkynes results in the formation of silylvinylidenes which are subsequently readily desilylated. " Alkynyl-substituted silylvinylidenes have been obtained from silylated diynes and the Fe(N2)(CO)2 P(OMe)3 2/ Fe(CO)2[P(OMe)3]2 2(/t-N2) reagent and similar species are implicated in the reactions of several Group 8 metal complexes with mono- and bis-trialkylsilyl diynes. " ... 

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