Triethylsilanes, phenylacetylene hydrosilylations

The intermediacy of the complex [Os(SiEt3)Cl(H2)(CO)(P Pr3)2] in the catalytic hydrosilylation of phenylacetylene was first observed by Oro and co-workers when the neutral hydride [OsHCl(CO)(P Pr3)2] was reacted with triethylsilane and the alkyne [81]. A theoretical study of silane addition across the C-C triple bond has also been reported [82] and the general scope of this reaction has been amply reviewed [17],... 

Hydrosilylation of phenylacetylene with triethylsilane catalysed by rm -chloro(car-bonyl)bis(triphenylphosphine)iridium yields the trans-2idduct 111, accompanied by traces of the cis-isomQT 278 and of the regioisomer 219. ... 

To further substantiate the validity of this correlation, we decided to probe the influence of the cr-donating ability of the NHC on the regioselectivity. For this purpose, the hydrosilylation of phenylacetylene by triethylsilane imder the standard conditions was performed with three catalysts possessing the same limited steric hindrance but completely different electronic properties (Figure 5.18) [32]. As can be seen, identical selectivities were obtained, despite the fundamental differences between the catalysts, thereby reinforcing our proposal that the regioselectivity of the hydrosilylation of alkynes is controlled essentially by steric parameters. It is noteworthy that the major isomer obtained in this case is the a-adduct. This is not surprising since arylacetylenes are known to lead... 

Hydrosilylation. [Cp RhCl2]2 is effective for the hydrosi-lylation of phenylacetylene with triethylsilane, triethoxysilane, and triphenylsilane under mild reaction conditions with a typical anti-addition manner to yield the p-Z isomer. ... 

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