RHCL(PPH(3))(3) CATALYZED HYDROSILYLATION OF STYRENE AND PHENYLACETYLENE WITH PHENYLSILANES

Reaction of styrene with Ph(2)SiH(2) catalyzed by RhCl(PPh(3))(3) (<0.3 mol%) proceeds smoothly in THF to give Ph(2)SiH(CH(2)CH(2)Ph) in 77-89% yields although the reaction is accompanied by formation of Ph(2)SiH(CH=CHPh), ethylbenzene, and Ph(3)SiH in small amounts. Similar reaction in toluene also gives a mixture of Ph(2)SiH(CH(2)CH(2)Ph), Ph(2)SiH(CH=CHPh), ethylbenzene, and Ph(3)SiH with lower yield of the hydrosilylation product than the reaction in THF. Reaction of styrene with Ph(2)SiD(2) catalyzed by RhCl(PPh(3))(3) in toluene gives a mixture of these products which are partly deuterated on the non-aromatic hydrogens, The H-1 NMR spectrum of the products indicates complete deuterium scrambling on the hydrogen atoms of styrene and the phenylsilanes prior to or during the reaction. Further reaction of Ph(2)SiH(CH(2)CH(2)Ph) with HSPh catalyzed by RhCl(PPh(3))(3) gives Ph(2)Si(SPh) (CH(2)CH(2)Ph). Hydrosilylation of styrene with PhSiH(3) catalyzed by RhCl(PPh(3))(3) is much slower than the reaction with Ph(2)SiH(2). Hydrosilylation of phenylacetylene with PhSiH(3) catalyzed by 0.1 mol% of RhCl(PPh(3))(3) gives PhSiH(2)(CH=CHPh) in 67% as the sole reaction product. Similar reaction of 1-octyne gives PhSiH(2)[CH=CH(CH2)(5)Me]. These hydrosilylation products are converted into thiolato substituted organosilane through RhCl(PPh(3))(3) catalyzed dehydrogenative condensation with HSAr (Ar = C6H5, C6H4-p-Me, C6H4-o-Me).