Hydrosilylation and Hydroarylation

More recently, Gacal and coworkers used Wilkinson s catalyst in the hydrosilylation of polyisoprene-f)/ocfe-poly(vinyl trimethylsilane) (PIP-6-PVTMS). They achieved 80% hydrosilylation of the PIP unit and then 

By contrast, platinum complexes such as the Speier s H2PtCl6 catalyst tend to induce anti-Markovnikov additions of vinyl C=C bonds selectively, which results in terminal hydrosilylation products exclusively. Compared with the internal double bonds in the polymer backbone, the pendant double bonds are significantly more reactive during hydrosilylation and give terminal sdane-functionahzed PBD. As with small alkenes, evidence of the isomerization of cis double bonds to trans double bonds was observed during the hydrosilylation of PBD. 

Using an alternative to Speier s catalyst, Chauhan and coworkers reported that recyclable platinum nanoclusters can function as catalysts in PBD hydrosilylation (Fig. 14). These nanoclusters, which were prepared via reduction of Me2Pt(COD) and recovered after the reaction by centrifugation, showed consistent activity up to five cycles of consecutive hydro-silylations. Complete conversion of 1,2-PBD was achieved with a variety of silane structures and yielded the hydrosilylation product via anti-Markovnikov addition at the terminal positions of 1,2-butadiene units. The retention of a narrow molecular weight (M /M =. 4—. 5) in the GPC analysis confirmed that no chain scission or cross-finking occurred in the polymer chains during hydrosilylation. 

Similar to Speier s catalyst, Karstedt s symmetrical divinyltetramethyldisiloxane catalyst [1,3-divinyltetramethyldisiloxane 

In the early 2000s, Hou and coworkers demonstrated the unique func-tionahzation of polystyrene-6/orfe-polyisoprene (PS-1 -P1P containing approximately 40 mol% isoprene with more than 80% pendant vinyl group) via hydrosilylation catalyzed by H2PtCl6 and Heck olefin coupling reaction 

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