Isomerization of Silyl Olefins

However, in the presence of iridium siloxide and bulky substituents at the silicon in vinylsilanes instead of silylative coupling, the codimerization (hydrovi-nylation) of styrene and vinylsilanes occurs according to Equation 14.13  

The alcoholysis of hydrosilanes (or the 0-silylation of alcohols) represents a crucial way of synthesizing the silyl ethers that are among the most widely used protective groups of the hydroxyl functionality in organic synthesis (Equation 14.14) [73]. 

Many transition-metal complexes have been reported as catalysts of this reaction, including [lr(g-Cl)(coe)2]2 [74] and [lrH2(solv.)(PPh3)][SbF6] [75]. The latter catalyst appeared to be a very active and highly selective. The hydroxyl group can be selectively silylated, even in the presence of other potentially reactive C=C and C=0 groups. The order of relative reactivities of alcohol isomers is secondary alcohol primary alcohol tertiary alcohol. 

Iridium cationic complexes have recently been used as highly effective catalysts for the regioselective di- and tri-silylation of simple glycopyranosides with tert-butyldimethylsilane [76]. 

Other cationic Ir(I) complexes containing the bidentate ligands, such as bis(l-pyrazolyl)methane (BPM) and bis(3,5-dimethyl-l-pyrazolyl)methane (dmBPM), that is [Ir(BPM)(CO)2] [BPli4p and [Ir(dmBPM)(CO)2] BPh4]T were also reported to be effective catalysts for the alcoholysis of binary and tertiary silanes [77]. 

---

By contrast, the isomerization of silyl olefins and addition of silylacetylenes =C—H bond into imines catalyzed by iridium complexes appears to serve as a suitable route for the synthesis of silylfunctionahzed organic compounds. Hence, the acquisition of experimental data on catalysis by iridium complexes in silicon chemistry may be regarded as an initial stage in the quest for catalytic processes leading to the synthesis of other p-block (e.g. B, Ge, Sn, P)-carbon bond-containing compounds. 

---