Synthesis of Unsaturated Organosilicon Compounds Via Alkene Metathesis and Metathesis Polymerization

New efficient synthetic routes for preparation of molecular and macromolecular organosilicon compounds based on silicon-containing alkene metathesis and metathesis polymerization catalyzed by transition metals (W, Mo, Re and Ru), which initate the formation of metal carbenes (ill-defined first generation catalysts), or by metallacarbene complexes (second generation catalysts, most of which are well defined) are reviewed.The group of reactions involve self-metathesis and cross- metathesis of alkenes (ring closing metathesis (RCM) of dienes, tandem ring opening of cycloalkene - cross-metathesis of alkenes (ROM/CM), as well as alkyne and enyne metathesis, which lead to molecular unsaturated organosilicon products. On the other hand, ring opening metathesis polymerization (ROMP) of silaalkenes and acyclic diene metathesis (ADMET) polymerization of siladienes yield linear macromolecular unsaturated organosilicon compounds. Polymer degradation via crossmetathesis with silicon-containing alkenes is also discussed in this review.All these reactions of alkenyl substituted (except vinylsubstituted) silicon compounds proceed according to the generally accepted metallacarbene mechanism. Vinylderivatives of organosilicon compounds while being inert to self-metathesis and ADMET polymerization, in the presence of complexes containing M-H and M-Si bonds (or initiating their formation) undergo effective transformations leading, in most cases, to metathesis-type products according to a non-metallacarbene mechanism.