Role of hypercoordinated silicon(IV) complexes in activation of carbon–silicon bonds: An overview on utility in synthetic chemistry

The chemistry of organosilicon compounds has been one of the indispensable and inseparable parts of synthetic organic transformations. The synthesis of new silicon reagents and organic products derived from organosilanes continues to attract interest. Similar to the problems associated with the selective cleavage of C–C bonds, the activation of C–Si bonds in a selective manner is relatively limited. If the dissociation of a C–Si bond is achievable, then it is possible to develop new synthetic approaches toward fascinating silicon-based architectures. There are various methods reported for synthesizing value-added products derived from the formation of new carbon–carbon and carbon–oxygen bonds by activation of C–Si bonds due to their selective and remarkable flexibility of reactions. In this regard, the present review describes the activation of the silicon-carbon bonds through (i) either stoichiometric or catalytic metal mediation (Pd, Pt, Rh, Ru, Fe, Co, Cu, Au, etc.), (ii) the formation of penta- and hexacoordinate silicon(IV) intermediates, (iii) direct reactions of hypercoordinate silicon(IV) species, and (iv) the oxidation of the Si-C bonds by peroxides and their utility in organic synthesis. Also, the possible mechanistic pathways are discussed consisting of hypercoordinated silicon(IV) intermediates. Furthermore, the applications of the C–Si bond activations are highlighted.