Some synthetically useful transformations of organosilicon compounds have been developed since the mid 1970s, based on the new concept that the silicon-carbon bonds are activated toward electrophilic cleavage via the formation of penta- and hexa-coordinate species. This review mainly consists of the following aspects: (1) a general concept for the activation of the silicon-carbon bond via penta- and hexa-coordinate species, (2) synthetic application of hexa-coordinate organopentafluorosilicates, and (3) development of the H₂O₂ oxidation of the silicon-carbon bond and its synthetic applications via the intramolecular hydrosilylation, silicon-tethered intramolecular radical cyclization and Diels-Alder reaction, and some silicon-containing organometallic reagents for nucleophilic hydroxymethylation and hydroxyallylation synthons.

(Communicated by Hitosi NOZAKI, M.J.A.)