Electrochemical Reactions of Organosilicon Compounds

Although the electrochemical reactivity of unfunctionalized tetraalkylisilanes is low, organosilicon compounds containing π-systems and heteroatoms exhibit unique electrochemical activitv. Upon α-substitution, silyl groups have electron-accepting effects and upon β-substitution, silyl groups have electron-donating effects to π systems. Silyl groups also have electron-donating effects to β-situated heteroatoms such as oxygen, nitrogen, and sulfur. It is also noteworthy that silyl groups control the regiochemistry of the electrochemical reactions of these compounds. On the basis of such silicon effects, various types of electrochemical reactions of organosilicon compounds have been developed and some of them are utilized as useful tools in organic synthesis. The electrochemical behaviour of organosilicon compounds containing Si-Si bonds is also interesting. Si-Si bonds are susceptible to both anodic oxidation and cathodic reduction. Halosilanes are rather inert to electrochemical redox reactions and are often used as effective trapping agents of carbanion intermediates generated by cathodic reduction of organic halides. However, in the absence of other reducible substrates, halosilanes can be reduced cathodically to form Si-Si bonds.