THE ELECTROCHEMICAL OXIDATION OF BETA-SILYL-SUBSTITUTED ARYLSULFIDES AND ARYLSELENIDES

The oxidation of ring-substituted aryl(timethylsilylmethyl)sulfides an d aryl(trimethylsilylmethyl)selenides (R = H, Me, MeO, Cl, Br) in MeCN consists of a reversible electron transfer followed by the dimerizati on of the primary cation radicals and the rupture of the C-sp3-chalcog enide bonds of the dicationic intermediate (E + C2 + Cl + E scheme). I n MeOH, the oxidation leads to PhSCH2OMe and PhSeCH2OMe resulting from the cleavage of the C-Si bond. The diaryldichalcogenides, which are t he main products in MeCN, are practically absent. The electrochemical reactivity of arylchalcogenides is determined by their electronic stru cture. The specificity of the latter is a decrease in the role of the transmission of the electronic effects through the aromatic ring and a n increase in the susceptibility of the heteroatom to direct electroni c effects when going from ArSMe to ArSeMe and to their silylated deriv atives. (C) 1998 Elsevier Science Ltd. All rights reserved.