The electrochemical oxidation of β-silyl-substituted arylsulfides and arylselenides

Abstract

The oxidation of ring-substituted aryl(timethylsilylmethyl)sulfides and aryl(trimethylsilylmethyl)-selenides (R = H, Me, MeO, Cl, Br) in MeCN consists of a reversible electron transfer followed by the dimerization of the primary cation radicals and the rupture of the Csp3-chalcogenide bonds of the dicationic intermediate (E + C2 + C1 + E scheme). In MeOH, the oxidation leads to PhSCH2OMe and PhSeCH2OMe resulting from the cleavage of the C - Si bond. The diaryldichalcogenides, which are the main products in MeCN, are practically absent. The electrochemical reactivity of arylchalcogenides is determined by their electronic structure. The specificity of the latter is a decrease in the role of the transmission of the electronic effects through the aromatic ring and an increase in the susceptibility of the heteroatom to direct electronic effects when going from ArSMe to ArSeMe and to their silylated derivatives. © 1998 Elsevier Science Ltd. All rights reserved.