Electrochemical reduction of substituted isothiazole-3-thiones in aprotic media

Abstract

The title compounds are obtained in good yields from 1,2-dithiole-3-thiones. Using cyclic voltammetry in dimethylformamide, two kinds of behaviour are evidenced and discussed in terms of the aromaticity of the 5-substituent (Ar). With Ar = pyrazinyl or pyridazinyl, isothiazole-3-thiones undergo an electrochemical chemical electrochemical mechanism and the rate constant of the chemical step has been deduced from voltammetric measurements. When the aromaticity increases (Ar = pyridyl or phenyl) an apparent one-step irreversible two-electron addition occurs. Whatever the nature of Ar the resulting two-electron reduction product has been isolated after controlled-potential electrolysis (CPE). In addition, in acetonitrile, CPE affords a thiophene derivative as a secondary product.