Electrochemical cleavage of sulphones: Part III. Cathodic elimination study of some β-substituted sulphones as a function of the acidity of the solvent

The sulphones, substituted in the β-position by a group capable of leaving are electrochemically reduced with olefin formation in weakly protic solvents. When the proton concentration is too high, the protonation of the carbanion produced after the 2-electron step reduction of the sulphonyl group is fast and cathodic elimination does not occur. On the other hand, in aprotic media, the instability of the substrate in contact with the electrogenerated bases leads to the retrocondensation reaction (β-hydroxysulphone) or to a basic elimination reaction (β-acetoxysulphone) with formation of the corresponding electrolysis products. The range of proton availability for obtaining olefins in good yields is consequently rather narrow and will depend on the structure of the starting material.