Cathodic cleavage of 1-trifluoromethyl alkenyl sulfone and sulfoxide

Abstract

The controlled potential electrolysis of α,β-unsaturated sulfone 2 and sulfoxide 3 bearing a trifluoromethyl group in N,N-dimethylformamide containing excess benzoic acid was subjected to an electroreductive desulfurization to afford the corresponding trifluoromethyl-substituted olefin 4 in good yields. The use of a sacrificial Mg anode resulted in a large increase in the yield of 4. Furthermore, the use of the sacrificial Mg anode in the absence of the acid gave unexpected products 5 and 6 from 2, and 7 and 8 from 3, respectively, with concomitant formation of 4. In the presence of acetic anhydride or carbon dioxide any carbonylated product was not obtained and the simple reduction to 4 occurred predominantly.