Cathodic elimination of β-acetoxy phenyl sulfones in acetonitrile

Abstract

The synthesis of polyenes by electrolysis of β-acetoxy phenyl sulfones having some double bonds was studied in acetonitrile using a Hg pool cathode and a sacrificial Mg anode. Most unsaturated β-acetoxy phenyl sulfones were subject to the electroreductive elimination of both the acetoxy and the sulfonyl groups, but did not give the desired polyenes because of partial hydrogenation of double bonds. The electrolytic reduction of a β-acetoxy phenyl sulfone having a trifluoromethyl group at the β-position was subjected to such 1,2-elimination followed by reductive removal of all fluorine atoms to afford the corresponding unsaturated hydrocarbons, whereas β-acetoxy phenyl sulfones having a fluorine atom at the α-position gave the desired fluoro-olefins in high yields. All saturated β-acetoxy phenyl sulfones afforded the desired alkenes in high yields.