Anodic oxidation of substituted [4-hydroxy-3-coumarinyl]-phenylthiomethanes in acetonitrile. Evidence for a cationic intermediate in carbon–sulfur bond fragmentation

Abstract

Abstract The anodic oxidation of substituted [4-hydroxy-3-coumarinyl]-phenylthiomethanes, 1a–1c, in acetonitrile is shown to correspond to a one electron process. The radical cation produced undergoes carbon–sulfur bond fragmentation through loss of a phenylthio radical to give a cation which is trapped by Ritter reaction with acetonitrile to yield the final products 2a–2c in 64–82% yield. In the case of geranyl [4-hydroxy-3-coumarinyl]-phenylthiomethane, 1d, the intermediate allylic cation is attacked intramolecularly by a hydroxy nucleophile followed by loss of a proton, to give 2d in 40% yield.