Solvent-Mediated Switching Between Oxidative Addition and Addition-Oxidation: Access to β-Hydroxysulfides and β-Arylsulfones by Addition of Thiols to Olefins in the Presence of Oxone

The reaction between aryl olefins and thiols in the presence of Oxone in toluene-water (9:1, v/v) affords β-hydroxy-2-arylethyl aryl sulfides smoothly by interception of the intermediary thiyl radicals with aryl olefins; the former are generated by oxidation of thiols with Oxone in the biphasic medium. However, change of the solvent system to acetonitrile-water facilitates a nonradical and concerted pathway leading to 2-arylethyl aryl sulfones exclusively via tandem click reaction followed by oxidation. In essence, ‘oxidative addition’ is facilitated in toluene-water medium, while ‘addition-oxidation’ is promoted in acetonitrile-water. Given that Oxone is readily available, environmentally-benign, and cheap, solvent-mediated switching constitutes facile and direct access to two disparate products, namely, β-hydroxy-2-arylethyl aryl sulfides and 2-arylethyl aryl sulfones.