OXIDATION OF SULFUR-CONTAINING-COMPOUNDS WITH HOF-CENTER-DOT-CH3CN

The HOF . CH3CN complex, easily prepared by passing F-2 through aqueou s acetonitrile, is an exceptionally efficient oxygen transfer agent. A ll types of sulfides have been oxidized to sulfones in excellent yield s, in a few minutes at room temperature. The reaction proceeds through the formation of sulfoxides which at low temperatures of around -75 d egrees C could be isolated in good yields. It was demonstrated through a reaction with thianthrene 5-oxide (20) that HOF . CH3CN is strongly electrophilic in nature. Sulfides with an electron-depleted sulfur at om such as perfluoroalkyl or aryl sulfides, which could not be well ox idized by any other method, were also efficiently converted to the cor responding sulfones in minutes. Thiophenes are generally hard to oxidi ze to the corresponding S-dioxides since the conditions required by th e orthodox oxidants encourage consecutive typical ene and diene reacti ons. HOF . CH3CN requires;short reaction times and low temperatures, t hus enabling the isolation of thiophene dioxides, some of which could not be made by any other way. It seems that apart from unprotected ami nes, other functional groups such as aromatic rings, ketones, hydroxyl s, and ethers do not interfere, since the sulfur atom reacts considera bly faster.