An efficient and selective aerobic oxidation of sulfides to sulfoxides catalyzed by Fe(NO3)3–FeBr3

The binary system Fe(NO3)3–FeBr3 is a very efficient catalyst for the selective air-oxidation of sulfides to sulfoxides. Since the oxidation is selective, it may be applied to any type of dialkyl and alkyl aryl sulfide, as well as to substrates of biological interest. It develops in mild conditions, giving a high yield in the presence of different functional groups on the sulfide. Other binary systems such as Fe(NO3)3–FeBr2 and Cu(NO3)2–CuBr2 are also effective catalysts for sulfoxidation. In contrast to previous oxygenation methods, this oxidation requires neither an aldehyde nor a transition metal complex.