Sulfur is a readily available, stable and nontoxic reagent. Sulfur is less reactive than oxygen.
The use of elemental sulfur as traceless oxidizing agent enables a remarkably simple solvent-free and catalyst-free synthesis of benzazoles from alkylamines and o-hydroxy/amino/mercaptan anilines.
T. B. Nguyen, L. Ermolenko, W. A. Dean, A. Al-Mourabit, Org. Lett., 2012, 14, 5948-5951.
Elemental sulfur is an excellent oxidant for an oxidative rearranging coupling between o-aminophenols and ketones in the presence of N-methylpiperidine to provide a wide range of 2-alkylbenzoxazoles under mild conditions.
T. B. Nguyen, P. Retailleau, Org. Lett., 2017, 19, 3887-3890.