Fe/S-Catalyzed Redox Condensation of <i>o</i>-Nitrophenols with Isothiocyanates to 2-Aminobenzoxazoles
Le Anh Nguyen, Supasorn Phaenok, Duc Long Le, Thi Thu Tram Nguyen, Thi Thu Tram Nguyen, Quoc Anh Ngo, Thanh Binh Nguyen, Thanh Binh Nguyen
Abstract
As frequently encountered byproducts of isocyanate chemistry, hydrogen sulfide and related sulfur containing compounds should be treated in a safe way to lower their adverse health and environmental effects, especially in large scale syntheses. As a proof of concept, we report herein an example of in situ recycling of sulfur byproduct to reductant in the synthesis of bioactive 2-aminobenzoxazoles 3 . Using an Fe/S catalytic system, this heterocyclic scaffold could be obtained from o- nitrophenols 1 with isothiocyates 2 via direct redox condensation consisting of reduction of the nitro group of 1 by the sulfur moiety of 2 .