Elemental Sulfur-Mediated Synthesis of Quinoxalines from Sulfoxonium Ylides.

A novel straightforward and catalyst-free approach for synthesizing quinoxaline derivatives from sulfoxonium ylides and -phenylenediamines mediated by elemental sulfur has been described. Due to the simple and mild reaction conditions, the sulfoxonium ylides and -phenylenediamines decorated with different functional groups furnished moderate to high yields of quinoxaline derivatives and were well tolerated. Finally, large-scale reactions, the synthesis of pyrazines, and some bioactive compounds are used to illustrate the potential utility of the developed approach.