Sulfur/DABCO Promoted Reductive Coupling/Annulation Cascade Reaction between o-Hydroxy/Amino Nitrobenzenes and Benzaldehydes

Sulfur/DABCO was found to be an efficient reagent in promoting­ the reductive coupling/annulation of o-nitrophenols or o-nitroanilines with benzaldehydes. This method represents a simple, straightforward, and green approach to the construction of benz­oxazoles and benzimidazoles.