Acid-Catalyzed Condensation of o-Phenylenediammines and o-Aminophenols with α-Oxodithioesters: A Divergent and Regioselective Synthesis of 2-Methylthio-3-aryl/Heteroarylquinoxalines and 2-Acylbenzoxazoles

Abstract

o-Phenylenediammines and o-aminophenols were reacted with α-oxodithioesters in a highly regioselective fashion to give 2-methylthio-3-aryl/heteroarylquinoxalines and 2-acylbenzoxazoles in 55–94% and 45–86%, respectively, in the presence of p-toluene sulfonic acid catalyst. Control experiments involving reaction of aniline with a α-oxodithioester indicated that the thiocarbonyl group is more reactive than the carbonyl group. Based on this, probable mechanisms for the formation of quinoxalines and benzoxazoles are given. Biological targets of the quinoxalines and benzoxazoles were identified by bioinformatics. It was found that quinoxalines have good binding affinity with human dual-specificity tyrosine-phosphorylation-regulated kinase 1A and benzoxazoles with human carboxylesterase.