NH4Cl-CH3OH: an efficient, acid- and metal-free catalyst system for the synthesis of quinoxalines

Abstract

The direct condensation of various benzene-1,2-diamines [4-R-Ph-(NH2)2, where R = H, Me, Cl and NO2] and 1,2-dicarbonyl compounds (R'-CO-CO-R', where R' = Ph, 4-MeO-Ph and Me) has been successfully achieved mostly in excellent yields (95-100%) using (NH4Cl-CH3OH) as a mild, efficient, cost-effective, readily available, acid-free, metal-free and eco-friendly catalyst system at room temperature. The procedure can be performed for a broad scope of quinoxalines, however, the nature of the functional group on the aromatic ring of 1,2-diamine exerts a strong influence on the time and the reaction yield. The condensation efficiency could be further regulated by the amount of catalyst and reaction time.