Tandem Protocol of Hexahydroquinoline Synthesis Using [H(2)-DABCO][HSO(4)](2) Ionic Liquid as a Green Catalyst at Room Temperature

[Image: see text] Green, eco-benign, and sustainable synthesis is paramount in present chemistry. Here, a facile, efficient, and [H(2)-DABCO][HSO(4)](2) ionic-liquid-catalyzed one-pot multicomponent synthesis of hexahydroquinolines was reported under ambient reaction conditions. The reaction of 1,3-dicarbonyls, malononitrile, and ammonium acetate with various aldehydes in the presence of an ionic liquid catalyst and EtOH solvent at room temperature afforded excellent yields (76–100%) of hexahydroquinolines under a short reaction time (5–15 min). Mild reaction conditions, broad substrate scope (28 derivatives), and column-chromatography-free synthesis with excellent catalytic efficiency and good recyclability rendered this protocol superior and practical. The greenness of the present method was assessed through eco-score and E-factor. The significant results in gram-scale synthetic conditions validate its applicability in industries as well as academia in the near future.