H5BW12O40-Catalyzed syntheses of 1,4-dihydropyridines and polyhydroquinolines via Hantzsch reaction: Joint experimental and computational studies

Abstract A series of polyhydroquinoline derivatives were effectively synthesized via Hantzsch reaction in high yields in the presence of catalytic amounts of a highly negatively charged borotungstic acid H5BW12O40 in refluxing EtOH under green and mild reaction conditions. It is a Keggin-type heteropoly acid with a higher negative charge and strong Bronsted acidity. Moreover, a comparative mechanistical analysis of Hantzsch reaction was made based on the structural, thermodynamical and electronic properties along the reaction pathway using density functional theory (DFT) and quantum theory of atoms in molecules (QTAIM) approaches.