Tungstate sulfuric acid/ KMnO4 as a novel heterogeneous system for the rapid aromatization of hantzsch 1, 4-dihydropyridines under mild conditions

Abstract

Neat chlorosulfonic acid reacts with anhydrous sodium tungstate to give tungstate sulfuric acid (TSA) as a new two basic inorganic solid acid in which two sulfuric acid connect to tungstate moiety via covalent bond. Hantzsch 1, 4-dihydro pyridines (1, 4-DHP) were aromatized efficiently to their corresponding pyridine derivatives by heterogeneous (wet TSA)/KMnO4 system in dichloromethane under mild conditions in excellent yields.