Hantzsch reaction: The important key for pyridine/dihydropyridine synthesis

Pyridines and its derivatives are an important class of heterocyclic compounds of low molecular weight. They have been used in the treatment of a various diseases like cardiovascular disease, antioxidant, antibacterial, anti-tubercular, anticancer, anticoagulant, etc. In 1882, Arthur Hantzsch reported pyridine derivative synthesis using different aldehydes, 2 molecules β-keto ester and ammonium acetate to give a Hantzsch ester or 1,4-dihydropyridine derivatives. This review article focuses on different protocols for Hantzsch reaction using different catalysts like β-cyclodextrin–polyurethane polymer (β-CDPU), chitosan nanoparticles (NPs), salicylic acid, p-toluenesulfonic acid (p-TSA), alginic acid, Fe-TUD-1, PdRuNi@GO, Ceric Ammonium Nitrate (CAN), sulfate polyborate, etc. for the synthesis of pyridine derivatives.