PEG-mediated synthesis of polyhydroquinoline derivatives under ultrasonic irradiation

Hantzsch reaction is classified as a one-pot, three-component process for the synthesis of 1,4-dihydropyridine(DHP) and polyhydroquinoline(PHQ) derivatives. Typically, it is accomplished using an aldehyde, -dicarbonyls and ammonium acetate or ammonia at high temperature. PHQs are one of the most important classes of heterocyclic scaffolds providing major ligands for biological receptors. PHQs are source of some valuable drugs which have been prepared efficiently. For instance, they demonstrate activity for the treatment of angina pectoris, hypertension .Therefore, developing more efficient methods, working under mild conditions and using more environmentally acceptable catalysts is in high demand.

PEGs are commercially available, non-toxic, used as a green solvent and catalyst, thermally stable and inexpensive compared to conventional phase-transfer catalyst such as crown ethers. PEG helps in maintaining a neutral reaction. Organic synthesis in PEG under solvent-free conditions is significant in modern organic synthesis.