(NH4)2.5H0.5PW12O40-catalyzed rapid and efficient one-pot synthesis of dihydropyridines via the Hantzsch reaction under solvent-free conditions

Diversified Synthetic Pathway of 1, 4-Dihydropyridines: A Class of Pharmacologically Important Molecules

The current review discusses the different synthetic pathways for one of the most important and interesting heterocyclic ring systems, 1,4-dihydropyridine. This cyclic system depicts diverse pharmacological action on several receptors, channels, and enzymes. Dihydropyridine moiety plays an important role in several calcium-channel blockers. Moreover, it has been exploited for the treatment of a variety of cardiovascular diseases due to its potential antihypertensive, anti-angina, vasodilator, and cardiac depressant activities. Furthermore, it also shows antibacterial, anticancer, anti-leishmanial, anticoagulant, anticonvulsant, anti-tubercular, antioxidant, antiulcer, and neuroprotective properties. Several reports have demonstrated dihydropyridine derivatives as a potentiator of cystic fibrosis transmembrane conductance regulator protein, potent antimalarial agent and HIV-1 protease inhibitor. Herein, we have briefly reviewed different novel chemistry and the synthesis of 1,4-dihydropyridine.

Amine-functionalized graphene oxide nanosheets (AFGONs): an efficient bifunctional catalyst for selective formation of 1,4-dihydropyridines, acridinediones and polyhydroquinolines

We report here selective formation of functionalized 1,4-dihydropyridines (DHP), acridinediones and polyhydroquinolines in high yields using amine-functionalized graphene oxide nanosheets (AFGONs) as the bifunctional catalyst. The method overcomes the limitations of previous protocols affording a mixture of DHP and pyridine derivatives using graphene oxide as the catalyst. The mild reaction conditions are found compatible with a wide range of functional groups. It is presumed that a cooperative effect between the acidic and basic functionalities present in AFGONs may have exerted high catalytic efficiency as well as prevented further oxidation to pyridine derivatives. A plausible mechanism is proposed on the basis of some control experiments. The reactions can be scaled up conveniently, and the catalyst can be recycled for five consecutive runs without loss of its activity.

Cellulose matrix embedded copper decorated magnetic bionanocomposite as a green catalyst in the synthesis of dihydropyridines and polyhydroquinolines

A new biopolymer-based magnetic nanocomposite was prepared and characterized by Fourier transform infrared (FT-IR) spectroscopy, energy-dispersive X-ray (EDX) analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images, inductively-coupled plasma atomic emission spectroscopy (ICP-AES) analysis, thermogravimetric/differential thermal (TG/DT) analysis and atomic force microscopy (AFM) image analysis. Then, it was applied as an efficient heterogeneous catalyst in two important three- and four-component one-pot organic condensation reactions for the synthesis of Hantzsch 1,4-dihydropyridine and polyhydroquinoline derivatives in high yields under solvent-free condition at room temperature. The first design and development of a low-leaching bionanostructure, easy separation and reusability of the nanocatalyst, simple work-up procedure, mild, green and environmentally friendly conditions are some important features and advantages of the present work.