Green synthesis of 1,4-dihydropyridines using cobalt carbon nanotubes as recyclable catalysts

Heterocyclic compounds occur widely in nature and in drug molecules. The activity of many nitrogen-containing heterocyclic compounds is unique. For example, 1,4-dihydropyridines display good antitumor and antibacterial effects and can be commercially used as calcium channel blocker agents in the treatment of cardiovascular diseases. To reduce the use of toxic catalysts in the synthesis of 1,4-dihydropyridines, here we designed cobalt carbon nanotubes as a heterogeneous catalyst. We report the efficient synthesis of 1,4-dihydropyridines under mild conditions, which allows to access a wide array of 1,4-dihydropyridines from aromatic aldehyde in high yields, up to 96%. Advantages include the use of ethanol as solvent, low catalyst loading of 6% mol, short reaction time of 5–15 min, easy preparation and recyclable catalyst.