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Efficient synthesis of pyrano[2,3-b]pyridine derivatives using microwave or solar energy
- Abdel Hameed, Afaf M.
- Environmental chemistry letters 2018 v.16 no.4 pp. 1423-1427
- aldehydes, byproducts, ethanol, microwave treatment, potassium carbonate, pyridones, solar thermal energy, toxicity
- Pyranopyridine derivatives are an important class of heterocyclic compounds due to their biological activities such as antitumor and antibacterial. However, conventional procedures for their synthesis produce large amounts of toxic by-products. Therefore, there is a need to develop simple, efficient and environmentally benign procedures. Here, a one-pot multicomponent protocol is designed for the synthesis of pyrano[2,3-b]pyridone derivatives by reaction of equimolar amounts of 6-hydroxy-1,4-dimethyl-1,2-dihydropyridines, aryl aldehydes and malononitrile, using both microwave heating and solar thermal energy in aqueous EtOH (50%) in the presence of a catalytic amount of K₂CO₃. The products were obtained in 84–90% yields in 10–20 min by microwave heating, and in 90–96% yields in 2–3 h using solar energy.