Facile synthesis of new pyrano[3,2-c]quinolones via the reaction of quinolin-2-ones with ethene-1,2,3,4-tetracarbonitrile

Synthesis of heteroannulated pyrano[3,2-c]quinolones was established starting from the reaction of 4-hydroxyquinolin-2-ones with ethene-1,2,3,4-tetracarbonitrile. Several conditions were carried out, and the corresponding product yields were illustrated. The neutral and non-polar condition was the best procedure for product formation. The structure of products was elucidated by NMR, IR, mass spectra, and elemental analysis. X-ray structure analysis was also used to elucidate the structure of the obtained products. The mechanism of products formation was also discussed. Graphical abstract: [Figure not available: see fulltext.]