One‐Step Synthesis of 2‐Amino‐3‐cyano‐4‐ aryl‐1,4,5,6‐tetrahydropyrano[3,2‐<i>c</i>]quinolin‐5‐one Derivatives Using KF–Al<sub>2</sub>O<sub>3</sub> as Catalyst
A series of 2-amino-3-cyano-4-aryl-1,4,5,6-tetrahydropyrano[3,2-c] quinolin-5-one derivatives were synthesized by the reaction of arylaldehyde, malononitrile, and 4-hydroxyquinolin-2-one in ethyl alcohol at 80degreesC catalyzed by KF-Al2O3. The structure of the product was confirmed by x-ray analysis.