The Convenient Synthesis of 11-Methyl-3,8-disubstituted-12-aryl-3,4,7,8,9,12-hexahydro-1H-chromeno[2,3-b]quinoline-1,10(2H)-dione Derivatives

The 2-arylidene-3-oxobutanenitrile derivatives 2 were prepared by the Knoevenagel condensation between aldehydes and 3-oxobutanenitrile 1 , which was obtained by acid hydrolysis of β-aminocrotononitrile. 3-Acetyl-2-amino-4 H -chromen-5(6 H )-one derivatives 3 were synthesized by reaction of 2-arylidene-3-oxobutanenitrile 2 and 5-substituted-1,3-cyclohexanedione in ethylene glycol. The 11-methyl-3,8-disubstituted-12-aryl-3,4,7,8,9,12-hexahydro-1 H -chromeno[2,3- b ]quinoline-1,10(2 H )-dione derivatives 4 were obtained by Friedländer reaction of compounds 3 with 5-substituted-1,3-cyclohexanedione, using p -toluenesulfonic acid monohydrate as catalyst. The structures of all novel compounds were characterized by elemental analysis, IR, MS, and 1 H NMR spectra. The crystal and molecular structure of compound 4f has been determined by single crystal XRD analysis.