Heteroannulated Coumarins and Chromones from Chemical Transformations of 6,8-Dimethylchromone-3-carbonitrile

Abstract

A novel series of heterocyclic systems fused coumarins and chromones were efficiently synthesized from chemical transformations of 6,8-dimethylchromone-3-carbonitrile (1) with a variety of carbon nucleophilic reagents. Ring opening ring closure reactions of carbonitrile 1 with cyanoacetohydrazide, malononitrile dimer (2-aminoprop-1-ene-1,1,3-tricarbonitrile), and isomeric cyclohexanediones led to a diversity of coumarins and chromones fused nitrogen heterocyclic systems. Also, 1-ethyl-4-hydroxyquinolin-2(1H)-one (13) and 6-ethyl-4-hydroxypyrano[3,2-c]quinoline-2,5(6H)-dione (14) are chemical equivalent towards carbonitrile 1 leading to benzo [h]chromeno[2,3-b][1, 6] naphthyridine derivative 15. Structures of the new synthesized products were deduced on the basis of their analytical and spectral data.