4-Amino-3-formylcoumarin as Building Block for Construction of Novel Heteroannulated Coumarins: Synthesis, Characterization and Antimicrobial Evaluation

Abstract

The chemical reactivity of 4-amino-3-formylcoumarin (1) was examined towards a diversity of carbon nucleophilic reagents as well as isomeric cyclohexanediones. A variety of heterocyclic compounds namely chromeno[4,3b]pyrazolo[4,3-e]pyridines, chromeno[4,3-b]benzo[1,6]naphthyridine, chromeno-[4,3-b]quinoline and bis[1]chromenophenanthrolines were efficiently synthesized. Chromeno[4,3-b]quinoline 6 upon Vilsmeier-Haack formylation afforded the novel β-chloroenaldehyde 10 which used as a key intermediate for buliding a diversity of polyfused systems conatining coumarin moiety. Antimicrobial evaluation of the tested compounds showed excellent efficiency especially compounds 2-5, 12 and 14. On the basis of spectral and analytical analysis, the structures of the new products were determined.