Synthesis and Chemical Reactivity of the Novel 4-Hydroxy-6-methyl-2,5-dioxo-5,6-dihydro-2H-pyrano[3,2-c]quinoline-3-carboxaldehyde

Abstract

Vilsmeier–Haack formylation of 3-(4-hydroxy-1-methy1-2-oxo-(1H)-quinolin-3-yl)-3-oxopropanoic acid (2) produced the novel 4-hydroxy-6-methyl-2,5-dioxo-5,6-dihydro-2H-pyrano[3,2-c]quinoline-3-carboxaldehyde (4). The chemical reactivity of carboxaldehyde 4 with a diversity of nitrogen nucleophilic reagents was studied, and a variety of products were obtained. Some 1,3,4-oxadiazolyl/1,3,4-thiadiazolyl/benzothiazolyl linked pyrano[3,2-c]quinoline-2,5(6H)-dione were efficiently synthesized. Structures of the new synthesized products were deduced on the basis of their analytical and spectral data.