Synthesis and antimicrobial evaluation of 6-hydroxy-4,7-dimethoxybenzofuranylcarbonyl tethered annulated pyridines

Abstract

2-Chloro-5-[(6-hydroxy-4,7-dimethoxy-1-benzofuran-5-yl)carbonyl]pyridine-3-carbonitrile (3) was synthesized and its chemical reactivity was investigated toward a diversity of binucleophiles. Treatment of compound 3 hydrazine hydrate and phenylhydrazine produced pyrazolo[3,4-b]pyridines while isoxazolo[5,4-b]pyridine was obtained from reacting compound 3 with hydroxylamine. A diversity of pyrido[2,3-d]pyrimidines was synthesized from treatment of staring substrate 3 with some 1,3-N,N-binucleophiles. Treating compound 3 with some 1,4-binucleophiles including ethylenediamine, o-phenylenediamine, 2-aminophenol and 2-aminothiophenol furnished pyrido[2,3-e][1,4]diazepine 12 and pyrido[2,3-b][1,5] benzodiazepine 13, pyrido[2,3-b][1,5]benzoxazepine 14 and pyrido[2,3-b][1,5] benzothiazepine 15, respectively. The synthesize compounds shown remarkable effect against yeast and fungus, while compounds 4 and 7–11 exhibit excellent efficacy against all types of Gram + and Gram - bacteria. Structures of the produced compounds were established using analytical and spectroscopic tools.