Abstract
The chemical reactivity of 4,9-dimethoxy-5-oxo-5H-furo[3,2-g]-chromene-6-carbonitrile (1) was studied towards a variety of active methylene nitriles namely; malononitrile, cyanoacetamide, N-phenylcyanoacetamide, (phenylthio)acetonitrile, ethyl cyanoacetate and benzothiazol-2-ylacetonitrile producing the novel annulated furo[3',2':6,7]chromeno[2,3-b]pyridines. Reactions of carbonitrile 1 with malononitrile dimer, cyanoacetohydrazide and 1H-benzimidazol-2-ylacetonitrile showed different behavior giving the novel angular heteroannulated fiirochromenes 10, 11 and 13, respectively. A series of novel furo[3 '' 2 '':6',7']chromeno[3,2':5,6]pyrido[2,3-d]pyrimidines were also synthesized. The proposed mechanisms for the different synthetic pathways were also discussed. The prepared compounds were screened in vitro for their antimicrobial activity and some of them showed notable activity against the tested microorganisms. Structures of the synthesized products were confirmed based on their analytical and spectral data.