Abstract
The chemical behavior of 4,9-dimethoxy-5-oxo-5H-furo[3,2-g]-chromene-6-carbonitrile (khellin-6-carbonitrile) (1) was examined towards a variety of nitrogen nucleophiles. Some novel Schiff bases 5-7 were prepared from reaction of carbonitrile 1 with some heterocyclic amines. Treatment of carbonitrile 1 with some hydrazine derivatives in boiling ethanol afforded pyrazole derivatives 8-13. Khellin-6-carbonitrile (1) reacted with hydrazine hydrate and phenylhydrazine in acetic acid to afford angular heteroannulated furo[3',2':6,7]-chromeno [4,3-c]pyrazol-4(1H)-one derivatives 14 and 15. Triazolo[1,5-a]pyrimidine 16 and pyrimido[1,2-a]benzimidazole 17 were synthesized through ring opening and recyclization reactions of compound 1 with 3-amino-1,2,4-triazole and 2-aminobenzimidazole, respectively. Reaction of compound 1 with guanidine and cyanoguanidine in ethanolic potassium hydroxide solution resulted in ring conversion giving the novel angular furo [3 ',2' :6,7] chromeno [4,3-d]pyrimidin-5-ones 18 and 19. The antimicrobial activity of the prepared compounds appeared distinguish activity against the selected microorganisms.