Synthetic approach for building heteroannulated furo[3,2-g]chromenes using 4,9-dimethoxy-5-oxo-5h-furo-[3,2-g]chromene-6-carbonitrile and cyclic carbon nucleophiles

Abstract

A novel series of polyfused heterocyclic systems containing furo[3,2-g]chromenes were efficiently synthesized. The reactivity of 4,9-dimethoxy-5-oxo-5H-furo[3,2-g]chromene-6-carbonitrile (1) was studied towards a variety of carbon nucleophilic reagents such as heterocyclic enols, heterocyclic enamines and cyclic active methylene compounds. Treatment of carbonitrile 1 with 4-hydroxycoumarin, 4-hydroxy-1-methylquinolin-2(1H)-one (3), 2-hydroxy-4H-pyrido[1,2-a]pyrimidin-4-one (4) afforded furodichromenopyridine 2, furochromenonaphthyridine 5, furochromenodipyridopyrimidine 6. Reaction of carbonitrile 1 with 4(6)-aminouracil and 5-amino-3-methyl-1H-pyrazole proceed through ring opening followed by cycloaddition into the nitrile group giving pyrido[2,3-d]pyrimidine 7 and pyrazolo[3,4-b]pyridine 8. Also, reaction of carbonitrile 1 with 5-amino-2,4-dihydro-3H-pyrazol-3-one (9), 2-(phenylimino)-1,3-thiazolidin-4- one (11), thiobarbituric acid and cyclohexane-1,3-dione produced the novel annulated furo[3,2-g]chromenes 10, 12-14, respectively. Cyclohexane-1,2-dione reacted with carbonitrile 1 in 1:2 molar ratio afforded bis-(furochromeno)[1,10]phenanthroline 15. The prepared compounds were screened in vitro for their antimicrobial activity and some of them appeared notable activity against the tested microorganisms.