Preparation of new polycyclic compounds derived from benzofurans and furochromones. An approach to novel 1,2,3-thia-, and selena-diazolofurochromones of anticipated antitumor activities

Base catalyzed condensation of enaminoketones (3a,b) with malononitrile yields the respective 7-imino-5[2(substituted)prop-1-enyl]furochromene-6-carbonitriles (4a-d) according to the nature of base used. Compounds (3a, b) condense also with indan-1,3-diketone (5) to give α, β-unsaturated carbonyl compounds (6a) and (6b), respectively. Pyrrolidine-catalyzed condensation of visnaginone (2a) and khellinone (2b) with active methylenes yields the corresponding 1-[7,7-(substituted) furobenzodihydropyrone derivatives (7a-e) which condense with semicarbazide to give the respective semicarbazones (8a-e). Compounds (8b,e) react with thionyl chloride to give the respective 1,2,3-thiadiazoles (9a,b) meanwhile compounds (8a-e) react also with selenium dioxide to give 1,2,3-selenadiazoles (9c-g), respectively. Chalcones (11a,b) were obtained upon condensing (2a,b) with ferrocene-2-carboxaldehyde (10). Compatible elementary and spectroscopic measurements were in good accord with the structures postulated for the new compounds. The antitumor activities of certain selected new compounds were screened, in vitro, against a panel of four (breast: MCF-7, cervix: HELA, colon: HCT116 and liver: HEPG2) human solid tumor cell lines and the structure activity relationship (SAR) was discussed.