Synthesis and Reactions of Some New Benzopyranone Derivatives With Potential Biological Activities

Reaction of visnaginone which derived from the naturally occurring compound visnagine, with allyl bromide gave O-allyl visnaginone 1, which underwent Claisen rearrangement to yield 7-allylbenzofuran 2 derivative. Vilsmeier Haack formylation of 2 afforded our versatile starting compound furochromene-6-carboxaldehyde (3) which was condensed with cyclohexane-1,3-dione, indandione, malononitrile or ethyl cyanoacetate to yield the ylidene nicotinonitrile and pyridone derivatives 4,7,10a-b. Reaction of 3 with aniline or aniline acting on multiple function X-H (X = NH, 0, S) at its ortho position afforded the corresponding anils, imidazolylfurochromene and azepines compounds 11-17. On the other hand, oxidation of visnagin afforded chromene-6-carboxaldehyde derivative 18 which was condensed with different aryl or (heteroaryl) acetonitrile followed by hydrolysis to give pyrano[3,2-g]chromen-4,8-dione derivatives 20a-d and 22.