Studies in the chemistry of chromone epoxides

Article abstract of DOI:10.1016/S0040-4020(01)83137-9

Chromones and isoflavones, but not flavones, were epoxidized by alkaline hydrogen peroxide. 3-Substituted chromone epoxides were considerably more stable than others; one isoflavone epoxide was converted into a fluorohydrin, another into a 1,2-diol. The latter is a 2-hydroxychromanone and a similarly structured compound was obtained by the cyclisation of 2'-benzoyloxy-2,2-dibromoacetophenone. Acid-catalysed ring-opening of chromone epoxides occurred regioselectively yielding 3-hydroxychromanones. Base-catalysed ring-opening also occurred regioselectively but at the 3-position. Acid- and base-catalysed hydrolysis of 2-methy-lisoflavone epoxide resulted in cleavage of both heterocyclic rings, yielding, respectively, a 1,3- and a 1,2-diketone. This epoxide formed a cyclic sulphate with sulphuric acid.