DIMETHYLDIOXIRANE EPOXIDATION OF AURONES AND ISOFLAVONES

The synthesis of the corresponding epoxides 2 and 4 by epoxidation of aurones (2-benzylidenebenzofuran-3(2H)-ones, 1) and isoflavones (3-aryl-4H-1-benzopyran-4-ones, 3) with dimethyldioxirane at subambient temperatures is reported. These acid- and base-sensitive epoxides, which have been previously difficult to prepare, were isolated in excellent yields and were completely characterized by spectral and microanalytical data. The now readily available aurone and/or isoflavone oxides may serve as convenient precursors to flavonoid-type natural products.