FLAVONOID EPOXIDES .20. SOME UNUSUAL REACTIONS OF DIMETHYLDIOXIRANE (DMD) WITH FLAVONOID COMPOUNDS

Dimethyldioxirane (DMD), generally as a solution in acetone, has prove d itself to be an excellent epoxidising agent. It was observed that ei ther the 2'-hydroxychalcone epoxide or the trans-2,3-dihydroflavonol c ould be obtained depending on the pH of the reaction mixture and the: type of p-arene ring present in the substrate. Using this methodology trans-2,3-dihydroflavonols can be synthesised in far better yields tha n by the most commonly used method for their synthesis, that of the Al gar-Flynn-Oyamada reaction. Treatment of both flavonol 14 and the nove l isoaurone 21 with DMD gave unusual products instead of the expected epoxides, but nonetheless, an epoxide was assumed to have formed durin g the reaction. (C) 1997 Elsevier Science Ltd.