摘要:
                                The synthesis of epoxides 2 by epoxidation of flavones 1 with isolated dimethyldioxirane (as acetone solution) at subambient temperatures is reported.  These labile epoxides were isolated and completely characterized by UV, IR, H-1 and C-13 NMR, MS, and C, H analyses.  Warming to room temperature led to rearrangement to afford quantitatively the 3-hydroxyflavones 3b,h,i,n.  Treatment of the epoxides 2b,f with methanol led to the 3-hydroxy-2-methoxyflavanones 4b,f as a mixture of cis and trans isomers.