Dimethyldioxirane oxidation of (E,E)-cinnamylideneacetophenones

The (E,E)-cinnamylideneacetophenones 1a-f were oxidised by isolated dimethy ldioxirane (DMD, as acetone solution) at room temperature, giving diastereo meric mixtures of the alpha, beta:gamma,delta -diepoxides 3a-f when an exce ss of oxidant was used. alpha,beta -Monoepoxides, found as minor components of the reaction, could be detected in only two cases (2c,d) when one equiv alent of DMD was used, Dimethyldioxirane oxidation of (E,E)-2 ' -hydroxycin namylideneacetophenones (4a-d) led to the formation of diastereomeric mixtu res of the alpha,beta:gamma,delta -diepoxides 6a-d as well as to the gamma, delta -monoepoxides 5a-d as minor products. The diepoxides 6a-d were transf ormed into the isolable coumaranone derivatives 7a-d during their chromatog raphic purification. All the compounds described have been fully characteri sed by NMR spectroscopy.