Reactions of enone ethylene ketals with methyl diazomalonate/bis(acetylacetonato)copper(II)

Several cyclic and acyclic enones and their ethylene ketals/acetals were reacted with dimethyl diazomalonate under bis(acetylacetonaro)copper(II) catalysis. Cyclohex-2-en-1-one (1) yielded only C-H insertion products 2 and 3, whereas but-3-en-2-one gave a cyclopropane albeit in very low yield. The ethylene ketals 6 of cyclopent-2-en-1-one and cyclohex-2-en-1-one gave the corresponding cyclopropanes 7, which were in turn cleaved to the ketones 8. The acetals 9 and 10 of crotonaldehyde ((E)-but-2-enal) and cinnamaldehyde ((E)-3-phenylprop-2-enal), respectively, yielded C-O insertion and [2,3]-sigmatropic rearrangement products 11b, c and 12b,c, as well as cyclopropanes 11a and 11b, all of which are polyfunctional and synthetically useful compounds.