Spirodiepoxides in total synthesis: epoxomicin.

The first use of the spirodiepoxide functional group in total synthesis, a study culminating in an efficient synthesis of the potent proteasome inhibitor epoxomicin, is described. Spirodiepoxides derived from allenes by oxidation are shown to give syn disubstituted ketones and their derivatives, including ortho ester, oxazoline, azido epoxide, as well as sulfonamide-, amide-, and azide-containing hydroxy ketones.