James R. Hanson, Peter B. Hitchcock and Ismail Kiran
The epoxidation of some androsta-4,6-dienes with m-chloroperbenzoic acid has been shown to give the 4β,5β;6α,7α-diepoxides, the stereochemistry can be rationalized in terms of the directing effect of one epoxide on the facial selectivity of the second epoxidation.