Applications of high-potential quinones. Part VII. The synthesis of steroidal phenanthrenes by double methyl migration

Steroidal phenanthrenes are formed from 17 α-methyl-Δ9(11)-testosterones by the action of dichlorodicyanobenzoquinone and toluene-p-sulphonic acid in refluxing dioxan. Initial dehydration occurs without rearrangement to give δ16-derivatives, which undergo double methyl migration and oxidation to the phenanthrenes. Isolation of the Δ16-intermediates is ascribed to the presence of the Δ9(11)-bond, which eliminates the usual 11 β-H–13-Me diaxial interaction in ring C.