Configuration of the C/D Ring Junction in Equilenin and Other Steroids

THE configuration of the C / D ring fusion in equilenin has been the subject of a number of communications 1–3 . We consider that the arguments advanced for a trans ring junction leave much to be desired. Shoppee's 1 conclusion that the dehydrogenation of equilin to equilenin under mild conditions proves the steric identity of the C / D union in these two substances can no longer be accepted, since iso equilin, which is now known 4,5 to be also trans , gives iso equilenin (which has the opposite C / D configuration to equilenin) under the same conditions 6 .