Selective aromatization of ring B in 19-norsteroids and synthesis of equilenin-type compounds

Abstract

The preparation of 7α-acetoxy-3,3:17,17-bis(ethylenedioxy)-5,10-epoxy-5β,10β-oestran-6-one (4) is described. When heated with alkali it undergoes ring B aromatization to give 3,3:17,17-bis(ethylenedioxy)oestra-5(10),6,8-triene-6,7-diol (7), without configurational change at C(14). Bis-deacetalization of the corresponding diacetate (8), followed by lead tetra-acetate aromatization of ring A in the resulting diketone (9), produces 6,7-diacetoxyequilenin (10), which is finally converted into its 3-acetate (11). The same ester product (11) could also be obtained by conversion of the diketone (9) into its 3-enol acetate (12), followed by lead tetra-acetate dehydrogenation.