Synthetic steroids. Part IX. A new route to 19-nor-steroids

Abstract

3-Methoxyoestra-1,3,5(10)-trien-17-one has been synthesised by removing the aromatic methyl group from 3-methoxy-1-methyloestra-1,3,5(10)-trien-17-one, which was itself obtained by hydrogenating the product from a dienone–phenol rearrangement of androsta-1,4,6-triene-3,17-dione. The two-stage procedure for the removal of an aromatic methyl group from a steroid consists of oxidising the methyl group to an aldehyde with cerium(IV) in aqueous acid and then decarbonylating the aldehyde with tris(triphenylphosphine)rhodium chloride. It is not necessary to purify the intermediate aldehyde, and the overall conversion of CH₃ to H is approximately 50%. 3-Methoxyoestra-1,3,5(10)-trien-17β-ol and 3-methoxy-19-norcholesta-1,3,5(10)-triene have also been prepared by this route.