title: Preparative chemical methods for aromatization of 19-nor-delta 4-3-oxosteroids.
abstract: Two preparative chemical methods for aromatization of 19-nor-delta 4-3-oxosteroids are described. The first method consists of an oxidative aromatization of 19-nor-delta 4-3-oxosteroids with iodine-ceric ammonium nitrate in methanol to give a mixture of 3-methoxy ring-A aromatized derivatives consisting of the desired product, the delta 9,11 derivative, the 6-oxo derivative as well as some ring-A iodinated material. Conversion of this material to a mixture of the 3-methoxy ring-A aromatized derivative and its 6-oxo derivative was achieved by catalytic hydrogenation. Finally, reduction of the 6-oxo function with triethylsilane in trifluoroacetic acid gave the 3-methoxy-17-trifluoroacetate ring-A aromatized derivative as a single product. In the second method, reaction of 19-nor-delta 4-3-oxosteroids with copper (II) bromide in acetonitrile at room temperature resulted in aromatic steroids in a single step in excellent yields. The second method was used in the first practical chemical synthesis of a 6-dehydroestrogen from a 19-nor-delta 4,6-3-oxosteroid.
authors.affiliation: Department of Organic Chemistry, Southwest Foundation for Biomedical Research, San Antonio, Texas 78228-0147.
authors.forename: P N
authors.initials: PN
authors.lastname: Rao
authors.forename: J W
authors.initials: JW
authors.lastname: Cessac
authors.forename: H K
authors.initials: HK
authors.lastname: Kim
mesh_terms: D001141:Aromatase / Q000378:metabolism; D007664:Ketosteroids / Q000737:chemistry*; D015394:Molecular Structure; D010084:Oxidation-Reduction
chemical_list: D007664:Ketosteroids; D001141:Aromatase