title: 6beta-Hydroxy-5beta-methyl-20-oxo-19-norpregn-9(10)-en-3beta-yl acetate.
abstract: In the title compound, C(23)H(34)O(4), which is an intermediate in the synthesis of pregnane derivatives with a modified skeleton that show potent abortion-inducing activity, the conformation of ring B is close to half-chair due to the presence of both the C=C double bond and the axial 5beta-methyl group. Rings A and C have conformations close to chair, while ring D has a twisted conformation around the bridgehead C-C bond. Molecules are hydrogen bonded via the hydroxyl and acetoxy groups into infinite chains. Quantum-mechanical ab initio Roothan Hartree-Fock calculations show that crystal packing might be responsible for the low values of the angles between rings A and B, and between ring A and rings C and D, as well as for a different steric position of the methyl ketone side chain compared to the geometry of the free molecule.
authors.affiliation: Laboratório de Química Farmacêutica, Faculdade de Farmácia, Universidade de Coimbra, P-3000-295 Coimbra, Portugal.
authors.forename: R M A
authors.initials: RM
authors.lastname: Pinto
authors.forename: M
authors.initials: M
authors.lastname: Ramos Silva
authors.forename: A
authors.initials: A
authors.lastname: Matos Beja
authors.forename: J A R
authors.initials: JA
authors.lastname: Salvador
authors.forename: J A
authors.initials: JA
authors.lastname: Paixão
mesh_terms: D000021:Abortifacient Agents, Steroidal / Q000138:chemical synthesis / Q000737:chemistry*; D018360:Crystallography, X-Ray; D005260:Female; D006801:Humans; D006860:Hydrogen Bonding; D008968:Molecular Conformation; D009650:Norpregnanes / Q000138:chemical synthesis / Q000737:chemistry*; D011247:Pregnancy; D011278:Pregnanes / Q000138:chemical synthesis / Q000737:chemistry*; D011789:Quantum Theory
chemical_list: C542178:6beta-hydroxy-5beta-methyl-20-oxo-19-norpregn-9(10)-en-3beta-yl acetate; D000021:Abortifacient Agents, Steroidal; D009650:Norpregnanes; D011278:Pregnanes