title: 17-Oxo-5 alpha-androst-6-en-3 beta-yl acetate.
abstract: In the title compound, C(21)H(30)O(3), a potential inhibitor of aromatase, all rings are fused trans. Rings A and C have chair conformations which are slightly flattened, whereas the conformation of ring B is close to a half-chair. Ring D has a 14 alpha-envelope conformation. The steroid nucleus has a small twist, as shown by the C19-C10...C13-C18 (steroid numbering) torsion angle of -6.9 (3) degrees. Ab initio calculations of the equilibrium geometry of the molecule reproduce this small twist, which appears to be due to the conformation of ring B rather than to packing effects.
authors.affiliation: Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, P-3004-535 Coimbra, Portugal.
authors.forename: J I F
authors.initials: JI
authors.lastname: Paixão
authors.forename: J A R
authors.initials: JA
authors.lastname: Salvador
authors.forename: J A
authors.initials: JA
authors.lastname: Paixão
authors.forename: A Matos
authors.initials: AM
authors.lastname: Beja
authors.forename: M Ramos
authors.initials: MR
authors.lastname: Silva
authors.forename: A M d'A Rocha
authors.initials: AM
authors.lastname: Gonsalves