The crystal and molecular structure of 9α-bromo-17β-hydroxy-17α-methylandrost-4-ene-3,11-dione
Abstract
Enhancement of activity of biologically-active steroids may often be obtained by 9α- or 12α-halogenation of the steroid. The crystal and molecular structure of the activated anabolic agent, 9α-bromo-17β-hydroxy-17α-methylandrost-4-ene-3,11-dione(C20H27O3Br), has been determined by X-ray methods. The crystals occur in space group P21 with a= 7·042, b= 20·429, c= 6·481 Å, β= 104·30°, Z= 2. Compared to the structures of 9α-H steroids, 9α-halogenation has had the effect of flattening the B and C rings and of further lowering the functional 11-oxo group to a more equatorial configuration where it is less shielded by the hydrogen atoms on the β-surface of the steroid. In the steroid nucleus, the cyclohexenone A ring is not puckered about the Δ4-bond, as is commonly supposed, but has atom C(1) lying almost in the plane of atoms C(3), C(4), C(5), C(6), and (C10), with the puckering mainly at C(2). This implies that the conjugated Δ4-3-one system is not planar.