3β-Acetoxy-19-hydroxy-Δ5-pregnen-20-one

In the title compound, C23H34O4, the C/D and D/E rings are trans fused and the A/B ring possesses an anti fusion. The two cyclohexane rings adopt a chair conformation while the cyclohexene ring exhibits a half-chair conformation. The cyclopentane ring displays an envelope conformation with the C atom bearing the methyl group as the flap. In the crystal, the molecules are linked by O—H⋯O hydrogen bonds, forming chains along the b axis.

In the title compound, C 23 H 34 O 4 , the C/D and D/E rings are trans fused and the A/B ring possesses an anti fusion. The two cyclohexane rings adopt a chair conformation while the cyclohexene ring exhibits a half-chair conformation. The cyclopentane ring displays an envelope conformation with the C atom bearing the methyl group as the flap. In the crystal, the molecules are linked by O-HÁ Á ÁO hydrogen bonds, forming chains along the b axis.   Table 1 Hydrogen-bond geometry (Å , ). supplementary materials Acta Cryst. (2013). E69, o313 [doi:10.1107/S1600536813002493] 3β-Acetoxy-19-hydroxy-Δ 5 -pregnen-20-one Aike Meier zu Greffen, Darius P. Kranz, Jörg-M. Neudörfl and Hans-Günther Schmalz

Comment
The structural diversity of steroids as well as their unsurpassed biological potential qualify them as challenging targets for chemical synthesis and as lead structures for pharmacological research (Fieser & Fieser, 1961;Hanson, 2010). In recent years, some unusual steroids displaying a rearranged A/B-ring system with promising biological properties have been reported (Du et al., 2008;Aoki et al., 2006;Flyer et al., 2010). Important intermediates for the synthesis of such rearranged derivatives are C-19 functionalized steroids (El Sheikh et al., 2007;Shenvi et al., 2008). The functionalization of the unactivated angular C-10 methyl group is achieved by remote functionalization (Heusler et al., 1964;Reese, 2001).

Experimental
The title compound C 23 H 34 O 4 was prepared in 3 steps starting from commercial pregnenolone-acetate (Kranz et al., 2011).

Refinement
All hydrogen atoms were placed in geometrically idealized positions and refined with using riding model with C-H = 0.95 Å and U iso (H) = 1.2U eq (C) for CH, C-H = 0.99 Å and U iso (H) = 1.2U eq (C) for CH 2 , C-H = 0.98 Å and U iso (H) = 1.5U eq (C) for CH 3 and OH.   Plot of the unit cell; the b axis is perpendicular to the plane of the paper and the a and c axes are horizontal and vertical, respectively. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.23 e Å −3 Δρ min = −0.23 e Å −3

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.