3β,12β,14α-Trihydroxypregnan-20-one

The title compound, C21H34O4, is a steriod of the pregnane family prepared by the sequential oxidation and reduction of 3β,12β-diacetoxy-20-ethylenedioxypregnan-14-ene. The conformations of the six-membered rings are close to chair forms, while the five-membered ring adopts an envelope conformation. All the rings are trans-fused and an intramolecular O—H⋯O hydrogen bond occurs. In the crystal structure, intermolecular O—H⋯O hydrogen bonds link the molecules into a two-dimensional network.

The title compound, C 21 H 34 O 4 , is a steriod of the pregnane family prepared by the sequential oxidation and reduction of 3,12-diacetoxy-20-ethylenedioxypregnan-14-ene. The conformations of the six-membered rings are close to chair forms, while the five-membered ring adopts an envelope conformation. All the rings are trans-fused and an intramolecular O-HÁ Á ÁO hydrogen bond occurs. In the crystal structure, intermolecular O-HÁ Á ÁO hydrogen bonds link the molecules into a two-dimensional network.
dioxy-14-ene, which was prepared from hecogenin (Fell & Heathcock, 2002;Ranu & Samanta, 2003). We have undertaken the X-ray crystal structure determination of (I) in order to establish its molecular conformation and relative stereochemistry.
The hydroxyl group at C12 and the acetyl group at C17 are beta-oriented respectively, whereas the hydroxyl group at C14 is alpha-oriented (Fig. 1). The conformation of the six-membered rings in both molecules are close to chair forms, while the five-membered ring adopts an envelope conformation. All rings in both molecules are trans-fused. The molecules of (I) are held together by an extensive O-H···O hydrogen-bonding two-dimensional network (Table 1, Fig. 2).

Experimental
The title compound was prepared according to the literature method (Fell & Heathcock, 2002;Templeton & Yan 1992).
Crystals suitable for X-ray analysis were obtained by slow evaporation of a methanol solution at room temperature (m.p.

Refinement
Anomalous dispersion was negligible and Friedel pairs were merged before refinement. The O-bond H atoms were located in a difference map and their positions were freely refined with U iso (H) = 1.5U eq (O). The C-bound H atoms were fixed geometrically at ideal positions (C-H = 0.96-0.98 Å) and refined as riding with U iso (H) = 1.2U eq (C) or 1.5U eq (methyl C). Fig. 1. The molecular structure of (I) with displacement ellipsoids for the non-H atoms drawn at the 50% probability level.  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 Rfactors(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.

Figures
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )