Crystal structure of cholest-5-en-3β-yl 3-(2,4-dimethoxy-3-methylphenyl)prop-2-enoate

In the title compound, C39H58O4, the steroid rings A and C adopt a chair conformation, while ring B adopts a half-chair conformation, and ring D has an envelope conformation, with the methyl-substituted C atom as the flap. In the crystal, molecules pack within layers parallel to (100), with their long axis parallel to the [101] direction. Adjacent layers are linked via C—H⋯O hydrogen bonds and C—H⋯π interactions, forming a three-dimensional framework.

The conformational analysis of rings A, B, C and D was carried out. It was found that rings A and C adopt a chair conformation, while ring B adopts a half-chair conformation, and ring D adopts an envelope conformation with the methyl substituted C atom as the flap.
In the crystal, molecules are arranged in separate layers parallel to (1 0 0). Within each layer, translation related molecules form columns extend along [1 0 1] with their long molecular axis collinear with this direction (Figure 3).
Molecules in the neighbouring columns exhibit head to tail arrangement with C-H···O interactions occurring between the 2-methoxy group (O3) of one cinnamate unit with the C6-H (H36) of the other molecule's cinnamate unit ( Table 1).
The neighboring layers are packed in such a manner that there are two close contact, (C21-H21A···O3) and (C22-H22B···π) between molecules in a head-to-tail arrangement, with a dihedral angle between the steroidal mean planes of these contacting molecules of 46.7 (2)° ( Fig. 2 and Table 1). These interactions lead to the formation of a threedimensional framework.

S3. Refinement
All H atoms were placed in calculated positions with C-H distances of 0.95 -1.00 Å and refined as riding with U iso (H) = 1.5U eq (C) for methyl H atoms and = 1.2U eq (C) for other H-atoms. In the final cycles of refinement, in the absence of significant anomalous scattering effects, the Friedel pairs were merged and Δf ′ set to zero.

Figure 1
A view of molecular structure of the title molecule, with atom labelling. Displacement ellipsoids are shown at the 50% probability level. The short intramolecular C-H···O contacts are shown as green dashed lines (see Table 1 for details).

Cholest-5-en-3β-yl 3-(2,4-dimethoxy-3-methylphenyl)prop-2-enoate
Crystal data  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.