(4RS)-Methyl 4-cyano-4-cyclohexyl-4-phenylbutanoate

In the crystal structure of the title compound, C18H23NO2, there are only van der Waals interactions present. The cyclohexyl ring has a chair conformation. The longer axes of the displacement parameters of the non-H atoms forming the ethylmethylcarboxylate skeleton are perpendicular to the plane through the non-H atoms of this skeleton.

In the crystal structure of the title compound, C 18 H 23 NO 2 , there are only van der Waals interactions present. The cyclohexyl ring has a chair conformation. The longer axes of the displacement parameters of the non-H atoms forming the ethylmethylcarboxylate skeleton are perpendicular to the plane through the non-H atoms of this skeleton.
The title molecule is shown in Fig. 1. The cyclohexane ring adopts a chair conformation. There are no weak hydrogen bonds and no significant intermolecular π-π electron interactions in the structure. The longer axes of the displacement parameters of the non-hydrogen atoms forming the ethylmethylcarboxylate skeleton are perpendicular to the plane through the non-hydrogen atoms through this skeleton. The displacement parameters of these atoms are rather elongated, possibly due to weak intermolecular interactions between the molecules which may enable more intense thermal agitation of the molecules in the structure.

Experimental
Powdered potassium carbonate (6.9 g, 0.05 mol) and tetrabutylammonium bromide (0.8 g, 0.0025 mol) were added to a solution of 2-cyclohexyl-2-phenylacetonitrile (9.95 g, 0.05 mol) in toluene (35 ml). Methyl acrylate (5.16 g, 0.06 mol) was slowly added in the mixture at 110 °C. After refluxing for 7h, the mixture was cooled and water was added, extracted with ethyl acetate (3 × 50 ml), combined organic solutions, washed with water (3 × 50 ml), and dried over MgSO 4 . The volatiles were removed in vacuo and the crude product was purified by column chromatography over silica gel with ethyl acetate/petroleum ether (1:20 v/v). The title compound was isolated in 96% yield as a white solid. Colourless transparent block-like crystals with approx. dimensions 0.2 × 0.4 × 0.5 mm were obtained by slow evaporation of ethyl acetate/petroleum ether (1:20 v/v).

Refinement
All the H atoms were located in the difference electron density map. Nevertheless, the H atoms were constrained and refined in the riding motion approximation: C aryl -H = 0.93, C methine -H = 0.98, C methylene -H = 0.97, C methyl -H = 0.96 Å.
U iso (H aryl/methane/methylene ) = 1.2 × U eq (C carrier ) and U iso (H methyl ) = 1.5 × U eq (C carrier ).  The title molecule with the atom labels and the displacement ellipsoids shown at the 30% probability level.

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.