N-(2-Oxo-2H-chromen-3-yl)cyclohexanecarboxamide

In the title compound, C16H17NO3, the coumarin moiety is essentially planar [maximum deviation from the mean plane formed by the C and O atoms of the coumarin = 0.0183 (12) Å] and that the cyclohexane ring adopts the usual chair conformation. The dihedral angle between the mean plane of the coumarin residue and the plane of the amide residue (defined as the N, C and O atoms) is 18.9 (2)°. There are two intramolecular hydrogen bonds involving the amide group. In one, the N atom acts as donor to the ketonic O atom and in the other, the amide O atom acts as acceptor of a C—H group of the coumarin. In the crystal, molecules are linked into inversion dimers by pairs of N—H⋯O contacts and these dimers are linked into pairs by weak C—H⋯O hydrogen bonds. The combination of these interactions creates a chain of rings which runs parallel to [2-10]. C—H⋯π and π–π [centroid–centroid distance = 3.8654 (10) Å] interactions are also observed.

In the title compound, C 16 H 17 NO 3 , the coumarin moiety is essentially planar [maximum deviation from the mean plane formed by the C and O atoms of the coumarin = 0.0183 (12) Å ] and that the cyclohexane ring adopts the usual chair conformation. The dihedral angle between the mean plane of the coumarin residue and the plane of the amide residue (defined as the N, C and O atoms) is 18.9 (2) . There are two intramolecular hydrogen bonds involving the amide group. In one, the N atom acts as donor to the ketonic O atom and in the other, the amide O atom acts as acceptor of a C-H group of the coumarin. In the crystal, molecules are linked into inversion dimers by pairs of N-HÁ Á ÁO contacts and these dimers are linked into pairs by weak C-HÁ Á ÁO hydrogen bonds. The combination of these interactions creates a chain of rings which runs parallel to [210]. C-HÁ Á Á and -[centroid-centroid distance = 3.8654 (10) Å ] interactions are also observed.

Maria J. Matos, Lourdes Santana and Eugenio Uriarte Comment
Coumarin derivatives are very interesting molecules due to the biological properties that they may display (Borges et al. 2009;Matos et al. 2009Matos et al. , 2010Matos, Terán et al., 2011). The title structure is a 3substituted coumarin derivative that posses one cyclohexane ring linked by an amidic bridge at that position. Therefore, the X-ray analysis of this compound (figure 1) aims to contribute to the elucidation of structural requirements needed to understand the partial planarity of the compound (coumarin nucleus) and the torsion of the 3-substituent. Also, the X-ray analysis allows understanding the chair conformation of the cyclohexane. There are intramolecular short contacts N12-H12···011 and C4-H4···O14.
Combination of these pair of interactions creates a chain of rings which runs parallel to [210] There are C-H···π interactions between C16 and C17 and the centroids of the rings containing O11 and C9 respectively at (-x,-y,-z).
In addition there is π-π stacking between the rings containg O1 at (x,y,z) and (-x,-y+1,-z) in which the centroid to centroid distance is 3.8654 (10)Å, the perpendicular distance between the rings is 3.4428 (6)Å and the offset is 1.757Å.

Experimental
N-(coumarin-3-yl)cyclohexanecarboxamide was prepared according to the protocol described by (Viña, Matos, Ferino et al. 2012;Viña, Matos, Yáñez et al. 2012). To a solution of 3-aminocoumarin (1 mmol) and pyridine (1.1 mmol) in dichlorometane (9 ml), the corresponding acid chloride (1.1 mmol) was added dropwise and the reaction was stirred, at room temperature, for 3 h. The solvent was evaporated under vacuum and the dry residue was purified by FC (hexane/ethyl acetate 9:1). A pale yellow solid was obtained in a yield of 72%. Suitable crystals for X-ray studies were grown from slow evaporation from acetone/ethanol: Mp 180-181 °C.

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 F2. The threshold expression of F 2 > 2σ(F 2 ) is used only for supplementary materials calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Figure 1
The molecular structure of the title compound with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30%probability level. The dashed lines indicate intramolecular close contacts.  Part of the crystal structure of (2) showing the chain formed by molecules linked by R 2 2 (10) and R 2 2 (18) rings which runs parallel to the the {210]. Atoms labelled with an asterisk (*), hash (#) or dollar ($), are at(-x+1,-y,-z), (-x-1,-y+1,-z) and x+2,y-1,z respectively. Hydrogen atoms not involved in the hydrogen bonding have been omitted.

N-(2-Oxo-2H-chromen-3-yl)cyclohexanecarboxamide
Crystal data  6,25.7,29.7,43.0,116.6,120.2,123.4,124.3,125.4,128.0,129.8,150.1,159.2,175.9;DEPT: 25.6,25.7,29.7,43.0,116.6,120.2,124.3,125.4,128 Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq O1 0.24398 (