3-(4-Chloroanilino)-5,5-dimethylcyclohex-2-en-1-one

The asymmetric unit of the title compound, C14H16ClNO, contains two independent molecules, both with the cyclohexene ring in a sofa conformation. In the crystal, N—H⋯O hydrogen bonds link the molecules related by translation along the a axis into two crystallographically independent chains. Weak C—H⋯π interactions are also observed.

The asymmetric unit of the title compound, C 14 H 16 ClNO, contains two independent molecules, both with the cyclohexene ring in a sofa conformation. In the crystal, N-HÁ Á ÁO hydrogen bonds link the molecules related by translation along the a axis into two crystallographically independent chains. Weak C-HÁ Á Á interactions are also observed.

Comment
Enamines are versatile substrates for the preparation of useful bioactive alkaloids, such as pyrazoles (Heller & Natarajan 2006), quinolines (Katritzky et al.,1993) and carbazoles (Campaigine & Lake 1959). The compounds are generally prepared by heating aldehydes or ketones with primary amines in presence of strong acids.However, these methods are associated with the limitations of low yield, undesirable side reactions and polymerization. Therefore, there is a need to develop an alternative efficient methodology for the preparation of these compounds, under ambient reaction conditions.Herein, we describe the preparation and XRD studies of the model the title compound from dimedone and pchloroaniline in the presence of triethylammonium trifluoromethanesulfonate and triethylamine at room temperature.
The asymmetric unit of the title compound comprises of two crystallographically independent molecules, A and B, respectively (Fig. 1). The geometry of both the asymmetric molecules, A and B, indicates a high degree of similarity in terms of their bond distances and bond angles. A comparison of these parameters with some related structures (Mehdi et al., 2010;Bertolasi et al., 1998) indicates a good agreement. The average aromatic bond length in the phenyl ring is  (Allen et al., 1987)and lengthening of the C1=O1 double bond is due to strong intermolecular hydrogen bond between N1 and O1. The dihedral angle between the cyclohexene ring and phenyl ring is 58.2 (1)° (molecule A) and 57.5 (1)° (molecule B). In cyclohexene ring, the C2=C3 distance of 1.361 (3) Å (molecule A) and 1.370 (3) Å (molecule B) confirms the localization of a double bond at this position. This double bond imposes a sofa conformation on cyclohexene ring, with asymmetry parameters: ΔCs (C2A-C5A) (molecule A) = 6.11; ΔCs (C2B-C5B) (molecule B) = 3.30.
In the crystal, adjacent molecules are interconnected through N-H···O hydrogen bonds (Table 1). The crystal structure is further stabilized by C-H···π hydrogen bonding (Table 1, Cg1 and Cg2 represent the centre of gravity of benzene ring C9-C14 in molecules A and B, respectively).

Refinement
H1A attached to N1A and H1B attached to N1B were located from the difference map and isotropically refined with the restraints N-H = 0.84 (3) Å. The remaining H atoms were positioned geometrically and were treated as riding on their parent C atoms, with C-H distances of 0.93-0.97 Å; and with U iso (H) = 1.2-1.5 U eq (C).

Computing details
Data collection: CrysAlis PRO (Oxford Diffraction, 2010); cell refinement: CrysAlis PRO (Oxford Diffraction, 2010); data reduction: CrysAlis PRO (Oxford Diffraction, 2010); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: PLATON (Spek, 2009). 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.