1-(2,2-Dichloroacetyl)-3-ethyl-2,6-diphenylpiperidin-4-one

The asymmetric unit of the title compound, C21H21Cl2NO2, contains two independent molecules that show similar geometrical features. The piperidine ring adopts a distorted boat conformation. The phenyl rings substituted at the 2- and 6-positions of the piperidine ring are oriented at angles of 65.4 (1) [64.7 (2)°] and 89.2 (1)° [86.3 (2)°] with respect to the least-squares plane of the piperidine ring. In the crystal, adjacent molecules are linked by a network of C—H⋯O interactions, forming a C(6) chain along the c-axis direction.

The asymmetric unit of the title compound, C 21 H 21 Cl 2 NO 2 , contains two independent molecules that show similar geometrical features. The piperidine ring adopts a distorted boat conformation. The phenyl rings substituted at the 2-and 6-positions of the piperidine ring are oriented at angles of 65.4 (1) [64.7 (2) ] and 89.2 (1) [86.3 (2) ] with respect to the least-squares plane of the piperidine ring. In the crystal, adjacent molecules are linked by a network of C-HÁ Á ÁO interactions, forming a C(6) chain along the c-axis direction.
Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009). PS thanks the UGC, New Delhi, for financial support in the form of a Research Fellowship in Science for Meritorious Students. SP thanks the UGC, New Delhi, for financial assistance in the form of a major research project. 1991). Piperidines have been found to exhibit blood cholesterol-lowering activities (Nalanishi et al., 1974). Against this background and to ascertain the molecular structure and conformation, crystallographic study of the title compound has been carried out.
The ORTEP plot of the molecule is shown in Fig. 1. The chloro substituted piperidine derivative crystallizes in monoclinic space group P2 1 /c. The piperidine ring adopts distorted boat conformation with the puckering parameters (Cremer & Pople, 1975) and the asymmetry parameters (Nardelli, 1983) are: q 2 =0.651 (3)  The crystal packing reveals that the symmetry related molecules are linked through a network of C-H···O type of intermolecular interactions.
The course of the reaction was monitored by TLC. The organic layer was dried over anhydrous Na 2 SO 4 and the resulting pasty mass was purified by recrystallization from ethyl acetate. Yield: 74%, Melting point: 140-142°C

Refinement
N and C-bound H atoms were positioned geometrically (C-H = 0.93-0.98 Å) and allowed to ride on their parent atoms, with U iso (H) = 1.5U eq (C) for methyl H atoms and 1.2U eq (C) for all other H atoms.

Figure 1
The molecular structure of the title compound, showing the atomic numbering and displacement ellipsoids drawn at 50% probability level.  The crystal packing of the molecules. H atoms not involved in hydrogen bonding (dashed lines) have been omitted for clarity.

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.