1-Dichloroacetyl-t-3-isopropyl-r-2,c-6-diphenylpiperidin-4-one

In the title compound, C22H23Cl2NO2, the piperidine ring adopts a twist-boat conformation. The phenyl rings substituted at the 2- and 6-positions of the piperidine ring subtend dihedral angles of 60.6 (2) and 84.2 (1)°, respectively, with the mean plane of the piperidine ring. In the crystal, molecules are linked by C—H⋯O interactions into zigzag chains running along the c-axis direction.

In the title compound, C 22 H 23 Cl 2 NO 2 , the piperidine ring adopts a twist-boat conformation. The phenyl rings substituted at the 2-and 6-positions of the piperidine ring subtend dihedral angles of 60.6 (2) and 84.2 (1) , respectively, with the mean plane of the piperidine ring. In the crystal, molecules are linked by C-HÁ Á ÁO interactions into zigzag chains running along the c-axis direction.
The ORTEP plot of the molecule is shown in Fig. 1. The piperidine ring adopts a twist-boat conformation, with puckering parameters (Cremer & Pople, 1975) and asymmetry parameters (Nardelli, 1983) of: q 2 = 0.632 (2) Å, q 3 = The crystal packing reveals that the symmetry-related molecules are linked through a network of C-H···O type of intermolecular interactions. Atom C2 (x, y, z) donates a proton to atom O1 (-x + 3/2, y, z + 1/2), which form a chain in zigzag fashion running along the c direction as shown in Fig. 2.

Experimental
t-3-Isopropyl-r-2,c-6-diphenylpiperidin-4-ones (5 mmol) was dissolved in 60 ml of anhydrous benzene. To this solution, dichloroacetylchloride (20 mmol) and triethylamine (20 mmol) were added and the reaction mixture was allowed to stir for 8 h. 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: 70%, m.p. 156-158°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.  (8) Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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.