3-Ethyl-cis-2,6-diphenylpiperidine

In the title compound, C19H23N, the piperidine ring adopts a chair conformation. The phenyl rings at the 2,6-positions of the piperidine ring occupy equatorial orientations. The crystal structure features C—H⋯π interactions.

In the title compound, C 19 H 23 N, the piperidine ring adopts a chair conformation. The phenyl rings at the 2,6-positions of the piperidine ring occupy equatorial orientations. The crystal structure features C-HÁ Á Á interactions.

Comment
Piperidine derivatives are the valued heterocyclic compounds in the field of medicinal chemistry. As an example, 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, the X-ray crystal structure determination of the title compound has been carried out.
The planar phenyl rings at 2,6-positions of the piperidine ring occupy equatorial orientation as can be seen from the (1)°, respectively. The dihedral angle between the two phenyl rings is 64.22 (7)°. The ethyl group substituted at 3 rd position of the piperdine moiety is in equatorial oreintation.
The molecules are controlled by C-H ··· π type of intermolecular interactions in addition to van der Waals forces. The molecules are stacked one over the other while packing in the unit cell (Fig. 2).

Experimental
A mixture of piperidin-4-one (10 mM), and 80% hydrazine hydrate (3.1 ml) in diethylene glycol (100 ml) was heated on a steam bath for 2 h. Potassium hydroxide pellets (2.8 g) were added to the mixture and the contents were refluxed for another 2 h. The reaction mixture was cooled (Ponnuswamy et al., 2002). The product formed was filtered and recrystallized from ethanol.

Refinement
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. The N-bound H was located in a difference Fourier map and was refined with a distance restraint; its temperature factor was refined.   The crystal packing of the molecules viewed down a axis.

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.