(E)-3-Methyl-2,6-diphenylpiperidin-4-one O-(3-methylbenzoyl)oxime

In the title compound, C26H26N2O2, the piperidine ring exhibits a chair conformation. The phenyl rings are attached to the central heterocycle in an equatorial position. The dihedral angle between the planes of the phenyl rings is 57.58 (8)°. In the crystal, C—H⋯O interactions connect the molecules into zigzag chains along [001].

In the title compound, C 26 H 26 N 2 O 2 , the piperidine ring exhibits a chair conformation. The phenyl rings are attached to the central heterocycle in an equatorial position. The dihedral angle between the planes of the phenyl rings is 57.58 (8) . In the crystal, C-HÁ Á ÁO interactions connect the molecules into zigzag chains along [001].

S1. Comment
The chemistry of oxime esters are serving as important synthetic intermediate, and have been employed as starting materials for both synthetic and medicinal chemistry (Crichlow et al. 2007;Hwu et al.2008;Neely et al.2013). Oxime esters have received great potential in biologically active molecules such as agrochemical industries (Liu et al., 2011).
The bond distances and bond angles in the title compound agree very well with the corresponding values reported in closely related compounds (Park et al., 2012a,b). This stucture was stabilized by C-H···O intramolecular interactions linking the molecules to zigzag chains running parallel to [001] axis.

S2. Experimental
A mixture of 3-methyl-2,6-diphenylpiperidin-4-one oxime (0.73 g, 2.5 mmol) and m-methylbenzoic acid (0.37 g, 2.75 mmol) in dry pyridine (7 ml) was stirred at ambient temperature. POCl 3 (0.25 ml, 2.75 mmol) was added drop wise to the reaction mixture and stirring is continued for 20 to 30 min. The progress of the reaction was monitored by TLC. After completion of the reaction, a saturated solution of NaHCO3 was added portion wise to the reaction mixture and the crude product was thrown out as a precipitate. The crude product was then recrystallized from absolute ethanol to get the pure 3-methyl-2,6-diphenylpiperidin-4-one-O-(3-methylbenzoyl) oxime. Yield 0.76 g (78%).

S3. Refinement
The positions of the hydrogen atoms were identified from difference electron density maps. The hydrogen atoms bound  The molecular structure of the title compound with the atom numbering scheme, displacement ellipsoids are drawn at 30% probability level. H atoms are present as small spheres of arbitary radius.

Figure 2
Part of crystal structure of the title compound, showing the formation one dimensional C(12) chains running parallel to [0 0 1] axis.  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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq H1A 0.018 (