1,3,3-Tribenzylindolin-2-one

In the title compound, C29H25NO, the dihedral angles between the indolin-2-one ring system and the three benzene rings are 62.78 (9), 31.69 (9) and 80.94 (9)°.


Related literature
For general background to the use of indoline-2-one compounds as precursors for the synthesis of antitumor agents, see: Wang et al. (2011). For a related structure, see: Katritzky et al. (1997).
In the course of exploring new antitumor medicine, we obtained a intermediate compound C 29 H 25 NO (I), the synthesis and structure of which are reported here.

Experimental
Indolin-2-one (0.50 g, 3.76 mmol) was dissolved in THF (20 mL) and KOH (0.80 g, 14.3 mmol) was slowly added. After heating the stirred mixture at reflux temperature for 30 min, a solution of 1-(chloromethyl)benzene (2.00 g, 15.9 mmol) in THF was slowly added and the refluxing continued for 2 h. The mixture was then cooled to 333 K and poured into water (200 mL) and was extracted with chloroform and dried over Na 2 SO 4 . After removing the solvent, the crude product was purified by column chromatography on silica gel, affording the title compound (yield: 0.23 g, 15%). The compound was then dissolved in THF, and colorless crystals were formed on slow evaporation at room temperature over one week.

Refinement
All H atoms were placed in geometrically calculated positions and refined using a riding model with C-H = 0.93 Å and with U iso (H) = 1.2U eq (C). Fig. 1. The molecular structure of the title compound with the atom numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.

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.