1-Benzyl-3-[(4-methylphenyl)imino]indolin-2-one

In the title compound, C22H18N2O, the phenyl and tolyl rings make dihedral angles of 84.71 (7) and 65.11 (6)°, respectively, with the isatin group. The aromatic rings make a dihedral angle of 60.90 (8)°. The imino C=N double bond, exists in an E conformation. In the crystal, molecules are linked by weak π–π stacking interactions [centroid–centroid distance = 3.6598 (13) Å].

In the title compound, C 22 H 18 N 2 O, the phenyl and tolyl rings make dihedral angles of 84.71 (7) and 65.11 (6) , respectively, with the isatin group. The aromatic rings make a dihedral angle of 60.90 (8) . The imino C N double bond, exists in an E conformation. In the crystal, molecules are linked by weak stacking interactions [centroid-centroid distance = 3.6598 (13) Å ].

1-Benzyl-3-[(4-methylphenyl)imino]indolin-2-one Adebomi A. Ikotun, Pius O. Adelani and Gabriel O. Egharevba Comment
Indole-2, 3-dione commonly known as isatin is an endogenous indole present in mammalian tissues and fluids (Igosheva et al., 2004). It has largely been used as a versatile reagent in organic synthesis, to obtain heterocyclic compounds, and as a raw material for drugs (Abele et al., 2003). Several novel Schiff bases of isatin have been reported with a variety of pharmacological actions, including anticonvulsant, antimicrobial and antiviral activities, inhibition of monoamine oxidase (Medvedev et al., 1996). The study of the metal complexes of the Schiff base ligands derived from isatin and their biological applications has also received much attention (Singh et al., 2005;Chohan et al., 2006;Ikotun et al., 2012).
Some first row transition metal complexes of the Schiff base of isatin derivatives were designed, prepared and characterized by spectroscopic means (Adetoye et al., 2009). The significance of these metal complexes of isatin derivatives has even been extended to the design of novel anticancer drugs (Rodriguez-Arguelles et al., 2004). N-benzylindole-2, 3-dione (N-benzylisatin) has also been prepared and the X-ray crystallographic structure has been established (Akkurt et al., 2006). N-alkylated isatins have interesting pharmacological activities such as antibacterial and anticancer (Chazeau et al., 1992). They are also reversible and competitive inhibitors of monoamine oxidase A and B (Medvedev et al., 1996). Some mono-and bis-spiro-b-benzylisatin have been prepared and characterized by spectroscopic means (Jarrahpour et al., 2007). A series of N-benzyl isatin oximes have also been developed as inhibitors of the mitogenactivated kinase, KNK3 (Cao et al., 2009). Thus the motivation and need to design novel Schiff bases of N-benzyl isatin, which would be of great biological significance, is the propelling force for this research. In the title compound , Fig. 1, the phenyl and benzene rings make dihedral angles of 84.71 (7)° and 65.11 (6)° with isatin group respectively. The aromatic rings make a dihedral angle of 60.90 (8)°.The imino C═N double bond, exists in an E conformation. In the crystal the molecules are linked by weak π-π stacking interaction (centroid-centroid distance 3.6598 (13) Å (Cg1=C4/C5/C6/C7/C8/C9 ; Cg2 i =C17/C18/C19/C20/C21/C22, symmetry code (i): x,1/2-y, 1/2+z), Fig. 2.

Experimental
N-benzylisatin was first prepared and recrystallized in ethanol using the method of Akkurt et al., 2006 with slight modifications. N-benzylisatin (2.00 g; 8.44 mmol) was then dissolved in 30 ml hot ethanol. P-toluidine (0.90 g; 8.44 mmol) was dissolved in 10 ml ethanol. The solutions were mixed and refluxed for 6 h. The solution was allowed to cool and the deep orange solid was filtered under vacuum. The product was purified with flash column chromatography and the orange crystal as analyzed. The product was obtained at a yield of 78% (2.13 g). Flash Column Chromatographic purification of the product was carried out using a mixture of chloroform: diethyl ether (50%:50%) and single X-ray suitable crystals were got after the solvent was evaporated under vacuum.

Refinement
The H atoms of the water molecule were located on a Fourier difference map, restrained by DFIX command 0.85 Å for O -H distances and by DFIX 1.39 Å for H···H distance, and refined as riding with U iso (H) = 1.5U eq (O). Other atoms were placed in their calculated positions, with C-H = 0.93 or 0.96 Å, and refined using a riding model, with U iso (H) = 1.2 or 1.5U eq (C).