1-Octylindoline-2,3-dione

In the title compound, C16H21NO2, the indoline ring and the two ketone O atoms are approximately coplanar, the largest deviation from the mean plane being 0.063 (2) Å. The mean plane through the fused ring system is nearly perpendicular to the mean plane passing through the 1-octyl chain [dihedral angle = 77.53 (17)°]. In the crystal, molecules are linked by C—H⋯O hydrogen bonds, forming a three-dimensional network.


Comment
Isatin, 1H-indole-2,3-dione, is a heterocyclic compound of significant importance in medicinal chemistry. It is a synthetically versatile molecule, a precursor for a large number of pharmacologically active compounds. Isatin and its derivatives have aroused great attention in recent years due to their wide variety of biological activities, relevant to application as insecticides and fungicides and in a broad range of drug therapies, including anticancer drugs, antibiotics and antidepressants (Bhrigu et al., 2010;Malhotra et al., 2011;Da Silva et al., 2001;Ramachandran, 2011;Smitha et al., 2008). As a continuation of our research work devoted to the development of isatin derivatives (Mamari et al., 2010), we report in this paper the synthesis of a new indoline-2,3-dione derivative by action of alkyl halides to explore other applications.
The molecule of title compound is build up from a fused five-and six-membered rings linked to a 1-octyl chain and to two ketonic oxygen atoms as shown in Fig. 1. The indoline ring and the two ketonic oxygen atoms are nearly coplanar, with the largest deviation from the mean plane of 0.063 (2) Å for atom O2. The fused ring system plan is nearly perpendicular to the mean plane passing through the 1-octyl chain as indicated by the torsion angle C1-N1-C9-C10 of -93.2 (2)°. In the crystal, the molecules are linked by C-H···O hydrogen bonds (Table 1) to build a three-dimensional network as shown in Fig. 2.
The mixture was stirred for 48 h and the reaction monitored by thin layer chromatography. The mixture was filtered and the solvent removed under vacuum. The solid obtained was recrystallized from ethanol to afford the title compound as orange crystals (yield: 72%; mp = 317 K).

Refinement
All H atoms could be located in a difference Fourier map. However, they were placed in calculated positions with C-H = 0.93-0.97 Å and refined as riding on their parent atoms with U iso (H) = 1.2 U eq (C) or 1.5 U eq (C) for methyl H atoms.  Molecular plot the title compound with displacement ellipsoids drawn at the 50% probability level. H atoms are represented as small circles.

Figure 2
Intermolecular hydrogen interactions (dashed lines) in the title compound. Atoms labelled with suffixes a, b and c are generated by the symmetry operators 1-x, 3-y, 1-z; x, 3/2-y, 1/2+z and x, 5/2-y, 1/2+z, respectively. 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 > 2σ(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.