5-Methylspiro[indoline-3,7′-[6H,7H,8H]pyrano[3,2-c:5,6-c′]di[1]benzopyran]-2,6′,8′-trione chloroform hemisolvate

In the title compound, C27H15NO6·0.5CHCl3, the central pyran ring and both the benzopyran systems are planar, with the dihedral angle between the outer rings being 3.24 (6)°. The indolin-2-one system is in a perpendicular configuration with respect to the pyran ring [dihedral angle = 87.58 (2)°]. Supramolecular layers in the ac plane are formed in the crystal structure whereby inversion-related molecules are connected by N—H⋯O hydrogen bonds. These are further linked by C—H⋯O interactions, forming a supramolecular layer in the ac plane. Disordered CHCl3 solvent in the structure was modelled with the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148–155].

In the title compound, C 27 H 15 NO 6 Á0.5CHCl 3 , the central pyran ring and both the benzopyran systems are planar, with the dihedral angle between the outer rings being 3.24 (6) . The indolin-2-one system is in a perpendicular configuration with respect to the pyran ring [dihedral angle = 87.58 (2) ]. Supramolecular layers in the ac plane are formed in the crystal structure whereby inversion-related molecules are connected by N-HÁ Á ÁO hydrogen bonds. These are further linked by C-HÁ Á ÁO interactions, forming a supramolecular layer in the ac plane. Disordered CHCl 3 solvent in the structure was modelled with the SQUEEZE routine in PLATON [Spek (2009). Acta Cryst. D65,[148][149][150][151][152][153][154][155].

Suresh Comment
Benzopyran is a structural motif observed in many biologically active natural products and it plays an important role in binding with various biopolymers (Martin et al., 1999;Teague et al., 1999). Of the various spiro indoles, the spiro[indolepyran] system has attracted attention due to its interesting pharmacological properties (Ninamiya et al., 1980;Kobayashi et al., 1970). The biological importance of these heterocycles in conjunction with our research interests prompted us to synthesize and report the X-ray structure of the title compound.
In the title compound, Fig 1, the central pyrano ring and both the benzopyran rings are planar. In the indolin-2-one system, the benzene and pyrrole rings are individually planar and make a dihedral angle of 1.42 (1)°. The indoline-2-one system is in a perpendicular configuration with respect to the pyrano ring, as can be seen from the dihedral angle of 87.58 (2)°. The sum of the angles at atom N1 of the indolin-2-one moiety is in accordance with sp 2 -hybridization [359.85 (2)°].
After completion of the reaction, as evidenced from TLC, the precipitated solid was filtered and washed with water to afford the product which was recrystallized from CHCl 3 to produce the title compound as colourless crystals. Yield 76%.

Refinement
Initial structural solution showed a disordered co-crystallized solvent chloroform molecule for which a suitable model could not be found. Therefore, the data set was treated with SQUEEZE routine of PLATON (Spek, 2009) to model the electron density in the void regions. There are two cavities of 277 Å 3 per unit cell. Each cavity contains approximately 125 electrons which were assigned to two solvent chloroform molecules. The N-bound H atom was located in a difference map and refined freely. The C-bound H atoms were placed at calculated positions and allowed to ride on their carrier atoms with C-H = 0.93-0.96 Å, and with U iso = 1.2 to 1.5U eq (C).

Figure 1
The molecular structure of (I), showing 50% probability displacement ellipsoids and the atom-numbering scheme.  A packing diagram for (I).  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.