Ethyl 8′′-chloro-1′-methyl-2,12′′-dioxo-12′′H-dispiro[indoline-3,2′-pyrrolidine- 3′,6′′-indolo[2,1-b]quinazoline]-4′-carboxylate

In the title compound, C29H23ClN4O4, the quinazoline-indole system and the indolin-2-one system are each essentially planar, with maximum deviations from their mean planes of 0.150 (2) and 0.072 (2) Å, respectively. The central pyrrolidine ring adopts a twisted conformation on the C—C bond involving the spiro C atoms. Its mean plane forms dihedral angles of 83.37 (9) and 86.56 (8)°, respectively, with the indole rings of the indolin-2-one and quinazoline-indole systems. In the crystal, molecules are linked via pairs of N—H⋯O hydrogen bonds, forming inversion dimers. The dimers are linked via C—H⋯O hydrogen bonds, forming chains propagating along [001].

In the title compound, C 29 H 23 ClN 4 O 4 , the quinazoline-indole system and the indolin-2-one system are each essentially planar, with maximum deviations from their mean planes of 0.150 (2) and 0.072 (2) Å , respectively. The central pyrrolidine ring adopts a twisted conformation on the C-C bond involving the spiro C atoms. Its mean plane forms dihedral angles of 83.37 (9) and 86.56 (8) , respectively, with the indole rings of the indolin-2-one and quinazoline-indole systems. In the crystal, molecules are linked via pairs of N-HÁ Á ÁO hydrogen bonds, forming inversion dimers. The dimers are linked via C-HÁ Á ÁO hydrogen bonds, forming chains propagating along [001].
In view of their importance and in continuation of our work on the crystal structure analysis of pyrrolidine and quinazoline derivatives, we report herein on the crystal structure of the title compound.
In the crystal, molecules are linked via pairs of N-H···O hydrogen bonds forming inversion dimers. The dimers are linked via C-H···O hydrogen bonds forming chains propagating along the c axis direction. (Table 1).

Experimental
Isatin (0.25 mmol) , sarcosine (0.3 mmol), (E)-ethyl 2-(8-chloro-12-oxoindolo[2,1-b]quinazolin-6(12H)-ylidene)acetate (0.25 mmol) in ethanol were refluxed for 120 min. The progress of the reaction was followed by TLC. After completion, the solvent was removed under reduced pressure and the resulting crude product was subjected to column chromatography eluted with n-hexane/EtOAc (8.5:1.5). The product was recrystallised from ethanol. Single crystals suitable for X-ray diffraction were obtained by slow evaporation of the solution of the title compound in ethanol at room temperature.

Refinement
All the H atoms were fixed geometrically and allowed to ride on their parent C atoms: N-H = 0.86 Å, C-H = 0.93-0.97 Å with U iso (H) = 1.5U eq (C-methyl) and = 1.

Figure 1
The molecular structure of the title molecule, with the atom labelling. 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.