2-Methyl-4-(naphthalen-2-yl)-3a-nitro-3,3a,4,9b-tetrahydro-2H-spiro[chromeno[3,4-c]pyrrole-1,3′-indolin]-2′-one

In the title compound, C29H23N3O4, the 2-methylpyrrolidine ring adopts a twist conformation on the N—C bond involving the spiro C atom, while the hydropyran ring adopts an envelope conformation with the methine C atom bonded to the O atom as the flap. The mean plane of the indoline-2-one ring system is almost perpendicular to the mean plane of the pyrrolidine ring, making a dihedral angle of 89.73 (8)°. The latter ring makes dihedral angles of 47.80 (8) with the naphthalene ring system and 32.38 (8)° with the hydropyran ring mean plane. There is an intramolecular C-H⋯O hydrogen bond involving the indoline-2-one O atom. In the crystal, adjacent molecules are linked via N—H⋯O hydrogen bonds, forming chains propagating along [100]. The chains are linked via weak C—H⋯O hydrogen bonds, forming two-dimensional networks, lying parallel to (101), and consolidated by C—H⋯π interactions.

In the title compound, C 29 H 23 N 3 O 4 , the 2-methylpyrrolidine ring adopts a twist conformation on the N-C bond involving the spiro C atom, while the hydropyran ring adopts an envelope conformation with the methine C atom bonded to the O atom as the flap. The mean plane of the indoline-2-one ring system is almost perpendicular to the mean plane of the pyrrolidine ring, making a dihedral angle of 89.73 (8) . The latter ring makes dihedral angles of 47.80 (8) with the naphthalene ring system and 32.38 (8) with the hydropyran ring mean plane. There is an intramolecular C-HÁ Á ÁO hydrogen bond involving the indoline-2-one O atom. In the crystal, adjacent molecules are linked via N-HÁ Á ÁO hydrogen bonds, forming chains propagating along [100]. The chains are linked via weak C-HÁ Á ÁO hydrogen bonds, forming twodimensional networks, lying parallel to (101), and consolidated by C-HÁ Á Á interactions.
In the crystal, adjacent molecules are linked via N-H···O hydrogen bonds forming chains propagating along [100]; see Table 1 and Fig. 2. The chains are linked via weak C-H···O hydrogen bonds forming two-dimensional networks, lying parallel to (101), and consolidated by C-H···π interactions (Table 1).

Experimental
To a solution of isatin (1 equiv) and sarcosine (1.4 equiv) in dry toluene, was added 2-(naphthalen-1-yl)-3-nitro-2Hchromene (1 equiv) under a nitrogen atmosphere. The reaction mixture was refluxed for 24h in a Dean-Stark apparatus to give the cycloadducts. After completion of the reaction as indicated by TLC, the solvent was evaporated under reduced pressure. The crude product was extracted with dichloromethane. The organic layer was dried with anhydrous sodium sulphate and concentrated in vacuo. The crude product obtained was purified by column chromatography using hexane/EtOAc (7:3) as eluent. Single crystals suitable for X-ray diffraction were obtained by slow evaporation of a solution of the title compound in ethyl acetate at room temperature.

Refinement
The NH H atom was located in a difference Fourier map and refined with a distance restraint of N-H = 0.88 (1)  0.97 Å, with U iso (H) = 1.5U eq (C) for methyl H atoms and = 1.2U eq (C) for other H atoms.

Figure 1
The molecular structure of the title molecule, with atom labelling. Displacement ellipsoids are drawn at the 30% probability level.  A partial view, ca. perpendicular to (110), of the crystal packing of the title compound. The hydrogen bonds are shown as dashed lines -see Table 1 for details; H-atoms not involved in hydrogen bonding have been omitted for clarity.  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.