Ethyl 1′′-benzyl-1′-methyl-2′′-oxodispiro[indeno[1,2-b]quinoxaline-11,3′-pyrrolidine-2′,3′′-indoline]-4′-carboxylate

In the title compound, C36H30N4O3, the quinoxaline–indene system is roughly planar, with a maximum deviation from the mean plane of 0.218 Å for the C atom shared with the central pyrrolidine ring. This latter ring forms dihedral angles of 84.54 (7) and 83.91 (8)° with the quinoxaline–indene system and the indole ring, respectively. The central pyrrolidine ring has an envelope conformation with the N atom as the flap, while the pyrrolidine and five-membered rings of the indole group adopt twisted conformation and envelope (with the C atom bearing the quinoxaline–indene system as the flap) conformations, respectively. In the crystal, molecules are linked via weak C—H⋯N hydrogen bonds, forming a chain running along [100].

In the title compound, C 36 H 30 N 4 O 3 , the quinoxaline-indene system is roughly planar, with a maximum deviation from the mean plane of 0.218 Å for the C atom shared with the central pyrrolidine ring. This latter ring forms dihedral angles of 84.54 (7) and 83.91 (8) with the quinoxaline-indene system and the indole ring, respectively. The central pyrrolidine ring has an envelope conformation with the N atom as the flap, while the pyrrolidine and five-membered rings of the indole group adopt twisted conformation and envelope (with the C atom bearing the quinoxaline-indene system as the flap) conformations, respectively. In the crystal, molecules are linked via weak C-HÁ Á ÁN hydrogen bonds, forming a chain running along [100].
Fig 1 presents a molecular view of (I). The quinoxaline-indene system C1-C15/N1-N2), is essentially planar, with maximum deviation from the mean plane of 0.218Å for atom C15.
In the crystal packing, molecules are linked via weak C-H···N intermolecular hydrogen bonds (Table 1) et al., 2005). 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. The product was recrystallised from methanol. Single crystals suitable for X-ray diffraction were obtained by slow evaporation of a solution of the title compound in methanol at room temperature.

Refinement
All H atoms were fixed geometrically and allowed to ride on their parent C atoms, with C-H distances fixed in the range 0.93-0.97 Å with U iso (H) = 1.5U eq (C) for methyl and 1.2U eq (C) for all other H atoms. The positions of methyl hydrogens were optimized rotationally.

Figure 1
The molecular structure of the title compound with the atom numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.

Figure 2
A packing viewed of the structure, projected down the c axis, showing the way in which the [100] chains are formed.