1′,6-Dimethyl-4′-phenyldispiro[1-benzopyran-3(4H),3′-pyrrolidine-2′,3′′-indoline]-2,2′′-dione

In the title compound, C27H24N2O3, the five-membered pyrroldine ring adopts an envelope conformation (with the N atom in the flap position) and the six-membered pyranone ring of the coumarine ring system adopts a slightly distorted boat conformation. The oxindole unit makes dihedral angles of 89.7 (1) and 25.6 (1)°, respectively, with the pyrrolidine ring and the coumarin ring system. The molecular structure is stabilized by two intramolecular C—H⋯O contacts and two intramolecular π–π interactions [centroid–centroid seperations of 3.514 (1) and 3.623 (1) Å]. The crystal packing features N—H⋯O hydrogen bonds, which link the molecules into cyclic centrosymmetric R 2 2(8) dimers, and C—H⋯π interactions.

In the title compound, C 27 H 24 N 2 O 3 , the five-membered pyrroldine ring adopts an envelope conformation (with the N atom in the flap position) and the six-membered pyranone ring of the coumarine ring system adopts a slightly distorted boat conformation. The oxindole unit makes dihedral angles of 89.7 (1) and 25.6 (1) , respectively, with the pyrrolidine ring and the coumarin ring system. The molecular structure is stabilized by two intramolecular C-HÁ Á ÁO contacts and two intramolecularinteractions [centroid-centroid seperations of 3.514 (1) and 3.623 (1) Å ]. The crystal packing features N-HÁ Á ÁO hydrogen bonds, which link the molecules into cyclic centrosymmetric R 2 2 (8) dimers, and C-HÁ Á Á interactions.

Comment
Highly functionalized pyrrolidines have gained much interest in the past few years as they constitute the main structural element of many natural and synthetic pharmacologically active compounds (Waldmann, 1995). Optically active pyrrolidines have been used as intermediates, chiral ligands or auxiliaries in controlled asymmetric synthesis (Suzuki et al., 1994;Huryn et al., 1991). In view of this importance, the crystal structure of the title compound has been carried out and the results are presented here.
The title compound consists of a pyrrolidine ring connected to a oxindole ring system at C1, a coumarine moiety at C2 and a benzene ring at C3. The X-ray analysis confirms the molecular structure and atom connectivity as illustrated in Fig.1.

Experimental
A mixture of E-3-benzylidene-6-methylchroman-2-one (0.125 g, 0.5 mmol), isatin (0.08 g, 0.55 mmol) and N-methylglycine (0.025 g, 0.55 mmol) in toluene (5 ml) as solvent was allowed to reflux for 6 hours. After work up, the crude mass was purified by column chromatography to yield the pure product (0.199 g, 94 % yield). The compound was recrystallized from ethyl acetate solvent. Single crystals suitable for X-ray diffraction were obtained by slow evaporation of a ethylacetate solution at room temperature.

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.