5′′-(4-Chlorobenzylidene)-4′-(4-chlorophenyl)-5-fluoro-1′,1′′-dimethylindoline-3-spiro-2′-pyrrolidine-3′-spiro-3′′-piperidine-2,4′′-dione

The piperidine ring of the title compound, C30H26Cl2FN3O2, adopts a twisted chair conformation. The pyrrolidine ring has a twisted envelope structure with the N atom at the flap [displaced by 0.592 (3) Å]. The fluorooxindole, chlorophenyl and chlorobenzylidene groups are planar with r.m.s. deviations of 0.0348, 0.0048 and 0.0048 Å, respectively. The structure is stabilized by intermolecular N—H⋯O hydrogen bonds.

The piperidine ring of the title compound, C 30 H 26 Cl 2 FN 3 O 2 , adopts a twisted chair conformation. The pyrrolidine ring has a twisted envelope structure with the N atom at the flap [displaced by 0.592 (3) Å ]. The fluorooxindole, chlorophenyl and chlorobenzylidene groups are planar with r.m.s. deviations of 0.0348, 0.0048 and 0.0048 Å , respectively. The structure is stabilized by intermolecular N-HÁ Á ÁO hydrogen bonds.
Hence, the present X-ray crystallographic study of the title compound has been carried out to determine the conformation of the system.
Fluorooxindole, the chlorophenyl and chlorophenylmethylidine groups are planar as confirmed by thevalues of the r.m.s. deviation (0.0348 Å, 0.0048Å and 0.0048 Å), respectively,from the mean planes of the above groups. Flurooxindole is inclined with the plane of chlorophenyl by 33.99 (2)° and 55.56 (2)° with the mean plane of chlorophenylmethilidine. The sum of the bond angles around N1 atom (334.22°) of the piperidine ring in the molecule is in accordance with the sp 2 hybridization. Further, the structure is stabilized by intermolecular N-H···O hydrogen bond and intramolecular C-H···O hydrogen bonds.

Experimental
A mixture of 1-methyl-3,5-bis[(E)-chlorobenzylidene]tetrahydro-4 (1H)-pyridin-ones (1 mmol), 5-fluoroisatin (1 mmol) and sarcosine in methanol (10 ml) was refluxed for 30 min. After completion of the reaction as evident from TLC, the mixture was poured into water (50 ml). The precipitated solid was filtered and washed with water to obtain the pure product. The product was dissolved in methonol and allowed to evoporate at room temperature. Transparent, needle-shaped, colourless crystals of small sizes (8 x 2 x 2 mm 3 )were obtained in a period of about a week. Yield:94%; M.p:224 °C

Refinement
H atoms were placed at calculated positions and allowed to ride on their carrier atoms with C-H = 0.93-0.97 Å, and U iso = 1.2U eq (C) for CH 2 and CH groups and U iso = 1.5U eq (C) for CH 3 group.The N-bound H atom is located in a difference Fourier map and its positional parameters were refined.  Fig. 1. The molecular structure of (I), showing 30% probability displacement ellipsoids and the atom-numbering scheme.