7′-(Naphthalen-1-yl)-5′′-[(naphthalen-2-yl)methylidene]-1′,3′,5′,6′,7′,7a′-hexahydrodispiro[acenaphthene-1,5′-pyrrolo[1,2-c]thiazole-6′,3′′-piperidine]-2(1H),4′′-dione

In the title compound, C43H34N2O2S, the six-membered piperidine ring adopts a half-chair conformation. The five-membered thiazole ring adopts a slightly twisted envelope conformation and the pyrrole ring adopts an envelope conformation; in each case, the C atom linking the rings is the flap atom. The molecular structure features inter- and intramolecular C—H⋯O interactions. Furthermore, the crystal packing is stabilized by four intermolecular C—H⋯π interactions.

In the title compound, C 43 H 34 N 2 O 2 S, the six-membered piperidine ring adopts a half-chair conformation. The fivemembered thiazole ring adopts a slightly twisted envelope conformation and the pyrrole ring adopts an envelope conformation; in each case, the C atom linking the rings is the flap atom. The molecular structure features inter-and intramolecular C-HÁ Á ÁO interactions. Furthermore, the crystal packing is stabilized by four intermolecular C-HÁ Á Á interactions.

Experimental
A mixture of 1-methyl-3,5-bis[(E)-naphthylmethylidene]tetrahydro-4(1H)-pyridinone (1 mmol), acenaphthenequinone (0.182 g, 1 mmol) and 1,3-thiazolane-4-carboxylic acid (0.133 g, 1 mmol) was dissolved in methanol (10 ml) and 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 (100 ml) to obtain pure product as pale yellow solid. The product was dissolved in 5 ml of ethyl acetate. The mixture was heated on a water bath to boiling and filtered to a beaker.
The solution was kept aside undisturbed for crystallization via slow evaporation of the solvent. Fine crystals of the compound appeared as the solvent evaporated. Then the solvent was decanted and the crystals were washed with cold ethyl acetate to obtain suitable crystals for the X-ray analysis. Refinement H atoms were placed at calculated positions and allowed to ride on their carrier atoms with C-H = 0.93-0.98 Å. U iso = 1.2U eq (C) for CH 2 and CH groups and U iso = 1.5U eq (C) for CH 3 group.

Figure 1
The molecular structure of (I), showing 10% probability displacement ellipsoids and the atom-numbering scheme. H atoms that do not take part in the H-bonding and some carbon atoms are omitted for clarity.

Figure 2
The partial packing diagram of the molecule.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > σ(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.