Ethyl 3-(4-chlorobenzoyl)-1-(4-chlorobenzyl)-4-(4-chlorophenyl)-2,2-dioxo-3,4,6,7,8,8a-hexahydro-1H-pyrrolo[2,1-c][1,4]thiazine-1-carboxylate

In the title compound, C30H28Cl3NO5S, the pyrrolidine ring adopts an envelope conformation (with the N atom as the flap) and the thiazine ring is in a distorted chair conformation. The molecular structure shows three intramolecular C—H⋯O interactions leading to self-associated ring S(6) and two S(7) motifs. In the crystal, the molecules are linked by C—H⋯O and C—H⋯Cl interactions. Two R 2 2(10) and one R 2 2(16) centrosymmetrically related ring motifs are observed in the unit cell and they are connected through C(6) and C(11) chain motifs extending along the b and c axes, respectively.

In the title compound, C 30 H 28 Cl 3 NO 5 S, the pyrrolidine ring adopts an envelope conformation (with the N atom as the flap) and the thiazine ring is in a distorted chair conformation. The molecular structure shows three intramolecular C-HÁ Á ÁO interactions leading to self-associated ring S(6) and two S(7) motifs. In the crystal, the molecules are linked by C-HÁ Á ÁO and C-HÁ Á ÁCl interactions. Two R 2 2 (10) and one R 2 2 (16) centrosymmetrically related ring motifs are observed in the unit cell and they are connected through C(6) and C(11) chain motifs extending along the b and c axes, respectively.

Experimental
Crystal data
Thus, the centrosymmetrically related dimers are tailored through these two chain motifs and the packing is stabilized.

Experimental
A mixture of ethyl 2-[2-(4-chlorophenyl)-2-oxoethyl]sulfonylacetate (1.6 mmol), p-chloro benzaldehyde (3.2 mmol) and pyrrolidine (1.6 mmol) was dissolved in ethanol (10 ml), heated until the solution turned yellow and stirred at room temperature for 2-5 days. After completion of the reaction, the crude product was purified using flash column chromatography on silica gel (230-400 mesh) with petroleum ether and ethyl acetate mixture (95:5 v/v) as an eluent and subsequently it was recrystallized from ethanol.

Refinement
All the H atoms were positioned geometrically and refined by the riding model approximation with d(C-H) = 0.93 -0.98 Å and U iso (H) = 1.2-1.5U eq (C).

Figure 1
The molecular structure of the title compound with atom numbering scheme and 50% probability displacement ellipsoids.
H-bonds are shown as dashed lines.  Packing diagram of the title compound viewed down the a-axis. H-bonds are shown as dashed lines.

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.