Crystal structure of ethyl 2-phenyl-9-phenylsulfonyl-9H-carbazole-3-carboxylate

In the title compound, C27H21NO4S, the dihedral angles between the carbazole ring system (r.m.s. deviation = 0.015 Å) and the sulfur-bonded and directly linked benzene rings are 79.98 (11) and 53.51 (18)°, respectively. The benzene rings subtend a dihedral angle of 48.4 (2)°. The ethyl side chain of the ester group has an extended conformation [C—O—C—C = −172.3 (3)°]. In the crystal, inversion dimers linked by pairs of weak C—H⋯O hydrogen bonds generate R 2 2(22) loops. The dimers are linked by weak C—H⋯π and π–π [centroid-to-centroid distances ranging from 3.5042 (14) to 3.888 (2) Å] interactions, thereby forming a three-dimensional supramolecular network.

Cg2 is the centroid of the C1-C6 ring.

S1. Comment
Carbazole and its derivatives have become quite attractive compounds owing to their applications in pharmacy and molecular electronics. It has been reported that carbazole derivatives exhibit various biological activities such as antitumor (Itoigawa, et al. 2000), anti-inflammatory and antimutagenic (Ramsewak, et al. 1999). The molecular structure of the title compound (I) is shown in Fig. 1. The geometric parameters of (I) are comparable with the similar structures [Chakkaravarthi et al. 2008[Chakkaravarthi et al. , 2009].

S2. Experimental
The thermal electrocyclization of 3-(1-(phenylsulfonyl)-2-styryl -1H-indol-3-yl) acrylate (0.25 g) in dry xylenes (10 ml), 10% Pd/C (0.08 g) was added and the reaction mixture was refluxed for 12 h. After completion of the reaction (monitored by TLC), the reaction mass was filtered through celite bed and washed with hot xylenes (10 ml). The combined filtrate was evaporated under reduced presser followed by tituration of the resulting crude product with methanol afforded the title compound as a colourless solid.

Figure 1
The molecular structure of (I), with 30% probability displacement ellipsoids for non-H atoms.

Figure 2
The crystal packing of the title compound viewed along the b axis. The hydrogen bonds are shown as dashed lines (see Table 1), and C-bound H atoms have been omitted for clarity.

Ethyl 2-phenyl-9-phenylsulfonyl-9H-carbazole-3-carboxylate
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.  (3) O2-S1 1.4163 (18)