3-Ethenyl-1-(4-methylphenylsulfonyl)-1H-indole

Two independent but very similar molecules comprise the asymmetric unit of the title compound, C17H15NO2S. The molecules have L-shapes with the dihedral angles between the fused-ring system (r.m.s. deviations = 0.036 and 0.019 Å, respectively) and the benzene ring being almost the same, i.e. 82.98 (12) and 84.46 (13)°, respectively. The terminal ethenyl group is almost coplanar with the ring to which it is connected [C—C—C—C torsion angles = −173.7 (4) and −171.7 (4)°, respectively]. Supramolecular arrays parallel to (-124) stabilized by C—H⋯O and C—H⋯π interactions feature in the crystal packing.

Two independent but very similar molecules comprise the asymmetric unit of the title compound, C 17 H 15 NO 2 S. The molecules have L-shapes with the dihedral angles between the fused-ring system (r.m.s. deviations = 0.036 and 0.019 Å , respectively) and the benzene ring being almost the same, i.e. 82.98 (12) and 84.46 (13) , respectively. The terminal ethenyl group is almost coplanar with the ring to which it is connected [C-C-C-C torsion angles = À173.7 (4) and À171.7 (4) , respectively]. Supramolecular arrays parallel to (124) stabilized by C-HÁ Á ÁO and C-HÁ Á Á interactions feature in the crystal packing.  Table 1 Hydrogen-bond geometry (Å , ).
There are two independent molecules in the asymmetric unit of (I), Fig. 1, and as seen from the overlay diagram in  et al., 2002). For each molecule, the terminal ethenyl group is almost co-planar to the ring to which it is connected as seen in the values of the C8-C7-C9-C10 and C25-C24-C26-C27 torsion angles of -173.7 (4) and -171.7 (4)°, respectively.
The crystal packing of (I) is sustained by C-H···O and C-H···π interactions, Table 1. These lead to supramolecular arrays parallel to (1 2 4), Fig. 2, which stack with no specific intermolecular interactions between them, Fig. 3.

Experimental
A solution of methyltriphenylphosphonium iodide (0.34 g, 0.84 mmol, 1.4 eq.) in THF (5 ml) at 273 K was poured into a two-necked round-bottomed flask under a nitrogen atmosphere and then under continuous stirring nBuLi (0.36 ml, 0.72 mmol,1.2 eq.) was added drop-wise at 195 K. The mixture was left in a water/ice bath for 20 min, then a solution of 1tosyl-1-H-indol-carbaldehide (0.181 g) in THF (5 ml) was added. After stirring for another 20 min. the solution was warmed to room temperature and water added. The mixture was extracted with Et 2 O, washed with NH 4 Cl and dried under

Figure 1
The molecular structures of the two independent molecules in (I) showing atom labelling scheme and displacement ellipsoids at the 50% probability level (arbitrary spheres for the H atoms).

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