N-(3-Chloro-1-methyl-1H-indazol-5-yl)-4-methylbenzenesulfonamide

The asymmetric unit of the title compound, C15H14ClN3O2S, contains two independent molecules showing different conformations: in one molecule, the indazole ring system makes a dihedral angle of 51.5 (1)° with the benzene ring whereas in the other, the indazole unit is almost perpendicular to the benzene ring [dihedral angle 77.7 (1)°]. In the crystal, the molecules are linked by N—H⋯N and N—H⋯O hydrogen bonds, forming a set of four molecules linked in pairs about an inversion centre.

The asymmetric unit of the title compound, C 15 H 14 ClN 3 O 2 S, contains two independent molecules showing different conformations: in one molecule, the indazole ring system makes a dihedral angle of 51.5 (1) with the benzene ring whereas in the other, the indazole unit is almost perpendicular to the benzene ring [dihedral angle 77.7 (1) ]. In the crystal, the molecules are linked by N-HÁ Á ÁN and N-HÁ Á ÁO hydrogen bonds, forming a set of four molecules linked in pairs about an inversion centre. 398 parameters H-atom parameters constrained Á max = 0.36 e Å À3 Á min = À0.31 e Å À3 Table 1 Hydrogen-bond geometry (Å , ).

Comment
Sulfonamides are an important class of compounds which are widely used in the design of diverse classes of drug candidates (El-Sayed et al., 2011;Mustafa et al., 2012;Scozzafava et al., 2003). Recently, some N-[7(6)-indazolyl]arylsulfonamides prepared by our research group showed important antiproliferative activity against some human and murine cell lines (Abbassi et al., 2012;Bouissane et al., 2006). The present work is a continuation of the investigation of the sulfonamides derivatives published recently by our team (Abbassi et al., 2013;Chicha et al., 2013).
Each of the two independent molecules of the title compound is built up from fused five-and six-membered rings linked to a methylbenzenesulfonamide group as shown in Fig. 1. The molecules show different conformations. In the first molecule, the indazole ring system (N1/N2/C1-C7) makes a dihedral angle of 51.5 (1)° with the plane through the atoms forming the benzene ring (C9-C14). On the other hand, in the second molecule, the fused five-and six-membered ring system (N4/N5/C16-C22) is almost perpendicular to the benzene plane (C24-C29), as indicated by the dihedral angle of 77.7 (1)°. In the crystal, the molecules are interconnected by N3-H3N···N5 and N6-H6N···O3 hydrogen bonds (Table 1) in the way to form a set of four molecules linked in pairs by the inversion centre as shown in Fig. 2.

Experimental
A mixture of 3-chloro-1-methyl-5-nitroindazole (1.22 mmol) and anhydrous SnCl 2 (1.1 g, 6.1 mmol) in 25 ml of absolute ethanol was heated at 60 °C for 5 h. After reduction, the starting material disappeared, and the solution was allowed to cool down. The pH was made slightly basic (pH 7-8) by addition of 5% aqueous potassium bicarbonate before extraction with ethyl acetate. The organic phase was washed with brine and dried over magnesium sulfate. The solvent was removed to afford the amine, which was immediately dissolved in pyridine (5 ml) and then reacted with 4-methylbenzenesulfonyl chloride (1.25 mmol) at room temperature for 24 h. After the reaction mixture was concentrated in vacuo, the resulting residue was purified by flash chromatography (eluted with ethyl acetate/hexane 2:8 v/). The title compound was recrystallized from ethanol, at room temperature, giving colourless crystals (m.p. 397 K, yield: 56%).

Refinement
All H atoms were located in a difference Fourier map and treated as riding with N-H = 0.89 Å, C-H = 0.93-0.96 Å, and with U iso (H) = 1.2 U eq (C, N) or 1.5 U eq (C) for methyl H atoms. Two outliers (0 1 1, 0 2 1) were omitted in the last cycles of refinement.  The two independent molecules building the asymmetric unit of the title compound. Displacement ellipsoids are drawn at the 50% probability level. H atoms are represented as small circles.

Figure 2
A set of four molecules of the title compound interconnected by hydrogen bonds (dashed line) and linked in pairs by an inversion centre.

N-(3-Chloro-1-methyl-1H-indazol-5-yl)-4-methylbenzenesulfonamide
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.