N-(1-Allyl-1H-indazol-5-yl)-4-methylbenzenesulfonamide

The asymmetric unit of the title compound, C17H17N3O2S, contains two independent molecules linked by an N—H⋯O hydrogen bond. The molecules show different conformations. In the first molecule, the fused five- and six-membered ring system is almost perpendicular to the plane through the atoms forming the allyl group, as indicated by the dihedral angle of 85.1 (4)°. The dihedral angle with the methylbenzenesulfonamide group is 78.8 (1)°. On the other hand, in the second molecule, the dihedral angles between the indazole plane and the allyl and methylbenzenesulfonamide groups are 80.3 (3) and 41.5 (1)°, respectively. In the crystal, molecules are further linked by N—H⋯N and C—H⋯O hydrogen bonds, forming a three-dimensional network.

The asymmetric unit of the title compound, C 17 H 17 N 3 O 2 S, contains two independent molecules linked by an N-HÁ Á ÁO hydrogen bond. The molecules show different conformations. In the first molecule, the fused five-and six-membered ring system is almost perpendicular to the plane through the atoms forming the allyl group, as indicated by the dihedral angle of 85.1 (4) . The dihedral angle with the methylbenzenesulfonamide group is 78.8 (1) . On the other hand, in the second molecule, the dihedral angles between the indazole plane and the allyl and methylbenzenesulfonamide groups are 80.3 (3) and 41.5 (1) , respectively. In the crystal, molecules are further linked by N-HÁ Á ÁN and C-HÁ Á ÁO hydrogen bonds, forming a three-dimensional network. 415 parameters H-atom parameters constrained Á max = 0.32 e Å À3 Á min = À0.28 e Å À3 Table 1 Hydrogen-bond geometry (Å , ). Sulfonamides are an important class of compounds which are widely used in the design of diverse classes of drug candidates. These compounds exhibit a wide range of biological activities such as anticancer, anti-inflammatory, and antiviral functions (Bouissane, et al., 2006;El-Sayed, et al., 2011;Mustafa, et al. 2012). The present work is a continuation of the investigation of sulfonamides derivatives published recently by our team (Abbassi, et al., 2012;Abbassi, et al., 2013;Chicha, et al., 2013).

Related literature
The two independent molecules forming the asymmetric unit of the title compound are linked by a weak hydrogen bond (C13-H13···O4) and have different conformations as shown in Fig.1. Each molecule is built up from fused five-and sixmembered rings linked to a methylbenzenesulfonamide and allyl groups. In the first molecule, the indazole ring system makes dihedral angles of 78.8 (1)° and 85.1 (4)° with the plane through the methylbenzenesulfonamide group and that through the allyl group, respectively. In the second molecule, the indazole system is almost perpendicular to the plane through the atoms forming the allyl group, as indicated by the dihedral angle of 80.3 (3)°. The dihedral angle between the indazole ring and the benzene ring belonging to the methylbenzenesulfonamide is 41.5 (1)°. In addition, the most important difference between the two conformations of molecules is the orientation of their allyl substituents (Fig.2). In the crystal, molecules are linked by N-H···N, N-H···O and C-H···O hydrogen bonds, forming a three-dimensional network (Table 1).

Experimental
A mixture of 1-allyl-5-nitroindazole (250 mg, 1.22 mmol) and anhydrous SnCl 2 (1.1 g, 6.1 mmol) in 25 ml of absolute ethanol was heated to 333 K for 6 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 (240 mg, 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 1:9). The title compound was recrystallized from ethanol at room temperature (yield: 75%, m.p. 374 K).

Refinement
H atoms were located in a difference map and treated as riding with N-H = 0.89 Å, C-H = 0.96 Å (methyl), C-H = 0.97 Å (methylene) and C-H = 0.93 Å (aromatic CH, terminal =CH 2 ), respectively. All hydrogen atoms were refined using a riding model with U iso (H) = 1.5 U eq (C) for methyl groups and U iso (H) = 1.2 U eq (C,N) for all other hydrogen atoms.
Values of atomic displacements of C1, C2, C14 and C15 which belong to the first molecule (S1, O1, O2, N1 -N3, C1 -C17) and are larger than those observed in the second molecule for corresponding carbons.

Figure 1
The two molecules building the asymmetric unit of the title compound with the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are represented as small circles.  Automatic fit of the two crystallographically independent molecules. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.32 e Å −3 Δρ min = −0.28 e Å −3

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 > 2σ(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.