Crystal structure of N-(1-allyl-3-chloro-1H-indazol-5-yl)-4-methylbenzenesulfonamide

The 3-chloro-1H-indazole system in the title molecule, C17H16ClN3O2S, is almost planar, with the largest deviation from the mean plane being 0.029 (2) Å for one of the N atoms. This system is nearly perpendicular to the allyl chain, as indicated by the C—C—N—N torsion angle of −90.1 (6)° between them. The allyl group is split into two fragments, the major component has a site occupancy of 0.579 (7). The indazole system makes a dihedral angle of 47.53 (10)° with the plane through the benzene ring. In the crystal, molecules are connected by N—H⋯O and C—H⋯O hydrogen bonds, forming a three-dimensional network.


S2. Structural commentary
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). Previously, we identified a series of indazoles bearing a sulfonamide moiety with good antiproliferative activities (Abbassi et al., 2012;Abbassi, et al. 2013;Chicha et al., 2014).
The molecule of the title compound is built up from two fused five-and six-membered rings (N1 N2 C2 to C8) almost coplanar, with a maximum deviation of 0.029 (2) Å for N1 atom (Fig. 1). The dihedral angle between the indazol system and the plane through the benzene ring (C9 to C14) is of 47.53 (10)°. The allyl chain is perpendicular to the fused rings system as indicated by the C(16A)-C(15)-N(1)-N(2) torsion angle of -90.1 (6)°.

S5. Synthesis and crystallization
A mixture of 1-allyl-3-chloro-5-nitroindazole (1.22 mmol) and anhydrous SnCl 2 (1.1 g, 6.1 mmol) in 25 ml of absolute ethanol was heated at 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 (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). The title compound was recrystallized from its ethanol solution. Yield: 65%, M.pt: 394 K.

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ. (