N-(1-Allyl-1H-indazol-5-yl)-4-methoxybenzenesulfonamide hemihydrate

In the title compound, C17H17N3O3 .0.5H2O, the indazole system makes a dihedral angle of 46.19 (8)° with the plane through the benzene ring and is nearly perpendicular to the allyl group, as indicated by the dihedral angle of 81.2 (3)°. In the crystal, the water molecule, disordered over two sites related by an inversion center, forms O—H⋯N bridges between indazole N atoms of two sulfonamide molecules. It is also connected via N—H⋯O interaction to the third sulfonamide molecule; however, due to the water molecule disorder, only every second molecule of sulfonamide participates in this interaction. This missing interaction results in a slight disorder of the sulfonamide S,O and N atoms which are split over two sites with half occupancy. With the help of C–H⋯O hydrogen bonds, the molecules are further connected into a three-dimensional network.

In the title compound, C 17 H 17 N 3 O 3 . 0.5H 2 O, the indazole system makes a dihedral angle of 46.19 (8) with the plane through the benzene ring and is nearly perpendicular to the allyl group, as indicated by the dihedral angle of 81.2 (3) . In the crystal, the water molecule, disordered over two sites related by an inversion center, forms O-HÁ Á ÁN bridges between indazole N atoms of two sulfonamide molecules. It is also connected via N-HÁ Á ÁO interaction to the third sulfonamide molecule; however, due to the water molecule disorder, only every second molecule of sulfonamide participates in this interaction. This missing interaction results in a slight disorder of the sulfonamide S,O and N atoms which are split over two sites with half occupancy. With the help of C-HÁ Á ÁO hydrogen bonds, the molecules are further connected into a three-dimensional network.

Comment
Sulfonamides are an important class of compounds which are widely used in the design of diverse classes of drug candidates (Supuran & Scozzafava, 2003;Smith & Jones 2008;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. The present structure is a continuation of the investigation of the sulfonamide derivatives published recently by our team (Abbassi et al., 2012;Bouissane et al., 2006;Abbassi et al., 2013).
In this structure, the sulfonamide N1, S1, O1 and O2 atoms are splitted over two sites. They were refined with the occupancy factor of 0.5 as their disorder is related to the disorder of the water molecule: the water molecule is disordered over two sites related by an inversion center.
The allyl group is nearly perpendicular to the indazole rings as indicated by the dihedral angle of 81.2 (3)°.
In the crystal, the water molecule acts as a bridge between two molecules through O-H···N hydrogen bonds and every second sulfonamide molecule is involved in N-H···O interaction with the water O atom. The molecules are also interconnected by C-H···O hydrogen bonds forming a three-dimensional network ( Fig.2 and Table 1).

Experimental
A mixture of 1-allyl-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-methoxybenzenesulfonyl 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 1:9). The title compound was recrystallized from ethanol (m.p. 370 K, yield: 78%).

Refinement
H atoms were located in a difference map and were refined as riding with the distance constraints: C-H = 0.93-0.97 Å, O-H = 0.86 Å and N-H = 0.89 Å and with U iso (H) = 1.2 U eq (aromatic, OH, NH) and U iso (H) = 1.5 U eq for methyl group.

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.