1-Allyl-6-nitro-1H-indazole

The fused five- and six-membered rings in the title molecule, C10H9N3O2, are essentially coplanar, the largest deviation from the mean plane being 0.012 (1) Å for the C atom linked to the nitro group. The fused-ring system makes a dihedral angle of 11.34 (6)° with the nitro group, leading to a syn-periplanar conformation. The plane through the atoms forming the allyl group is nearly perpendicular to the indazole fused-ring system, as indicated by the dihedral angle of 73.3 (5)°. In the crystal, each molecule is linked to its symmetry equivalent about the center of inversion by pairs of non-classical C—H⋯O hydrogen bonds, forming an extended tape motif parallel to the (-12-1) plane.

The fused five-and six-membered rings in the title molecule, C 10 H 9 N 3 O 2 , are essentially coplanar, the largest deviation from the mean plane being 0.012 (1) Å for the C atom linked to the nitro group. The fused-ring system makes a dihedral angle of 11.34 (6) with the nitro group, leading to a synperiplanar conformation. The plane through the atoms forming the allyl group is nearly perpendicular to the indazole fused-ring system, as indicated by the dihedral angle of 73.3 (5) . In the crystal, each molecule is linked to its symmetry equivalent about the center of inversion by pairs of non-classical C-HÁ Á ÁO hydrogen bonds, forming an extended tape motif parallel to the (121) plane.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: PK2452). Indazole derivatives constitute an exciting heterocyclic family because of their important biological activities. Thus substituted indazoles are generally found to be of pharmaceutical interest in a variety of therapeutic areas (Saczewski et al., 2008, Jones et al., 2009) and with significant cytotoxicities against human (colon and prostate) and murine (leukemia) cell lines (Bouissane et al., 2006).
The plot of the structure of the title compound shows the indazole ring system is linked to a C 3 H 5 chain and to a nitro group (Fig.1). The fused-ring system is essentially planar, with a maximum deviation of 0.012 (1) Å for C1. The allyl group is nearly perpendicular to indazole plane as indicated by the torsion angle of C9 C8 N2 N3 = 88.35 (18)°.
Experimental 6-nitroindazole (5 mmol) and allyl bromide (10 mmol) were reacted in THF (40 ml) in the presence of potassium carbonate (10 mmol) and tetra-n-butylammonium bromide (0.5 mmol). The mixture was stirred for 24 h, filtered, and the THF removed under vacuum. The product was separated by chromatography on silica gel with a hexane:ethyl acetate (9:1) solvent system. The compound was obtained as yellow crystals in 68% yield.

Computing details
Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and Mercury (Macrae et al. 2008); software used to prepare material for publication: PLATON (Spek, 2009) and publCIF (Westrip, 2010).   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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq C1 0.5250 (