4-(2H-1,3-Benzodioxol-5-yl)-1-(4-methylphenyl)-1H-pyrazol-5-amine

In the title compound, C17H15N3O2, two independent molecules (A and B) comprise the asymmetric unit. The major conformational difference arises in the relative orientation of the pyrazole ring amine and dioxole substituents which are anti in A and syn in B. The five-membered dioxole ring in each molecule has an envelope conformation with the methylene C atom as the flap. The mean plane through the benzodioxole and benzene groups make dihedral angles of 31.67 (8) and 68.22 (9)°, respectively, with the pyrazole ring in A; the equivalent values for B are 47.18 (7) and 49.08 (9)°. In the crystal, supramolecular zigzag chains along the b-axis direction arise as a result of N—H⋯N hydrogen bonding. These are consolidated into supramolecular double chains via C—H⋯O and C—H⋯π interactions.

In the title compound, C 17 H 15 N 3 O 2 , two independent molecules (A and B) comprise the asymmetric unit. The major conformational difference arises in the relative orientation of the pyrazole ring amine and dioxole substituents which are anti in A and syn in B. The five-membered dioxole ring in each molecule has an envelope conformation with the methylene C atom as the flap. The mean plane through the benzodioxole and benzene groups make dihedral angles of 31.67 (8) and 68.22 (9) , respectively, with the pyrazole ring in A; the equivalent values for B are 47.18 (7) and 49.08 (9) . In the crystal, supramolecular zigzag chains along the b-axis direction arise as a result of N-HÁ Á ÁN hydrogen bonding. These are consolidated into supramolecular double chains via C-HÁ Á ÁO and C-HÁ Á Á interactions.

Comment
The amino substituted pyrazole unit is an important backbone in the area of synthetic as well as medicinal chemistry due to the broad range of biological activities of such compounds, such as anti-depressant, anti-anxiety, anti-fungal, antibacterial, anti-diabetic and anti-cancer (Tanitame et al., 2004;Chimenti et al., 2006;Ding et al.,2009;Shen et al., 2011;Deng et al., 2012). In this connection, the title compound, (I), was synthesized and its crystal structure is reported on herein.
Two independent molecules (A and B), comprise the asymmetric unit of (I), see  (Muruganantham et al., 2007).
The presence of N-H···N hydrogen bonding leads to supramolecular zigzag chains along the b axis in the crystal structure of (I), see Fig. 3 and Table 1. These are consolidated into supramolecular double chains via C-H···O and C-H···π interactions (Table 1). These stack with no specific intermolecular interactions between them (Fig. 4).

Experimental
A mixture of 3,4-methyleneoxyphenyl acetonitrile (2 g, 0.012 mol) and N,N-dimethylformamide dimethylacetal (4.89 ml, 0.037 mol) was stirred at 355 K; progress of the reaction was monitored by TLC. At the end of the reaction, the solvent was removed under vacuum. The residual crude mass was mixed with 4-methyl phenyl hydrazine hydrochloride (1.96 g, 0.012 mol) in methanol (20 ml) at room temperature. The mixture was refluxed and the reaction progress was monitored by TLC. At the end of the reaction, the solvent was removed under reduced pressure. The residue was dissolved in water and NaHCO 3 solution was added until basic pH was obtained. The product was extracted in ethyl acetate (200 ml × 2), and this ethyl acetate layer passed through Na 2 SO 4 and concentrated to dryness. The crude mass was purified by silica gel column chromatography, eluted with ethyl acetate:hexane (1:4) to produced 2.8 g of a yellow solid [Yield: 77%. M.pt: 422-423 K]. Single crystals suitable for X-ray measurements were obtained by repeated re-crystallization from ethyl acetate at room temperature.
Being affected by the beam-stop, the (0 0 1) reflection was removed from the final cycles of refinement.

Figure 1
The molecular structure of the two independent molecules comprising the asymmetric unit of the title compound (I), showing the atom labelling. Displacement ellipsoids are drawn at the 35% probability level.

Figure 2
Overlay diagram of the N1-and inverted N2-containing molecules (red and blue, respectively), where the pyrazole rings have been superimposed.  View of the supramolecular zigzag chain along the b axis in compound (I), mediated by N-H···N hydrogen bonds (dashed lines; see Table 1 for details).  A view in projection along the b axis of the crystal packing of compound (I). The N-H···N, C-H···O (obscured) and C -H···π interactions are shown as dashed lines (see Table 1 for details).  (Sheldrick, 2008), Fc * =kFc[1+0.001xFc 2 λ 3 /sin(2θ)] -1/4 Extinction coefficient: 0.0100 (15) 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 > 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.