Crystal structure of 2-[2-(2,5-dichlorobenzyloxy)-2-(furan-2-yl)ethyl]-2H-indazole

In the title compound, the indazole ring system is oriented at dihedral angles of 25.04 (4) and 5.10 (4)° o the furan and benzene rings, respectively

In the title compound, C 20 H 16 Cl 2 N 2 O 2 , the indazole ring system is approximately planar [maximum deviation = 0.033 (1) Å ], its mean plane is oriented at dihedral angles of 25.04 (4) and 5.10 (4) to the furan and benzene rings, respectively. In the crystal, pairs of C-H ind Á Á ÁO bo (ind = indazole and bo = benzyloxy) hydrogen bonds link the molecules into centrosymmetric dimers with graph-set motif R 2 2 (12). Weak C-HÁ Á Á interactions is also observed. Aromaticstacking between the benzene and the pyrazole rings from neighbouring molecules [centroid-centroid distance = 3.8894 (7) Å ] further consolidates the crystal packing.

Chemical context
Ethers such as miconazole and econazole possessing an imidazole ring have been developed for clinical uses as azole antifungals (Godefroi et al., 1969). The crystal structures of miconazole (Peeters et al., 1979) and econazole (Freer et al., 1986) have previously been reported. Another azole ring system, indazole, is an important structural unit of many biologically active compounds. Some indazole derivatives have been shown to exhibit antifungal (Lebouvier et al., 2007;Park et al., 2007), antibacterial (Wang et al., 2015), antiproliferative (Bü chel et al., 2012), antitumor (Abbassi et al., 2014) activity and act as inhibitors of nitric oxide synthase with antioxidant properties (Salerno et al., 2012). The crystal structures of some indazole derivatives have been reported (Gerpe et al., 2007;Raffa et al., 2009;Boulhaoua et al., 2015). In addition, the crystal structures of ketones containing an indazole group (Ö zel Gü ven et al., 2013(Ö zel Gü ven et al., , 2014a and ether (Ö zel Gü ven et al., 2014b) have been described. As a continuation of our studies in this area, we synthesized the title compound and report herein its crystal structure.

Synthesis and crystallization
The title compound was synthesized by the reaction of 1-(furan-2-yl)-2-(2H-indazol-2-yl)ethanol with NaH and 2,5dichlorobenzyl bromide. NaH (16 mg, 0.394 mmol) was added in small fractions to a solution of alcohol (90 mg, 0.394 mmol) in DMF (3-4 ml). Then, 2,5-dichlorobenzyl bromide (95 mg, 0.394 mmol) was added portionwise. The mixture was stirred at room temperature for 3 h, and the excess hydride was decomposed with a small amount of methyl alcohol. After evaporation to dryness under reduced pressure, a small amount of water was added and extracted with methylene chloride. The organic layer was separated, dried over anhydrous sodium sulfate, and then evaporated to dryness. The crude residue was purified by chromatography on a silica-gel column using a hexane-ethyl acetate mixture (10:1) as eluent. The ether was recrystallized from 2-propanol solution to obtain colourless crystals suitable for X-ray analysis (yield; 70 mg, 46%).

Refinement
The experimental details including the crystal data, data collection and refinement are summarized in Table 2. The Cbound H atoms were positioned geometrically with C-H = 0.93, 0.97 and 0.98 Å , for aromatic, methylene and methine Hatoms, respectively, and constrained to ride on their parent atoms, with U iso (H) = 1.2U eq (C). The molecular structure of the title compound, showing the atomnumbering scheme. Displacement ellipsoids are drawn at the 30% probability level. Table 1 Hydrogen-bond geometry (Å , ).

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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.  (16)