(4-Methylphenyl)[3-(5-nitro-2-furyl)-1-phenyl-1H-pyrazol-4-yl]methanone

In the title pyrazole compound, C21H15N3O4, an intramolecular C—H⋯O hydrogen bond generates an S(7) ring motif. The essentially planar furan and pyrazole rings [maximum atomic deviations of 0.011 (2) and 0.006 (2) Å, respectively] make a dihedral angle of 9.21 (11)°. The nitro group is approximately coplanar with the attached furan ring, as indicated by the dihedral angle of 4.5 (2)°. In the crystal structure, intermolecular C—H⋯O interactions form bifurcated hydrogen bonds, generating R 1 2(7) ring motifs. These hydrogen bonds link the molecules into infinite chains along the a axis. The crystal structure is further stabilized by weak intermolecular π–π interactions [centroid–centroid distance = 3.4118 (10) Å].

In the title pyrazole compound, C 21 H 15 N 3 O 4 , an intramolecular C-HÁ Á ÁO hydrogen bond generates an S(7) ring motif. The essentially planar furan and pyrazole rings [maximum atomic deviations of 0.011 (2) and 0.006 (2) Å , respectively] make a dihedral angle of 9.21 (11) . The nitro group is approximately coplanar with the attached furan ring, as indicated by the dihedral angle of 4.5 (2) . In the crystal structure, intermolecular C-HÁ Á ÁO interactions form bifurcated hydrogen bonds, generating R 1 2 (7) ring motifs. These hydrogen bonds link the molecules into infinite chains along the a axis. The crystal structure is further stabilized by weak intermolecularinteractions [centroid-centroid distance = 3.4118 (10) Å ].

Comment
The pyrazole nucleus constitutes an interesting class of organic compound with diverse chemical applications. They possess anti-pyretic, anti-tumor, tranquilizing and herbicidal activities. Sydnones are easily accessible aromatic compounds and versatile synthetic intermediates with a masked azomethine imine unit. The 1,3-dipolar cycloaddition reaction with various dipolarophiles offers a convenient synthetic route for the preparation of pyrazole derivatives and has been studied extensively Rai et al., 2008).
The incorporation of 5-nitrofuran moiety into various heterocyclic systems has found to increase their biological activities. We have reported a few heterocyclic systems carrying 5-nitrofuran moiety as potent anti-microbial agents (Hegde et al., 2006). In continuation of our studies on 1,3-dipolar cycloaddition reactions of sydnones with dipolarophiles carrying nitrofuran moiety (Kalluraya et al., 1994), we herein report the synthesis of this new pyrazole.
Experimental 3-Phenyl sydnone (0.01 mol) and 1-(p-methylphenyl)-3-(5-nitro-2-furyl)-2-propyn-1-one (0.01 mol) were dissolved in 10 ml dry xylene and refluxed for 4 h. After completion of the reaction, the solvent was removed by distillation under reduced pressure. The crude product obtained was purified by recrystallization from ethanol and DMF mixture. The solid obtained was collected by filtration, washed with ethanol and dried. Single crystals suitable for X-ray analysis were obtained from a 1:2 mixture of DMF and ethanol by slow evaporation.

Refinement
All the hydrogen atoms were placed in their calculated positions, with C-H = 0.93 -0.96 Å, and refined using a riding model, with U iso = 1.2 or 1.5 U eq (C). A rotating group model was used for the methyl group. Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids for non-H atoms and the atom-numbering scheme. An intramolecular hydrogen bond is shown as dashed line.

Special details
Experimental. The crystal was placed in the cold stream of an Oxford Cyrosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1)K.
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.