1-[2,6-Dichloro-4-(trifluoromethyl)phenyl]-3,4-dimethylpyrano[2,3-c]pyrazol-6(1H)-one

In the title compound, C15H9Cl2F3N2O2, the 1,6-dihydropyrano[2,3-c]pyrazole ring system is almost planar, with a maximum deviation of 0.0226 (14) Å, and forms a dihedral angle of 69.90 (6)° with the benzene ring. In the crystal, molecules are linked into a helical chain along the c axis by C—H⋯O hydrogen bonds.

In the title compound, C 15 H 9 Cl 2 F 3 N 2 O 2 , the 1,6-dihydropyrano[2,3-c]pyrazole ring system is almost planar, with a maximum deviation of 0.0226 (14) Å , and forms a dihedral angle of 69.90 (6) with the benzene ring. In the crystal, molecules are linked into a helical chain along the c axis by C-HÁ Á ÁO hydrogen bonds.
In the crystal packing as shown in Fig. 2, the molecules are linked into chains along the c axis by the intermolecular C11 -H11A···O2 hydrogen bonds (Table 1).

Experimental
(2,6-Dichloro-4-trifluoromethyl)phenyl hydrazine (1.225 g, 0.005 mol) was added to ethyl acetoacetate (1.3 g, 0.01 mol) and charged in a microwave for 3 minutes at 360 W. The reaction mixture was quenched into ether and kept for some time to get the residue. The residue was recrystallized by slow evaporation from ethanol to give block-shaped orange crystals suitable for X-ray diffraction. M.p. = 431 K.

Refinement
All H atoms were positioned geometrically and were refined with a riding model with U iso (H) = 1.2 or 1.5 U eq (C) (C-H = 0.95 or 0.98 Å). A rotating group model was applied to the methyl groups.

Figure 2
The crystal packing of the title compound, viewed along the a axis, showing the chain along the c axis. H atoms not involved in the intermolecular interactions (dashed lines) have been omitted for clarity.

1-[2,6-Dichloro-4-(trifluoromethyl)phenyl]-3,4-dimethylpyrano[2,3-c]pyrazol-6(1H)-one
Crystal data C 15 H 9 Cl 2 F 3 N 2 O 2 M r = 377.14 Orthorhombic, Pbca Hall symbol: -P 2ac 2ab a = 13.3348 (2) (Cosier & Glazer, 1986) operating at 100.0 (1) K. Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'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.