5-Chloro-3,6-dimethyl-1-phenyl-1H,4H-pyrano[2,3-c]pyrazol-4-one

In the title compound, C14H11ClN2O2, two independent molecules (A and B) comprise the asymmetric unit with the main difference between them being the relative orientation of the pendent phenyl ring with respect to the fused-ring system [dihedral angles = 8.32 (8)° (A) and 28.32 (8)° (B)]. In the crystal, the A molecules are connected into a linear supramolecular chain along the a axis via C—H⋯O interactions and linked to this via C—H⋯Cl interactions are the B molecules. The chains are connected into layers in the ab plane by π–π interactions between pyrazole (A) and pyran (B) rings, and between pyrazole (B) and pyran (A) rings [centroid–centroid distances = 3.5442 (11) and 3.4022 (10) Å, respectively].

In the title compound, C 14 H 11 ClN 2 O 2 , two independent molecules (A and B) comprise the asymmetric unit with the main difference between them being the relative orientation of the pendent phenyl ring with respect to the fused-ring system [dihedral angles = 8.32 (8) (A) and 28.32 (8) (B)]. In the crystal, the A molecules are connected into a linear supramolecular chain along the a axis via C-HÁ Á ÁO interactions and linked to this via C-HÁ Á ÁCl interactions are the B molecules. The chains are connected into layers in the ab plane byinteractions between pyrazole (A) and pyran (B) rings, and between pyrazole (B) and pyran (A) rings [centroid-centroid distances = 3.5442 (11) and 3.4022 (10) Å , respectively].

Tiekink Comment
In connection with reports that pyrano[2,3-c]pyrazole derivatives possess analgesic and anti-inflammatory activities (Kuo et al., 1984), the title compound (I) was synthesized, following a literature procedure (Gelin et al., 1983), and its crystal and molecular structure are reported on herein.
In (I), Fig. 1, two independent molecules comprise the asymmetric unit. As seen from the overlay diagram, Fig. 2, these are virtually super-imposable. The primary difference between the molecules relates to the relative orientation of the pendent phenyl ring with respect to the fused-ring system [r.m.s. deviations = 0.024 and 0.021 Å, respectively] as seen in the dihedral angles of 8.32 (8) and 28.32 (8)°, respectively. In the structure of the derivative without a chloro substituent, the molecule is planar with the r.m.s. of all non-hydrogen atoms being 0.038 Å (Asiri et al., 2012).
In the crystal, the Cl1-containing molecules are connected into a linear supramolecular chain along the a axis via C-H···O interactions and linked to this via C-H···Cl interactions are the Cl2-containing molecules, Fig. 3 and Table 1.

Refinement
C-bound H-atoms were placed in calculated positions and included in the refinement in the riding model approximation: C-H = 0.95 and 0.98 Å for CH and CH 3 H-atoms, respectively, with U iso (H) = k × U eq (C) where k = 1.5 for CH 3 Hatoms and = 1.2 for other H-atoms.

Figure 1
The molecular structure of the two independent molecules of (I), showing the atom-labelling scheme and displacement ellipsoids at the 50% probability level.

Figure 4
A view in projection down the a axis of the unit-cell contents of (I) highlighting the stacks of supramolecular layers along the c axis. The C-H···O, C-H···Cl and π-π interactions are shown as orange, blue and purple dashed lines, respectively. 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.