Crystal structure of (5-chloro-2-hydroxyphenyl)(3-methylisoxazolo[5,4-b]pyridin-5-yl)methanone

In the title compound, C14H9ClN2O3, the fused pyridine and isoxazole rings are approximately planar, making a dihedral angle of 1.14 (16)°. The molecule is twisted with the benzene ring and the mean plane through the fused pyridine-isoxazole ring system being inclined to one another by 47.03 (13)°. There is an intramolecular O—H⋯O hydrogen bond forming an S(6) ring motif. In the crystal, molecules are linked by C—H⋯N hydrogen bonds, forming chains propagating along [001]. The chains are linked by slipped parallel π–π interactions, involving inversion-related benzene rings, forming slabs lying parallel to the bc plane {inter-centroid distance = 3.770 (2) Å].


S2. Structural commentary
In the title compound, Fig. 1, the fused pyridine ring (N1/C8-C12) and isoxazole ring (O3/N2/C13/C11/C10) are almost coplanar being inclined to one another by 1.14 (16) °. The molecule is twisted with the benzene ring (C1-C6) and the mean plane through the fused pyridine-isoxazole ring system being inclined to one another by 47.03 (13) °. The molecular conformation is partly determined by the intramolecular O-H···O hydrogen bond which forms an S(6) ring motif.
In the crystal, molecules are linked by C-H···N hydrogen bond to form chains propagating along the c axis direction (Table 1 and

S3. Synthesis and crystallization
To a mixture of 6-chloro-3-formylchromone (1 mmol) and 3-methylisoxazol-5-amine (1 mmol) in ethanol (3 ml) was added a catalytic amount (0.050 mmol) of In(OTf) 3 and the mixture was refluxed for about 20 min. The precipitated solid was filtered and dried under vacuum to afford the pure product in 87% yield. The purified compound was recrystallized from ethanol and DMSO-D 6 by slow evaporation giving colourless block-like crystals.

S4. Refinement
Crystal data, data collection and structure refinement details are summarized in  The molecular structure of the title compound, with atom labelling. Displacement ellipsoids are drawn at the 30% probability level.

Figure 2
A view along the b-axis of the crystal packing of the title compound. The hydrogen bonds are shown as dashed lines (see Table 1 for details). 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.