(Z)-4-Benzylidene-3-methylisoxazol-5(4H)-one

In the title compound C11H9NO2, the phenyl and isoxazole rings are almost coplanar, making a dihedral angle of 1.14 (9)°. This planarity is also assisted by an intramolecular C—H⋯O hydrogen bond between the phenyl ring and the carbonyl O atom. In the crystal, weak C—H⋯O interactions generate a layered structure parallel to the ac plane.

In the title compound C 11 H 9 NO 2 , the phenyl and isoxazole rings are almost coplanar, making a dihedral angle of 1.14 (9) . This planarity is also assisted by an intramolecular C-HÁ Á ÁO hydrogen bond between the phenyl ring and the carbonyl O atom. In the crystal, weak C-HÁ Á ÁO interactions generate a layered structure parallel to the ac plane.

D-HÁ
With this extensive background of isoxazole derivatives, we have synthesized the title compound to study its crystal structure.
In the molecular structure of the title compound ( Fig. 1), the dihedral angle between the phenyl ring (C9/C10/C11/C12/C13/C14) and isoxazole ring (C1/C3/C4/N5/O6) is 1.14 (9)°. The isoxazole moiety is in a synperiplanar conformation with respect to the phenyl ring, as indicated by the torsion angle value of 0.5 (2)°. The bond lengths and angles agree with those reported for a related structure (Wolf et al., 1995). There are no classic hydrogen bonds. In the crystal structure weak C-H···O hydrogen bonds link molecules into sheets Table 1. The packing diagram viewed down the b axis shows a layered stacking feature (Fig. 2).

Experimental
A mixture of benzaldehyde oxime (1 mmol), ethyl acetoacetate (2 mmol) and anhydrous zinc chloride (0.1 mmol) were taken in a 10 ml round bottomed flask and contents were gradually heated to 120°C without any solvent for about one hour. After completion of the reaction (as indicated by TLC), the mixture was cooled to room temperature and methanol was added with stirring for about 30 min; the solids thus obtained were filtered and recrystallized from hot ethanol.

Refinement
H atoms were placed at idealized positions and allowed to ride on their parent atoms with C-H distances in the range of 0.93 to 0.96 Å; U iso (H) = 1.2-1.5U eq (carrier atom) for all H atoms.

Computing details
Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008   where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.19 e Å −3 Δρ min = −0.14 e Å −3 Special details Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles Refinement. Refinement on F 2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses 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 observed criterion of F 2 > σ(F 2 ) is used only for calculating -R-factor-obs 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.