(Z)-4-[4-(Dimethylamino)benzylidene]-3-methylisoxazol-5(4H)-one

The title compound, C13H14N2O2, an isoxazol-5-one derivative, was synthesized by a one-pot, three-component condensation reaction of methyl acetoacetate, hydroxylamine hydrochloride and 4-(dimethylamino)benzaldehyde. All the non-H atoms are co-planar [r.m.s deviation = 0.0039 Å], with a Z configuration about the C=C bond. The dihedral angle between the phenyl ring and the isoxazole ring is 2.58 (19)°.

The title compound, C 13 H 14 N 2 O 2 , an isoxazol-5-one derivative, was synthesized by a one-pot, three-component condensation reaction of methyl acetoacetate, hydroxylamine hydrochloride and 4-(dimethylamino)benzaldehyde. All the non-H atoms are co-planar [r.m.s deviation = 0.0039 Å ], with a Z configuration about the C C bond. The dihedral angle between the phenyl ring and the isoxazole ring is 2.58 (19) .

Experimental
The molecular structure of the title compound is illustrated in Fig. 1, and geometrical parameters are given in the archived CIF. The bond lengths and angles agree well with those reported for the related compound 4-(N-(2,4,6-Tri-tbutylphenyl)iminomethylene)-3-t-butylisoxazol-5(4H)-one (Wolf et al., 1995). The molecular structure adopts a planar conformation with Z-configuration about the C2═C5 double bond.

S2. Experimental
A mixture of methyl acetoacetate (4 mol), hydroxylamine hydrochloride (4 mmol), and pyridine(4 mmol) in distilled water(10 ml) was irradiated in the water bath of an ultrasonic cleaner for 10 min, then 4-dimethylaminobenzaldehyde(4 mmol) was slowly added to the mixture. The resulting mixture was irradiated in the water bath of an ultrasonic cleaner for 0.5 h. The solution was kept at r.t. overnight, giving a turbid solution. It was filtered to give a solid that was washed with cold water and ethanol. The crude product was recrystallized from ethanol to afford the title compound as a yellow solid. Single crystals, suitable for X-ray analysis, were obtained by slow evaporation of an aqueous ethanol (95%) solution at ambient temperature after 4 d. Elemental analysis, calculated for C 13 H 14 N 2 O 2 : C 67.81, H 6.13, N 12.17%; found: C 67.87, H 6.19, N 12.11%.

S3. Refinement
The H-atoms were included in calculated positions and allowed to ride on their parent atoms:

Figure 1
The molecular structure of the title compound with displacement ellipsoids drawn at the 30% probability level. Special details 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.