4-(2,3-Dimethylanilino)pent-3-en-2-one

In the title compound, C13H17NO, the dihedral angle between the aryl ring and the aminoacrylaldehyde mean plane [N—C=C—C=O; maximum deviation = 0.0144 (9) Å] is 53.43 (4)°. There is an intramolecular N—H⋯O hydrogen bond involving the amine and carbonyl groups. In the crystal, molecules are linked by C—H⋯O hydrogen bonds, forming chains propagating along [001].


4-(2,3-Dimethylanilino)pent-3-en-2-one Gertruida J. S. Venter, Gideon Steyl and Andreas Roodt Comment
The β-diketone compound AcacH (acetylacetone; or when coordinated acetylacetonato, acac -) has been studied extensively, with a multitude of derivatives synthesized to date. One such derivative type, known as enaminoketones, containing N and O atoms as well as an unsaturated C═C bond, and are of interest in various fields including liquid crystals (Pyżuk et al., 1993)  indicates an unsaturated bond in the pentenone backbone. Here the intramolecular distance N1···O1 is 2.6348 (13) Å which is considerably less (~ 0.2 Å) than that observed when the ligand is coordinated to rhodium for example (Venter et al., 2009a,b;2012;Damoense et al., 1994).
The intramolecular N-H···O hydrogen bond that is formed ( Fig. 1 and Table 1)

Experimental
The title compound was prepared following the literature procedure (Shaheen et al., 2006;Venter et al., 2010).

Refinement
The NH H atom was located in a difference Fourier map and freely refined. The H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms: 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 H atoms and = 1.2 for other H atoms. The methyl groups were generated to fit the difference electron density and the groups were then refined as rigid rotors.

Figure 1
The molecular structure of the title molecule, with the atom numbering. the displacement ellipsoids are drawn at the 50% probability displacement level. The intramolecular N-H···O hydrogen bond is shown as a yellow dashed line (see Table   1 for details).

Special details
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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.