2,2-Dimethyl-5-[(2-nitroanilino)methylidene]-1,3-dioxane-4,6-dione

The crystal of the title compound, C13H12N2O6, contains a bifurcated intramolecular hydrogen bond between the N—H group and one of the O atoms from both the nitro group and the dioxane-4,6-dione moiety. In addition, molecules are linked by a series of intermolecular C—H⋯O secondary interactions. The dihedral angles between the benzene ring and the nitro group and the conjugated part of the dioxane-4,6-dione moiety are 19.1 (2) and 17.89 (7)°, respectively.

The crystal of the title compound, C 13 H 12 N 2 O 6 , contains a bifurcated intramolecular hydrogen bond between the N-H group and one of the O atoms from both the nitro group and the dioxane-4,6-dione moiety. In addition, molecules are linked by a series of intermolecular C-HÁ Á ÁO secondary interactions. The dihedral angles between the benzene ring and the nitro group and the conjugated part of the dioxane-4,6-dione moiety are 19.1 (2) and 17.89 (7) , respectively.

Related literature
The title compound is an important intermediate drug discovery. For the synthesis and structures of related antitumor precursors, see: Cassis et al. (1985). For related literature, see Dolomanov et al. (2009 Table 1 Hydrogen-bond geometry (Å , ). be used to synthesize the 4(1H)quinolone derivatives by thermolysis, which can then be used as precursors for anti-malarial agents or anti-cancer agents. The structure contains an bifurcated intramolecular hydrogen bond between the N-H and one of the O's from both the nitro group and the dioxane-4,6-dione moiety. In addition the molecules are linked by a series of intermolecular C-H···O secondary interactions. The dihedral angles between the phenyl group and both the nitro and conjugated part of the dioxane-4,6-dione moiety are 19.1 (2)° and 17.89 (7)°, respectively.

Experimental
A mixture of 2,2-dimethyl-1,3-dioxane-4,6-dione(1.44 g, 0.01 mol) and methylorthoformate (1.27 g, 0.012 mol) was heated to reflux for 0.5 h, then 2-nitroaniline(1.38 g, 0.01 mol) in ethanol (20 mL) was added into the above solution. The mixture was heated under reflux for another 2 h and poured into cold water then filtered to obtain a powder. Single crystals were obtained from the powder in CH 2 Cl 2 and methanol after 3 days.

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds supplementary materials sup-3 in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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.