N-[3-(Dimethylamino)propyl]-N′-(2-hydroxy-5-methylphenyl)oxamide

In the title compound, C14H21N3O3, the oxamide group has a transoid conformation. In the crystal, the molecules are connected by N—H⋯O and O—H⋯N hydrogen bonds into a double chain running along the b axis.

As shown in Fig. 1, the title compound has a trans-conformation of the oxamide group. The whole compound likes the alphabet `L′. The benzene ring is almost coplanar to the oxamide group [11.44 (9)°], just like that in the compound of N,N′-bis(2-Hydroxyphenyl)oxamide (Martinez et al., 1998). However, the plane through the other substituent group, aminopropyl, is perpendicular to the oxamide plane [83.49 (12)°]. The torsion angle of C9-N2-C10-C11 is 106.7 (2)° (Table 1) Table 2). These dimers are further assembled to a chain parallel to the b-axis through the hydrogen bonds between the phenolic hydroxyl groups and the tertiary amino groups.

Experimental
All reagents were of AR grade and obtained commercially without further purification. The title compound was prepared according to the method proposed by Han et al. (2007). A tetrahydrofuran (THF) solution (8 ml) of ethyl oxalyl chloride (1.11 ml, 10 mmol) was added dropwise into a THF solution (50 ml) of 2-amino-4-methylphenol (1.23 g, 10 mmol) with continuous stirring. The mixture was stirred quickly for 1 h and became clear. Then 20 ml ethanol was further added and the mixture was added dropwise into the solution (10 ml) of 3-dimethylamino-propylamine (1.02 g, 10 mmol) with stirring and kept the temperature at 273 K for 9 h. The title compound was precipitated as a white powder and washed with ethanol for several times and dried under vacuum. Yield: 1.83 g (66%). Colourless crystals of compound with the suitable size for X-ray analysis were obtained from an ethanol/water (1:1) mixture by slow evaporation for one week at room temperature.

Refinement
All H atoms were found in a difference Fourier map. Those bonded to N and O were freely refined with the O1-H1A bond restrained to a length of 0.86 (2)  (aromatic), 0.97 (methylene) and 0.96 (methyl), and refined using a riding model with U iso (H) = 1.2U eq C or 1.5U eq C(methyl).

Figure 1
The molecular structure of the title compound. The displacement ellipsoids are drawn at the 30% probability levels and H atoms are shown as small spheres of arbitrary radii.

N-[3-(Dimethylamino)propyl]-N′-(2-hydroxy-5-methylphenyl)ethanediamide
Crystal data 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.