4-[(4-Bromophenyl)amino]-2-methylidene-4-oxobutanoic acid

In the title compound, C11H10BrNO3, two independent molecules (A and B) crystallize in the asymmetric unit. The dihedral angles between the mean planes of the 4-bromophenyl ring and amide group are 24.8 (7) in molecule A and 77.1 (6)° in molecule B. The mean plane of the methylidene group is further inclined by 75.6 (4) in molecule A and 72.5 (6)° in molecule B from that of the amide group. In the crystal, N—H⋯O hydrogen bonds formed by amide groups and O—H⋯O hydrogen bonds formed by carboxylic acid groups are observed and supported additionally by weak C—H⋯O interactions between the methylidene and amide groups. Together, these link the molecules into chains of dimers along [110] and form R 2 2(8) graph-set motifs.


Comment
Amide bonds play a major role in the elaboration and composition of biological systems, which are the main chemical bonds that link amino acid building blocks together to give proteins. Amide bonds are not limited to biological systems and are indeed present in a huge array of molecules, including major marketed drugs. Amide derivatives possessing antiinflammatory (Galanakis et al., 2004;Kumar et al., 1993;Ban et al., 1998), antimicrobial (Ukrainets et al., 2006), antitubercular (Lesyk et al., 2004 and antiproliferative (Gududuru et al., 2004) activities are reported in the literature.
In the title compound, two independent molecules (A & B) crystallize in the asymmetric unit (

Refinement
All of the H atoms were placed in their calculated positions and then refined using the riding model with Atom-H lengths of 0.95Å (CH), 0.99Å (CH 2 ), 0.88Å (NH) or 0.84Å (OH). Isotropic displacement parameters for these atoms were set to 1.2 (CH, CH 2 , NH) or 1.5 (OH) times U eq of the parent atom. The idealised tetrahedral OH was refined as a supporting information rotating group: O3A(H3A), O3B(H3B). The highest four peaks in the residual density map are at approximately 1Å from the bromine atoms and have a height of about 2 e -/Å 3 .

Figure 1
ORTEP drawing of the title compound, C 11 H 10 BrNO 3 , showing the labeling scheme with 30% probability displacement ellipsoids. H atoms not involved in hydrogen bonding have been removed for clarity.

sup-4
Acta Cryst. (2014). E70, o779-o780 where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 2.73 e Å −3 Δρ min = −0.79 e Å −3 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 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq