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

In the title compound, C13H13NO4, the N-C(=O) bond length of 1.354 (2) Å is indicative of amide-type resonance. The dihedral angle between the mean planes of the benzene ring and oxo-amine group is 36.4 (3)°, while the mean plane of the 2-methyl-idene group is inclined by 84.2 (01)° from that of the oxo-amine group. In the crystal, classical O-H⋯O hydrogen bonds formed by the carb-oxy-lic acid groups and weak N-H⋯O weak inter-actions formed by the amide groups and supported by weak C-H⋯O inter-actions between the 2-methyl-idene, phenyl and acetyl groups with the carb-oxy-lic acid, oxo-amine and acetyl O atoms, together link the mol-ecules into dimeric chains along [010]. The O-H⋯O hydrogen bonds form R 2 (2)(8) graph-set motifs.