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

In the title compound, C(13)H(13)NO(4), 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 oxo­amine group is 36.4 (3)°, while the mean plane of the 2-methyl­idene group is inclined by 84.2 (01)° from that of the oxo­amine group. In the crystal, classical O—H⋯O hydrogen bonds formed by the carb­oxy­lic acid groups and weak N—H⋯O weak inter­actions formed by the amide groups and supported by weak C—H⋯O inter­actions between the 2-methyl­idene, phenyl and acetyl groups with the carb­oxy­lic acid, oxo­amine and acetyl O atoms, together link the mol­ecules into dimeric chains along [010]. The O—H⋯O hydrogen bonds form R (2) (2)(8) graph-set motifs.