Key indicators: single-crystal X-ray study; T = 100 K; mean (C-C) = 0.002 Å; R factor = 0.043; wR factor = 0.123; data-to-parameter ratio = 10.6.In the title compound, C 15 H 15 NO 2 , the dihedral angle between the aromatic rings is 5.86 (6) , and an intramolecular N-HÁ Á ÁO hydrogen bond generates an S(6) motif, which helps to stabilize the enamine-keto tautomer. An intramolecular O-HÁ Á ÁO hydrogen bond also occurs. In the crystal, inversion dimers linked by pairs of O-HÁ Á ÁO hydrogen bonds generate