In the title compound, C16H20N2O2, the seven-membered ring adopts a bowl-shaped conformation while the orientation of the 2-oxopropylidene substituent is determined by an intramolecular N—H...O hydrogen bond, which generates an S(6) ring. In the crystal, inversion dimers linked by pairs of very weak C—H...O interactions occur, which generate R
2
2(8) loops.