3,3-Dimethyl-9-phenyl-3,4-dihydro­acridin-1(2H)-one

In the mol­ecule of the title compound, C(21)H(19)NO, the terminal saturated six-membered ring of the dihydro­acridine unit adopts an envelope conformation, while the other two fused rings are nearly coplanar, with a dihedral angle of 2.61 (3)°. The coplanar ring system is oriented with respect to the phenyl ring at a dihedral angle of 74.58 (3)°. In the crystal structure, there is a C—H⋯π contact between the central ring of the dihydro­acridine system and the phenyl ring and a π–π contact between the two central rings [centroid–centroid distance = 3.809 (1) Å].