3-(Di­phenyl­amino)­isobenzo­furan-1(3H)-one

In the title isobenzo­furan­one derivative, C₂₀H₁₅NO₂, the planar fused-ring system (r.m.s. deviation for the 10 fitted atoms = 0.031 Å) forms dihedral angles of 63.58 (6) and 63.17 (8)° with the N-bound phenyl rings; the dihedral angle between the planes of these phenyl rings is 85.92 (7)°. In the crystal, mol­ecules are linked by weak C—H...O inter­actions, involving both O atoms, forming helical supra­molecular chains along [001].