In the title compound, C20H22N2O2, the central five-membered imidazolidine ring makes dihedral angles of 63.85 (6) and 70.38 (6)° with the two substituent phenyl rings. In the crystal, molecules form an inversion dimer through a pair of N—H...O hydrogen bonds. These are linked into a three-dimensional network via C—H...O hydrogen bonds. The n-pentyl chain is disordered over two sites, with an occupancy ratio of 0.876 (2):0.124 (2).
