The five-membered ring in the title imidazolidinone derivative, C(11)H(12)N(2)O(2)S, adopts an envelope conformation with the S-bound C atom being the flap atom. Overall, the mol-ecule has a U-shaped conformation as both rings are folded towards each other [dihedral angle = 31.66 (6)°]. An eight-membered amide {⋯HNCO}(2) synthon leads to hydrogen-bonded dimeric aggregates in the crystal: these are additionally linked by C-H⋯π inter-actions.