(4S)-5'-Chloro-3,7,7-trimethyl-5,6,7,8-tetra-hydro-4H-spiro-[1,2-oxazolo[5,4-b]quinoline-4,3'-indole]-2',5-dione.

In the title compound, C20H18ClN3O3, the five- and six-membered heterocycles fused through a spiro C atom are inclined to each other at an angle of 87.4 (1)°. In the tricyclic ring system, the cyclo-hexene ring adopts an envelope conformation with the spiro atom as the flap. In the crystal, two sets of N-H⋯O hydrogen bonds link the mol-ecules into columns containing centrosymmetric R 2 (2)(7) ring motifs and propagating along the b-axis direction.