Crystal strucutre of rac-methyl (11aR*,12S*,13R*,15aS*,15bS*)-11-oxo-11,11a,12,13-tetra-hydro-9H,15bH-13,15a-ep-oxy-isoindolo[1,2-c]pyrrolo[1,2-a][1,4]benzodiazepine-12-carboxyl-ate.

The title compound, C21H18N2O4, obtained as a racemate, contains a novel heterocyclic system, viz. isoindolo[1,2-c]pyrrolo-[1,2-a][1,4]benzodiazepine. The central diazepane ring has a distorted boat conformation with two phenyl-ene-fused and one methine C atom deviating by 0.931 (1), 0.887 (1) and 0.561 (1) Å, respectively, from the mean plane of the rest of the ring. The γ-lactone ring has an envelope conformation, with the C atom opposite to amide bond deviating by 0.355 (1) Å from its plane. In the crystal, mol-ecules form centrosymmetric dimers through pairs of C-H⋯O hydrogen bonds.