Diethyl 2,6,11-trioxo-2,3-dihydro-1H-anthra[1,2-d]imidazole-1,3-diacetate

The title compound, C(23)H(20)N(2)O(7), consists of three fused six-membered rings (A, B and C) and one five-membered ring (D), linked to two ethyl acetate groups. The four fused rings are slightly folded around the O=C⋯C=O direction of the anthraquinone system, with a dihedral angle of 3.07 (8)° between the fused five- and six-membered rings (C and D) and the terminal ring (A). The planes through the atoms forming each acetate group are nearly perpendicular to the mean plane of the anthra[1,2-d]imidazole system, as indicated by the dihedral angles between them of 79.94 (9) and 85.90 (9)°. The crystal packing displays non-classical C—H⋯O hydrogen bonds.