Treatment of 7-oxo-7H-benzo[e]perimidine-4-carboxylic acid (I) with carbonyldiimidazole produced the corresponding acyl imidazolide (II). Reaction of this intermediate with 1,2-cyclohexanediamine (III) in DMF at 50 C afforded a mixture of amide (IV) and the title hexacyclic compound (V), which were separated by means of preparative HPLC. Alternatively, imidazolide (II) was first coupled with one equivalent of diamine (III) in DMF at r.t. to give amide (IV), which was then converted into the title compound by treatment with an excess of diamine (III) at 50 C.