cis,cis-1,5-Cyclooctadiene is the starting point for the synthesis of quinoxaline-and pyrazinecontaining heterocycles with three, four or five rings in linear arrays with a central eightmembered carbocyclic ring.

Key indicators: single-crystal X-ray study; T = 100 K; mean (C-C) = 0.003 Å; disorder in main residue; R factor = 0.041; wR factor = 0.089; data-to-parameter ratio = 14.0. Bruker (2001). SMART (Version 5.625) and SHELXTL (Version 6.12). References

ABSTRACT. At present study, we synthesized the imidazo[4 ' ,5 ' :5,6]cycloocta[1,2-b]quinoxaline-2-ones (-2-thione) with an additional double bond in the eight-membered ring via the reaction of a quinoxaline-fused cyclooctane-1,2-dione with urea (or thiourea) and N,N'-dimethylurea.