In the title compound, C16H12O4, a 9,10‐anthraquinone derivative, the crystal packing is stabilized by C—H⋯O non‐classical hydrogen bonds with quinone O atoms as acceptors. There are no π–π stacking inter­actions in the crystal structure. The molecule lies across a crystallographic mirror plane.

Key indicatorsSingle-crystal X-ray study T = 298 K Mean (C-C) = 0.007 Å R factor = 0.037 wR factor = 0.097 Data-to-parameter ratio = 21.0 For details of how these key indicators were automatically derived from the article, see

Die erste Totalsynthese des Titelditerpens wurde ausgehend vom Wieland‐Miescher‐Keton erreicht. Eine diastereoselektive Sulfa‐Michael‐Addition ermöglichte die Erzeugung der empfindlichen β,γ‐ungesättigten Ketoneinheit, während das tetracyclische Kempan‐Gerüst problemlos durch Dominometathese aufgebaut wurde.

Key indicatorsSingle-crystal X-ray study T = 297 K Mean (C-C) = 0.005 Å R factor = 0.068 wR factor = 0.152 Data-to-parameter ratio = 15.8For details of how these key indicators were automatically derived from the article, see

Key indicators: single-crystal X-ray study; T = 300 K; mean (C-C) = 0.002 Å; disorder in main residue; R factor = 0.056; wR factor = 0.152; data-to-parameter ratio = 15.6.The title compound, C 12 H 18 N 4 O 6 , exhibits a hydrogenbonding network, which contains intermolecular classical N-HÁ Á ÁO C(imidazolone rings) hydrogen bonds and, in addition, intermolecular C-HÁ Á ÁO interactions that stabilize the crystal structure. Two ethyl groups are each disordered over two positions, with site occupancy factors in a ratio of ca 3:2.