Hexahydrocycloocta-[b]quinoxaline formation from 1,2-diacetoxycycloocta-5, 6-dione

The reaction of 1,2-diacet-oxycyclo-octane-5,6-dione with ortho-phenyl-enediamine in acetic acid gave trans-6,7,8,9,10,11-hexa-hydro- cyclo-octa-[b]quinoxaline-8,9-diyl diacetate, C18H20N2O4. The saturated H atoms in the structure display almost perfect gauche orientations and the two acet-oxy groups are oriented almost perfectly anti-periplanar. There are C - H⋯N bonding inter-actions linking the mol-ecules into chains and inter-molecular π-π stacking inter-actions between pyrazine rings [centroid-centroid distance = 3.6569 (9) Å and perpendicular distance = 3.426 Å]. © International Union of Crystallography 2007.