Syntheses and crystal structures of the anhydride 4-oxa-tetra-cyclo-[5.3.2.0.0]dodec-11-ene-3,5-dione and the related imide 4-(4-bromo-phen-yl)-4-aza-tetra-cyclo-[5.3.2.0.0]dodec-11-ene-3,5-dione.

The syntheses and crystal structures of the two title compounds, CHO () and CHBrNO (), both containing the bi-cyclo-[2.2.2]octene ring system, are reported here [the structure of has been reported previously: White & Goh (2014 ▸). Private Communication (refcode HOKRIK). CCDC, Cambridge, England]. The bond lengths and angles of the bi-cyclo-[2.2.2]octene ring system are similar for both structures. The imide functional group of features carbonyl C=O bond lengths of 1.209 (2) and 1.210 (2) Å, with C-N bond lengths of 1.393 (2) and 1.397 (2) Å. The five-membered imide ring is nearly planar, and it is positioned relative to the alkene bridgehead carbon atoms of the bi-cyclo-[2.2.2]octene ring system. Non-covalent inter-actions present in the crystal structure of include a number of C-H⋯O inter-actions. The extended structure of also features C-H⋯O hydrogen bonds as well as C-H⋯π and lone pair-π inter-actions, which combine together to create supra-molecular sheets.