3A,3b,6a,6b-tetramethylcyclobuta[1,2-c:3,4-c']difuran-1,3,4,6(3aH,3bH,6aH,6bH)-tetraone
4,5,9,10-Tetrabromoisochromeno[6,5,4-def]isochromene-1,3,6,8-tetraone
(3aR,4S,7R,7aS)-rel-Hexahydro-4,7-methanoisobenzofuran-1,3-dione
Ethane-1,2-diyl bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate)