The title compound (5b), prepared by the oxidation of anthracene-1, 4, 9, 10-tetrone (4) with m-chloroperbenzoic acid, undergoes Dieels–Aldr reactions with cyclohexa-1, 3-diene, cyclopentadiene, and 2-methylbuta-1, 3-diene to give 5a, 11a-epoxy-1, 4-ethano-1, 4, 4a, 5a, 11a, 12a-hexahydronaphthacene-5, 6, 11, 12-tetrone (7a), 5a, 11 a epoxy-1, 4, 4a, 5a, 11 a, 12a-hexahydro-1, 4-methanonaphthacene-5, 6, 11, 12-tetrone (7b), and 5a, 11a- ...