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A series of caged 1,4‐diols, 26, 29a/29b, 31, were synthesized from the Diels‐Alder cycloadduct 21 of 1,2,3,4‐tetrachloro‐5,5‐dimethoxycyclopentadiene and 1,4‐benzoquinone. Reduction of enedione 21 with aqueous TiCl3, followed by base‐catalyzed enolization in the presence of acetic anhydride, gave diene 23b, which reacted with maleic anhydride and 1,4‐benzoquinone to produce the corresponding [4+2] cycloadducts 24b and 27, respectively. The adduct 24b was converted to birdcaged 1,4‐diol 26 by photocyclization followed by decarboxylative olefination of resulted caged anhydride 25b. The adduct 27 was photocyclized to cage compound 28, which was aromatized to dihydroquinone 29a by acid‐catalyzed enolization, or benzo‐annulated compound 31 by reduction and dehydration. The birdcaged 1,4‐diols 26 and 31 underwent fragmentation induced by (diacetoxyiodo)benzene to give enediones 38/39 and 41/42, respectively. Photocyclization of 38 and 39 produced the corresponding caged compounds 43 and 44, respectively, possessing homosecohexaprismane skeletons. The corresponding monohydrate 43a of 43 was structurally characterized by single‐crystal X‐ray diffraction.

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The title compound 30 was synthesized starting from the endo,syn,endo Diels‐Alder adduct 3a of hexahydro‐5,6,7,8‐tetrachloro‐9,9‐dimethoxy‐5,8‐methanonaphthalene‐1,4‐diol diacetate 6 and 1,2,3,4‐tetrachloro‐5,5‐dimethoxycyclopentadiene (TDCp) in six steps, keyed upon a symmetry‐allowed [4+4] photocyclization of decahydro‐11,12‐dioxo‐[1,4;5,8]dimethanoanthracene‐9,10‐diol diacetate 22. The epimeric monoacetate 26 related to 22 was also synthesized and their thermolysis and photolysis were investigated. Oxidation of diol 30 afforded hexacyclic bridged hemiacetal 31 as a result of transannular reaction. The structure of hemiacetal 31 was analyzed by single‐crystal X‐ray crystallography.