Tricyclic system containing large rings. The synthesis of fully-conjugated [12](1,3)[12](4,6)cyclophanpolyenepolyynes and related compounds

For the purpose of preparing the ring-expanded analogue of anthracene, 1,2,4,5-tetrakis[(1E,3Z)-4-methylhexa-1,3-dien-5-ynyl]benzene, 8, and 1,2,4,5-tetrakis[(Z)-2(2-ethnylphenyl)ethenyl]benzene, 16, were oxidatively coupled; however, both of them afforded m-bridged derivatives, i.e., 1,3:4,6-bis[(1E,3Z,9Z,11E)-4,9-dimethyldodeca-1,3,9,11-tetraene-5,7-diyne-1,12-diyl]benzene, 3, and 1,3:4,6-bis[(1E,11E)-3,4:9,10-dibenzdodeca-1,11-diene-5,7-diyne-1,12-diyl]benzene, 5. To ascertain the structures of 3 and 5, the related model compounds were also prepared.