Abstract:
Many studies, both theoretical and practical, have been made of compounds containing a seven-membered ring with aromatic rings fused around it.
Pullman et al Pullman, B., Pullman, A., Berthier, G., Pontis, J., J. Chim. Phys. 1952, 49, 20. made a theoretical study of pleiadiene (I), acepleiadylene (II), pleiadene (III) and benzo[4, 5] cyclohepta[l,2,3-de] naphthalene (IV). Pleiadiene (I) and acepleiadylene (II), which were synthesysed by Boekelheide and Vick Boekelheide, V., Vick, G.K., J. Am. Chem. Soc., 1956, 78, 653. were found to have physical and chemical properties which agreed with those predicted by calculation.
In 1963, Cava and Schlessinger Cava, M.P., Schlessinger, R.H., J. Am. Chem. Soc., 1963, 85, 835 described an attempted synthesis of pleiadene (III) and its acenaphthalene analogue (V). They found, however, that these were much less stable than pleiadiene (I) or acepleiadylene (II). Neither compound could be isolated except as the dimer resulting from Diels-Alder self-condensation.
