The synthesis of 8-cyano-7, 8-dihydro-7-oxobenzo [4,5] cyclo-hepta [1,2,3-de] naphthalene

Abstract

In 1952 Pullman et al. Pullman, B., Pullman, A., Berthier, G., and Pontis, J., J. Chim. Phys., 1952, 49, 20. made a theoretical study of pleiadiene (I), acepleiadylene (II), pleiadene (III) and benzo[4,5] cyclohepta- [1,2,3-de] naphthalene (IV). Boekelheide and Vick Boekelheide, V., and Vick, G. K., J. Am. Chem. Soc., 1956, 78, 653 were able to synthesize pleiadiene (I) and acepleiadylene (II) and it was found that their physical and chemical properties agreed with those calculated by Pullman et al. Cava and Schlessinger, Cava, M. P., and Schlessinger, R. H., J. Am. Chem, Soc., 1963, 85, 835 in 1963, attempted to synthesize pleiadene (III) and its acenaphthylene analogue (v). They showed these were much less stable than pleiadiene (I) or acepleiadylene (II). Pleiadene (III) and its acenaphthylene analogue (v) could only be isolated as a dimer resulting from a Diels-Alder self condensation. This instability might be expected as acenes decrease in stability as the number of linearly fused rings increases.