Unsaturated 8-membered ring compounds. VII. Synthesis and cycloaddition reactions of 7,8-dimethylene-1,3,5-cyclooctatrienes. The synthesis of dicyclooctatetraeno[1,2:4,5]benzene
An expedient new synthesis of benzo[c]octalene starting from the Diels-Alder adduct of benzocyclobutadiene to 7,8-dimethylenecycloocta-1,3,5-triene is described. This octalenederivative, in solution, exists as an equilibrating mixture of the double bond isomers (2) and (3) whereas in its crystalline state only the isomer (2) is present.