Effect of benzocyclobutadieno-annelation on cyclic conjugation in fluoranthene congeners.

Earlier studies revealed that benzo-annelation has a peculiar effect on the intensity of cyclic conjugation in the five-membered ring of fluoranthene congeners. Now, the analogous effect of benzocyclobutadieno-annelation was examined and it was found show it is opposite to the effect of benzo-annelation: a benzocyclobutadiene fragment in angular (resp. linear) position with regard to the five-membered ring, decreases (resp. increases) the intensity of cyclic conjugation in the five-membered ring. [ABSTRACT FROM AUTHOR]