Effect of benzocyclobutadieno-annelation on cyclic conjugation in perylene

Abstract

Earlier studies showed that the intensity of cyclic conjugation in the central ring R of perylenecan be significantly altered by means of benzo-annelation. In particular, linear (resp. angular) benzoannelationwas found to decrease (resp. increase) the intensity of cyclic conjugation in R .We now examinethe analogous effect of benzocyclobutadieno-annelation, and show that linear annelation strongly increasesthe cyclic conjugation in R, whereas the effect of angular annelation is negligibly small.