Acephenanthrylenes from flash vacuum thermolysis of diarylmethylidenecycloproparenes

Upon flash vacuum thermolysis at 750 °C fluorenylidenecyclopropa[b]naphthalene (1) undergoes opening of the three-membered ring and rearrangement to give a range of C24H14 polycyclic aromatic hydrocarbons. Dibenz[e.l]- and -[e.k]acephenanthrylene (7) and (12), respectively, have been identified while the plausible naphth[1,2-e]- and [2,3-e]acephenanthrylenes (9) and (14) were not detected. With diphenylmethylidenecyclopropa[b]naphthalene (2) cyclodehydrogenation and rearrangement also provide C24H14 polycycles; dibenz[e.k]acephenanthrylene (12) is identified and dibenz[a.e]aceanthrylene (15) is a proposed product.