Thermal generation and (inter)conversion of (multi) cyclopenta-fused polycyclic aromatic hydrocarbons

FVT of 1,1-dichloro- and/or 1-chloroethenyl substituted PAH's gives access to the CP-PAH's pyracylene (1), cyclopenta[cd]pyrene (12) and benz[ghi]fluoranthene (13), cyclopent[hi] aceanthrylene (18) and cyclopent [hi]acephenanthrylene (19), and the novel cyclopenta[cd]fluoranthene (22) and isomeric cyclopent[fg]- (25a), cyclopent[jk]-(25b) and cyclopent[mn]acepyrylene (25c), respectively. The propensity of CP-PAH's to interconvert under high temperature FVT conditions is illustrated. Possible mechanisms, such as ring-contraction/ring-expansion via 1,2-H and 1,2-C are discussed.