Twisted Polycyclic Aromatic Hydrocarbon with a Cyclooctatetraene Core via Formal [4+4] Dimerization of Indenofluorene

摘要: A polycyclic aromatic hydrocarbon having a twisted cyclooctatetraene (COT) core was prepared by formal [4+4] dimerization of an in situ generated indeno[2,1-a]fluorene derivative. The compound consists two indenofluorene frameworks connected with double bonds and adopts geometry to avoid intramolecular steric repulsion. It exhibits long-wavelength absorption band maximum at 634 nm extending about 850 nm, which is consistent the moderate antiaromaticity COT ring as indicated NICS value (+11.9). mechanism for cycloaddition reaction proposed terms stepwise bond formations due diradical character framework, on basis completely different product obtained from extended benzo analogue.