Synthesis of Cyclopenta-HBCs and their Regioselective Chlorination During Oxidative Cyclodehydrogenation.

Hexa-peri-hexabenzocoronenes with a bay-fused five-membered ring are synthesized from fluorenyl precursors. The key oxidative cyclodehydrogenation step is accompanied by regioselective chlorination that is enhanced by methylation at the cyclopenta-ring or increased reaction concentration. The CpHBC products undergo mild electrophilic aromatic bromination, without catalyst, to afford adducts suitable for π-extension by cross-coupling.