Synthesis of Cyclopenta‐HBCs and their Regioselective Chlorination During Oxidative Cyclodehydrogenation

Abstract

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.

One‐step Annulation/Chlorination towards Chlorinated Diphenanthro, Dibenzophenanthro, and Dichrysenothiophens

“…[7] In that work, some chlorinated carbazole derivatives were isolated as the side products, apparently resulted from chlorination reactions after Scholl reactions. However, gathering from this work and other reports, [8] it is noted these chlorination reactions did not always occur with polyaryl carbazoles.…”

Helical Nanographenes Bearing Pentagon‐Heptagon Pairs by Stepwise Dehydrocyclization

“…Similarly, the double dioxaborolane HBC precursor ( 9 ) was prepared from the previously reported tetra‐ tert ‐butyl‐HBC ( 10 ) [15] via Hartwig–Miyaura C−H borylation, with a yield of 80 %. Subsequently, a Suzuki coupling reaction was performed between 11 and 9 to give 7 with a yield of 64 %.…”