Functionalization of Azapentabenzocorannulenes by Fivefold C-H Borylation and Cross-Coupling Arylation: Application to Columnar Liquid-Crystalline Materials.

Herein, the one-shot fivefold functionalization of azapentabenzocorannulenes by an iridium-catalyzed fivefold C-H borylation reaction that exhibits excellent regioselectivity is reported. The borylated product can be used as a versatile synthetic intermediate for further derivatization via Suzuki-Miyaura cross-coupling reactions. This fivefold borylation/arylation sequence was employed to synthesize liquid-crystalline azapentabenzocorannulenes with five 3,4,5-trialkoxyphenyl groups, which assemble into 1D hexagonal columnar structures over a wide temperature range. The present method expands the variety and utility of azapentabenzocorannulenes as promising π-conjugated cores.