An Annulative Synthetic Strategy for Building Triphenylene Frameworks by Multiple C−H Bond Activations

C−H activation is a versatile tool for appending aryl groups to aromatic systems. However, heavy demands on multiple catalytic cycle operations and site‐selectivity have limited its use for graphene segment synthesis. A Pd‐catal‐ yzed one‐step synthesis of functionalized triphenylene frameworks is disclosed, which proceeds by 2‐ or 4‐fold C−H arylation of unactivated benzene derivatives. A Pd2(dibenzylideneacetone)3 catalytic system, using cyclic diaryliodonium salts as π‐extending agents, leads to site‐selective inter‐ and intramolecular tandem arylation sequences. Moreover, N‐substituted triphenylenes are applied to a field‐effect transistor sensor for rapid, sensitive, and reversible alcohol vapor detection. Closing the circle: Palladium‐catalyzed 2‐ or 4‐fold C−H arylation of unactivated arenes was developed to access substituted triphenylene frameworks.