Pd(II)-Catalyzed Regioselective Multiple C–H Arylations of 1‑Naphthamides with Cyclic Diaryliodonium Salts: One-Step Access to [4]- and [5]Carbohelicenes

Highly efficient and rapid construction of carbohelicenes is a desired but challenging task, especially starting from simple substrates. Herein, Pd­(II)-catalyzed regioselective multiple C–H arylations of 1-naphthamides with cyclic diaryliodoniums have been accomplished for the first time, which enables facile one-step syntheses of [4]- and [5]­carbohelicenes from readily available starting materials. The resulting single and double [4]­carbohelicenes emit violet to deep-blue fluorescence; [4,5,4]-fused triple carbohelicenes exhibit sky-blue emissions, and phenoxazine-modified [4]­carbohelicene shows a delayed fluorescence emission.