Described herein is a strategy to construct cationic azahelicenes through the three‐component annulation reaction of isoquinoline, indole, and 1,2‐dichloroethane (DCE), in which DCE serves as an in situ activating agent for C1−H activation of isoquinoline, a vinyl equivalent, and a solvent. This in situ activation annulation reaction features a facile one‐step synthesis and complete regioselectivity. The complete regioselectivity of C1 over C3 for the isoquinoline ring paves a path to the helical structure in a highly ordered sequence. One of the synthesized ionic [5]azahelicenium fluorophores exhibits the potential to serve as a mitochondria‐targeted biomarker with good photostability and low cytotoxicity.

Described herein is a copper-catalyzed oxidative C–H annulation of quinolines with 1,2-chloroethane (DCE), providing a concise synthetic approach to benzoquinoliziniums. In this protocol, DCE not only serves as a solvent and an in situ activation agent of quinoline C2–H but also works as vinyl equivalents to constitute the six-membered azonia ring. Furthermore, the resultant benzoquinolizinium library exhibits good properties of binding to DNA and low cytotoxicity.

Described herein is a strategy to construct cationic azahelicenes through the three‐component annulation reaction of isoquinoline, indole, and 1,2‐dichloroethane (DCE), in which DCE serves as an in situ activating agent for C1−H activation of isoquinoline, a vinyl equivalent, and a solvent. This in situ activation annulation reaction features a facile one‐step synthesis and complete regioselectivity. The complete regioselectivity of C1 over C3 for the isoquinoline ring paves a path to the helical structure in a highly ordered sequence. One of the synthesized ionic [5]azahelicenium fluorophores exhibits the potential to serve as a mitochondria‐targeted biomarker with good photostability and low cytotoxicity.