Advancements in the Synthesis and Applications of Cationic N‐Heterocycles through Transition Metal‐Catalyzed C−H Activation

Cationic N‐heterocycles are an important class of organic compounds largely present in natural and bioactive molecules. They are widely used as fluorescent dyes for biological studies, as well as in spectroscopic and microscopic methods. These compounds are key intermediates in many natural and pharmaceutical syntheses. They are also a potential candidate for organic light‐emitting diodes (OLEDs). Because of these useful applications, the development of new methods for the synthesis of cationic N‐heterocycles has received a lot of attention. In particular, many C?H activation methodologies that realize high step‐ and atom‐economies toward these compounds have been developed. In this review, recent advancements in the synthesis and applications of cationic N‐heterocycles through C?H activation reactions are summarized. The new C?H activation reactions described in this review are preferred over their classical analogs.