Annulative π‐Extension (APEX): Rapid Access to Fused Arenes, Heteroarenes, and Nanographenes

The annulative π‐extension (APEX) reaction has the potential to have a tremendous impact on the fields of materials science and bioimaging, as well as on the pharmaceutical/agrochemical industries, since it allows access to fused aromatic systems from relatively simple aromatic compounds in a single step. Typically, an APEX reaction facilitates a one‐pot π‐extension without the need to prefunctionalize the aromatic compounds. This advantageous feature is extremely useful for tuning and modifying molecular properties in the last step of a synthesis. In this Review, the progress and applications of APEX reactions of unfunctionalized arenes and heteroarenes are described.