Development of the Peripheral Functionalization Chemistry of meso‐Free Corroles

In contrast to the extensive development of the meso‐functionalization of porphyrins, that of corroles had rarely been explored until the development of practical synthetic methods for meso‐free corroles in 2015. The ready availability of meso‐free corroles opened up meso‐functionalization chemistry of corroles, giving rise to successful synthesis of various meso‐substituted corroles such as meso‐halogen, meso‐nitro, meso‐amino, meso‐oxo, and meso‐iminocorroles as well as meso–meso‐linked corrole dimers and corrole tapes. In some cases, 2NH corroles exist as stable or transient radical species. The impact of meso‐functionalization on the structures, electronic properties, optical characteristics, and aromaticity of corroles are highlighted in this Minireview. Since reliable synthetic methods for meso‐free corroles were developed, the peripheral functionalization chemistry of corroles has blossomed again. In this Minireview, classical electrophilic reactions, SNAr reactions, and unique oxidation behavior are introduced, and their impact on the structures, electronic states, optical properties, and aromaticities of corroles are highlighted.