The First Synthesis of Subporphyrins

Because of the rich coordination chemistry and unique optical and electrochemical properties, porphyrin analogues have been intensively investigated. Among them, subporphyrins have been long-awaited molecules, with only their boron complexes known to date because of the crucial role of the central boron atom as a template in synthesis. The challenges related to the synthesis of a genuine subporphyrin (boron-free) have finally been met and reported in a recent article from Kim, Osuka, and Song. A key strategy of their synthesis lies in the introduction of an exocyclic double bond at the meso-position and subsequent reduction to obtain macrocyclic conjugation. Considering the fact that the development of porphyrin chemistry is ultimately linked to the availability of free base porphyrins, this seminal work will facilitate studies on coordination chemistry and applications in materials science.

Automated summary

Porphyrin analogues have attracted intensive investigations due to their rich coordination chemistry and unique optical and electrochemical properties. Among them, subporphyrins, especially the boron-free ones, have long been awaited. Recently, Kim, Osuka, and Song successfully synthesized a boron-free subporphyrin by introducing an exocyclic double bond at the meso-position and subsequent reduction to obtain macrocyclic conjugation. This seminal work will significantly facilitate studies on coordination chemistry and applications in materials science, as the availability of free base porphyrins is crucial for the development of porphyrin chemistry.