Iron-Promoted Radical Reactions: Current Status and Perspectives

Catalysis based on precious metals has reached an incredible level of sophistication and has found widespread use and application, both in academia and in industry. However, owing to the environmental impact, cost, and low abundance, catalysis based on inexpensive, abundant, and environmentally benign first-row transition metals has become a valuable alternative to traditional reactions promoted by their less-abundant counterparts. From economic and ecological perspectives, iron salts and iron metal complexes are highly promising candidates to replace costly and toxic metals. In recent years, iron complexes have been used to promote the formation of radicals. Photoredox chemistry is a valuable method for the generation of radical species under mild conditions, but it often relies on rare-earth-metal complexes. The employment of iron complexes for the generation of radicals is attractive for the development of sustainable, simple, and effective procedures. In this Focus Review, we highlight and summarize recent radical reactions promoted by iron complexes and their application in organic reactions.