Metalloradical Catalysis: General Approach for Controlling Reactivity and Selectivity of Homolytic Radical Reactions

• Published in: Angewandte Chemie International Edition Vol. 63; no. 20; pp. e202320243 - n/a
• Main Authors: Lee, Wan‐Chen Cindy, Zhang, X. Peter
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 13.05.2024
• Edition: International ed. in English
• Subjects: aziridination; Catalysis; Catalysts; Chemical reactions; Chemical synthesis; Chemistry; Coordination compounds; cyclopropanation; C−H functionalization; Intermediates; Metal complexes; metalloradical catalysis; radical reaction; Radicals; Reactivity; Stereoselectivity; Substrates; Transition metal compounds; Urea; C−H functionalization; radical reaction; aziridination; cyclopropanation; metalloradical catalysis
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202320243

Since Friedrich Wöhler's groundbreaking synthesis of urea in 1828, organic synthesis over the past two centuries has predominantly relied on the exploration and utilization of chemical reactions rooted in two‐electron heterolytic ionic chemistry. While one‐electron homolytic radical chemistry is both rich in fundamental reactivities and attractive with practical advantages, the synthetic application of radical reactions has been long hampered by the formidable challenges associated with the control over reactivity and selectivity of high‐energy radical intermediates. To fully harness the untapped potential of radical chemistry for organic synthesis, there is a pressing need to formulate radically different concepts and broadly applicable strategies to address these outstanding issues. In pursuit of this objective, researchers have been actively developing metalloradical catalysis (MRC) as a comprehensive framework to guide the design of general approaches for controlling over reactivity and stereoselectivity of homolytic radical reactions. Essentially, MRC exploits the metal‐centered radicals present in open‐shell metal complexes as one‐electron catalysts for homolytic activation of substrates to generate metal‐entangled organic radicals as the key intermediates to govern the reaction pathway and stereochemical course of subsequent catalytic radical processes. Different from the conventional two‐electron catalysis by transition metal complexes, MRC operates through one‐electron chemistry utilizing stepwise radical mechanisms. Metalloradical catalysis (MRC) represents a versatile approach for controlling reactivity and selectivity in radical chemistry. By harnessing metalloradicals as one‐electron catalysts, MRC facilitates the homolytic activation of substrates, leading to the generation of metal‐entangled organic radicals as pivotal intermediates. The distinctive stepwise radical mechanism in MRC paves the way for innovative advancements in the field of organic synthesis.