Chalcogen σ-hole interaction enabled radical reactions

Abstract

Chalcogen bonding (ChB), an attractive noncovalent σ-hole interaction involving Group 16 elements, has recently emerged as a powerful activation mode in synthetic chemistry. This review provides a comprehensive overview of the burgeoning field of ChB enabled radical reactions, highlighting how these σ-hole interactions unlock unprecedented reactivities under mild, transition metal-free, and photocatalyst-free conditions. The discussion is structured around two principal mechanistic themes. The first section examines cationic ChB enabled processes, wherein sulfonium and selenonium salts act as potent σ-hole donors to form photoactive charge transfer complexes with Lewis bases or dichalcogenides. The second section explores neutral ChB enabled radical reactions. Detailed mechanistic insights from spectroscopic, computational, and radical trapping experiments underscore the critical role of ChB in orchestrating single electron transfer. By consolidating these advances, this review illuminates the capabilities of chalcogen bonding as a tunable and versatile platform for radical generation and aims to inspire future developments in asymmetric catalysis, multicatalytic networks, and continuous flow applications.