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.