Dichalcogenides (disulfides and diselenides), as reactants for organic transformations, are important and widely used because of their potential to react with nucleophiles, electrophilic reagents, and radical precursors. In recent years, in combination with photochemical technology, the application of dichalcogenides as stable radical reagents has opened up a new route to the synthesis of various sulfur- and selenium-containing compounds. In this paper, synthetic strategies for disulfides and diselenides and their applications with photochemical technology are reviewed: (i) Cyclization of dichalcogenides with alkenes and alkynes; (ii) direct selenylation/sulfuration of C−H/C−C/C−N bonds; (iii) visible-light-enabled seleno- and sulfur-bifunctionalization of alkenes/alkynes; and (iv) Direct construction of the C(sp)–S bond. In addition, the scopes, limitations, and mechanisms of some reactions are also described.

Thios/selenium sulfonates are key structural skeletons in natural products, synthetic bioactive molecules and marketed therapeutic drugs, as well as important building material in organic synthesis, and are widely used in drug molecules and materials science. With the rapid development of transition metal-catalyzed, photocatalytic and electrocatalytic radical reactions, breakthroughs in radical chemistry have been achieved in the field of synthesis. Therefore, the applications of thios/selenium sulfonates as radical reagent have attracted extensive attention. The applications of thios/selenium sulfonates as radical reagent in metal catalysis, visible light catalysis, metal-light synergistic catalysis and other types of catalysis, which have been developed rapidly in recent years, are reviewed, and the mechanisms of some reactions are discussed in detail.