Cu(I)‐Catalyzed Interrupted Cycloaddition Between Azides, Ag(I)‐Acetylides, and Diorganoyl Dichalcogenides

Herein, an efficient and mild Cu(I)‐catalyzed interrupted cycloaddition is described between organic azides and Ag(I)‐acetylides, using diorganoyl dichalcogenides as trapping reagents of the Cu(I) triazolide intermediate to prepare fully substituted 1,2,3‐triazoles containing an organochalcogen (S, Se, Te) group at C5 position. It is found that chalcogenoacetylenes and 1,4‐disubstituted‐1,2,3‐triazoles are competitive side products in this reaction, but the use of Ag(I)‐acetylides and LiCl as an additive in dimethyl sulfoxide (DMSO) significantly increased the yields and selectivity for 1,4‐disubstituted‐5‐organochalcogen‐1,2,3‐triazoles. Ag(I)‐acetylides are well‐known for their low solubility in organic solvents. However, the LiCl/DMSO mixture exhibits an interesting, unexplored ability to dramatically increase the solubility of Ag(I)‐acetylides regardless of their molecular structure. The complete solubilization of Ag(I)‐acetylides is the key to controlling the reaction chemoselectivity, and insights on this effect and its interplay with the reaction mechanism are discussed.