Cu-catalyzed [2+2+1] cascade annulation of vinyl iodonium salts with elemental sulfur/selenium for the modular synthesis of thiophenes and selenophenes

A [2 + 2 + 1] annulation protocol has been established for the modular synthesis of 2,4-disubstituted thiophenes/selenophenes, with excellent regioselectivity. The reactions have been catalyzed by copper salt with elemental sulfur and selenium serving as the chalcogen source. The mechanistic study has revealed that this process was initiated by a trisulfur radical anion using EPR.

Automated summary

A [2 + 2 + 1] annulation protocol has been developed for the modular synthesis of 2,4-disubstituted thiophenes/selenophenes, showing excellent regioselectivity. Catalyzed by copper salt, the reactions utilize elemental sulfur and selenium as the chalcogen source. Mechanistic studies indicate that the process is initiated by a trisulfur radical anion detected using EPR.