Copper-Catalyzed [3+2] Annulation of Azides with a (Difluorovinyl)zinc Complex, Fluoroacetylene Equivalent

The copper-catalyzed [3 + 2] annulation of organic azides with (2,2-difluorovinyl)zinc chloride-TMEDA was achieved via C-F bond cleavage. Thus, a series of 1-substituted 4-fluorotriazoles was synthesized in high yields. In this reaction, the difluorovinylzinc complex functions as an easy-to-handle equivalent of fluoroacetylene (FC CH) to undergo cycloaddition with azides. This work offers a facile and practical method for the use of fluoroacetylene, which has been considered to be highly reactive and difficult to handle and control for synthetic applications.