F- Nucleophilic-Addition-Induced [3 + 2] Annulation: Direct Access to CF3-Substituted Indenes.

An efficient [3 + 2] annulation of (2,2-difluorovinyl)-2-iodoarenes and internal alkynes was developed for the synthesis of 1-(trifluoromethyl)-1 H-indenes. The success of this strategy hinges upon a well-balanced process for the generation of two transient reactive species, specifically trifluoroethylsilver and alkenylpalladium intermediates, in the same molecule, as well as a smooth transmetalation step, which delicately joins together these two different metallic intermediates.