Silver-catalyzed Vinylic C-F Bond Activation: Synthesis of 2-Fluoroindoles from β,β-Difluoro-o-sulfonamidostyrenes

An electrophilic 5-endo-trig cyclization of beta,beta-difluoro-o-sulfonamidostyrenes was performed in 1,1,1,3,3,3-hexafluoropropan-2-ol using a Ag(I) catalyst and N,O-bis(trimethylsilyl)acetamide. In this process, vinylic C-F bond activation was achieved via silver-catalyzed beta-fluorine elimination, accompanied by C-N bond formation, which led to the synthesis of 2-fluoroindoles.