Radical Reactions of Vinyl Triflates and its Derivatives

Abstract

Vinyl triflates are valuable precursors for vinyl cations, vinyl carbenes, and electrophiles for transition-metal-catalyzed cross-coupling reactions. However, in these reactions, the trifluoromethyl group is not installed in the final products. The radical reactions of vinyl triflates were limited until our beginning. We initially achieved the synthesis of α-trifluoromethylated ketones from vinyl triflates using triethyl borane as a radical initiator. Since the reaction proceeds chemoselectivity toward the conjugated vinyl triflates, we achieved the chemo- and regio-selective trifluoromethylation of 1,3-bis(vinyl triflates). We developed one-pot trifluoromethylation from aryl alkynes with perfluoroalkanesulfonic acids in the presence of AIBN as a radical initiator. In addition, a crossover experiment and DFT calculations support that the reaction proceeds through an intermolecular pathway. The radical reaction of vinyl triflates in the presence of alkenes afforded γ-trifluoromethylated ketones. We also developed a one-pot triflation-trifluoromethylation-triflation of imines leading trifluoromethyl-substituted vinyl trifluoromethanesulfonic amides.