Transition-Metal-Free ipso-Trifluoromethylthiolation of Lithium Aryl Boronates.

A transition-metal-free direct trifluoromethylthiolation of the ipso-carbon of lithium aryl boronates with trifluoromethanesulfenate under mild conditions was described. In addition, late-stage site-selective C-H borylation/trifluoromethylation and C-Cl borylation/trifluoromethylthiolation of biologically active molecules was developed. Initial mechanistic study suggested that the Li+ cation plays a vital role by coordinating to the oxygen atom of an aryl boronate complex and the oxygen of the reagent, thus allowing the aryl group to directly attack the trifluoromethylthio group of the trifluoromethylthiolating reagent.