A new high yielding method for the preparation of a shelf-stable electrophilic trifluoromethylthiolating reagent, N-(trifluoromethylthio)phthalimide, is described. Reaction of this reagent with a variety of aryl and vinyl boronic acids in the presence of a copper catalyst generated the trifluoromethylthiolated arenes and alkenes in good to excellent yields.