Hydrotrifluoromethylthiolation of Unactivated Alkenes and Alkynes with Trifluoromethanesulfonic Anhydride through Deoxygenative Reduction and Photoredox Radical Processes

Abstract An ongoing challenge in trifluoromethylthiolation reactions is the use of less expensive and easily available trifluoromethylthio sources. Herein, we disclose an unprecedented usage of trifluoromethanesulfonic anhydride (Tf 2 O) as a radical trifluoromethylthiolating reagent. Hydrotrifluoromethylthiolation of unactivated alkenes and alkynes with Tf 2 O in the presence of PMePh 2 and H 2 O under visible‐light photoredox catalysis gave the addition products. The trifluoromethylthio radical ( . SCF 3 ) was first formed from Tf 2 O through a photoredox radical processes and deoxygenative reduction of PMePh 2 , and H 2 O serves as the H‐atom donor for the hydrotrifluoromethylthiolation reaction. This reaction provides a new strategy for radical trifluoromethylthiolation.