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 (Tf2O) as a radical trifluoromethylthiolating reagent. Hydrotrifluoromethylthiolation of unactivated alkenes and alkynes with Tf2O in the presence of PMePh2 and H2O under visible‐light photoredox catalysis gave the addition products. The trifluoromethylthio radical (.SCF3) was first formed from Tf2O through a photoredox radical processes and deoxygenative reduction of PMePh2, and H2O serves as the H‐atom donor for the hydrotrifluoromethylthiolation reaction. This reaction provides a new strategy for radical trifluoromethylthiolation.

Radical reactions promoted by trivalent tertiary phosphines

“…29). 53 Trifluoromethanesulfonic anhydride (abbreviated as Tf 2 O) was used as the trifluoromethylthiolation reagent in this process; methyldiphenylphosphine (PPh 2 CH 3 ) was used as both a reducing reagent for the Tf 2 O and a radical carrier for the radical chain reactions. A broad scope of trifluoromethylthiolated alkanes 190 and alkenes 191 were afforded through this approach in moderate to excellent yields ( Fig.…”

Metal-free visible-light-enabled vicinal trifluoromethyl dithiolation of unactivated alkenes

“…In 2017, the photoredox-catalyzed intermolecular trifluoromethylthio–trifluoromethylation and thiosulfonylation reaction of unactivated alkenes have been respectively developed by Liu [ 34 ] and Xu [ 42 ]. Recently, Qing [ 43 ] and co-workers reported an efficient anti -Markovnikov hydrotrifluoromethylthiolation of alkenes utilizing trifluoromethanesulfonic anhydride (Tf 2 O) as a radical trifluoromethylthiolating reagent through a deoxygenative reduction and a photoredox radical pathway ( Scheme 1b ). The C–S bond [ 44 – 45 ] is an important structural motif that is widely present in natural products, drug molecules, biologically active molecules, and functional materials.…”

Metal-free visible-light-enabled vicinal trifluoromethyl dithiolation of unactivated alkenes

“…Recently, Qing [43] and co-workers reported an efficient anti-Markovnikov hydrotrifluoromethylthiolation of alkenes utilizing trifluoromethanesulfonic anhydride (Tf2O) as a radical trifluoromethylthiolatin reagent through deoxygentive reduction and photoredox radical pathway (Scheme 1b). The C-S bonds [44,45] are important structural motifs and widely present in natural products, drug molecules, biologically active molecules and functional materials.…”