Electrochemical oxidations of thioethers: Modulation of oxidation potential using a hydrogen bonding network

Electrochemistry Enabled Selective Vicinal Fluorosulfenylation and Fluorosulfoxidation of Alkenes

“…Monitoring the reaction revealed that a facile Z→E isomerization of (Z)-stilbene 46 occurred before the anticipated fluorosulfenylation, which was likely a thiyl-radical-mediated process. 47 The oxygen atoms in the sulfoxide product likely originated from the adventitious H2O in the reaction mixture 48 rather than O2, as a similar yield of fluorosulfoxide (63) was obtained under rigorously oxygen-free conditions. This was further substantiated by the O 18 isotope labelling experiments, which showed that the degree of O 18 incorporation in the fluorosulfoxide (63) was roughly proportional to the amount of H2O 18 added (Scheme 2E).…”

Electrochemistry Enabled Selective Vicinal Fluorosulfenylation and Fluorosulfoxidation of Alkenes

“…Monitoring the reaction revealed that a facile Z→E isomerization of (Z)-stilbene 46 occurred before the anticipated fluorosulfenylation, 10 which was likely a thiyl-radical-mediated process. 47 The oxygen atoms in the sulfoxide product likely originated from the adventitious H2O in the reaction mixture 48 rather than O2, as a similar yield of fluorosulfoxide (63) was obtained under rigorously oxygen-free conditions. This was further substantiated by the O 18 isotope labelling experiments, which showed that the degree of O 18 incorporation in the fluorosulfoxide (63) was roughly proportional to the amount of H2O 18 added (Scheme 2E).…”

“…Furthermore, a variety of thiophenols bearing electron-donating or electronwithdrawing groups all reacted to afford the desired fluorosulfides in moderate to good yields (39-46, 38%-87%). Encouragingly, cyclohexyl-(47), benzyl- (48), and heterocycle-containing (49-52) thiols were all competent thiolating agents. Note that the applied cell potential was readjusted to 2.8 V when the electro-deficient 5-mercapto-1-methyltetrazole (51) and 2-mercapto-5-methyl-1,3,4-thiadiazole (52) were employed as the thiolating agents.…”

Sulfoxide and Sulfone Synthesis via Electrochemical Oxidation of Sulfides

“…However, both approaches are limited to the formation of sulfoxides from sulfides, and they did not show any example of the formation of sulfones . Although electrochemical sulfide oxidation under constant voltage has been reported to provide the corresponding sulfoxides and sulfones, only a few examples of diaryl sulfones have been accessed via these methods . Very recently, the electrochemical oxidations of sulfide under constant current were also reported; however, they did not show the formation of diaryl sulfones .…”

“…12 Although electrochemical sulfide oxidation under constant voltage has been reported to provide the corresponding sulfoxides and sulfones, only a few examples of diaryl sulfones have been accessed via these methods. 13 Very recently, the electrochemical oxidations of sulfide under constant current were also reported; however, they did not show the formation of diaryl sulfones. 14 development of the selective electrochemical synthesis of sulfoxides and sulfones including diaryl sulfones is highly demanded.…”