The Shuttle of Sulfur Dioxide: Iridium/Copper‐Cocatalyzed Trifluoromethylfluorosulfonylation of Alkenes

Abstract

Depending on the nature of the attached functional moiety, the sulfonyl radical can either undergo an automatic SO 2 liberation or react directly as the thermodynamically favored sulfonyl radical. Taking advantage of this unique property, we envisioned that through rational reaction design, the in situ release and re-insertion of SO 2 , i. e., the shuttle of SO 2 , can be realized. Herein we report our recent progress in copper metallaphotoredox cocatalyzed trifluoromethyl-fluorosulfonylation of alkenes with TFSP as both the CF 3 and SO 2 source. Valuable functional groups are added across the double bonds. Besides, A wide array of synthetically useful moieties featuring distinct electronic patterns and various nitrogenous heterocycles are well tolerated by this strategy.

Recent Advances in Developing Radical Methods for the Synthesis of Aliphatic Sulfonyl Fluorides

“…Recently, the Xiao group reported a trifluoromethyl‐fluorosulfonylation reaction of alkenes with a new reagent, TFSP, as a competent source of both CF 3 radicals and SO 2 via copper/Ir(ppy) 3 co‐catalyzed photoredox pathway (Scheme 31). [48] This method provided an efficient and facile access to FSO 2 ‐containing molecules through SO 2 shuttle. Furthermore, this transformation could be well applied to a range of alkene substrates and showed a good tolerance to various functional groups as well as pharmaceutically relevant heterocycles.…”

Recent Developments in Selenylation and Thiolation of Alkenes via Three‐component Reactions

“…The synthetic condition was mild, avoiding hazardous reagents and transition-metal catalysts (Scheme 58). The Xiao group [78] reported a novel SO 2 surrogate 59.1 and its application in sulfonylation-trifluoromethylation 59.2. Both sulfonyl and trifluoromethyl radicals came from the pyridinium salt 59.1.…”

“…The Xiao group [78] reported a novel SO 2 surrogate 59.1 and its application in sulfonylation‐trifluoromethylation 59.2 . Both sulfonyl and trifluoromethyl radicals came from the pyridinium salt 59.1 .…”

Photocatalytic Keto- and Amino-Trifluoromethylation of Alkenes

“…Based on the mechanistic investigation and our previous studies, , we propose a plausible mechanism, as shown in Scheme . The photoreductive cleavage of TFSP by the excited-state photocatalyst results in the formation of radical A , which then undergoes homolysis to produce DMAP and radical B .…”

“…The imidazolium salt (IMDN-SO 2 CF 3 ), developed by Wang and his colleagues, has shown promising capabilities in enabling the C­(sp 3 )–H trifluoromethylation of azines and the trifluoromethylation-borylation of unsaturated hydrocarbons . Although the TFSP pyridinium salt was previously known, it was first developed as a trifluoromethylation reagent by our research team. , …”