Electrophotocatalytic Undirected C−H Trifluoromethylations of (Het)Arenes

Abstract

Electrophotochemistry has enabled arene C−H trifluoromethylation with the Langlois reagent CF3SO2Na under mild reaction conditions. The merger of electrosynthesis and photoredox catalysis provided a chemical oxidant‐free approach for the generation of the CF3 radical. The electrophotochemistry was carried out in an operationally simple manner, setting the stage for challenging C−H trifluoromethylations of unactivated arenes and heteroarenes. The robust nature of the electrophotochemical manifold was reflected by a wide scope, including electron‐rich and electron‐deficient benzenes, as well as naturally occurring heteroarenes. Electrophotochemical C−H trifluoromethylation was further achieved in flow with a modular electro‐flow‐cell equipped with an in‐operando monitoring unit for on‐line flow‐NMR spectroscopy, providing support for the single electron transfer processes.

The Dark Side of Photocatalysis: One Thousand Ways to Close the Cycle

“…Also in this case, the anode took care of recovering the PC RED formed in solution, while the cathode reduced protons to hydrogen gas. Notably, Ru(bpy) 3 (PF 6 ) 2 was found to be competent in promoting the formation of the desired products as well …”

Recent Advances in Rapid Synthesis of Non-proteinogenic Amino Acids from Proteinogenic Amino Acids Derivatives via Direct Photo-Mediated C–H Functionalization

“…NaSO 2 CF 3 as a stable, inexpensive, and easy-handling trifluoromethyl synthon has been applied in the trifluoromethylation of tryptophans catalyzed by the mesoporous graphitic carbon nitride (mpg-CN) [63] and iridium complex [64], respectively. Notably, electrochemistry was merged with photochemistry to catalyze the trifluoromethylation of tryptophan with NaSO 2 CF 3 [65]. The cooperative catalysis by electrophotochemistry relied on the anodic electrooxidation to undergo the regeneration of the photocatalyst, rather than the chemical oxidants.…”

Hole-Mediated PhotoRedox Catalysis: Tris(p-Substituted)biarylaminium Radical Cations as Tunable, Precomplexing and Potent Photooxidants

“…(38)(39) A third category involves an intimate and synergistic relationship of photo-and electrochemical steps within the same catalytic cycle. (40-51) A variety of nomenclature has been coined in the literature for this sub-category of PEC, such as: "electrophotocatalysis" (45-47,51) "photoelectrocatalysis" (46,50) and "electron-primed photoredox catalysis" (51). We coined the general nomenclature "electrochemically-mediated PhotoRedox Catalysis (e-PRC)" as a blanket term to cover both net-oxidative and net-reductive variants (29) and to avoid misunderstanding with iPEC.…”

“…We coined the general nomenclature "electrochemically-mediated PhotoRedox Catalysis (e-PRC)" as a blanket term to cover both net-oxidative and net-reductive variants (29) and to avoid misunderstanding with iPEC. e-PRC leverages the unique benefits of both parent technologies PRC and SOE in order to i) compile potential and photon energies to achieve photocatalyst excited-state potentials beyond those normally accessible via visible light photons alone (44)(45)(46)51) and to ii) obviate the need for sacrificial oxidants/reductants. (48,50) Pioneering reports on e-PRC realized these benefits in a number of net-reductive/net-oxidative transformations.…”

“…(48,50) Pioneering reports on e-PRC realized these benefits in a number of net-reductive/net-oxidative transformations. (44)(45)(46)(47)(48)(49)(50)(51) In the net-oxidative direction , previous examples of electroactivated PhotoRedox Catalysts (e-PRCats) include i) 9-mesityl-10-methylacridinium dye, (44) ii) phenothiazine (40) (Figure 1).…”