Photoredox Catalyzed Remote C(sp3)–H Trifluoromethylation

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We plan to develop a photoredox-catalyzed trifluoromethylation of remote unactivated C(sp3)–H bonds intramolecularly directed by an amide group. We propose that this catalysis proceeds via oxidation of an in-situ-formed amidyl anion by a metal-based photocatalyst, which undergoes quickly a 1,5-hydrogen atom transfer. The resulted carbon-centered radical can be coupled with a trifluoromethyl radical by another transition metal catalyst via radical cross-coupling. Optimization studies will include screenings of trifluoromethylating reagents, used solvents and bases, as well as screenings of the photocatalysts and cross-coupling catalysts. Our final plans are to expand this methodology toward intermolecular trifluoromethylation of secondary C(sp3)–H bonds in simple alkanes by an intermolecular hydrogen abstraction. Moreover, the fluorination of unactivated C(sp3)–H bonds would be of similar interest to us. Analytical methods like cyclic voltammetry and Stern-Vollmer experiments should help elucidating the reaction mechanism of this catalysis.