A new electrophilic CF2H reagent and metal-free photocatalytic di- and tri-fluoromethylation by perylene were developed.

Monofluoromethyl (CH2F) radical can be easily generated from a sulfoximine-based precursor (CH2F–S­(=O)­(=NTs)-Ph) by the action of visible-light metal-free photoredox catalysis with readily accessible 1,4-bis­(diphenylamino)­naphthalene. The catalyst design based on the high excitation energy (E 0,0) and interchromophoric conjugation features a strong reducing power and a high quantum yield of emission of the photocatalyst. In addition, their photophysical properties are preserved in various polar solvents. The present system is amenable to oxy-monofluoromethylation of alkenes with high functional-group tolerance, i.e., single-step synthesis of γ-fluoroalcohol scaffolds from various alkenes. Applications to late-stage functionalization of potentially bioactive molecules are also shown.

Well-defined 9,10-bis­(di­(p-tert-butylphenyl)­amino)­anthracene serves as a photocatalyst for radical fluoroalkylation under visible light irradiation. The diarylamine (Donor)–anthracene (π conjugated system)–diarylamine (Donor) scaffolds are easily accessed by typical palladium-catalyzed cross-coupling protocols of the corresponding halogenated anthracenes with various lithium diarylamides. The anthracene-based photocatalyst exhibits high reducing power, leading to generation of versatile fluoroalkyl radicals such as tri- and difluoroethyl and tri- and difluoromethyl radicals from the corresponding electron-accepting precursors. Catalyst design strongly influences the absorption capability of visible light and stability toward redox stimuli. The detailed mechanistic studies on the metal-free photocatalytic amino-trifluoroethylation of styrene with diphenyl­(2,2,2-trifluoroethyl)­sulfonium trifluoromethanesulfonate suggest that the reaction proceeds via catalytic radical processes rather than radical chain processes. In addition, the static quenching process is involved in the first single-electron-transfer (SET) process from the photocatalyst to the fluoroalkylating reagent. Furthermore, the 1e-oxidized cationic radical species of 9,10-bis­(di­(p-tert-butylphenyl)­amino)­anthracene, a key active catalytic species with long lifetime and a characteristic IVCT (Intervalence Charge Transfer) band in the near IR (NIR) region, is detected. From the viewpoint of elemental strategy initiative and green chemistry, the present noble metal-free organic photocatalytic system provides a pivotal technology to replace ruthenium- and iridium-based metal photocatalysis.