Visible-light-driven intramolecular xanthylation of remote unactivated C(sp3)-H bonds

Remote C(sp3)–H heteroarylation of N-fluorocarboxamides with quinoxalin-2(1H)-ones under visible-light-induced photocatalyst-free conditions

“…Hence, the development of a general and "greener" methodology in the construction of functionally amidated quinoxalin-2(1H)ones via an amidyl-initiated 1,5-HAT process is highly desirable. Based on our previous work on 1,5-HAT catalysis, 14 we herein disclose an eco-friendly visible-light-induced site-selective C(sp 3 )-H heteroarylation of N-fluoroamides via radicalinvolved 1,5-HAT cascades (Scheme 1c). Importantly, our method involves the use of visible light as the energy input and occurs under metal-, external photocatalyst-, and strong oxidant-free conditions at room temperature, providing an efficient and practical synthetic methodology for the functionalization of quinoxalin-2(1H)-ones and amides.…”

Visible-light-driven selective difluoroalkylation of α-CF3 alkenes to access CF2-containing gem-difluoroalkenes and trifluoromethylalkanes

“…As part of our continued interest in photoredox catalysis, 15 we herein developed a photoredox-catalyzed defluorinative difluoroalkylation and hydrodifluoroalkylation of α-trifluoromethyl alkenes through intermolecular difluoroalkyl radical addition, which gives various difluoromethylene-containing gem -difluoroalkenes and trifluoromethylalkanes in good yields (Scheme 1d). Generally, the α-trifluoromethyl alkene fragment is electrically prone to undergo an addition reaction with difluoroalkyl radicals, resulting in an α-CF 3 alkyl radical, which allows two terminative patterns of β-F elimination and protonation.…”

Copper-Catalyzed Asymmetric Remote C(sp3)–H Alkylation of N-Fluorocarboxamides with Glycine Derivatives and Peptides

“…Recently, the Hofmann–Löffler–Freytag (HLF) reaction has been extensively studied and shown its effectiveness as an alternative for the specific activation of remote inert C­(sp 3 )–H bonds triggered by 1,5-HAT that in situ forms N-centered radicals (NCRs) . So far, the research of the HLF reaction has been mainly limited to C–H halogenation, cyanation, trifluoromethylation, azidation, arylation, sulfonylation, alkynylation, and xanthylation . Despite these notable precedents, asymmetric HLF-type remote C­(sp 3 )–H functionalization remains exceptionally uncommon, and only asymmetric remote C­(sp 3 )–H cyanation and alkynylation have been realized (Scheme B) …”