Visible‐Light Promoted Radical Fluoroalkylation of O‐ and N‐Substituted Alkenes

Abstract

Interaction of enol ethers enol acetates, enamides and enamines with fluorinated reagents may be considered as a reliable method for the synthesis of organofluorine compounds. While classic nucleophile/electrophile substitution or addition mechanisms cannot be realized for coupling of these components, their intrinsic reactivities are revealed with the aid of photoredox catalysis. A combination of these electron donating and accepting components provides a perfect balance needed for individual redox steps, which in some cases may proceed even without a photocatalyst. The same electronic factors also support the key C,C‐bond forming event involving addition of fluorinated radical at the electron rich double bond.

Visible-Light-Triggered Difluoroacetylation/Cyclization of Chromone-Tethered Alkenes Enabling Synthesis of Tetrahydroxanthones

“…Based on the above experimental results and the related previous reports, ,− a possible mechanism for this visible light-induced reaction is proposed in Scheme . In the presence of different photocatalysts, the reaction with bromodifluoroacetate or bromodifluoroacetamides as coupling partners proceeds via different pathways.…”

“…For the reaction with 4CzIPN as the photocatalyst (Scheme a), the initial step is the generation of an excited state *4CzIPN under visible light irradiation. The excited photocatalyst oxidizes the C–C double bond of compound 1a to give the radical cation intermediate A along with the formation of 4CzIPN – . Then, oxidation of 4CzIPN – by bromodifluoroacetamide 2a affords the difluoroacetamide radical intermediate B as well as regeneration of 4CzIPN for the next catalytic cycle.…”

Recent Advances in Visible Light‐Mediated Radical Fluoro‐alkylation, ‐alkoxylation, ‐alkylthiolation, ‐alkylselenolation, and ‐alkylamination

“…Additional insight into each of these reagents scaffolds can be found in recent reviews in the literature. [7][8][9][10][11][12][13]…”

“…Protocols involving the reactivity change (i. e. oxidation of a nucleophilic species to the radical) are also possible and have been reported recently in the context of radical fluorofunctionalization. Additional insight into each of these reagents scaffolds can be found in recent reviews in the literature [7–13] …”