Radical Substitution of Polyfluoroarenes and Heteroarenes Promoted by Photoredox Activation of Organozinc Iodides

Abstract

Aromatic compounds interact with organozinc reagents under photoredox conditions, leading to the substitution products. The reaction is performed under blue light irradiation via in situ generated organozinc reagents (Barbier conditions), which are oxidized by the photocatalyst, followed by radical attack at the aromatic substrate. The method works with polyfluorinated arenes, 2‐chlorobenzoxazoles, and 2‐sulfonyl‐substituted benzothiazole.

Photoinduced radical alkylation of aldehydes with potassium alkyltrifluoroborates

“…In the case of perfluorobenzaldehyde 3g , the lower yield may be explained by the possible radical attack on the perfluorinated ring. 21 Electron-donating ( 3h,i ) and electron-withdrawing groups ( 3k–3o ) had little impact on the reaction yields. Aldehydes with free hydroxylic and carboxylic groups ( 3p,q ) were competent substrates, although they needed slightly altered conditions.…”

Radical reactions enabled by polyfluoroaryl fragments: photocatalysis and beyond

“…It involves the use of zinc as a reducing agent in a photocatalytic reaction (Scheme 33). 115 Apparently, unlike the previous process, zinc does not interact with the photocatalyst but provides an in situ generation of organozinc reagents. Oxidation of the latter leads to the formation of the target alkyl radical and further reaction proceeds similarly to the previous cases.…”

Photoredox Activation of Fluorinated Organozinc Reagents: Hydrofluoroalkylation of Unactivated and Electron Deficient Alkenes

“…With the advent of photocatalysis, , formation of radicals via single electron oxidation of the C–M bond was successfully realized, and photoredox activation of organoboranes, , siliconates, , germanes, , alkylzirconiums, , and alkyl stannanes was reported (Scheme A). Recently, we also described light promoted activation of benzyl and alkyl organozinc reagents. − …”