Visible light-mediated difluoroalkylation of electron-deficient alkenes

Abstract

A method for the reductive difluoroalkylation of electron-deficient alkenes using 1,1-difluorinated iodides mediated by irradiation with blue light is described. The reaction involves radical addition of 1,1-difluorinated radicals at the double bond followed by hydrogen atom transfer from sodium cyanoborohydride.

Progress in Visible Light‐Induced Difluroalkylation of Olefins

“…The reaction used readily available boron cyanohydride as a source of hydrogen and as a trigger for the generation of free radicals by the irradiation of visible light. The authors proposed the reaction mechanism that involved the radical addition of 1,1‐difluorinated radicals at the double bond followed by hydrogen atom transfer from sodium cyanoborohydride [73] …”

“…The authors proposed the reaction mechanism that involved the radical addition of 1,1-difluorinated radicals at the double bond followed by hydrogen atom transfer from sodium cyanoborohydride. [73] Hydrodifluoromethylation of alkenes derived from oxindoles with (difluoromethyl)triphenylphosphonium bromide, [PPh 3 CF 2 H] + Br À using fac-[Ir(ppy) 3 ] as photocatalyst was described (Scheme 6). [74] This protocol offered a series of previously unknown difluoromethylated oxindoles containing CF 2 H quaternary centers in moderate to excellent yields.…”

(Fluoro)alkylation of alkenes promoted by photolysis of alkylzirconocenes

“…Although nucleophilic substitution of aliphatic electrophiles with carbon nucleophiles is well known, the adoption of a similar strategy to react difluoroalkyl halides with aliphatic nucleophiles remains challenging and has not been reported yet. 11 In this context, transition-metal 12 or photo-redox 13 catalyzed difluoroalkylation reactions to construct the alkylCF 2 -alkyl bond have been developed ( Fig. 1B(b) and B(c) ).…”

Reductive Bromodifluoromethylation of Nitrones Promoted by Visible Light

“…Photoredox catalysis has emerged as a powerful methodology for performing radical reactions The key feature of such processes is the ability of visible light to initiate organic reactions through catalyst excitation followed by single electron transfer. Fluorinated halides serve as excellent substrates for single electron reduction, thereby generating fluorinated radicals . Recently we have described a concept for light‐promoted reductive addition of fluorinated halides to nitrones, in which ascorbic acid serves as a stoichiometric reducing agent .…”