Ru(bpy)₃Cl₂ as a Photocatalyst for Visible‐Light‐Induced Fluoroalkylation of Anilines with BrCF₂CF₂Br: A Facile Route to 2‐Bromo‐1,1,2,2‐tetrafluoroethyl Arenes

Abstract

Ac onvenientm ethod for the preparation of 2bromo-1,1,2,2-tetrafluoroethyl arenes, using commercially available anilinesa nd BrCF 2 CF 2 Br as starting materials was developed. The reaction proceeded in high efficiency under the irradiation of blue LEDs, and enables the installation of amino and fluoroalkyl moieties. Moreover,t he product can be easily transformed to many other 1,1,2,2tetrafluoroethylated reagents, thus demonstratingi ts high potential use for furthermodifications.

The role of photocatalysts in radical chains in homolytic aromatic substitution, radical addition to olefins, and nucleophilic radical substitution mechanisms

“…Scenarios of both processes (i.e. : oxidative [7][8][9] and reductive 10,11 ) are present in the literature. Radical chains in photoinitiated reactions [12][13][14][15] are currently postulated in the literature as well as closed catalytic loops.…”

Radical Fluoroalkylation Reactions

“…Li, He, and co-workers recently reported a visible-light-promoted direct fluoroalkylation of anilines with BrCF 2 CF 2 Br through the use of Ru­(bpy) 2 Cl 2 as the photocatalyst. A brief scope of the reaction is depicted in Scheme A.…”

“…The authors proposed a reaction mechanism such as that illustrated in Scheme B. The Ru­(bpy) 3 2+ photocatalyst is excited through irradiation with a blue LED.…”

“…In this case, the phosphate anion undergoes hydrogen bonding with the tertiary alcohol (see structure III ), leading to activation of the C–C bond toward cleavage, affording ketyl radical (ion) IV , which by an ET to R F –I propagates the cycle and affords the final product V . This methodology has also been proposed , for the perfluoroalkylation of olefins followed by β-alkynylation …”