Electrochemical Arylation of Electron‐Deficient Arenes through Reductive Activation

Abstract

An electrochemical method has been developed to achieve arylation of electron‐deficient arenes through reductive activation. Various electron‐deficient arenes and aryldiazonium tetrafluoroborates are amenable to this transformation within the conditions of an undivided cell, providing the desired products in up to 92 % yield. Instead of preparing diazonium reagents, these reactions can begin from anilines, and they can be carried out in one pot. Electron paramagnetic resonance studies indicate that cathodic reduction of quinoxaline occurs using the transformation. Moreover, cyclic voltammetry indicates that both quinoxaline and aryl diazonium salt have relatively low reduction potentials, which suggests they can be activated through reduction during the reaction.

Time-Resolved EPR Revealed the Formation, Structure, and Reactivity of N-Centered Radicals in an Electrochemical C(sp3)–H Arylation Reaction

“…Through previous reports, N -heteroarenes could be reduced to radical anion at the cathode and then coupled with another C-centered radical to build the C–C bond. To determine whether the cathodic reduction of 3a involved in this reaction, we measured the reductive potential of 3a (Figure S19).…”

Mechanochemical Synthesis of 2‐Arylquinoxalines and 3‐Arylquinoxalin‐2(1H)‐ones via Aryldiazonium Salts

“…Contemporaneously, Kim’ group [7] developed analogously visible light photoredox‐catalyzed arylation of quinoxalin‐2(1 H )‐ones with aryldiazonium salts in DMSO (Figure 1). In 2019, Lei and Zhang's team [8] developed a electrochemical arylation method for the synthesis of 2‐arylquinoxaline and other electron‐deficient arenes utilizing acetonitrile (CH 3 CN) and trifluoroacetic acid (TFA) as the co‐solvent (Figure 1). Almost at the same time, Zeng and co‐workers [9] developed electrochemical cross‐coupling of C(sp 2 )−H with aryldiazonium salts in DMSO, affording the product of 2‐arylquinoxaline and 3‐arylquinoxalin‐2(1 H )‐one (Figure 1).…”

Electrocatalytic Deuteration of Halides with D2O as the Deuterium Source over a Copper Nanowire Arrays Cathode

“…A decreased conversion of the product after adding tertiary butanol ( t ‐BuOH), which could scavenge the hydrogen atoms, was observed, identifying the role of hydrogen radicals in this electrocatalytic reduction reaction (Supporting Information, Figure S7). However, a direct abstraction of deuterium atom from the D 2 O molecule by carbon radicals for deuterium incorporation could not be fully ruled out …”