Divergent C−H Amidations and Imidations by Tuning Electrochemical Reaction Potentials

Abstract

Electrochemical C−H functionalizations are attractive transformations, as they are capable of avoiding the use of transition metals, pre‐oxidized precursors, or suprastoichiometric amounts of terminal oxidants. Herein an electrochemically tunable method was developed that enabled the divergent formation of cyclic amines or imines by applying different reaction potentials. Detailed cyclic voltammetry analyses, coupled with chronopotentiometry experiments, were carried out to provide insight into the mechanism, while atom economy was assessed through a paired electrolysis. Selective C−H amidations and imidations were achieved to afford five‐ to seven‐membered sulfonamide motifs that could be employed for late‐stage modifications.

Recent advances in electrochemical C–H bond amination

“…Carbon cations could be attacked by primary amines instead of the secondary amines mentioned above after electrooxidation. In the approach by Schomaker, 40 primary sulfonyl amine 13 was used instead of secondary amine 9 described above, and C–H oxidative amination was still achievable electrochemically (Scheme 6). In the initial reaction stage, electron-rich benzene in 13 was readily oxidized to the corresponding radical cation 13A , which would form benzyl radical 13B by deprotonation.…”

Electrochemical Benzylic C(sp3)-H Imidation Enabled by Benzoic Acid Derived Radicals

“…Moreover, we also disclosed an electrochemical C­(sp 3 )-H amidation with the mediation of anodically generated nitrogen-centered radicals. As a part of our continuous interests in synthetic electrochemistry, we herein reported that anodically generated oxygen-centered radicals served as hydrogen-atom transfer (HAT) mediators to promote benzylic C­(sp 3 )-H imidation (Scheme c) . Interestingly, this protocol provides a complementary approach to accessing different chemoselectivity compared to the previous reports.…”