Direct Electrochemical C(sp3)-H Amidation Enabled by Hexafluoroisopropanol (HFIP)

Abstract A direct electrochemical amidation of xanthene was readily achieved under direct anodic oxidation. The reactivity of benzamides was significantly enhanced by the virtue of the solvent effect of hexafluoroisopropanol (HFIP). An obvious hydrogen bonding between HFIP and benzamide was detected, and the proton-coupled electron-transfer (PCET) effect was proposed for the enhancement effect of HFIP. In this transformation, a broad range of primary and secondary amides were readily used as amidating reagents, including l-proline-, naproxen-, and probencid-derived amides. We proposed a plausible reaction mechanism for this direct amidation based on the experimental observations.