N‑Hydroxyphthalimide-Mediated Electrochemical Denitrogenation of Aroylhydrazides to Generate Acyl Radicals and Their Applications in the Syntheses of Fluorenones

N-Hydroxyphthalimide (NHPI)-mediated electrochemical denitrogenation of aroylhydrazides is developed for the first time. The in situ generated acyl radicals could be intramolecularly trapped to give fluorenones with high efficiencies. This electrochemical method features external oxidant- and transition metal-free conditions. In addition, the use of the catalytic amount of 2,4,6-collidine as the base makes this method more attractive for the syntheses of fluorenones.