Photoinduced transformations of oxime derivatives via electron donor-acceptor complex activation

The photoexcitation of electron donor-acceptor (EDA) complexes has emerged as a powerful, often metal-free strategy for generating reactive radical species under mild conditions. Ketone-derived oxime esters, particularly O-aryl oximes and cyclic O-acyl oximes, serve as exemplary electron-accepting precursors due to their tunable redox potentials and weak N-O bonds. Regarding our continuous interest in photoactive EDA driven transformations of O-acyl oximes, this review systematically organizes and analyzes the extensive literature on EDA complex-mediated reactions of these oxime derivatives by classifying the fundamental reaction pathways of the initially generated iminyl radicals: (1) iminyl radical intramolecular cyclizations for the construction of N-heterocycles; (2) iminyl radical intermolecular chemistry involving radical addition or cross-coupling; (3) cyanoalkyl radical chemistry via ring-opening of cyclic iminyl radicals, a pathway that converts iminyl radicals into synthetically versatile cyanoalkyl radicals; and (4) formal 1,3- or 1,5-hydrogen atom transfer (HAT) of iminyl radicals for remote C-H functionalization. For each category, we present mechanistic discussions underpinned by spectroscopic, kinetic, and computational evidence, highlight strategic advantages and illustrate the broad synthetic utility of this rapidly evolving platform.