Photoinduced Transformations of Oxime Derivatives via Electron Donor-Acceptor Complexes Activation

Abstract

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.