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

Area of Science:

• Organic Chemistry
• Photochemistry
• Radical Chemistry

Background:

• Electron donor-acceptor (EDA) complexes enable metal-free radical generation via photoexcitation.
• Ketone-derived oxime esters, especially O-aryl and cyclic O-acyl oximes, are effective electron acceptors with tunable properties.
• The weak N-O bond in oxime esters facilitates radical formation under mild conditions.

Purpose of the Study:

• To systematically review and analyze the literature on EDA complex-mediated transformations of O-acyl oximes.
• To classify the fundamental reaction pathways of iminyl radicals generated from these precursors.
• To highlight the synthetic utility and mechanistic underpinnings of these photoactive transformations.

Main Methods:

• Literature review and systematic organization of EDA complex-mediated reactions of oxime derivatives.
• Classification of iminyl radical reaction pathways: intramolecular cyclization, intermolecular reactions, ring-opening to cyanoalkyl radicals, and remote C-H functionalization via HAT.
• Mechanistic analysis supported by spectroscopic, kinetic, and computational evidence.

Main Results:

• Identified four key pathways for iminyl radicals: N-heterocycle synthesis, radical addition/cross-coupling, conversion to cyanoalkyl radicals, and remote C-H functionalization.
• Demonstrated the broad synthetic utility of O-acyl oximes in photoactive EDA chemistry.
• Provided mechanistic insights into these transformations.

Conclusions:

• O-acyl oximes are versatile precursors for generating diverse radical species through EDA complex photoexcitation.
• The reviewed pathways offer strategic advantages for constructing complex molecules and functionalizing C-H bonds.
• This rapidly evolving platform provides powerful tools for modern organic synthesis.