Electron Donor–Acceptor Complexes Without Preinstalled Sacrificial Leaving Groups: Applications in Synthesis

ABSTRACT Electron donor–acceptor complexes provide a useful platform for photocatalyst‐free radical generation under visible light irradiation and has emerged as a sustainable strategy for synthetic applications. Previous synthetic strategies based on EDA‐complex formations are typically based on engineering leaving groups into the substrates to suppress back electron transfer that impedes forward reaction. However, such pre‐functionalization affects efficiency and atom economy. This review highlights recent developments in the use of strategies for EDA‐complex formations to induce photochemical coupling‐ and cyclization reactions that do not rely on preinstalled sacrificial leaving‐groups. Most examples rely on alternative strategies to circumvent back electron transfer such as bond cleavage, oxygen‐mediated oxidation, or excitation of EDA complex precursors. These studies illustrate the rising promise of EDA complexes without incorporation of sacrificial leaving‐groups and highlight their potential as a broadly applicable, atom‐economical platform for photocatalyst‐free radical transformations in modern organic synthesis.