Advances in Photochemical Alkene Difunctionalization via Electron Donor–Acceptor (EDA) Complexes

Alkenes are ubiquitous and versatile feedstocks in organic synthesis. Alkene difunctionalization, which enables the simultaneous installation of two functional groups across the carbon–carbon double bond, represents a highly efficient strategy for constructing complex molecular architectures. Although conventional visible‐light photoredox catalysis has proven effective for such transformations, its practical application is frequently hampered by the reliance on expensive metal photocatalysts. In this context, the photochemistry of electron donor–acceptor (EDA) complexes has emerged as a novel and environmentally benign synthetic paradigm. Obviating the need for exogenous photosensitizers, this strategy is driven by the visible‐light‐induced single‐electron transfer (SET) of in situ generated EDA complexes to afford reactive radical intermediates. The subsequent interception of these radicals by alkenes triggers diverse downstream transformations, including addition and cyclization processes. This review comprehensively summarizes recent advances in EDA‐complex‐mediated alkene difunctionalization. Categorized by intermolecular and intramolecular reaction modes, we systematically examine the experimental conditions, substrate scopes, advantages, and limitations of these transformations, while providing in‐depth insights into the underlying radical mechanisms. Furthermore, we highlight the persistent challenges and outline future directions in this rapidly evolving field, aiming to provide a valuable reference for the development of novel and sustainable synthetic methodologies.