Difunctionalization of Alkenes via Photoinduced Oxidative Radical-Polar Crossover.

Alkene difunctionalization represents one of the most powerful and straightforward tools for the rapid assembly of structurally diverse organic molecules. This review provides a comprehensive overview of recent developments in the difunctionalization of alkenes enabled by photoinduced oxidative radical-polar crossover (ORPC). By merging the advantages of radical reactivity and polar reaction pathways, this strategy enables the efficient construction of diverse 1,2-difunctionalized skeletons under mild and controllable photochemical conditions. We systematically categorize these advances according to the type of radical species that add to the carbon-carbon double bond: carbon-centered radicals (including alkyl, acyl, and allenyl radicals, etc.) and heteroatom-centered radicals (focusing on nitrogen-centered, sulfur-centered radicals, and oxygen-centered radicals). Mechanistic aspects involving radical generation, photoexcitation pathways, and various nucleophiles are discussed to underscore the distinctive role of photoredox catalysis in these transformations. Furthermore, we highlight the substrate scope, functional group tolerance, and synthetic utility of these reactions in complex molecule assembly and drug discovery.