Progress in intermolecular radical umpolung addition to alkenes

Conventional organic synthesis is constrained by innate polarity, often requiring multi-step sequences under harsh conditions. The "umpolung" strategy enables polarity reversal for unconventional bond formations, while radical chemistry efficiently forges C-C bonds under mild conditions. Integration of radical chemistry with umpolung tactics has rapidly evolved into a versatile paradigm, significantly expanding the synthetic toolbox. This review summarizes recent advances in the intermolecular umpolung radical (α-carbonyl, α-sulfonyl, and acyl radicals) addition to alkenes, focusing on radical generation, alkene addition, functionalization pathways, and mechanistic insights that enable efficient access to architecturally diverse molecules.