Persistent Radical Cation Catalysis Enables Radical-Polar Crossover Cycloisomerization of Unactivated Alkenes to...

Saturated heterocycles are privileged pharmacophores, yet their synthetic development is often limited by a narrow substrate scope and metal dependence. We describe a metal-free photochemical strategy catalyzed by a persistent radical cation (PTH^•+) that facilitates cycloisomerization via oxidative radical-polar crossover (ORPC). This approach converts CF₃•-derived alkyl radicals into alkylsulfonium intermediates as masked carbocations, enabling efficient synthesis of CF₃-functionalized γ-butyrolactones and tetrahydrofurans in 25-85% yields. The reaction features broad substrate compatibility, including challenging radicals, and proves to be effective in late-stage modification of bioactive molecules, highlighting its potential for complex heterocycle synthesis.