Photoinduced Radical-Polar Crossover of Bicyclo[1.1.0]butanes for the Synthesis of Fluorinated Spirocycles

Fluorinated spirocycles are privileged scaffolds in drug discovery, yet their efficient synthesis remains challenging. Herein, we report a visible-light-driven radical-polar crossover cascade between bicyclo[1.1.0]butanes (BCBs) and bromodifluoroacetamides to access fluorinated spirocyclic succinimides. The reaction proceeds under mild conditions through strain-release ring-opening of the BCB framework followed by intramolecular annulation. This protocol enables rapid access to fluorinated spirocyclic heterocycles with broad substrate scope and good functional group tolerance. Preliminary mechanistic studies support the proposed reaction pathway.