Photocatalyzed Cascade Reactions of Cyclopropanols and α-Trifluoromethyl-Substituted Olefins for the Synthesis of Fused gem-Difluorooxetanes.

Fluorinated fused rings are challenging to construct from simple starting materials. Herein, we report the first photocatalyzed cascade reactions of readily available cyclopropanols and α-trifluoromethyl-substituted olefins for the synthesis of fused gem-difluorooxetanes. Two rings and three bonds were efficiently constructed in one reaction. The reaction showed broad substrate scope and the downstream transformations of the products demonstrated the synthetic potential of the reaction. The mechanistic study supported the presence of cascade photoredox catalysis and energy transfer catalysis/direct photo-excitation processes.