Interrupted\nPlancher Rearrangement Initiated by Dearomative\nEpoxide–Indole Cyclization: Formal Umpolung Reactivity of Indoles

We herein report the serendipitous discovery of the interrupted\nPlancher rearrangement initiated by an HFIP-promoted dearomative epoxide–indole\ncyclization, unlocking a new blueprint to the formal C3 umpolung reactivity\nof indoles. This rapid complexity generating cascade process paves\nthe way toward a new class of fused–bridged indolines in high\nyields and under full regio- and diastereocontrol. The reaction is\namenable to a wide range of substituents in the starting materials.