Interrupted Plancher Rearrangement Initiated by Dearomative Epoxide–Indole Cyclization: Formal Umpolung Reactivity of Indoles

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