Synthesis of 3-Haloindoles via Cascade Oxidative Cyclization/Halogenation of 2-Alkenylanilines Mediated by PIDA and LiBr/KI

The treatment of 2-alkenylanilines with phenyliodine(III) diacetate (PIDA) and LiBr or KI in HFIP was found to afford the corresponding 3-haloindoles via cascade oxidative cyclization/halogenation encompassing oxidative C-N/C-X (X = Br, I) bond formations. A plausible mechanism involving the in situ formation of the reactive AcO-X (X = Br, I) from the reaction of PIDA and LiBr/KI was postulated.

Automated summary

The treatment of 2-alkenylanilines with PIDA and LiBr or KI in HFIP leads to the formation of 3-haloindoles via cascade oxidative cyclization/halogenation involving C-N/C-X (X = Br, I) bond formations. A proposed mechanism suggests the in situ formation of reactive AcO-X (X = Br, I) from the reaction of PIDA and LiBr/KI.