Mechanistic study on iodine-catalyzed aromatic bromination of aryl ethers by N-Bromosuccinimide

Although iodine-catalyzed reaction has rapid advances in recent years, examples on iodine-catalyzed bromination are rare and the mechanism of these reactions remains unclear. Herein, we reported an I₂-catalyzed aromatic bromination of aryl ethers by NBS and presented the details of the mechanistic study including kinetic study and the study of kinetic isotope effects. The study revealed that the reaction was actually catalyzed by IBr formed in the induction period, and the rate-determining step was the HBr-elimination of the Wheland intermediate assisted by IBr.