NH‐Heterocyclic Aryliodonium Salts and their Selective Conversion into N 1‐Aryl‐5‐iodoimidazoles

The synthesis of N ‐arylimidazoles substituted at the sterically encumbered 5‐position is a challenge for modern synthetic approaches. A new family of imidazolyl aryliodonium salts is reported, which serve as a stepping stone on the way to selective formation of N 1‐aryl‐5‐iodoimidazoles. Iodine acts as a “universal” placeholder poised for replacement by aryl substituents. These new λ 3 ‐iodanes are produced by treating the NH ‐imidazole with ArI(OAc) 2 , and are converted to N 1‐aryl‐5‐iodoimidazoles by a selective copper‐catalyzed aryl migration. The method tolerates a variety of aryl fragments and is also applicable to substituted imidazoles.