NH-Heterocyclic Aryliodonium Salts and their Selective Conversion into N1-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 N1‐aryl‐5‐iodoimidazoles. Iodine acts as a “universal” placeholder poised for replacement by aryl substituents. These new λ3‐iodanes are produced by treating the NH‐imidazole with ArI(OAc)2, and are converted to N1‐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. Stepping stones: Novel imidazolyl aryliodonium salts serve as intermediates on the way to N1‐aryl‐5‐iodoimidazoles. An iodine substituent acts as a “universal” placeholder, poised for replacement by other substituents. These new λ3‐iodanes are produced by treating the NH‐imidazole with ArI(OAc)2, and are converted into N1‐aryl‐5‐iodoimidazoles by a selective copper‐catalyzed aryl migration.