Mild and Metal‐Free CH Arylation of Imidazoles via In Situ Diazotization in Water

We report a metal‐free, open‐flask protocol for the direct CH arylation of imidazoles using aryldiazonium salts generated in situ under mild aqueous conditions. The reaction proceeds efficiently at room temperature and under air, without catalysts, ligands, or photo‐/electrochemical input, and affords monoarylated imidazoles in moderate to good yields. A wide range of anilines bearing electron‐withdrawing or electron‐donating substituents, including ortho‐ and meta‐substituted derivatives, are compatible, and carbon–halogen bonds remain intact in both coupling partners. The protocol can also be extended to related azoles under slightly modified conditions. The method thus provides a practical and scalable route to functionalized heteroaryl compounds. Importantly, this environmentally benign strategy avoids the hazards of isolated diazonium salts and expands the toolbox of sustainable CH functionalization.