Brønsted‐Acid‐Catalyzed para‐Selective Diazotization of Anilines with Aryl Diazonium Tetrafluoroborates

An efficient brønsted acid‐catalyzed method for the para‐selective diazotization at the aromatic carbon‐hydrogen sites para to an amido substituent in nonpolar solvent is illustrated, using aryl diazonium tetrafluoroborates as diazotization reagents. The direct transformation occurs under mild reaction conditions with ample scope, avoids the use of metals, and is tolerated with valuable functional groups. It is a simple way to generate a broad spectrum of functionalized azo anilines from basic starting materials with good to excellent yields. An efficient brønsted acid‐catalyzed method for the para‐selective diazotization at the aromatic carbon‐hydrogen sites para to an amido substituent in nonpolar solvent is illustrated, using aryl diazonium tetrafluoroborates as diazotization reagents. The approach avoids the use of transition metals and air‐sensitive reagents. The reaction can be performed under room temperature, generating a broad spectrum of functionalized azo anilines from basic starting materials with good to excellent yields.