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.

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