Direct C3−H Amination of Imidazo[1,2‐a]Pyridine under Simple and Mild Conditions

This paper reports a simple and efficient method for the direct regioselective C3−H amination of imidazo[1,2‐a]pyridine derivatives using diphenylsulfonimide as the amination source and PhI(OAc)₂ as the oxidant. The proposed conversion protocol, which is characterized by mild and safe reaction conditions (room temperature reaction), simple execution (catalyst‐free, transition‐metal‐free, and additive‐free), and broad substrate applicability, enables the synthesis of 3‐sulfonamido‐imidazo[1,2‐a]pyridine derivatives with a wide range of functional groups. Controlled experiments and theoretical calculations indicate that the amination occurs at the C3 position through a radical mechanism. In addition, a series of indole derivatives could also be used in this amination system. This study could guide future research on green organic synthesis, which has immense industrial and academic value.