Divergent Late‐Stage (Hetero)aryl C−H Amination by the Pyridinium Radical Cation

Generation of the highly reactive pyridinium radical cation enables C−H amination of both electron‐rich and ‐poor (hetero)arenes. The method is compatible with a broad range of structurally complex molecules, and provides access to aminated analogues that are difficult to synthesize otherwise. High exothermicity of the pyridinium radical addition to an arene is proposed to engender the extremely low electronic bias, both substrate‐ and position‐wise.

Abstract

(Hetero)arylamines constitute some of the most prevalent functional molecules, especially as pharmaceuticals. However, structurally complex aromatics currently cannot be converted into arylamines, so instead, each product isomer must be assembled through a multistep synthesis from simpler building blocks. Herein, we describe a late‐stage aryl C−H amination reaction for the synthesis of complex primary arylamines that other reactions cannot access directly. We show and rationalize through a mechanistic analysis the reasons for the wide substrate scope and the constitutional diversity of the reaction, which gives access to molecules that would not have been readily available otherwise.

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