Metal-free heteroarene C(sp2)–H amination with unprotected (hetero)arylamines†

Regioselective functionalization of C–H bonds has attracted the attention of chemists in recent years. However, transition metals are often expensive and indispensable in most C–H activation reactions. Here, we describe a metal-free intramolecular heteroarene C(sp²)–H amination from unprotected (hetero)arylamines. Exposure of 2-(pyridin-3-yl)aniline to potassium tert-butoxide was found to access N-heterocycles without additives, which unlocks a new breakthrough. This process is involved in the synthesis of a wide variety of N-heterocycles including natural products and bioactive compounds. Mechanistic studies have established that these reactions proceed through an S_NArH process. Such a unique transformation opens the door toward the regioselective intramolecular C–H amination of weakly reactive arylamines with heterocyclic compounds.