Metal-Free Sequential C(sp)-H/OH and C(sp)-H Aminations of Nitrosoarenes and N-Heterocycles to Ring-Fused Imidazoles.

Hydrogen bond assisted ortho-selective C(sp)-H amination of nitrosoarenes and subsequent α-C(sp)-H functionalization of aliphatic amines is achieved under metal-free conditions. The annulation of nitrosoarenes and 2-hydroxy-C-nitroso compounds with N-heterocycles provides a facile excess to a wide range of biologically relevant ring-fused benzimidazoles and structurally novel polycyclic imidazoles, respectively. Nucleophilic aromatic hydrogen substitution (SArH) was found to be preferred over classical SAr reaction during the C(sp)-H amination of halogenated nitrosoarenes.