Access to Aromatic Ring-Fused Benzimidazoles Using Photochemical Substitutions of the Benzimidazol-2-yl Radical
Received: 26 July 2012
Accepted after revision: 20 August 2012
31 August 2012 (eFirst)
Photochemical five-, six-, and seven-membered cyclizations from 2-iodo-1-(ω-arylalkyl)-1H-benzimidazoles are described. This method of producing aromatic ring-fused benzimidazoles is significantly more efficient than literature radical protocols using chemical initiators, although 2-iodo-1-(ω-pyridin-2-ylalkyl)-1H-benzimidazoles preferentially undergo a nucleophilic ipso-substitution onto the benzimidazole-2-position.