Intramolecular Homolytic Aromatic Substitution of Alkyl 2-Benzimidazolyl Sulfones as a Means of Entry into Alkyl Radicals for Organic Synthesis.

The intramolecular radical aromatic substitution of heteroaryl sulfones by tethered aryl radicals has been investigated as a source of alkyl radicals. The 1-(2-iodobenzyl)benzimidazole-2-sulfonyl system was found to be the most effective, while a tetrazole-based system did not undergo the desired radical aromatic substitution at all. Application of the benzimidazole-based system to the generation of alkyl radical and their subsequent use in radical cyclizations was demonstrated.