Synthetic Utility of Catalytic Fe(III)/Fe(II) Redox Cycling Towards Fused Heterocycles: A Facile Access to Substituted Benzimidazole, Bisbenzimidazole and Imidazopyridine Derivatives

A catalytic Fe(III)/Fe(II) redox cycling approach has been examined and applied towards synthesis of a wide range of benzimidazole, bis-benzimidazole and imidazopyridine derivatives from oxidative coupling of aromatic ortho-diamines with aromatic as well as heterocyclic aldehydes bearing different types of substituents. This versatile and convenient method has further proven to be particularly useful in expeditiously affording a number of novel bis-benzimidazole class of Hoechst 33 258 analogs towards potential development as fluorescent nucleic acid binding probes. Successful preparation and characterization of a diverse set of thirty different compounds is presented here.