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

Abstract

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 bisbenzimidazole class of Hoechst 33258 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.

Antiviral activity of benzimidazole derivatives. II. Antiviral activity of 2-phenylbenzimidazole derivatives

“…Method a: 13 the appropriate diamino compounds and aldehydes were reacted in the presence of FeCl 3 /O 2 ; in one case (13), adding chloranil was found useful.…”

Condensation products of 1‐aryl‐4‐carboxy‐ 2‐ pyrrolidinones with o‐diaminoarenes, o‐aminophenol, and their structural studies

“…NMR spectra of compounds 3d, 3e, 4f, and 7d showed that the introduction of the substituent (Cl or CH 3 ) at C-11 or N-1 position of benzimidazole fragment stabilized its form [17][18][19]. The carbon resonances of benzimidazole of benzene moiety became sharp.…”

Quinolizidinyl‐benzimidazoles as Platelet‐Antiaggregating Agents

“…Indeed, in most cases both methods gave only moderate or poor yields, probably as a consequence of the strong steric hindrance due to the bulky quinolizidine moiety. Preliminary attempts to form the benzimidazole nucleus by condensation of the diamino compounds 32 -36 either with aldehydes in the presence of FeCl 3 /O 2 [24], or with aldehyde -sodium bisulfite compounds [25], failed completely.…”