Divergent Synthesis of Unsymmetrical Annulated Biheterocyclic Compound Libraries: Benzimidazole Linked Indolo-benzodiazepines/quinoxaline

Diversity-oriented synthesis of novel benzimidazole linked indolo-benzodiazepine/quinoxaline ring systems using poly(ethylene glycol) as soluble polymer support is described. Commercially available 4-fluoro-3-nitrobenzoic acid and indoline were utilized for the construction of these annulated biheterocyclic compound libraries having multiple privileged structures with three-point structural diversity. A reagent based diversification approach coupled with the Pictet–Spengler-type condensation was used to construct the tetracyclic indolo-benzodiazepines/quinoxalines on substituted benzimidazoles.