K₂S₂O₈-enabled one-pot deaminative C-N bond formation for the synthesis of fused benzimidazopurines and benzimidazoquinazolines

Abstract

We report an unusual, transition metal-free oxidative cyclization strategy for the synthesis of benzoimidazopurine and benzoimidazoquinazoline derivatives via K₂S₂O₈-enabled intramolecular C-N bond formation. The reaction proceeds through an oxidative deamination pathway, wherein the nucleophilic purinyl nitrogen and the departing amino group cooperatively enable efficient cyclization. This simple protocol provides rapid access to complex polyheterocyclic scaffolds with excellent functional group tolerance. Notably, 2,6-dichloropurine derivatives undergo a divergent transformation, delivering benzimidazole-tethered purines wherein solvent DMA acts as an unexpected C1 source, unveiling a unique reactivity mode of purine substrates.