Nickel-Catalyzed Aerobic Oxidative Isocyanide Insertion: Access to Benzimidazoquinazoline Derivatives via a Sequential Double Annulation Cascade (SDAC) Strategy

An
efficient protocol for the synthesis of quinazoline derivatives through
nickel-catalyzed ligand-/base-free oxidative isocyanide insertion
under aerobic conditions with intramolecular bis-amine nucleophiles
has been developed. A one-pot sequential double annulation cascade
(SDAC) strategy involving an opening of isatoic anhydride and annulation
to benzimidazole and further nickel-catalyzed intramolecular isocyanide
insertion has also been demonstrated. The method is operationally
simple to implement with a wide variety of substrates and represents
a new approach for multiple C–N bond formations. The methodology
has been successfully applied to the syntheses of hitherto unreported
imidazo-fused benzimidazoquinazolines via a deprotection–GBB
reaction sequence. Further, a florescence study reveals the potential
of the present strategy for the discovery of highly fluorescent probes.