2‐(2‐Bromoaryl)‐ and 2‐(2‐bromovinyl)‐4,7‐dimethoxybenzimidazoles are coupled and cyclized with cyanamide as a building block in dimethylformamide in the presence of a catalytic amount of a copper catalyst along with a base to give the corresponding 2‐aminoquinazoline‐ and 2‐aminopyrimidine‐fused 4,7‐dimethoxybenzimidazoles in good yields. Subsequent oxidation of such N‐fused hybrid scaffolds by treatment of ceric ammonium nitrate in acetonitrile/H2O affords unprecedented 2‐aminoquinazoline‐ and 2‐aminopyrimidine‐fused benzimidazolequinones.
A green synthesis of trinuclear imidazole-fused hybrid scaffolds has been developed by transition metal-free double C(sp2)–N coupling and cyclization of 2-(2-bromoaryl)- and 2-(2-bromovinyl)imidazoles with 2-aminobenzimidazoles as building blocks under microwave irradiation.
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