Construction of trinuclear N-fused hybrid scaffolds by coupling and cyclization of 2-bromoaryl- and 2-bromovinylimidazoles with ureas under recyclable Cu/C–Al₂O₃ catalysis

2-(2-Bromoaryl)- and 2-(2-bromovinyl)imidazoles are coupled and cyclized with cyclic ureas as building blocks under recyclable heterogeneous Cu/C–Al₂O₃ catalysis to afford a class of trinuclear N-fused hybrid scaffolds, benzo[4,5]imidazo[1,2-a]imidazo[1,2-c]quinazolines and benzo[4,5]imidazo[1,2-a]imidazo[1,2-c]pyrimidines, respectively. The Cu/C–Al₂O₃ catalytic system could be recovered and reused three times without any loss of catalytic activity.