A microwave assisted efficient route to the synthesis of benzimidazole fused heterocycles through metal catalyzed endo-cyclization strategy involving imine and alkyne activation has been developed. In the presence of [RuCl₂(p-cymene)₂]₂, a variety of 2-ethynyl aldehydes underwent cascade cyclization with substituted benzenediamines to afford the corresponding benzo[4,5]imidazo[2,1-a] pyridine scaffold in moderate to good yields.