Highly Efficient [3 + 2] Cycloaddition: Click Synthesis of Novel 1 H ‐indol‐3‐yl‐benzo[ d ]imidazole Bis‐triazoles

A series of novel 1‐((1 H ‐1,2,3‐triazol‐4‐yl)methyl)‐2‐(1‐((1 H ‐1,2,3‐triazol‐4‐yl)methyl)‐5‐substituted‐1 H ‐indol‐3‐yl)‐6‐substituted‐1 H ‐benzo[ d ]imidazoles 5a – i have been prepared using click chemistry as an ideal strategy where [3 + 2] cycloaddition of azides with terminal alkynes has been developed as the target compounds. In route‐II, 5‐substituted‐1 H ‐indole‐3‐carbaldehydes 1a – c react with 5‐substituted orthophenylenediamine 8 to give desired products, that is, 6‐substituted‐2‐(5‐substituted‐1 H ‐indol‐3‐yl)‐1 H ‐benzo[ d ]imidazole 6a – i . Here, 6a – i react with 2 equiv of propargylbromide 7 to give novel 6‐substituted 2‐(5‐substituted‐1‐(prop‐2‐yn‐1‐yl)‐1 H ‐indol‐3‐yl)‐1‐(prop‐2‐yn‐1‐yl)‐1 H ‐benzo[ d ]imidazole 4a – i . 4a – i were reacted with 2 equiv of NaN 3 in t ‐butanol/water (1:2) and add catalytic amount of CuSO 4 .5H 2 O. Stir the reaction mixture at room temperature to get the target products 5a – i . Here, obtained products contain four rings, that is, one indole, two triazoles, and one benzimidazole. The main advantages of this method are short reaction times, easy workup, higher yields (88–92%), and no by‐products formation.