Copper(I)‐Catalyzed Interrupted Click Reaction: Synthesis of 1,4,5‐Trisubstituted 5‐Chloro‐1,2,3‐Triazoles

5‐Halo‐1,2,3‐triazoles are important scaffolds in organic chemistry, but current click reaction cannot produce 1,4,5‐trisubstituted 5‐chloro‐1,2,3‐triazoles in a simple way. Herein, we disclosed a Cu(I)‐catalyzed interrupted click reaction, using N‐chlorophthalimide as an electrophilic chlorine source, enabling the facile synthesis of 1,4,5‐trisubstituted 5‐chloro‐1,2,3‐triazoles in one step from readily available terminal alkynes and azides. Complete control of regioselectivities with a broad substrate scope was accomplished by this approach. Furthermore, a novel epoxidation was developed using 5‐chloro‐triazole as substrate, which could be further applied in various organic transformations.