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

Abstract 5‐Halo‐1,2,3‐triazoles are important scaffolds in organic chemistry, but current click reactions 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.