Copper-Catalyzed Aerobic Oxidative [3+2] Annulation for the Synthesis of 5‑Amino/Imino-Substituted 1,2,4-Thiadiazoles through C–N/N–S Bond Formation

A copper-catalyzed aerobic oxidative annulation reaction of 2-aminopyridine/amidine with isothiocyanate has been reported. This strategy involving C–N/N–S bond formations provides various 5-amino/imino-substituted 1,2,4-thiadiazole derivatives under a Cu/O2 catalytic system. This method has demonstrated high reactivity, mild reaction conditions, and a broad substrate scope. Furthermore, the synthetic utilities of the approach are demonstrated by further modifications.