Synthesis of 1,2,4-Triazole Derivatives Via Three-Component Tandem Cyclization Reactions Based on N–N Bond Formation

We report a three-component tandem cyclization protocol that efficiently synthesizes 1,2,4-triazole derivatives from readily available primary amines, aldehydes, and amidines. The proposed mechanism proceeds through a multistep sequence involving initial condensation of an aldehyde and amine to form an imine intermediate, subsequent nucleophilic attack of an amidine on the imine-type intermediate, and final copper-catalyzed aerobic oxidative intramolecular N–N bond formation to yield the target product. Mechanistic insights are further elucidated through comprehensive density functional theory calculation studies. This protocol is operationally simple, uses low-cost starting materials, and exhibits broad functional group compatibility and high atom economy; these features highlight its strong potential for applications in pharmaceutical synthesis.