Facile One-Pot Synthesis of Methyl 1-Aryl-1H-1,2,4-triazole-3-carboxylates from Nitrilimines with Vilsmeier Reagent

Two convenient and effective one-pot methods have been developed to synthesize methyl 1-aryl-1H-1,2,4-triazole1-3-carboxylates by using hydrazonoyl hydrochlorides (nitrilimines) with Vilsmeier reagent. The first, a direct one-pot method, involved the reaction between nitrilimines and Vilsmeier reagent at 85 degrees C for about 0.5 h. Another one-pot two-step cascade method proceeded via nucleophilic substitution with bis(trimethylsilyl)amine [NH(SiMe3)(2)] and subsequent intramolecular cycloaddition reaction with Vilsmeier reagent. Substrate scope, multicomponent examples, and mechanistic insights are discussed.