Synthesis, Reactions, and Biological Applications of 1,2,4-triazoles: A Review

Compounds containing the 1,2,4-triazole substructure have been shown to have broad biological activities. Many drugs with a 1,2,4-triazole structure have been developed and proven: for example, ribavirin (antiviral), fluconazole, itraconazole, voriconazole (antifungal), alprazolam (tranquilizer), estazolam (hypnotic, sedative), anastrozole, vorozole and letrozole (as non-steroidal aromatase inhibitors). Given the importance of 1,2,4-triazole scaffolds, the synthesis of their derivatives has attracted much attention. This review deals with the synthetic methods of 1,2,4-triazole compounds in the past 20 years and illustrates selected reactions of this class of compounds. Various biological activities of 1,2,4-triazoles as antifungal, antibacterial, anticancer, anticonvulsant, antituberculosis, antiviral, antiparasitic, analgesic, anti-inflammatory, and anthelmintic agents are also discussed.