Synthesis of Pyrrole, Pyrazole, Triazole, Thiazole, Thiadiazole, and Pyrazine Derivatives from Hydrazonoyl Halides (A Review)

A review of the synthesis of pyrrole, pyrazole, triazole, thiadiazole, and pyrazine derivatives from hydrazonoyl halides is presented. These heterocyclic compounds are a very important class in medicinal chemistry due to their antimicrobial, tuberculostatic, anticancer, antifungal, and other biological activities. Hydrazonoyl halides are an essential source of 1,3-dipolar reagents in alkaline media, which react with alkenes to give five-member rings.