Synthetic Approaches to Bis- and Tris-Thiazole Derivatives via Hydrazonoyl Halides and Thiosemicarbazones (2015-2025)

Abstract:

This review comprehensively summarizes synthetic strategies reported from 2015 to 2025 for the efficient preparation of bis-thiazole and tris-thiazole derivatives using hydrazonoyl halides and thiosemicarbazone-based reagents. It highlights six key synthetic pathways, including reactions between hydrazonoyl halides and bis-thiosemicarbazones, bis-hydrazonoyl halides with thiosemicarbazones, hydrazonoyl halides with biscarbothioamides, bis-hydrazonoyl halides with carbothioamides, hydrazonoyl halides with tris-thiosemicarbazones, and bis-hydrazonoyl halides with bis-thiosemicarbazones. The reviewed reactions are metal-free, regioselective, and operate under mild conditions, often assisted by green chemistry techniques like microwave irradiation or eco-friendly catalysts. The structural diversity of the synthesized thiazole derivatives is supported by extensive spectroscopic characterization. This review highlights the synthetic versatility of thiazole-based scaffolds in modern heterocyclic and medicinal chemistry.