Recent trends in ionic liquid-mediated synthesis of thiazoles: toward greener methodologies

Thiazole moieties represent a vital category of heterocycles, offering versatile uses across drug development, agricultural formulations, and advanced materials. Nevertheless, conventional methods for their synthesis frequently depend on toxic solvents and rigorous conditions, which raise significant environmental and safety concerns. Recently, ionic liquids (ILs) have gained recognition as sustainable and versatile solvents due to their exceptional physico-chemical characteristics, namely minimal vapor pressure, adjustable polarity, and recyclability. This review focuses on synthesizing thiazole derivatives through ionic liquid-mediated strategies, emphasizing their alignment with the principles of green chemistry. Recent advancements in catalyst-free protocols and recyclable ionic liquid (IL) systems are discussed in detail, along with comparisons to conventional methods in terms of green metrics. This review integrates recent advancements to deliver a focused and thorough summary of green synthetic approaches for thiazoles between 2004 and 2025. It highlights the current limitations and proposes directions for future research toward greener and more scalable methodologies.