Synthesis of Dihydropyrimidinones and Dihydropyrimidin(thio)ones in Ionic Liquid: A Systematic Review on Biginelli Reaction

The Biginelli reaction, first introduced in 1893, is a key one-pot condensation reaction in organic chemistry that facilitates the synthesis of dihydropyrimidinones (DHPMs) and dihydropyrimidin(thio)ones (DHPMTs). Traditional methods for this reaction often face challenges such as low yields, extended reaction times, and the use of hazardous solvents. Recent advancements have introduced ionic liquids (ILs) as sustainable alternatives that act both as solvents and catalysts, enhancing reaction efficiency while adhering to green chemistry principles. This systematic review examines the role of ILs in optimizing Biginelli reactions, emphasizing their benefits in reducing reaction time, increasing yields, and allowing for recyclability. Additionally, the study assesses the ecotoxicological impact of ILs, addressing concerns regarding their long-term environmental effects. The findings highlight ILs' potential to revolutionize heterocycle synthesis by balancing sustainability with efficiency. As research advances, the continued development of eco-friendly ILs and innovative catalytic systems will be crucial in refining synthetic methodologies and minimizing ecological impact.