Unveiling Ionic Liquid‐Based Green Approach for the Synthesis of Dihydropyrimidinone Analogues Utilizing Biginelli Reaction

ABSTRACT

Utilization of ionic liquids in the field of green chemistry proves to play a crucial role in the modern green organic synthesis due to their eco‐friendly and atom‐economic properties as a catalyst‐ cum ‐solvent in the facile synthesis. Dihydropyrimidinone is a class of heterocyclic compounds that showed great therapeutic potential. Hence, we aim to synthesize the dihydropyrimidinone analogues using 1,4‐diazabicyclo[2.2.2]octane‐based ionic liquid as a green alternative of toxic solvents and catalysts utilizing Biginelli reaction as a promising multi‐component reaction. Initially, two methodologies (conventional and ionic liquid‐based) were compared for the syntheses of methyl‐ester and benzyl‐ester derived dihydropyrimidinone analogues. Scope of reaction was expanded via preparing two sets of dihydropyrimidinone analogues with different substituents, as well as studied their effect on the % yields and reaction time. The two methods were also compared via calculating green metrics (atom economy, PMI, and RME), which revealed ionic liquid‐based method relatively better than the conventional method. On the account of these results, herein we report the synthesis of thirty‐eight dihydropyrimidinone analogues using DABCO‐ C ₇ ‐F ionic liquid. Our method was found to be green, eco‐friendly, efficient, functional group tolerant, has high reaction rate, and widely applicable, while the ionic liquid used as recyclable.