Efficient and Rapid Solvent‐Free Catalysis of the Biginelli Reaction by Praseodymium (III) Nitrate

Abstract The highly effective catalysis of the Biginelli reaction has been demonstrated under solvent‐free conditions, using praseodymium (III) nitrate (Pr(NO 3 ) 3 ·6H 2 O) as a novel catalyst. Notably, this is the first instance of Pr(NO 3 ) 3 ·6H 2 O being used as a catalyst in an organic reaction. This method offers several advantages, including high yields (85%–98%), easy product isolation, shorter reaction time (ranging from 8 to 25 min), and high turnover frequencies (TOFs) of up to 73.5. The solvent‐free nature of the reaction aligns with green chemistry principles by minimizing environmental impact. Additionally, the absence of by‐products ensures a clean and efficient process. Owing to its simplicity and effectiveness, this approach facilitates the synthesis of substituted 3,4‐dihydropyridine‐2 (1 H )‐ones/thiones which have potential applications in the pharmaceutical industry.