Bio-Waste Curd Water as a Greener Protocol for the Synthesis of Biginelli Products at Ambient Temperature

A highly efficient, greener and reusable protocol has been developed for the Biginelli reaction. The biowaste curd water employed as a green solvent as well as catalyst for the synthesis of dihydropyrimidinones derivatives. The soluble organic acid (i.e. lactic acid) responsible for the acidity to curd water which adequately fulfills the purpose of acid catalyzed reaction, where three component coupling of aldehyde, urea and ethyl acetoacetate reacted together in the presence of curd water at a low temperature and yields classical dihydropyrimidinones derivatives. During the reaction, continuous product formation and isolation was observed. The product precipitate was separated by the successive method of filtration. This bio-waste water catalyzed method is highly retrievable and advantageous over the trend of high-temperature Bronsted acid/metal acid catalyzed reactions offering the product. Compared with the classical Biginelli reaction conditions, this new method has the advantage of good yields (76-82%) and short reaction time (2-3 hours)