A new key for old lock: Glycerol as an OH-acid catalyzed one-pot three-component and fully green synthesis of 3,4-dihydropyrimidin-2(1H)-one and thiones

Glycerol is a non-toxic, biodegradable and recyclable liquid that is highly inert, stable and also dissolves organic compounds that are poorly miscible in water. Glycerol has also been used, for other miscellaneous applications, as a single solvent, as co-solvent, being part of a deep eutectic mixture, or playing the double role of solvent and reagent 1, such as aza-Michael addition of aromatic amines to electron-deficient α,β-unsaturated ketones to achieve β-aminoketone 2, the utility of glycerol as solvent and reducing agent for the generation of metal nanoparticles3 and the synthesis of vanillin-semicarbazone in crude glycerol 4 .In this study, the synthesis of 3,4-dihydropyrimidin-2(1H)-one and 3,4-dihydropyrimidin-2(1H)-thione derivatives (DHPMs) from aldehydes, ethyl acetoacetate and urea or thiourea using glycerol as an organo OH-acid, green and reusable catalyst is reported. The practical and simple protocol led to excellent yields of the dihydropyrimidin-2(1H)-one and thiones under mild reaction conditions and within short span of reaction times with easy reaction workup by maintaining excellent atom economy described (Scheme 1).