Hydrotalcite: A novel and reusable solid catalyst for one-pot synthesis of 3,4-dihydropyrimidinones and mechanistic study under solvent free conditions

Synthesis of 3,4-dihydropyrimidinones/thiones, a multicomponent synthesis using ethyl acetoacetate, substituted aromatic aldehydes, and urea/thiourea has been carried out in presence of Mg–Al–CO3 and Ca–Al–CO3 hydrotalcite as a reusable solid catalyst. The work has been carried out under thermal solvent-free conditions without microwave irradiations, and under microwave irradiation. In this method excellent yield of 3,4-dihydropyrimidinones/thiones is reported in shorter duration. Hydrotalcites are non-toxic, easy to separate and recyclable catalyst hence making this process environment friendly. Mechanistic study of the reaction using hydrotalcites as catalyst has been studied under thermal conditions without microwave irradiations.

Graphical abstract. Synthesis of 3,4-dihydropyrimidinones/thiones by cyclocondensation of ethyl acetoacetate, substituted aromatic aldehydes, and urea/thiourea using Mg–Al–CO3 and Ca–Al–CO3 hydrotalcites as a reusable catalyst has been reported under solvent-free conditions and microwave irradiations.Figure optionsDownload full-size imageDownload high-quality image (107 K)Download as PowerPoint slideHighlights► This catalytic reaction takes place under solvent free conditions thus eliminating organic solvent, it gains an environment friendly condition. ► Yield of the desired product is excellent in the present synthesis. ► Hydrotalcite is a reusable heterogeneous catalyst there is no significant loss of catalytic activity when tested up to five catalytic cycles. ► Hydrotalcite catalyst containing Mg, Al and Ca are environment friendly metals.