Biginelli Reaction Of Aldehyde Research Articles

Air‐stable zirconium (IV)‐salophen perfluorooctanesulfonate as a highly efficient and reusable catalyst for the synthesis of 3,4‐dihydropyrimidin‐2‐(1H)‐ones/thiones under solvent‐free conditions

An air‐stable complex of zirconium (IV)‐salophen perfluorooctanesulfonate (1) was successfully synthesized by reacting Zr (salphen)Cl2and C8F17SO3Ag. Complex1was characterized and studied by different techniques (NMR, IR, HRMS, TG‐DSC, conductivity and acidity measurements), and was found to be air‐stable, water tolerant, thermally stable and strongly Lewis‐acidic. Complex1exhibited high catalytic efficiency for the synthesis of 3,4‐dihydropyrimidin‐2‐(1H)‐ones/thiones via the Biginelli reaction of aldehydes, 1,3‐dicarbonyl compounds and urea/thiourea under solvent‐free conditions. Furthermore, complex1could be reused 5 times with minimal changes in catalytic efficiency. Compared with previously reported methods, the important features of this protocol are the solvent‐free conditions, the short reaction times, the wide substrate compatibility, the high efficiency and the good reusability.

Improving the Selectivity toward Three‐Component Biginelli versus Hantzsch Reactions by Controlling the Catalyst Hydrophobic/Hydrophilic Surface Balance

AbstractThe catalytic activities and selectivities of two kinds of mesoporous solid acids SBA‐15‐PrSO3H 1, SBA‐15‐Ph‐PrSO3H 2, and a periodic mesoporous organosilica (PMO) based solid acid Et‐PMO‐Me‐PrSO3H 3 that comprise different physicochemical surface properties were compared in an environmentally benign one‐pot, three‐component Biginelli reaction of aldehydes, β‐ketoesters and urea or thiourea under solvent‐free conditions. Among these mesoporous solid acid catalysts, 3, which has a hydrophobic/hydrophobic balance in the nanospaces (mesochannels) in which the active sites are located, is found to be a significantly more selective catalytic system in the Biginelli reaction; it produces the corresponding 3,4‐dihydropyrimidin‐2‐one\thione (DHPM) 5 derivatives in good to excellent yields and excellent selectivities. Notably, in the case of conducting the three‐component coupling reaction of benzaldehyde, metylacetoacetate and urea in the presence of 1 result in the generation of a mixture of Hantzsch dihydropyridine 4 (≈37 %) and Biginelli dihydropyrimidinone 5 (≈49 %), whereas the same reaction with 2 (catalyst loading of 1 mol % as well) furnishes the corresponding aldolic product methyl‐2‐benzylidene‐3‐oxobutanoate 6 as the major product (≈80 %) with concomitant formation of small amounts of 5 (<10 %) under essentially the same reaction conditions that are employed with catalyst 3. Water adsorption–desorption analysis of the catalysts is employed to possibly relate the observed selectivity to the difference in physicochemical properties of the materials.

Cu(ClO4)2 · 6H2O as an Efficient Catalyst for the Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones Under Solvent-Free Conditions

Cu(ClO4) · 6H2O efficiently catalyzes the three-component Biginelli reaction of aldehyde, β-dicarbonyl compounds, and urea or thiourea under solvent-free conditions to afford the corresponding 3,4-dihydropyrimidin-2(1H)-ones in excellent yields.

Ionic liquid-functionalized SBA-15 mesoporous material: efficient heterogeneous catalyst in versatile organic reactions

AbstractIonic liquid-functionalized mesoporous materials exhibited high catalytic activity in versatile organic reactions, such as cycloaddition of carbon dioxide (CO2) with epoxide, aza-Michael addition of amines to α, β-unsaturated carbonyl compounds, and the Biginelli reaction of aldehyde, ethyl acetoacetate and urea. Recycling of the catalyst in these reactions could be carried out and the catalyst used at least five times without significant loss in activity.

An Efficient Bakers′ Yeast Catalyzed Synthesis of 3,4‐Dihydropyrimidin‐2‐(1H)‐ones.

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