l-Asparagine-EDTA-amide silica-coated MNPs: a highly efficient and nano-ordered multifunctional core-shell organocatalyst for green synthesis of 3,4-dihydropyrimidin-2(1H)-one compounds

In this study, new l-asparagine grafted on 3-aminopropyl-modified Fe3O4@SiO2 core-shell magnetic nanoparticles using the EDTA linker (Fe3O4@SiO2-APTS-EDTA-asparagine) was prepared and its structures properly confirmed using different spectroscopic, microscopic and magnetic methods or techniques including FT-IR, EDX, XRD, FESEM, TEM, TGA and VSM. The Fe3O4@SiO2-APTS-EDTA-asparagine core-shell nanomaterial was found, as a highly efficient multifunctional and recoverable organocatalyst, to promote the efficient synthesis of a wide range of biologically-active 3,4-dihydropyrimidin-2(1H)-one derivatives under solvent-free conditions. It was proved that Fe3O4@SiO2-APTS-EDTA-asparagine MNPs, as a catalyst having excellent thermal and magnetic stability, specific morphology and acidic sites with appropriate geometry, can activate the Biginelli reaction components. Moreover, the environmental-friendliness and nontoxic nature of the catalyst, cost effectiveness, low catalyst loading, easy separation of the catalyst from the reaction mixture and short reaction time are some of the remarkable advantages of this green protocol.

Sulfonated carbons from agro-industrial residues: simple and efficient catalysts for the Biginelli reaction

An eco-friendly catalyst prepared from rice husk was used to synthesize dihydropyrimidinones (DHPMs) and achieved a yield of 92%.

Design, synthesis, spectral characterization and molecular docking studies of novel pyranoquinolinyl dihydropyridine carboxylates as potential antibacterial agents including Vibrio cholerae with minimal cytotoxity towards fibroblast cell line (L-929)

Novel pyranoquinolinyl dihydropyridine carboxylate (PDC) derivatives were designed by incorporating the multi-drug resistance modulating effects of 1,4 dihydropyridines along with potential antibacterial activity of quinolines in the molecular design. The designed PDC derivatives were synthesized by multi-step synthesis involving Michael addition, reduction followed by inverse electro demand Diels-Alder reaction to produce pyranoquinolinyl dihydropyridine carboxylates in good yields. All the PDC derivatives were characterized by ¹H NMR, ¹³C NMR, FT-IR, Mass spectral and CHN analysis. The Quinolinyl dihydropyridine carboxylate derivatives were evaluated for in vitro antibacterial activity by agar well diffusion method. Molecular docking studies revealed that the exo diethyl 4-(4aR,5S,10bR)-5-(4-chlorophenyl)-3,4,4a,5,6,10b-hexahydro-2H-pyrano[3,2-c]quinolin-8-yl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate diastereomer (5c) forms four hydrogen bonds with the cell wall protein of vibrio cholerae in comparison to the endo diethyl 4-((4aR,5R,10bR)-5-(4-chlorophenyl)-3,4,4a,5,6,10b-hexahydro-2H-pyrano[3,2-c]quinolin-8-yl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate diastereomer (4c) which forms two hydrogen bonds with the cell wall protein of vibrio cholerae and hence leading to better anchorage, enhanced gold score and relatively good antibacterial activity for the exo PDC derivatives. Minimum inhibitory concentration (MIC) of the active compounds was evaluated by macro dilution method. The mechanism of antibacterial action of the PDC derivatives was investigated by SEM studies. The cytotoxicity of PDC derivatives were evaluated against fibroblast cells (L-929).

Deep eutectic solvent assisted synthesis of dihydropyrimidinones/thiones via Biginelli reaction: theoretical investigations on their electronic and global reactivity descriptors

DES 2 (ZrOCl2·8H2O-ethylene glycol at 1 : 2 ratio) was used as a catalyst for the synthesis of dihydropyrimidinones/thiones via a Biginelli reaction.

One Pot Multicomponent Biginelli Reaction Employing Ionic Liquids as an Organocatalyst

Introduction:

The N-heterocyclic compounds have been extensively studied in pharmaceutical industries. Furthermore, syntheses of such compounds employing organo-catalyst have been associated with sustainable technology.

Methods:

The synthesis of new, stable ionic liquids and their catalytic applications in one-pot multicomponent Biginelli reaction is presented. The method provides broad substrate scope, yielding the corresponding 3,4-dihydropyrimidin-2(1H)-ones and 3,4-dihydropyrimidin-2(1H)-thiones, in good to excellent yields, respectively.

Results and Conclusion:

The developed reactions are associated with certain advantages, short reaction time and sustainable conditions. The protocol has advantages eco-friendly procedure, recovery and reusability of catalyst, which showed consistent activity.

A novel organic–inorganic hybrid material: production, characterization and catalytic performance for the reaction of arylaldehydes, dimedone and 6-amino-1,3-dimethyluracil

A novel silica-based organic–inorganic hybrid catalyst was prepared, characterized and applied for the synthesis of pyrimido[4,5-b]quinolines.