Ion-pair immobilization of l-prolinate anion onto cationic polymer support and a study of its catalytic activity as an efficient heterogeneous catalyst for the synthesis of 2-amino-4H-chromene derivatives

Synthesis of novel pyrano[2,3-f]chromene-dione derivatives using phosphoric acid-functionalized silica-coated Fe3O4 nanoparticles as a new reusable solid acid nanocatalyst

In this research, the synthesis of novel indeno[1,2-b]pyrano[2,3-f]chromene-2,12(13H)-dione derivatives in the presence of a newly introduced magnetically recoverable nanosolid acid catalyst is reported. At the first, phosphoric acid-functionalized silica-coated Fe₃O₄ nanoparticles (Fe₃O₄@SiO₂-(CH₂)₃OPO₃H₂) were prepared and well characterized using infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and energy-dispersive X-ray spectroscopy (EDS) techniques. Then, the catalytic activity of the prepared Fe₃O₄@ SiO₂-(CH₂)₃OPO₃H₂ nanocatalyst was investigated for the synthesis of novel indeno[1,2-b]pyrano[2,3-f]chromene-2,12(13H)-dione derivatives via a one-pot and three-component condensation between 5,7-dihydroxy-4-methylcoumarin, indane-1, 3-dione, and various aromatic aldehydes under solvent-free condition. All the products are unknown, and their characterization was performed with the spectral data information obtained from their FT-IR, ¹H and ¹³CNMR, elemental analysis, and their melting points. The reusability study of the introduced nanosolid acid catalyst showed that the catalytic stability is almost completely remained up to five consecutive runs.

Non-Covalent Supported of l-Proline on Graphene Oxide/Fe₃O₄ Nanocomposite: A Novel, Highly Efficient and Superparamagnetically Separable Catalyst for the Synthesis of Bis-Pyrazole Derivatives

A superparamagnetic graphene oxide/Fe₃O₄/l-proline nano hybrid that was obtained from the non-covalent immobilization of l-proline on graphene oxide/Fe₃O₄ nanocomposite was used as a new magnetically separable catalyst for the efficient synthesis of 4,4′-(arylmethylene)bis(1H-pyrazol-5-ol) derivatives. The prepared heterogeneous catalyst was characterized using FTIR, TGA, DTG, XRD, TEM, SEM, and elemental analysis techniques. Short reaction times (5–15 min), excellent yields (87–98%), and simple experimental procedure with an easy work-up are some of the advantages of the introduced catalyst.

Silica gel-immobilized multidisciplinary materials applicable in stereoselective organocatalysis and HPLC separation

In this pilot study, we present novel bifunctional silica gel-immobilized materials applicable as heterogeneous organocatalysts and stationary phases in HPLC. The materials provided high stereoselectivity in both batch and continuous flow catalysis of a model Michael addition (cyclohexanone to (E)-β-nitrostyrene). In the batch reaction, the catalysts proved their sustainable catalytic activity over five consecutive recycling experiments. Under continuous flow reaction conditions, the catalytic activity was found to be superior to the batch reaction, and moreover, the same immobilized materials were utilized as stationary phases in HPLC showing very good chemoselective separation of model acidic analytes.

Novel multidisciplinary silica gel-based materials were successfully employed in highly stereoselective Michael addition and as stationary phases in HPLC separation.

One-pot synthesis of benzopyrans catalyzed by silica supported dual acidic ionic liquid under solvent-free conditions

A mild and efficient method was developed for the preparation of tetrahydrobenzo[