Green Synthesis of Novel Pyridines via One-Pot Multicomponent Reaction and Their Anti-Inflammatory Evaluation

A functional and environmentally green procedure for the design of novel pyridine 5a-h and 7a-d derivatives through two pathways is presented. The first pathway is via a one-pot, four-component reaction of p-formylphenyl-4-toluenesulfonate (1), ethyl cyanoacetate (2), acetophenone derivatives 3a-h or acetyl derivatives 6a-d, and ammonium acetate (4) under microwave irradiation in ethanol. The advantages of this method are an excellent yield (82%-94%), pure products, a short reaction time (2-7 min), and low-cost processing. The second pathway was obtained by the traditional method with treatment of the same mixture under refluxing in ethanol, which afforded the same products, 5a-h and 7a-d, in less yield (71%-88%) and over a longer reaction time (6-9 h). The constructions of the novel compounds were articulated via spectral and elemental analysis. Overall, the compounds have been designed, synthesized, and studied for their in vitro anti-inflammatory activity using diclofenac as a reference drug (5 mg/kg). The most potent four compounds, 5a, 5f, 5g, and 5h, showed promising anti-inflammatory activity.

Sulfonic Acid-Functionalized Inorganic Materials as Efficient Catalysts in Various Applications: A Minireview

Acid catalysis is widely used in the chemical industry, and nowadays many efforts are being focused on replacing the more common homogeneous catalysts with heterogeneous ones in order to make greener the industrial processes. In this perspective, sulfonic solid acid materials represent a valid alternative to the homogenous mineral acid in several acid catalyzed reactions. In this minireview, an overview of the recent advances on the preparation, stability and application of these materials is reported. Special attention is addressed to the sustainability of the considered processes, starting from the catalyst’s preparation, the use of green solvents and reducing the possible reaction steps. Ways to tackle the main drawback represented by easy leaching of acid groups are described. For an easy catalyst recovery, the use of a magnetic core in a catalyst particle, with the related synthetic approaches, is also illustrated. Finally, a section is dedicated to the principal characterization techniques to identify the structural properties of the catalysts.

Rapid four-component synthesis of dihydropyrano[2,3-c]pyrazoles using nano-eggshell/Ti(IV) as a highly compatible natural based catalyst

Nano-eggshell/Ti(IV) as a novel naturally based catalyst was prepared, characterized and applied for the synthesis of dihydropyrano[2,3-c]pyrazole derivatives. The characterization of nano-eggshell/Ti(IV) was performed using Fourier Transform Infrared spectroscopy, X-ray Diffraction, Field Emission Scanning Electron Microscopy, Energy-Dispersive X-ray Spectroscopy, and Thermo Gravimetric Analysis. Dihydropyrano[2,3-c]pyrazoles were synthesized in the presence of nano-eggshell/Ti(IV) via a four component reaction of aldehydes, ethyl acetoacetate, malononitrile and hydrazine hydrate at room temperature under solvent free conditions. The principal affairs of this procedure are mild condition, short reaction times, easy work-up, high yields, reusability of the catalyst and the absence of toxic organic solvents.

Design and synthesis of a new magnetic metal organic framework as a versatile platform for immobilization of acidic catalysts and CO2 fixation reaction

The first report of the use of an acidic magnetic metal organic framework for the chemical fixation of CO2 as an environmentally friendly reaction.

Catalytic application of sulfamic acid-functionalized magnetic Fe3O4 nanoparticles (SA-MNPs) for protection of aromatic carbonyl compounds and alcohols: experimental and theoretical studies

Protection techniques of functional groups within the structure of organic compounds are important synthetic methods against unwanted attacks from various reagents during synthetic sequences. Acetal and thioacetal groups are well known as protective functional groups in organic reactions. In this study, acetalization of carbonyl compounds with diols and dithiols and methoxymethylation of alcohols with formaldehyde dimethyl acetal (FDMA) have been carried out using sulfamic acid-functionalized magnetic Fe3O4 nanoparticles (SA-MNPs) as a heterogeneous solid acid catalyst. Products were characterized by FT-IR and NMR spectroscopies. The structural and electronic properties of some products were computed by quantum mechanical (QM) methods. Depending on the stereochemistry and electronic properties that were obtained by computational results, we have suggested that hyperconjugation plays a key role in the structural properties of 2-phenyl-1,3-dioxolane derivatives, and also the electron transfer between π-electrons of the aromatic ring with the 3d orbital of S-atoms influences the 2-phenyl-1,3-dithiane derivatives' structure.

Functionalized magnetic PAMAM dendrimer as an efficient nanocatalyst for a new synthetic strategy of xanthene pigments

A green protocol has been developed for preparation of the wide variety of colored xanthene derivatives using a new efficient magnetic solid acid catalyst bearing polyamidoamine dendrimer moiety as a nanoscopic compound. Dendrimers, highly symmetric molecules around a core and 3D spherical morphology, show interesting traits based on their functionalized groups on the branched surface. They can be designed to provide water soluble structures or pseudo-active sites of biomolecules. The catalyst was assembled via a polyamidoamine dendrimer immobilized on the surface of γ-Fe₂O₃ followed by the sulfonylation of the amine groups by chlorosulfonic acid resulting in γ-Fe₂O₃@PAMAM-SO₃H. Herein, PAMAM dendrimer with repeating amine/amide branches as catchable sites of sulfonic acid groups was introduced as transformer of homogeneous to heterogeneous acidic catalysts. The physicochemical properties of synthesized catalyst were studied using by FT-IR, FE-SEM, XRD, VSM, EDS, TGA/DTG, and TEM. Finally, the catalytic activity of γ-Fe₂O₃@PAMAM-SO₃H was evaluated for the preparation of xanthene derivatives via a one-pot, three components reaction of aromatic aldehydes with i) β-naphthol, ii) cyclic 1,3-dicarbonyl, iii) β-naphthol and cyclic 1,3-dicarbonyl compounds, iv) 2-hydroxy-1,4-naphthoquinone, leading to the eco-riendly preparation of the target compounds in good to excellent yields. The catalyst could be easily recycled for at least five consecutive runs without significant loss in its catalytic activity.

Synthesis and application of chitosan supported vanadium oxo in the synthesis of 1,4-dihydropyridines and 2,4,6-triarylpyridines via anomeric based oxidation

1,4-Dihydropyridines and 2,4,6-triarylpyridines were synthesized via anomeric based oxidation using chitosan supported vanadium oxo.

Tungstic acid-functionalized Fe3O4@TiO2: preparation, characterization and its application for the synthesis of pyrano[2,3-c]pyrazole derivatives as a reusable magnetic nanocatalyst

A new nanocatalyst based on the immobilization of tungstic acid onto 3-chloropropyl-grafted TiO₂-coated Fe₃O₄ nanoparticles (Fe₃O₄@TiO₂@(CH₂)₃OWO₃H) was prepared, characterized, and applied for the synthesis of pyrano[2,3-c]pyrazoles.

[TEATNM] and [TEATCM] as novel catalysts for the synthesis of pyridine-3,5-dicarbonitriles via anomeric-based oxidation

The synthesis of 2-amino-4-aryl-6-(arylamino)pyridine-3,5-dicarbonitriles was carried out using [TEATNM] and [TEATCM] as catalysts via anomeric-based oxidation.

Design and preparation of [4,4′-bipyridine]-1,1′-diium trinitromethanide (BPDTNM) as a novel nanosized ionic liquid catalyst: application to the synthesis of 1-(benzoimidazolylamino)methyl-2-naphthols

A novel bifunctional nanosized molten salt catalyst promoted the synthesis of 1-(benzoimidazolylamino)methyl-2-naphthols.