Preparation of core–shell magnetic mesoporous N-doped silica nanoparticles as a new solid base catalyst was studied. obtained catalyst was used for the preparation of some arylpyrimido[4,5-b]quinoline diones under green conditions.
Herein, eco-friendly, mild and efficient synthesis of a new type of 1,4-dihydropyridines and some of the spirooxoindole dihydropyridine derivatives was developed by using L-proline as an effective homogeneous catalyst. The one-pot multicomponent reaction of malononitrile, different anilines, and benzaldehydes were performed in the presence of Water/EtOH (1 : 1) as solvent at 90°C and furnished the corresponding products in high yields. Further, we developed a threecomponent one-pot reaction of malononitrile, anilolactone, and differently substituted isatins to afford new spirooxindole dihydropyridine derivatives using the same catalyst and conditions. All of the obtained products were characterized by spectroscopic and analytical techniques.
Using heterogeneous basic catalysts has a great importance in chemical reactions because of their advantages (such as easy separation and thermal stability at harsh conditions) over homogeneous catalysts. In this study, magnetic mesoporous silica nanoparticles (mSiO2) containing graphitic carbon nitride layers (mSiO2/g‐C3N4(x)) were fabricated through a facile process (x signifies the amount of melamine applied during synthesis). Graphitic carbon nitride layers were decorated on mSiO2 by calcination of immobilized melamine (as graphitic carbon nitride precursor) on mSiO2 in the last step of catalyst synthesis. The structure of the prepared catalysts was confirmed using XRD, BET, FESEM, EDX, elemental mapping and TEM methods. The catalytic efficiency of the so‐obtained solid base composite was investigated for the synthesis of some dihydropyranochromenes and spiro‐dihydropyranochromenes under thermal and microwave conditions. Using mSiO2/g‐C3N4(x) led to high yields under green conditions and in short reaction times and without a decrease in catalytic activity after four consecutive cycles.
Nowadays, Solid acid catalysts which are the great replacement for the homogenous acid catalysts have attracted a great attention. In this research, glutamic acid anchored on ZnFe 2 O 4 nanoparticles (ZnFe 2 O 4 /GA) was prepared as a reusable heterogeneous catalyst. FT-IR, FESEM, SEM, EDX, XRD, TEM VSM and TGA analysis proved the structure of the prepared composite. The obtained catalyst was applied for the green synthesis of some pyrazolo pyrano pyrimidines through the four component reaction. The products were achieved in high to excellent yields and characterized using spectroscopic methods.
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