Magnetically Recoverable Catalysts: Catalysis in Synthesis of Polyhydroquinolines

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In this research, a rapid, green and efficient protocol for synthesis of bis (pyrazolyl)methane derivatives in the presence of Pd(0)‐guanidine@MCM‐41 catalysts under solvent‐free conditions by the following two methods has been reported: (i) via the one‐pot pseudo five‐component reaction among phenylhydrazine (2 equivalents), ethyl acetoacetate (2 equivalents) and aromatic aldehydes (1 equivalent); and (ii) the one‐pot pseudo three‐component reaction between 3‐methyl‐1‐phenyl‐1H‐pyrazol‐5(4H)‐one (2 equivalents) and aromatic aldehydes (1 equivalent). Some advantages of this protocol include: green conditions, extremely short times, high efficiency, proper one‐pot operation, generality of method, easy work‐up and recyclability, and reusability of the catalyst up to five times without significant loss in catalytic activity.

Section: Introductionmentioning

confidence: 99%

Pd(0)‐guanidine@MCM‐41: a very effective catalyst for rapid production of bis (pyrazolyl)methanes

Filian

Kohzadian

Mohammadi

et al. 2020

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“…[1,2] MCRs comprise an important class of chemical transformations which has been applied to almost all fields of organic and medicinal chemistry. [3,4] Tandem or domino (cascade) reactions consist of two or more successive independent reactions performed in a one-pot system without separating and purifying the intermediates. [5][6][7] These convergent procedures incorporate three or more reactants into the final product in just one pot.…”

Section: Introductionmentioning

confidence: 99%

“…Over the past decade, the field of synthetic chemistry has witnessed the multicomponent reactions (MCRs) renaissance as a powerful method for the preparation of products in a single‐step and synthetic operation with high efficiency . MCRs comprise an important class of chemical transformations which has been applied to almost all fields of organic and medicinal chemistry . Tandem or domino (cascade) reactions consist of two or more successive independent reactions performed in a one‐pot system without separating and purifying the intermediates .…”

Section: Introductionmentioning

confidence: 99%

Guanine‐La complex supported onto SBA‐15: A novel efficient heterogeneous mesoporous nanocatalyst for one‐pot, multi‐component Tandem Knoevenagel condensation–Michael addition–cyclization Reactions

Nikoorazm

Khanmoradi

Mohammadi

2020

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In this work, we present a simple, environmentally‐friendly and economical route for the preparation of a novel lanthanum (III) organometallic complex immobilized onto a highly stable mesoporous silica SBA‐15 (La‐guanine@SBA‐15) using an inexpensive and simple method and available materials. This mesoporous heterogenized complex was comprehensively characterized using FT‐IR, XRD, EDS, ICP, MAP, SEM, TGA and BET techniques. The catalytic activity of this mesoporous material was studied in one‐pot multi‐component tandem Knoevenagel condensation–Michael addition–cyclization reactions in order to prepare a series of benzo [a] pyrano [2, 3‐c] phenazine and 4,4′‐(arylmethylene)‐bis‐(3‐methyl‐1‐phenyl‐1H‐pyrazol‐5‐ols) derivatives under green conditions. This catalyst exhibited highly recoverable and recyclable features in consecutive reaction runs. Besides, the products were obtained in high yields and short reaction times. In this sense, simple preparation of the catalyst from the commercially available materials, simple operation, high catalytic activity, short reaction times, high yields and the use of green reaction conditions in the mentioned organic synthesis are the most significant advantages of this protocol. In addition, this nanocatalyst was easily recovered, using simple filtration, and reused several times without significant loss of its catalytic efficiency. Moreover, the leaching, heterogeneity and stability of La‐guanine@SBA‐15 were studied by hot filtration test and ICP technique. Finally, stability of the catalyst after recycling was confirmed by SEM and FT‐IR techniques.

“…Nanomaterial utilization has been expanded due to their specific properties, for example surface modification ability, easy work‐up, high surface area, high thermal and chemical durability, environmental friendliness, low cost, and simple isolation 44–51 . Organic molecules and complexes can be heterogenized on solid state nanomaterialsto provide support for catalyzing organic processes following the principles of green and sustainable chemistry 34,38,52 .…”

Section: Introductionmentioning

confidence: 99%

A novel nanomagnetic solid acid catalyst for the synthesis of new functionalized bis‐coumarin derivatives under microwave irradiations in green conditions

Zare‐Akbari

Dastmalchi

Edjlali

et al. 2020

In this study, a novel, green, environmentally friendly and magnetically heterogeneous catalyst based on the immobilization of sulfosalicylic acid onto Fe3O4 nanoparticles (Fe3O4@sulfosalicylic acid MNPs) is reported. The bis‐coumarin analogs were synthesized in high yield using the reaction of 1 equivalent of aryl aldehydes with 2 equivalents of 4‐hydroxycoumarin in water under microwave irradiation conditions. Scanning electron microscopy, transmission electron microscopy, energy‐dispersive X‐ray spectroscopy, X‐ray diffraction, thermogravimetric analysis, dynamic light scattering, vibrating sample magnetometry, Fourier transform infrared spectroscopy, UV–visible absorption, and Brunauer‐Emmett‐Teller (BET) techniques confirmed the successful synthesis of the catalyst. The main attractive characteristics of the presented green protocol are very short reaction times (10–15 min), excellent yields, and the avoidance of hazardous or toxic reagent and solvents. Thermal durability, easy separation, and high reusability are important advantages of the new catalyst in comparison to other catalysts.