(ZrO)2Fe2O5 as an efficient and recoverable nanocatalyst in C–C bond formation

2019

Self Cite

157

Molecules that contain polyhydroquinoline structural scaffolds are N‐containing heterocycles which are of great interest to organic chemists and biologists. Polyhydroquinoline structural scaffolds which are known as calcium channel blockers have emerged as one of the most important class of drugs used for the treatment of cardiovascular and Alzheimer's diseases. Besides, recovery and reusability of catalysts are important issues to be discussed in modern catalysis research especially in organic synthesis. The concept of magnetically recoverable catalysts has been rapidly developed in recent times. Magnetic separation is an efficient strategy for the rapid separation of catalysts from the reaction medium. Also, an alternative to time‐, solvent‐, and energy‐consuming separation techniques. In this review, we focused on the fabrication, surface‐modification and characterization of nanomagnetic materials and their application, as magnetically recoverable catalysts, in the synthesis of polyhydroquinoline structural scaffolds.

Section: Introductionmentioning

confidence: 99%

“…Magnetic nanoparticles can be readily separated from the reaction medium using an external magnet and without the need for filtration, centrifugation or other tedious workup processes . In fact, magnetic separable catalysts are among the favoured and fascinating strategies to bridge the split between heterogeneous and homogenous catalysis …”

Section: Introductionmentioning

confidence: 99%

Magnetically Recoverable Catalysts: Catalysis in Synthesis of Polyhydroquinolines

Kazemi

2019

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157

“…[13][14][15][16][17][18] Due to their small sizes, catalytic-active nanoparticles have higher surface areas and increased exposed active sites, and thereby improved contact areas with reactants, akin to those of homogeneous catalytic systems. [19][20][21][22][23] Preparation of chemical, industrial and pharmaceutical compounds by multi-component reactions (MCRs) is very significant in consideration of combinatorial chemistry. [21,24,25] In this technique, more than two starting materials react together in a one-pot reaction to form a product wherein all or most of the reactants atoms contribute.…”

Section: Introductionmentioning

confidence: 99%

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

Filian

Kohzadian

et al. 2020

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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.

“…Recent studies have demonstrated that several factors can control the condensation rates of SBA‐15 which contains amounts of inorganic salts, shape of surfactant micelles, stirring rate and condensation rate of silica . On the other hand, metal–organic complexes, involving rare earth elements such as lanthanide ions, are often used in catalysis field because they have the oxophilic nature and can easily build a framework structure …”

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

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.