The first catalytic application of oxidized carbon nanotubes in a four-component synthesis of fused heterocycles

Synthesis and characterization of Co-MOF@Ag2O nanocomposite and its application as a nano-organic catalyst for one-pot synthesis of pyrazolopyranopyrimidines

In this study, a Co-MOF was synthesized via a co-precipitation procedure and then used as support for stabilizing Ag ions and producing Co-MOF@Ag2O nanocomposite by microwave irradiation. The characterization of synthesized Co-MOF@Ag2O nanocomposite was performed by using different techniques such as field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX) analyses, X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET) and Fourier-transform infrared (FT-IR). The prepared Co-MOF@Ag2O nanocomposite was applied as a heterogeneous nano-catalyst in the synthesis of pyrazolopyranopyrimidines in water at 50 °C via the one-pot multicomponent reaction of ethyl acetoacetate, hydrazine hydrate, aromatic aldehydes and barbituric acid derivatives. Through this straightforward and effective protocol, different tricyclic fused pyrazolopyranopyrimidines were synthesized at high yields, and short reaction times, through an uncomplicated work-up process with no by-product. The Co-MOF@Ag2O nanocomposite has been effectively recycled for four consecutive cycles without appreciable loss in its activity. Cost-effectiveness, no need for column chromatography, mild conditions, catalyst recyclability, and eco-friendly nature make it a promising candidate compared to other methods.

Importance of Hybrid Catalysts toward the Synthesis of 5H-Pyrano[2,3-d]pyrimidine-2-ones/2,4-diones (Thiones)

The pyranopyrimidine core is a key precursor for medicinal and pharmaceutical industries due to its broader synthetic applications as well as its bioavailability. Among its four possible isomers, we found that 5H-pyrano[2,3-d]pyrimidine scaffolds have a wide range of applicability, and in recent years, they have been intensively investigated, but the development of the main core is found to be more challenging due to its structural existence. In this review article, we cover all of the synthetic pathways that are employed for the development of substituted 4-aryl-octahydropyrano/hexahydrofuro[2,3-d]pyrimidin-2-one (thiones) and 5-aryl-substituted pyrano[2,3-d]pyrimidindione (2-thiones) derivatives through a one-pot multicomponent reaction using diversified hybrid catalysts such as organocatalysts, metal catalysts, ionic liquid catalysts, nanocatalysts, green solvents, catalyst-/solvent-free conditions, and miscellaneous catalysts as well as the mechanism and recyclability of the catalysts. This review mainly focuses on the application of hybrid catalysts (from 1992 to 2022) for the synthesis of 5H-pyrano[2,3-d]pyrimidine scaffolds. This review will definitely attract the world's leading researchers to utilize broader catalytic applications for the development of lead molecules.

Sulfonated magnetic sugarcane bagasse as an efficient natural polymer-based catalyst for the synthesis of nitrogen-containing heterocyclic rings in water

A new species of catalysts that are prepared from biocompatible materials is demonstrated. Sulfonated magnetic sugarcane bagasse has been synthesized as a novel biodegradable and robust heterogeneous catalyst for organic transformations. The catalyst was characterized by different techniques. Next, the efficiency of this acid catalyst was examined with multi-component reactions for the synthesis of some biologically active scaffolds of heterocyclic organic compounds such 2,3-dihydroquinazolin-4(1H)-ones and pyrido[2,3-d]pyrimidin-4-one derivatives. A wide range of these heterocycles was synthesized with excellent yields in short reaction times under green conditions. In all cases, sulfonated magnetic sugarcane bagasse could be simply collected using an external magnet and reused for several runs without any significant loss of catalytic activity.

Greener organic synthetic methods: Sonochemistry and heterogeneous catalysis promoted multicomponent reactions

Ultrasound is an essential technique to improve organic synthesis from the point of view of green chemistry, as it can promote better yields and selectivities, in addition to shorter reaction times when compared to the conventional methods. Heterogeneous catalysis is another pillar of sustainable chemistry being the recycling and reuse of the catalysts one of its great advantage. In the other hand, multicomponent reactions provide the synthesis of structurally diverse compounds, in a one-pot fashion, without isolation and purification of intermediates. Thus, the combination of these protocols has proved to be a powerful tool to obtain biologically active organic compounds with lower costs, time and energy consumption. Herein, we provide a comprehensive overview of advances on methods of organic synthesis that have been reported over the past ten years with focus on ultrasound-assisted multicomponent reactions under heterogeneous catalysis. In particular, we present pharmacologically important N- and O-heterocyclic compounds, considering their synthetic methods using green solvents, and catalyst recycling.

SCMNPs@Uridine/Zn: An efficient and reusable heterogeneous nanocatalyst for the rapid one-pot synthesis of tricyclic fused pyrazolopyranopyrimidine and 3-methyl carboxylate substituted pyrano[2,3-c]pyrazole derivatives under solvent-free conditions

SCMNPs@Uridine/Zn is utilized as an environmental-friendly and efficient heterogeneous nanocatalyst for two one-pot four-component condensation reactions, containing hydrazine hydrate, arylaldehyde, ethyl acetoacetate, and barbituric acid to yield tricyclic fused pyrazolopyranopyrimidine derivatives (5a-q), and hydrazine hydrate, arylaldehyde, malononitrile, and dimethyl acetylenedicarboxylate/diethyl acetylenedicarboxylate to yield 3-methyl carboxylate substituted pyrano[2,3-c]pyrazole derivatives (8a-y) under solvent-free conditions with high to excellent yields. The main advantages of this process are easy work-up, short reaction times, no chromatographic purifications, and recyclability of the catalyst for a minimum of six runs without any significant decrease in yields of the products. Also, the prepared catalyst SCMNPs@Uridine/Zn was synthesized and fully characterized by various techniques including Fourier transform infrared spectroscopy (FT-IR), energy dispersive X-ray (EDX), thermogravimetric analysis (TGA), X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and Raman spectroscopy.

New heat shock protein (Hsp90) inhibitors, designed by pharmacophore modeling and virtual screening: synthesis, biological evaluation and molecular dynamics studies

Inhibition of heat shock protein 90 (Hsp90) is known to be a significantly effective strategy in cancer therapy. Here, pyrazolopyranopyrimidine derivatives were characterized as new Hsp90 inhibitors. The molecules' key structure (ZINC02819805) was determined by utilizing a pharmacophore model virtual screening workflow. Structural optimization was then carried out on compound ZINC02819805, pyrazolopyranopyrimidine derivatives were designed and six chosen derivatives were synthesized. The inhibition of Hsp90 ATPase activity of synthesized compounds revealed that para methylphenyl derivative of pyrazolopyranopyrimidine (HM3) was the most potent inhibitor (IC₅₀ = 5.5 µM). The anti-proliferative activity of this compound was evaluated against a panel of cell lines including MCF-7, HeLa and HUVEC (IC₅₀ = 1.28 µM, IC₅₀ = 1.74 µM and IC₅₀ = 61.48 µM respectively) by MTT method. The western blot analysis of treated MCF-7 cells with compound HM3 showed that the expression level of Hsp70 and Her2 proteins changed. The high level of Hsp70 expression and low level of Her2 expression suggest that compound HM3 exhibits inhibitory effect on Hsp90. Finally, the key interactions between HM3 and Hsp90 protein were studied by molecular dynamics simulation and showed that compound HM3 was stable in Hsp90 active cite during 200 ns simulation. AbbreviationsHsp90Heat shock protein 90MTT3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromideATPadenosine triphosphateMDmolecular dynamics simulationRMSDroot-mean-square deviationRMSFroot-mean-square fluctuationRggyration radiusm-SABNPsboehmite nanoparticles-supported sulfamic acidCommunicated by Ramaswamy H. Sarma.

A green, catalyst-free synthesis of pyrazolopyranopyrimidines in polyethylene glycol as a biodegradable medium at ambient temperature

A facile, efficient and environmentally safe strategy for the synthesis of pyrazolopyranopyrimidines via one-pot, four-component reaction of hydrazine hydrate, barbituric acid, ethyl acetoacetate, and aromatic aldehydes in polyethylene glycol (PEG) as a safe solvent in the absence of catalyst at ambient temperature has been described. The advantages of the present protocol, such as simplicity, mild conditions, high yields of products, straightforward workup procedure, a green and biodegradable reaction medium, make this new process an attractive to current methodologies.