Synthesis and antimicrobial study of 1,4-dihydropyrano[2,3-c]pyrazole derivatives in the presence of amino-functionalized silica-coated cobalt oxide nanostructures as catalyst

In situ generation and conversion of a half-zirconocene catalyst for the synthesis of N-acylpyrazoles

Pyrazoles are an important class of five-membered nitrogen heterocyclic compounds that have been widely used in agriculture and medicine. Exploring their synthesis methods under mild conditions has always been a hot research topic. Herein, a new strategy was developed to enhance the activity of a zirconium metal centre for the synthesis of N-acylpyrazole derivatives using Cp2ZrCl2 as a pre-catalyst. Cp2ZrCl2 was activated in situ within the catalytic system through cyclopentadienyl ring dissociation, leading to the formation of an activated species, [CpZrCl(acac)2]. The new approach demonstrates broad substrate scope under mild reaction conditions, leading to formation of (3,5-dimethyl-1H-pyrazol-1-yl)(phenyl)methanones with yields of up to 97%.

Design, Synthesis, Antimicrobial Activity, and Molecular Docking of Novel Thiazoles, Pyrazoles, 1,3-Thiazepinones, and 1,2,4-Triazolopyrimidines Derived from Quinoline-Pyrido[2,3-d] Pyrimidinones

BACKGROUND

Recently, pyrido[2,3-d] pyrimidine, triazolopyrimidine, thiazolopyrimidine, quinoline, and pyrazole derivatives have gained attention due to their diverse biological activities, including antimicrobial, antioxidant, antitubercular, antitumor, anti-inflammatory, and antiviral effects.

OBJECTIVE

The synthesis of new heterocyclic compounds including 5-quinoline-pyrido[2,3-d] pyrimidinone (1-2, 4, 6-7), 6-quinoline-pyrido[2,3-d]thiazolo[3,2-a]pyrimidinone (3, 5, 8-10), 1,2,4-triazole-6-quinoline-pyrido[2,3-d]thiazolo[3,2-a]pyrimidinone (11-13), and pyrido[2,3-d]thiazolo[3,2-a]pyrimidine-ethyl-(pyridine)-9-thiaazabenzo[cd]azulenone (14) derivatives was performed with high yields while evaluating antimicrobial activities.

METHODS

A new series of quinoline-pyrido[2,3-d]thiazolo[3,2-a]pyrimidine derivatives were prepared using a modern style and advanced technology, resulting in high yields of these new compounds. Various reagents were utilized, specifically tailored to the production needs of each compound, through reactions that included alkylation, addition, condensation, acylation, the formation of Schiff bases, and intramolecular cyclization.

RESULTS

The chemical structures of the new compounds were determined using spectroscopy analyses, including IR, NMR, and MS, achieving good yields ranging from 68% to 90% under mild conditions in a regular system. All compounds were tested for in vitro antimicrobial activity and compared to standard drugs, specifically cefotaxime sodium and nystatin. The results showed that compounds 10 to 14 exhibited excellent antimicrobial activity, with a minimum inhibitory concentration (MIC) of 1 to 5 µmol/mL, compared to that of the standard drugs, which had MIC values of 1 to 3 µmol/mL. Furthermore, molecular docking studies were conducted to explore the interactions of specific compounds with antimicrobial target proteins. The findings revealed that compounds 10 to 14 displayed significant binding energies, with ΔG values ranging from -7.20 to -11.70 kcal/mol, indicating effective binding to the active sites of antimicrobial protein receptors.

CONCLUSIONS

The SAR study confirmed a relationship between antimicrobial activity and the tested compounds. Molecular docking demonstrated that compounds 10, 11, 12, 13, and 14 exhibited significant binding energy, effectively interacting with the active sites of antimicrobial protein receptors. This consistent finding supports that these new compounds' practical and theoretical studies align regarding their antimicrobial activity.

Recent advances in the multicomponent synthesis of pyrazoles

Pyrazole moiety is considered as an important N-heterocycle in pharmaceuticals and many other functional molecules. The utilization of multicomponent reaction is a major tool in the current approaches of pyrazole synthesis. Considering the power and significance of multicomponent pyrazole synthesis, we review herein the latest developments in this field. According to the typical features, the contents are divided into reactions with different NN fragment sources, such as hydrazine, hydrazone, amidine, nitrile, and diazo compounds, in the pyrazole ring construction, covering the works published since 2019 to date.

Green multicomponent synthesis of pyrano[2,3-c]pyrazole derivatives: current insights and future directions

The past decade has witnessed significant progress in synthesizing structurally diverse and biologically relevant pyrano[2,3-c]pyrazole derivatives through the integration of green methodologies. This review summarizes the recent advances in the green multicomponent synthesis of pyrano[2,3-c]pyrazole and spiro-pyrano[2,3-c]pyrazole derivatives. These include the application of energy-efficient techniques such as microwave and ultrasound-assisted synthesis, benign catalysts and biodegradable composites, solvent selection with a focus on water as a renewable and non-toxic medium, and solvent-free conditions. The review consolidates the current knowledge and future research directions, providing a valuable resource for researchers dedicated to advancing green chemistry practices.

Water-SDS-[BMIm]Br composite system for one-pot multicomponent synthesis of pyrano[2,3-c]pyrazole derivatives and their structural assessment by NMR, X-ray, and DFT studies

Here, we report a simple, efficient, and green protocol for the one-pot synthesis of pyrano[2,3-c]pyrazole derivatives via a sequential three-component strategy using aromatic aldehydes, malononitrile and pyrazolin-5-one in a water-SDS-ionic liquid system. This is a base and volatile organic solvent-free approach that could be applicable to a wide substrate scope. The key advantages of the method over other established protocols are very high yield, eco-friendly conditions, chromatography-free purification and recyclability of the reaction medium. Our study revealed that the N-substituent present in pyrazolinone controls the selectivity of the process. N-unsubstituted pyrazolinone favours the formation of 2,4-dihydro pyrano[2,3-c]pyrazoles whereas under identical conditions N-phenyl substituent pyrazolinone favours the formation 1,4-dihydro pyrano[2,3-c]pyrazoles. Structures of the synthesized products were established by NMR and X-ray diffraction techniques. Energy optimized structures and energy gaps between the HOMO-LUMO of some selected compounds were estimated using density functional theory to explain the extra stability of the 2,4-dihydro pyrano[2,3-c]pyrazoles over 1,4-dihydro pyrano[2,3-c]pyrazoles.

Preparation and catalytic application of two different nanocatalysts based on hexagonal mesoporous silica (HMS) in synthesis of tetrahydrobenzo[b]pyran and 1,4-dihydropyrano[2,3-c]pyrazole derivatives

The present study describes the synthesis, characterization, and investigation of catalytic activity of xanthine-Ni complex (Xa-Ni) and 4-phenylthiosemicarbazide-Cu complex (PTSC-Cu) incorporated into functionalized hexagonal mesoporous silica (HMS/Pr-Xa-Ni and HMS/Pr-PTSC-Cu). These useful mesoporous catalysts had been synthesized and identified using various techniques such as FT-IR, XRD, adsorption-desorption of nitrogen, SEM, TEM, EDX-Map, TGA, AAS and ICP. These spectral techniques successfully confirmed the synthesis of the mesoporous catalysts. The catalytic activity of HMS/Pr-a-Ni (Catalyst A) and HMS/Pr-PTSC-Cu (Catalyst B) were evaluated for synthesis of tetrahydrobenzo[b]pyran and 1,4-dihydropyrano[2,3-c]pyrazole derivatives. HMS/Pr-PTSC-Cu exhibited higher efficiency in green media under milder reaction condition at room temperature. Furthermore, the synthesized nanocatalysts, exhibited appropriate recoverability that can be able to reuse for several times without significant loss of catalytic activity.

The Synthesis, Antimicrobial Activity, and Molecular Docking of New 1, 2, 4-Triazole, 1, 2, 4-Triazepine, Quinoline, and Pyrimidine Scaffolds Condensed to Naturally Occurring Furochromones

This study aims to synthesize a new series of furochromone derivatives, evaluate their antimicrobial properties, and improve the permeability of potent compounds to inhibit different types of bacteria and fungi. Hence, Substituted furo[3,2-g]chromene-6-carbonitrile (3a,b) readily form 7-amino-5-methyl-furo [3,2-g]chromene-6-carbonitrile (4a,b) via reduction using sodium borohydride in methanol. The same compounds of (4a,b) were used as starting materials for the synthesis of new furochromone derivatives such as furochromeno [2,3-d]pyrimidines, N- (6-cyano- 5-methyl-furochromene) acetamide, N-(6-cyano-5-methyl-furo chromene)-2-phenyl acetamide, N- (6-cyano-5-methyl-furochromene) formimidate, furochromeno[1,2,4]triazepin-5-amine, furochrom ene-6-carboxamide, furochromeno[1,2,4]triazolopyrimidines, and furochromeno[2,3-b]quinolin- 6-amine. The structures of the new compounds were determined using spectroscopy: Nuclear Magnetic Resonance (1H, 13C), Mass spectra, Infrared, and elemental analysis. Molecular docking studies were conducted to investigate the binding patterns of the prepared compounds against DNA-gyrase (PDB 1HNJ). The results displayed that compounds furochromenotriazolopyrimidine (20a,b), furochromenoquinolin-6-amine (21a,b), furochromenotriazepin-amine (9a,b), and furo- chromenopyrimidine-amine (19a,b) were excellent antimicrobials.

Synthesis and Evaluation of Some New 4H-Pyran Derivatives as Antioxidant, Antibacterial and Anti-HCT-116 Cells of CRC, with Molecular Docking, Antiproliferative, Apoptotic and ADME Investigations

Colorectal cancer oncogenesis is linked to dysbiosis, oxidative stress and overexpression of CDK2. The 4H-pyran scaffold is considered an antitumoral, antibacterial and antioxidant lead as well as a CDK2 inhibitor. Herein, certain 4H-pyran derivatives were evaluated as antibacterial, antioxidant and cytotoxic agents against HCT-116 cells. Derivatives 4g and 4j inhibited all the tested Gram-positive isolates, except for B. cereus (ATCC 14579), with lower IC₅₀ values (µM) than ampicillin. In addition, 4g and 4j demonstrated the strongest DPPH scavenging and reducing potencies, with 4j being more efficient than BHT. In cell viability assays, 4d and 4k suppressed the proliferation of HCT-116 cells, with the lowest IC₅₀ values being 75.1 and 85.88 µM, respectively. The results of molecular docking simulations of 4d and 4k, inhibitory kinase assays against CDK2, along with determination of CDK2 protein concentration and the expression level of CDK2 gene in the lysates of HCT-116 treated cells, suggested that these analogues blocked the proliferation of HCT-116 cells by inhibiting kinase activity and downregulating expression levels of CDK2 protein and gene. Moreover, 4d and 4k were found to induce apoptosis in HCT-116 cells via activation of the caspase-3 gene. Lastly, compounds 4g, 4j, 4d and 4k were predicted to comply with Lipinski’s rule of five, and they are expected to possess excellent physiochemical and pharmacokinetic properties suitable for in vivo bioavailability, as predicted by the SwissADME web tool.

A New Pathway for the Preparation of Pyrano[2,3-c]pyrazoles and molecular Docking as Inhibitors of p38 MAP Kinase

We report a new pathway to synthesize pyrano[2,3-c]pyrazoles and their binding mode to p38 MAP kinase. Pyrano[2,3-c]pyrazole derivatives have been prepared through a four-component reaction of benzyl alcohols, ethyl acetoacetate, phenylhydrazine, and malononitrile in the presence of sulfonated amorphous carbon and eosin Y as catalysts. All products were characterized by melting point, ¹H and ¹³C NMR, and HRMS (ESI). The products were screened in silico for their binding activities to both the ATP-binding pocket and the lipid-binding pocket of p38 MAP kinase, using a structure-based flexible docking provided by the engine ADFR. The results showed that eight synthesized compounds had a higher affinity to the lipid pocket than to the other target site, which implied potential applications as allosteric inhibitors. Finally, the most biologically active compound, 5, had a binding affinity comparable to those of other proven lipid pocket inhibitors, with affinity to the target pocket reaching -10.9932 kcal/mol, and also had the best binding affinity to the ATP-binding pockets in all of our products. Thus, our research provides a novel pathway for synthesizing pyrano[2,3-c]pyrazoles and bioinformatic evidence for their biological capability to block p38 MAP kinase pockets, which could be useful for developing cancer or immune drugs.

Substituted Pyrazoles and Their Heteroannulated Analogs-Recent Syntheses and Biological Activities

Pyrazoles are considered privileged scaffolds in medicinal chemistry. Previous reviews have discussed the importance of pyrazoles and their biological activities; however, few have dealt with the chemistry and the biology of heteroannulated derivatives. Therefore, we focused our attention on recent topics, up until 2020, for the synthesis of pyrazoles, their heteroannulated derivatives, and their applications as biologically active moieties. Moreover, we focused on traditional procedures used in the synthesis of pyrazoles.

Insight into 6-aminopenicillanic acid structure and study of the quantum mechanical calculations of the acid–base site on γ-Fe2O3@SiO2 core–shell nanocomposites and as efficient catalysts in multicomponent reactions

Magnetic 6-APA/γ-Fe₂O₃@Sio₂ nanocomposites have been developed by exploiting the potential of the acid–base bifunctional system to study the quantum mechanistic calculations.