Tetrasubstituted Imidazole Inhibitors of Cytokine Release: Probing Substituents in the N-1 Position

Magnetic polyborate nanoparticles as a green and efficient catalyst for one-pot four-component synthesis of highly substituted imidazole derivatives

In this study, magnetic polyborate nanoparticles (MPBNPs) were prepared via a simple procedure from boric acid by using ball-milling and then characterized by various spectroscopic, microscopic and analytical methods including FT-IR, EDX, XRD, FESEM, VSM and TGA analysis. The obtained MPBNPs were further explored, as a green and highly efficient catalyst, in the multi-component synthesis of a wide range of tetra-substituted imidazoles from cascade cyclocondensation as well as in situ air oxidation of benzil or benzoin, aromatic aldehydes, primary amine and ammonium acetate in EtOH, as a green solvent, under reflux conditions. Additionally, environmentally friendly conditions for the preparation of the catalyst by the use of non-toxic reactants, facile procedure and high to excellent yields of the desired products as well as the use of a green solvent are some advantages of this new protocol.

Photocaging of Pyridinylimidazole-Based Covalent JNK3 Inhibitors Affords Spatiotemporal Control of the Binding Affinity in Live Cells

The concept of photocaging represents a promising approach to acquire spatiotemporal control over molecular bioactivity. To apply this strategy to pyridinylimidazole-based covalent JNK3 inhibitors, we used acrylamido-N-(4-((4-(4-(4-fluorophenyl)-1-methyl-2-(methylthio)-1H-imidazol-5-yl)pyridin-2-yl)amino)phenyl)benzamide (1) as a lead compound to design novel covalent inhibitors of JNK3 by modifying the amide bond moiety in the linker. The newly synthesized inhibitors demonstrated IC50 values in the low double-digit nanomolar range in a radiometric kinase assay. They were further characterized in a NanoBRETTM intracellular JNK3 assay, where covalent engagement of the target enzyme was confirmed by compound washout experiments and a loss in binding affinity for a newly generated JNK3(C154A)-NLuc mutant. The most potent compound of the series, N-(3-acrylamidophenyl)-4-((4-(4-(4-fluorophenyl)-1-methyl-2-(methylthio)-1H-imidazol-5-yl)pyridin-2-yl)amino)benzamide (13), was equipped with a photolabile protecting group leading to a nearly 10-fold decrease in intracellular JNK3 binding affinity, which was fully recovered by UV irradiation at a wavelength of 365 nm within 8 min. Our results highlight that photocaged covalent inhibitors can serve as a pharmacological tool to control JNK3 activity in live cells with light.

Hydrogen transfer-induced S-C rearrangement in the molecular ion of thioanisole derivatives with site-specificity

In this study, the gas-phase fragmentations of molecular ions of thioanisole derivatives were investigated using electron ionization mass spectrometry (EI-MS). In the EI-MS spectrum, a characteristic fragment ion [M - SH]⁺ was observed. The same result with the molecular ion of 3-aminothioanisole was enhanced, while the same phenomenon was not obvious in the EI-MS spectra of 2- or 4-aminothioanisole. To explain the fragmentation, we proposed a mechanism that involved the hydrogen transfer-induced S-C rearrangement with 3 pathways. Substituent effect results, deuterium-labelled experiments and density functional theory (DFT) calculations also confirmed the proposed mechanism.

Silver-Mediated [3 + 2] Cycloaddition of Azomethine Ylides with Trifluoroacetimidoyl Chlorides for the Synthesis of 5-(Trifluoromethyl)imidazoles

A silver-mediated [3 + 2] cycloaddition of azomethine ylides with trifluoroacetimidoyl chlorides for the rapid assembly of 5-(trifluoromethyl)imidazoles has been developed. Notable features of the reaction include readily accessible reagents, a broad substrate scope, and high efficiency. The protocol can be successfully applied to construct the analogue of the specific allosteric modulator of GABA_A receptors. The silver species could be recycled by a simple operation.

One-pot synthesis of symmetric imidazolium ionic liquids N,N-disubstituted with long alkyl chains

The Debus–Radziszewski imidazole synthesis was adapted to directly yield long-chain imidazolium ionic liquids. Imidazolium acetate ionic liquids with side-chains up to sixteen carbon atoms were synthesised in excellent yields via an on-water, one-pot reaction. The imidazolium acetate ILs acted as surfactants when dissolved in various solvents. The imidazolium acetate ionic liquids were also derivatised via an acid metathesis to the chloride, nitrate, and hydrogen oxalate derivatives. The thermal behaviour of all the ionic liquids was determined via thermogravimetric and calorimetric analysis.

The modified Debus–Radziszewski reaction was used as a one-pot on-water reaction to allow a greener synthesis of long-chain 1,3-dialkylimidazolium acetate ionic liquids in high yield from long-chain linear amines.

Acid-Catalyzed 1,3-Dipolar Cycloaddition of 2H-Azirines with Nitrones: An Unexpected Access to 1,2,4,5-Tetrasubstituted Imidazoles

The first 1,3-dipolar cycloaddition of 2H-azirines with nitrones, a straightforward approach toward the regioselective synthesis of 1,2,4,5-tetrasubstituted imidazoles, is reported. This trifluoroacetic acid-catalyzed protocol tolerates a broad range of aliphatic and aromatic substrates, offering an efficient access to highly diverse, multisubstituted imidazoles in isolated yields up to 83% under mild conditions.

Current Advances in the Synthesis and Biological Evaluation of Pharmacologically Relevant 1,2,4,5-Tetrasubstituted-1H-Imidazole Derivatives

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In recent years, the synthesis and evaluation of the biological properties of 1,2,4,5-tetrasubstituted-1H-imidazole derivatives have been the subject of a large number of studies by academia and industry. In these studies it has been shown that this large and highly differentiated class of heteroarene derivatives includes high valuable compounds having important biological and pharmacological properties such as antibacterial, antifungal, anthelmintic, anti-inflammatory, anticancer, antiviral, antihypertensive, cholesterol-lowering, antifibrotic, antiuricemic, antidiabetic, antileishmanial and antiulcer activities.

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The present review with 411 references, in which we focused on the literature data published mainly from 2011 to 2017, aims to update the readers on the recent developments on the synthesis and biological evaluation of pharmacologically relevant 1,2,4,5-tetrasubstituted-1H-imidazole derivatives with an emphasis on their different molecular targets and their potential use as drugs to treat various types of diseases. Reference was also made to substantial literature data acquired before 2011 in this burgeoning research area.

Iodine mediated oxidative cross coupling of 2-aminopyridine and aromatic terminal alkyne: a practical route to imidazo[1,2-a]pyridine derivatives

A novel, transition-metal free route leading to imidazo[1,2-a]pyridine derivatives via iodine mediated oxidative coupling between 2-aminopyridine and aromatic terminal alkyne has been demonstrated. This newly developed method discloses an operationally simple way for the construction of imidazoheterocycles. Commercially available antiulcer drug zolimidine may readily be synthesized employing this method.

A Novel Tetrasubstituted Imidazole as a Prototype for the Development of Anti-inflammatory Drugs

Although inflammation is a biological phenomenon that exists to protect the host against infections and/or related problems, its unceasing activation results in the aggravation of several medical conditions. Imidazoles, whether natural or synthetic, are molecules related to a broad spectrum of biological effects, including anti-inflammatory properties. In this study, we screened eight novel small molecules of the imidazole class synthesized by our research group for their in vitro anti-inflammatory activity. The effect of the selected molecules was confirmed in an in vivo inflammatory model. We also analyzed whether the effects were caused by inhibition of nuclear factor kappa B (NF-κB) transcription factor transmigration. Of the eight imidazoles tested, methyl 1-allyl-2-(4-fluorophenyl)-5-phenyl-1H-imidazole-4-acetate (8) inhibited nitric oxide metabolites and pro-inflammatory cytokine (TNF-α, IL-6, and IL-1β) secretion in J774 macrophages stimulated with LPS. It also attenuated leukocyte migration and exudate formation in the pleural cavity of mice challenged with carrageenan. Furthermore, imidazole 8 reverted the oxidative stress pattern triggered by carrageenan in the pleural cavity by diminishing myeloperoxidase, superoxide dismutase, catalase, and glutathione S-transferase activities and reducing the production of nitric oxide metabolites and thiobarbituric acid-reactive substances. Finally, these effects can be attributed, at least in part, to the ability of this compound to prevent NF-κB transmigration. In this context, our results demonstrate that imidazole 8 has promising potential as a prototype for the development of a new anti-inflammatory drug to treat inflammatory conditions in which NF-κB and oxidative stress play a prominent role. Graphical Abstract ᅟ.

NIS-Mediated intermolecular hydroamination of allenamides with imidazole heterocycles: a facile protocol for the synthesis of allylic N,N-acetals

We report a new protocol to synthesize allylic N,N-acetal derivatives through NIS-mediated hydroamination of allenamides with imidazole heterocycles.

2-Alkylsulfanyl-4(5)-aryl-5(4)-heteroarylimidazoles: An Overview on Synthetic Strategies and Biological Activity

2-Alkylsulfanyl-4(5)-aryl-5(4)-heteroarylimidazoles represent an important class of ATP-competitive protein kinase inhibitors, offering the possibility of multiple interactions with different regions of the target enzyme. The necessity of exploring the effects of diverse chemical decorations around the imidazole core prompted the design of several synthetic routes aimed at achieving both efficiency and flexibility. Additionally, the optimization of established protocols and the extensive use of transition metal-catalyzed cross-coupling reactions have been broadening the spectrum of preparative methodologies within the last decade. This review summarizes the progress in the development of synthetic strategies leading to 2-alkylsulfanyl-4(5)-aryl-5(4)-heteroarylimidazoles and 1-alkyl-2-alkylsulfanyl-4(5)-aryl-5(4)-heteroarylimidazoles and offers a glance at the biological activities of this class of compounds.

Cycloadduct formation of α,β-unsaturated esters with azides catalyzed by NHC systems

NHC-catalyzed cycloadduct formation of α,β-unsaturated esters with azides has been developed. This strategy could generate 1,2,3-triazoles and dihydropyrazoles with high yields and regioselectivities. The broad substrate scope and mechanistic survey of this process are also presented.

Azomethine-isocyanide [3+2] cycloaddition to imidazoles promoted by silver and DBU

A new silver-promoted [3+2] cycloaddition of azomethine ylides with isocyanides has been described to construct a variety of 1,2,4-trisubstituted imidazoles of vital bioactive molecules.

Crosslinked chitosan nanoparticle-anchored magnetic multi-wall carbon nanotubes: a bio-nanoreactor with extremely high activity toward click-multi-component reactions

In the present study, we have designed a procedure for the synthesis of a bio-nanoreactor catalyst, crosslinked chitosan nanoparticle-anchored magnetic multi-wall carbon nanotubes (CS NPs/MWCNT@Fe₃O₄), via an in situ ionotropic gelation method.