Synthesis and Applications of 2‐Substituted Imidazole and Its Derivatives: A Review

Three-component cascade reaction of 3-ketonitriles, 2-unsubstituted imidazole N-oxides, and aldehydes

A three-component condensation of 2-unsubstituted imidazole N-oxides, 3-ketonitriles, and aldehydes is described. The reaction proceeds via sequential Knoevenagel condensation/Michael addition under mild, catalyst-free conditions with various substrates. Furthermore, the corresponding 2-functionalized imidazole N-oxides can be further dehydrated to (Z)-2-aroyl-3-(1H-imidazol-2-yl)-acrylonitriles, which may also be directly prepared by changing the reaction conditions as a cascade of Knoevenagel condensation/Michael addition/dehydration.

Synthesis, structural study and antitumor activity of novel alditol-based imidazophenanthrolines (aldo-IPs)

A series of 1H-imidazo [4,5-f][1,10] phenanthroline derivatives functionalized at 2-position with chiral, and conformationally flexible polyhydroxy alkyl chains derived from carbohydrates (alditol-based imidazophenanthrolines, aldo-IPs) is presented herein. These novel glycomimetics showed relevant and differential cytotoxic activity against several cultured tumor cell lines (PC3, HeLa and HT-29), dependent on the nature and stereochemistry of the polyhydroxy alkyl chain. The mannose-based aldo-IP demonstrated the higher cytotoxicity in the series, substantially better than cisplatin metallo-drug in all cell lines tested, and better than G-quadruplex ligand 360A in HeLa and HT29 cells. Cell cycle experiments and Annexin V-PI assays revealed that aldo-IPs induce apoptosis in HeLa cells. Initial study of DNA interactions by DNA FRET melting assays proved that the aldo-IPs produce only a slight thermal stabilization of DNA secondary structures, more pronounced in the case of quadruplex DNA. Viscosity titrations with CT dsDNA suggest that the compounds behave as DNA groove binders, whereas equilibrium dialysis assays showed that the compounds bind CT with Ka values in the range 104-105 M-1. The aldo-IP derivatives were obtained with synthetically useful yields through a feasible one-pot multistep process, by aerobic oxidative cyclization of 1,10-phenanthroline-5,6-diamine with a selection of unprotected aldoses using (NH4)2SO4 as promoter.

Synthesis of a bistriazolyl-phenanthroline-Cu(ii) complex immobilized on nanomagnetic iron oxide as a novel green catalyst for synthesis of imidazoles via annulation reactions

We designed and prepared a novel N-heterocycle-based nanocatalyst by a post synthetic method, namely the [Fe3O4@DAA-BTrzPhen-Cu(ii)] composite. In this method, bistriazolyl-phenanthroline groups were stepwise synthesized on an Fe3O4 substrate and used as a tetradentate nitrogenous ligand for coordinating to copper ions. The obtained nanocomposite was well characterized using FT-IR, PXRD, TGA, EDAX, ICP-OES, EDX-mapping, SEM, TEM, VSM and BET analyses, which confirm the formation of a thermostable crystalline spherical particle morphology with the particle size in the range of 17 nm to 25 nm and a magnetization value of 42 emu g-1. Also, the catalytic activity of [Fe3O4@DAA-BTrzPhen-Cu(ii)] as a novel and magnetically separable heterogeneous nanocatalyst was evaluated in preparing various tetrasubstituted imidazole derivatives from one-pot four-component condensation of anilines, aldehydes, 1,2-diketones and ammonium acetate, and favorable products were produced with excellent yields. The stability, low Cu leaching, and heterogenous nature of the nanocatalyst were confirmed by hot-filtration and leaching tests. The copper based nanocatalyst could be easily recovered by magnetic field separation and recycled at least 8 times in a row without noticeable loss in its catalytic activity.

Competitive inhibition of a non-natural cofactor dependent formaldehyde dehydrogenase by imidazole

OBJECTIVES

To better understand the unique inhibitory behavior of a non-natural cofactor preferred formaldehyde dehydrogenase (FalDH) mutant 9B2.

RESULTS

We described our serendipitous observation that 9B2 was reversibly inhibited by residual imidazole introduced during protein preparation, while the wild-type enzyme was not sensitive to imidazole. Kinetic analysis showed that imidazole was a competitive inhibitor of formaldehyde with a K_i of 16 μM and an uncompetitive inhibitor of Nicotinamide Cytosine Dinucleotide for 9B2, indicating that formaldehyde and imidazole were combined in the same position. Molecular docking results of 9B2 showed that imidazole could favorably bind very close to the nicotinamide moiety of the cofactor, where formaldehyde was expected to reside for catalysis, which was in line with a competitive inhibition.

CONCLUSION

The mutant 9B2 can be competitively inhibited by imidazole, suggesting that cautions should be taken to evaluate activities as protein mutants might attain unexpected sensitivity to a component in buffers for purification or activity assays.

Electrochemically Induced Synthesis of Imidazoles from Vinyl Azides and Benzyl Amines

An electrochemically induced synthesis of imidazoles from vinyl azides and benzyl amines was developed. A wide range of imidazoles were obtained, with yields of 30 to 64%. The discovered transformation is a multistep process whose main steps include the generation of electrophilic iodine species, 2H-azirine formation from the vinyl azide, followed by its reactions with benzyl amine and with imine generated from benzyl amine. The cyclization and aromatization of the obtained intermediate lead to the target imidazole. The synthesis proceeds under constant current conditions in an undivided cell. Despite possible cathodic reduction of various unsaturated intermediates with C=N bonds, the efficient electrochemically induced synthesis of imidazoles was carried out.

Exploration of chalcones and related heterocycle compounds as ligands of adenosine receptors: therapeutics development

Adenosine receptors (ARs) are ubiquitously distributed throughout the mammalian body where they are involved in an extensive list of physiological and pathological processes that scientists have only begun to decipher. Resultantly, AR agonists and antagonists have been the focus of multiple drug design and development programmes within the past few decades. Considered to be a privileged scaffold in medicinal chemistry, the chalcone framework has attracted a substantial amount of interest in this regard. Due to the potential liabilities associated with its structure, however, it has become necessary to explore other potentially promising compounds, such as heterocycles, which have successfully been obtained from chalcone precursors in the past. This review aims to summarise the emerging therapeutic importance of adenosine receptors and their ligands, especially in the central nervous system (CNS), while highlighting chalcone and heterocyclic derivatives as promising AR ligand lead compounds.

Arene Amination Instead of Fluorination: Substitution Pattern Governs the Reactivity of Dialkoxybenzenes with Selectfluor

Arene substitution patterns are well-known to affect the regioselectivity of a given transformation but not necessarily the type of reactivity. Herein, we report that the substitution pattern of alkoxyarenes dictates whether a putative one-electron or two-electron reaction predominates in reactions with Selectfluor. A series of amination products is presented, resulting from the single-electron oxidation of electron-rich arenes followed by direct C-H to C-N bond formation. We demonstrate the ability of this transformation to synthesize medicinally and biologically relevant nitrogen heterocycles. Lastly, this unusual "mechanistic switch" is probed with computational chemistry and competition experiments.

Rapid formation of 2-lithio-1-(triphenylmethyl)imidazole and substitution reactions in flow

The rapid formation and reaction of 2-lithio-1-(triphenylmethyl)imidazole in flow at ambient temperature is reported.

ZnO-nanocatalyst Promoted the Production of Imidazole Derivatives via four-component Reaction of Aminoacid: Study of Antioxidant and Antimicrobial Activity

AIM AND OBJECTIVE

In current research, imidazole derivatives are synthesized via a new process of four component reaction of trichloroacetonitrile, amides, alkyl bromides and amino acids catalyzed by zinc oxide nanoparticles (ZnO-NPs) as a simple and recyclable catalyst in water at room temperature. Among investigated compounds, compounds 5b have good results relative to butylated hydroxytoluene (BHT) and 2-tert-butylhydroquinone (TBHQ) as standard antioxidant. The achieved outcomes of disk diffusion experiment showed that these compounds avoided the growth of bacterial.

MATERIALS AND METHODS

In this research, all chemicals are purchased from Fluka (Buchs, Switzerland) and employed with any purification. For measuring infrared spectroscopy and melting point, a Shimadzu IR-460 spectrometer and Electrothermal 9100 apparatus are utilized respectively. BRUKER DRX-400 AVANCE spectrometer is used for giving the 1H, and 13CNMR spectra at 400.1 and 100 MHz respectively. For recording mass spectra, A FINNIGAN-MAT 8430 spectrometer with an ionization potential of 70 eV was utilized. The scanning electron microscopy (SEM) employing a Holland Philips XL30 microscope was used for determination of ZnO nanocomposites morphology. X-ray diffraction (XRD) analysis at room temperature using a Holland Philips Xpert X-ray powder diffractometer, with CuKα radiation (λ=0.15406 nm), with 2θ ranging from 20 to 80° was employed for characterization of crystalline structure of Fe3O4/CuO nanocomposites. Scherrer's formula; D= 0.9λ/β cosθ was employed for calculating the average crystallite size where D is the diameter of the nanoparticles, λ (CuKα) =1.5406 Å and β is the fullwidth at half-maximum of the diffraction lines. A general way to prepare of compounds 5 The trichloroacetonitrile 1 (2 mmol) and amides 2 (2 mmol) mixed with ZnO-NPs (10 mol%) in water (5 mL). after 45 min amino acids 3 (2 mmol) was added to previous mixture at room temperature. After 30 min α-haloketones 4 (2 mmol) was added to mixture and stirred for 3 h. After 3 h, the reaction is completed and TLC confirms progress of the reaction. At last, the solid residue was collected by filtration and cleaned with EtOAC to removing ZnO-NPs and after evaporating solvent and washing solid with Et2O compounds 5 afforded as pure product.

RESULTS

Without employing catalyst, these reactions have low yield and busy mixture. The synthesis of compound 5a as sample reaction and displayed the ZnO nanoparticles (10 mol%) is the best catalyst for sample reaction and H2O is the very better than other solvent in sample raection. Structures of 5 are confirmed by IR, 1H NMR, 13C NMR mass spectra.

CONCLUSION

In summary, imdazole derivatives were produced in excellent yield from the reaction of trichloroacetonitrile, amides, alkyl bromides and amino acids using ZnO-NPs in water at room temperature. In addition, the power of synthesized imidazole as antioxidant was determined by radical trapping of DPPH and power of reducing ferric analyzes. The tested imidazoles display good radical trapping of DPPH but exhibitted moderate FRAP relative to BHT and TBHQ as synthetic antioxidants.The outcomes of disk diffusion experiment exhibite that synthesized imidazole avoided the bacterial growth. The superiorities of this procedure are environmental, high yield of product and low amounts of catalyst and short time of reaction.

Base-Promoted Annulation of Amidoximes with Alkynes: Simple Access to 2,4-Disubstituted Imidazoles

An efficient construction of imidazole ring by a Cs₂CO₃-promoted annulation of amidoximes with terminal alkynes in DMSO has been developed. This protocol provides a simple synthetic route with high atom-utilization for the synthesis of 2,4-disubstituted imidazoles in good yields under transition-metal-free and ligand-free conditions. Internal alkynes can also undergo the annulation to give 2,4,5-trisubstituted imidazoles.

Carbodiimide-based synthesis of N-heterocycles: moving from two classical reactive sites to chemical bond breaking/forming reaction

Carbodiimides are a unique class of heterocumulene compounds that display distinctive chemical properties. The rich chemistry of carbodiimides has drawn increasing attention from chemists in recent years and has made them exceedingly useful compounds in modern organic chemistry, especially in the synthesis of N-heterocycles. This review has outlined the extensive application of carbodiimides in the synthesis of N-heterocycles from the 1980s to today. A wide range of reactions for the synthesis of various types of N-heterocyclic systems (three-, four-, five-, six-, seven-, larger-membered and fused heterocycles) have been developed on the basis of carbodiimides and their derivatives.

Synthesis of Imidazole-Based Medicinal Molecules Utilizing the van Leusen Imidazole Synthesis

Imidazole and its derivatives are one of the most vital and universal heterocycles in medicinal chemistry. Owing to their special structural features, these compounds exhibit a widespread spectrum of significant pharmacological or biological activities, and are widely researched and applied by pharmaceutical companies for drug discovery. The van Leusen reaction based on tosylmethylisocyanides (TosMICs) is one of the most appropriate strategies to synthetize imidazole-based medicinal molecules, which has been increasingly developed on account of its advantages. In this review, we summarize the recent developments of the chemical synthesis and bioactivity of imidazole-containing medicinal small molecules, utilizing the van Leusen imidazole synthesis from 1977.