Trisubstituted Thiazoles Research Articles

Multicomponent Synthesis of Fluorescent Thiazole-Indole Hybrids and Thiazole-Based Novel Polymers.

Herein, we report an efficient multicomponent reaction for the synthesis of trisubstituted thiazoles involving a one-pot C-C, C-N, and C-S bond-forming process from the readily available starting materials. The reaction of arylglyoxal, indole, and aryl thioamides in the acetic acid medium under sealed heating conditions provided 3-(2,4-diarylthiazol-5-yl)-1H-indoles (4) in good to excellent yields. Using a similar reaction strategy, the reaction of arylglyoxal, aryl thioamide, and 2,5-dihydroxy-1,4-benzoquinone provided structurally interesting bis-thiazoles having dihydroxy-1,4-benzoquinone linker (9). All of the products were fully characterized by spectroscopic techniques. We also recorded single-crystal X-ray diffraction (XRD) of compounds 4b and 9a for unambiguous structure determination. Indole-linked trisubstituted thiazoles (4) exhibit prominent fluorescence properties. The relative fluorescence quantum yields of all of the thiazole-linked indoles were measured in the dimethyl sulfoxide (DMSO) medium with respect to quinine sulfate in 0.1 M H2SO4 as reference. The scope of this reaction was further explored by preparing novel polymers 11a and 11b using naphthalene/benzene-1,4-bis(carbothioamide) in multicomponent polymerization.

Efficient one-pot synthesis of substituted diphenyl 1, 3-thiazole through multicomponent reaction by using green and efficient Iron-catalyst via Cross-Dehydrogenative Coupling(CDC)

A clean and efficient, multi-component strategy for the synthesis of biologically important trisubstituted thiazole via the reaction of readily available barbituric acid, acetophenone, and aryl thioamides is reported in the presence of FeCl3.6H2O /O2(Air) in DMF solvent. The advantages of the present methodology include a one-pot reaction, environment-friendly approach, cost-effectiveness, broad substrate scope, operational simplicity, short reaction time, easy workup procedure, and high yields.

Synthesis, Antimicrobial and Molecular Modeling Studies of Some Benzophenone-based Thiazole and 4-Thiazolidinone Derivatives

New series of thiazolyl hydrazones were designed and synthesized via the reaction of benzophenone thiosemicarbazone 2 with chloroacetic acid, (un)substituted phenacylbromide and ethyl-2-chloroacetoacetate to yield compounds 3, 5a-d & 6 respectively. Furthermore, reaction of the thiazolidin-4-one 3 with aromatic aldehydes afforded compounds 4a-g. Characterization data, along with in vitro antimicrobial activity for all compounds are herein reported. All the synthesized compounds were screened against Methicillin- Resistant Staphylococcus aureus (MRSA), E. coli, K. pneumonia, P. aeruginosa, A baumannii, C. albicans and C. neoformans var.grubii. Compounds 2 and 4e showed the highest bacterial growth inhibition with 28.6% and 28.7% against MRSA, respectively. Moreover, the trisubstituted thiazole derivative 6 was the most active compound against Gram-negative bacteria A. baumannii with 59% growth inhibition. Furthermore, compounds 4e & 6 showed 22.5% and 17.3% decrease in peptidoglycan density, respectively. Molecular docking into bacterial MurB enzyme active site was used to determine their binding modein which they showed good interactions with Gln229, Arg225 and Ser82 amino acid residues.

Synthesis of novel 2, 3, 5-tri-substituted thiazoles with anti-inflammatory and antibacterial effect causing clinical pathogens

BackgroundThe present work is an extension of ongoing efforts toward the development and identification of new molecules as monotherapy displaying anti-inflammatory and anti-infective activities and a wide-range of gastrointestinal selectivity. A series of novel set of trisubstituted thiazole compounds (AR-17a to AR-27a) have synthesized and evaluated for their in-vitro and in-vivo anti-inflammatory activities. Synthesized trisubstituted thiazole compounds were also evaluated for their potential antibacterial activity against clinical pathogens causing infectious disease. Material and MethodThe structures of synthesized compounds were characterized by FTIR, 1H NMR, Mass spectroscopic techniques and evaluated for their in-vitro and in-vivo anti-inflammatory effects using the human red blood cell (HRBC) membrane stabilization method and a carrageenan-induced rat paw oedema model, respectively, Diclofenac sodium and Ibuprofen were used as standard drugs. The synthesized compounds AR-17atoAR-27a screened for their in-vitro antibacterial activity against the gram-positive bacteria Staphylococcus aureus (ATCC25923) and Enterococcus faecalis (ATCC29212) and the gram-negative bacteria Escherichia coli (ATCC8739) and Pseudomonas aeruginosa (ATCC9027) using ciprofloxacin and cefdinir as standard drugs. ResultCompounds AR-17a and AR-27a elicited maximum anti-inflammatory activity, providing 59% and 61% protection at 20mg/kg, respectively, in the inflamed paw model. Among the tested compounds, AR-17a (6.25), (54) and AR-27a (1.56), (52) had the least minimum inhibitory concentration values and the highest zone of inhibition, indicating their marked antibacterial activities. The lowest conc. were observed at 1.56, 6.25μg/mL for inhibition of bacteria by most of the compounds. ConclusionNovel set of trisubstituted thiazole compounds (AR-17a to AR-27a) have synthesized and characterized successfully. The preliminary screening revealed that these compounds possess promising anti-inflammatory and antibacterial activities. In addition, the objective of the study was achieved with few of the promising structures like AR-17a to AR-27a, which are prove to be potential monotherapy candidates for the treatment of chronic inflammatory diseases and bacterial infections.

Synthesis and biological evaluation of 2,4,5-trisubstituted thiazoles as antituberculosis agents effective against drug-resistant tuberculosis

The dormant and resistant form of Mycobacterium tuberculosis presents a challenge in developing new anti-tubercular drugs. Herein, we report the synthesis and evaluation of trisubstituted thiazoles as antituberculosis agents. The SAR study has identified a requirement of hydrophobic substituent at C2, ester functionality at C4, and various groups with hydrogen bond acceptor character at C5 of thiazole scaffold. This has led to the identification of 13h and 13p as lead compounds. These compounds inhibited the dormant Mycobacterium tuberculosis H37Ra strain and M. tuberculosis H37Rv selectively. Importantly, 13h and 13p were non-toxic to CHO cells. The 13p showed activity against multidrug-resistant tuberculosis isolates.

Novel Tri-substituted Thiazoles Bearing Piperazine Ring: Synthesis and Evaluation of their Anticancer Activity

Background: Cancer cells are described as an unregulated growth and spread of abnormal cells. Recently, cancer has become the most important major reason for deaths in the world. Methods: For anticancer activity, we have used the MTT method and determine the early/late apoptosis by flow cytometry. Results: The title compounds were procured by reacting 2-chloro-N-[4-(pyridin-4-yl)thiazol-2- yl]acetamide with some substituted piperazine derivatives. The in vitro anticancer activity of synthesized compounds was tested against C6 rat glioma cells and A549 human lung carcinoma cells. As a result, the compounds 3d, 3e, 3f and 3g have shown anticancer activity against both cell line. Conclusion: Specifically, compound 3f was determined as the most active compound against C6 rat glioma cells. Also, as understood, the core structure which is substituted with piperazine bridge, the heterocyclic aromatic derivatives are more active than phenyl or benzyl derivatives.

Design and synthesis of disubstituted and trisubstituted thiazoles as multifunctional fluorophores with large Stokes shifts

A series of fluorophores based on a thiazole core have been synthesized and shown to be very sensitive to both structural changes and the microenvironment. Simple modifications of the substituents’ electronic nature, spatial effects and location in the molecule allow the tuning of the photophysical properties of the investigated compounds and their susceptibility to the environment via the exhibition of long-wavelength emission, large Stokes shifts and good quantum yields. Additionally, the thiazole-2-acrylonitrile fluorophores demonstrate a multifunctional character with significant fluorescence properties (i.e., quantum yields and a large Stokes shift in both the liquid and solid states). The influences of different factors, including the solvent polarity, on the fluorescence properties of the synthesized compounds are discussed in detail. Quantum mechanical methods are employed to understand the underlying transitions and explain the experimental results. This work provides further information for the design of new sensors that have large Stokes shifts.

Four-component thiazole formation from simple chemicals under metal-free conditions

Three diversely trisubstituted thiazoles were selectively constructed from simple raw materials under metal-free conditions.

Trisubstituted thiazoles as potent and selective inhibitors of Plasmodium falciparum protein kinase G (PfPKG)

A series of trisubstituted thiazoles have been identified as potent inhibitors of Plasmodium falciparum (Pf) cGMP-dependent protein kinase (PfPKG) through template hopping from known Eimeria PKG (EtPKG) inhibitors. The thiazole series has yielded compounds with improved potency, kinase selectivity and good in vitro ADME properties. These compounds could be useful tools in the development of new anti-malarial drugs in the fight against drug resistant malaria.

Synthesis of Thiazoles Bearing Aryl Enamine/Aza‐enamine Side Chains: Effect of the π‐Conjugated Spacer Structure and Hydrogen Bonding on Photophysical Properties

An efficient synthesis of a new series of di‐ and trisubstituted thiazoles (TZs) bearing aryl enamine side‐chains (ETZs) has been developed and the optical properties of these compounds compared with structural analogues containing the isoelectronic aza‐enamine group (ATZs). Spectral characterization demonstrated the difference in the absorption and fluorescence of the ETZs and ATZs in solution and the emergence of fluorescent ETZs in the solid state. The optimized structural geometries and weak intramolecular interactions, electronic characteristics of the ground and excited states, HOMO and LUMO analyses, changes in electron density after S0 → S1v excitation and maps of electrostatic potential (MEPs) calculated by means of DFT have allowed us to estimate the particularities of the geometric and electronic structures of the ETZs and ATZs in the ground and excited states. The availability, synthetic simplicity, stability, large Stokes shifts and high sensitivity to the microenvironment (fluorosolvatochromic behaviour) make the obtained TZs a useful platform for the further design and synthesis of new effective compounds for applications in the field of fluorescence imaging.

Synthesis and Biological Evaluation of Novel Di- and Trisubstituted Thiazole Derivatives

Synthesis and Biological Evaluation of Novel Di- and Trisubstituted Thiazole Derivatives

Synthesis, antimicrobial activity and advances in structure-activity relationships (SARs) of novel tri-substituted thiazole derivatives

Trisubstituted thiazoles were synthesized and studied for their antimicrobial activity and supported by theoretical calculations. In addition, MIC, MBC and MFC were also tested. Moreover, the present study was analyzed to scrutinize comprehensive structure-activity relationships. In fact, LUMO orbital energy and orbital orientation was reliable to explain their antibacterial and antifungal assay. Amongst the tested compounds, tri-methyl-substituted thiazole compound showed higher antimicrobial activity and low MIC value due to highest LUMO energy.

Studies on the IC50 of Trisubstituted Thiazoles as Cdc7 Kinase Inhibitors

In this study, a nonlinear quantitative structure-activity relationship model for the prediction of the IC50 of trisubstituted thiazoles as Cdc7 kinase inhibitors was developed by the gene expression programming (GEP). This model is based on five descriptors which were selected from the descriptors' pool by heuristic method (HM). GEP rendered a good correlation between the experimental and predicted log (IC50) values with a correlation coefficient and a mean error of 0.85 and 0.22 for the training set, 0.84 and 0.39 for the testing set, respectively. The results indicate that this QSAR model has good predictive capability and it points to further optimization opportunities for Cdc7 kinase inhibitors.

Molecular Modeling Studies of Trisubstituted Thiazoles as Cdc7 Kinase Inhibitors through 3D‐QSAR and Molecular Docking Simulation

The cell division cycle 7 (Cdc7) is a serine‐threonine protein kinase which plays an essential role in replication and initiation of DNA synthesis. Overexpression of the Cdc7 in various tumor growths and in cell proliferation makes it a novel target for cancer therapy. In the present study, we have performed 3D quantitative structure–activity relationship (3D‐QSAR) studies on a series of trisubstituted thiazole derivatives targeting Cdc7 kinase. Reasonable CoMFA (q 2 = 0.838, NOC = 5, r 2 = 0.984) and CoMSIA (q 2 = 0.875, NOC = 6, r 2 = 0.979) models were developed. All the developed models were validated using an external validation test set, leave‐out‐five, bootstrapping, progressive samplings, and rm 2 metrics. Both the models exhibited acceptable values on all validation techniques and hence were considered to be robust and predictive. Molecular docking study revealed the crucial interaction of the most active compound (compound 49) with the conserved active site residues. Our results are in line with the previous studies. Contour map analysis revealed the important insights that would help in increasing the potency of the compounds. From these results, we could suggest that bulky positive substitutions are favored in the R2 position of the phenyl ring. Hydrogen‐bond acceptor groups in the R1 position could increase the activity. Hydrogen‐bond donor groups are favored near the amino group of R3 position. Long substitution in the R3 position will reduce the activity and must be avoided. Our results could be used to design more potent trisubstituted thiazole derivative of Cdc7 kinase inhibitors in future.

ChemInform Abstract: “On‐Water” Synthesis of Novel Trisubstituted 1,3‐Thiazoles via Microwave‐Assisted Catalyst‐Free Domino Reactions.

AbstractA wide range of trisubstituted thiazoles is obtained by a clean and efficient three‐component domino reaction of arylglyoxals, cyclic 1,3‐dicarbonyl compounds and thioamides in H2O.

ChemInform Abstract: Synthesis of Trisubstituted Thiazoles by Ligand‐Free Palladium‐Catalyzed Direct 5‐Arylation of 2,4‐Disubstituted Thiazoles under Conventional and Microwave‐Assisted Heating.

Abstract Trisubstituted thiazoles were synthesized with excellent yields using ligand-free, palladium-catalyzed, direct 5-arylation of 2,4-disubstituted thiazole and conventional or microwave-assisted heating. The palladium-catalyzed reaction yields were significantly influenced by LiCl additive, solvent, and heating method. The reaction times were reduced dramatically by employing microwave radiation instead of conventional heating. The synthetic methods can be applied to diverse 2,4,5-trisubstituted thiazoles by varying the aryl bromide and disubstituted thiazole reactants.

Synthesis and structure–activity relationship of trisubstituted thiazoles as Cdc7 kinase inhibitors

The Cell division cycle 7 (Cdc7) protein kinase is essential for DNA replication and maintenance of genome stability. We systematically explored thiazole-based compounds as inhibitors of Cdc7 kinase activity in cancer cells. Our studies resulted in the identification of a potent, selective Cdc7 inhibitor that decreased phosphorylation of the direct substrate MCM2 in vitro and in vivo, and inhibited DNA synthesis and cell viability in vitro.

Synthesis of trisubstituted thiazoles by ligand-free palladium-catalyzed direct 5-arylation of 2,4-disubstituted thiazoles under conventional and microwave-assisted heating

Trisubstituted thiazoles were synthesized with excellent yields using ligand-free, palladium-catalyzed, direct 5-arylation of 2,4-disubstituted thiazole and conventional or microwave-assisted heating. The palladium-catalyzed reaction yields were significantly influenced by LiCl additive, solvent, and heating method. The reaction times were reduced dramatically by employing microwave radiation instead of conventional heating. The synthetic methods can be applied to diverse 2,4,5-trisubstituted thiazoles by varying the aryl bromide and disubstituted thiazole reactants.

Synthesis and structure–activity relationships of tri-substituted thiazoles as RAGE antagonists for the treatment of Alzheimer’s disease

A series of thiazole derivatives were designed, and prepared to develop RAGE antagonist for the treatment of Alzheimer’s disease (AD). SAR studies were performed to optimize inhibitory activity on Aβ-RAGE binding. SAR studies showed that introducing an amino group at part A was essential for inhibitory activity on Aβ-RAGE binding. Compounds selected from Aβ-RAGE binding screening displayed inhibitory activity on Aβ transport across BBB. They also showed inhibitory activity against Aβ-induced NF-κB activation. These results indicated that our derivatives had a potential as therapeutic agent for the treatment of AD.

ChemInform Abstract: Broensted Acid Catalyzed Cyclization of Propargylic Alcohols with Thioamides. Facile Synthesis of Di‐ and Trisubstituted Thiazoles.

AbstractSome limitations are observed.