Quinoline Moiety Research Articles

Efficient synthesis of some pyrimidine and thiazolidine derivatives bearing quinoline scaffold under microwave irradiation

An efficient and facile approach for the synthesis of new quinoline derivatives was accomplished via reactions of 2-chloroquinoline-3-carbaldehyde with active methylene compounds, for example, 1,3-dimethylbarbituric acid, thiobarbituric acid and 2,4-dioxothiazolidine and aromatic amines through one-pot multi-component reaction (MCR) as sources of pyrimidine and thiazolidine derivatives bearing quinoline moiety. All compounds were synthesized via conventional and Microwave Irradiation conditions. The best results (short reaction times, pure products, high yield) were obtained by microwave irradiation. The synthesized derivatives were characterized by various physicochemical and spectral techniques from their analytical and spectral data.

Discovery of N-substituted-3-phenyl-1,6-naphthyridinone derivatives bearing quinoline moiety as selective type II c-Met kinase inhibitors against VEGFR-2

New N-substituted-3-phenyl-1,6-naphthyridinone derivatives are designed and synthesized, based on structural modification of our previously reported compound 3. Extensive enzyme-based SAR studies and PK evaluation led to the discovery of compound 4r, with comparable c-Met potency to that of Cabozantinib and high VEGFR-2 selectivity, while Cabozantinib displayed no VEGFR-2 selectivity. More importantly, at oral doses of 45 mg/kg (Q.D.), compound 4r exhibits significant tumor growth inhibition (93%) in a U-87MG human gliobastoma xenograft model. The promising selectivity against VEGFR-2 and excellent tumor growth inhibition of compound 4r suggest that it could be used as a new lead molecule for further discovery of selective type II c-Met inhibitors.

Ru‐Catalyzed Sequential Dehydrogenative Friedlander Reaction/sp3 C–H Activation/Knovenagel Condensation in the Regioselective Synthesis of Chimanine B Analogues

Choline chloride (ChCl) based deep eutectic solvent (DES), facilitated the regioselective synthesis of (E)‐1‐(4‐phenyl‐2‐styrylquinolin‐3‐yl)ethan‐1‐one (4), and (E)‐3‐phenyl‐1‐(4‐phenyl‐2‐((E)‐styryl)quinolin‐3‐yl)prop‐2‐en‐1‐ones, (5) from the corresponding 2‐amino‐5‐chloro benzhydrol, (1) in one‐pot strategy. The 2‐methyl‐3‐acetylquinoline generated in situ from the 2‐amino‐5‐chloro benzhydrol, (1) and acetyl acetone, (2) via dehydrogenative Friedlander reaction in DES could enable subsequent regio‐selective C‐2 methyl group sp3 C–H activation and rapid alkenylation with alcohols, (3) to provide the desired (E)‐2‐styrylquinolin‐3‐yl)ethan‐1‐ones, 4 in short reaction time and high yields and purity. Likewise, through the simultaneous C‐2 and C‐3 sp3 C–H activation with aromatic alcohols, (3) the (E)‐2‐styrylquinolin‐3‐yl)prop‐2‐en‐1‐ones, (5) formation was carried out in DES in high yields and purity. The physicochemical properties viz., UV/Vis, and fluorescence studies of the synthesized compounds were investigated. The absorption and emission properties of these luminophores are attributable to the presence of auxochromes in the 6‐position of quinoline moiety, styryl‐functional group at the 2‐position, and the enone group at 3‐position.

Structural and Luminescence Properties of Heteronuclear Gold(I)/Thallium(I) Complexes Featuring Metallophilic Interactions Tuned by Quinoline Pendant Arm Derivatives of Mixed Donor Macrocycles.

Reaction of the heterometallic complex [{Au(C6F5)2}Tl]n with the quinoline pendant arm derivatives L1 and L2 of the mixed donor macrocycles [12]aneNS2O and PhenNS2 affords the new Au(I)/Tl(I) complexes [{Au(C6F5)2}Tl(L1)] (1), [{Au(C6F5)2}Tl(L2)] (2), [{Au(C6F5)2Tl}{Au(C6F5)2Tl(L1)}]2 (3), and [{Au(C6F5)2Tl}{Au(C6F5)2Tl(L2)}]n (4) depending on the reaction molar ratios used. These complexes present different optical properties strictly related to their structural features and to the presence of Au(I)···Tl(I) metallophilic interactions, which are finely tuned by the coordinating quinoline moiety and have been studied experimentally and theoretically via TD-DFT calculations.

Cytotoxicity of 4-substituted quinoline derivatives: Anticancer and antileishmanial potential

Chemical modifications of quinoline moiety have been recognized as a useful strategy to development of new drugs. Here, the cytotoxicity of a set of twenty-four 4-substituted quinolines (named HTI) was screened for their antitumor and antileishmanial potential in vitro, and the underlying mechanisms investigated. HTI 21 and HTI 22 exhibited the highest cytotoxicity, being selected to the subsequent studies. Both derivatives induced caspase-dependent apoptosis associated to the dissipation of the mitochondrial transmembrane potential (ΔΨ) and ROS generation. HTI-induced cell death was calcium dependent, associated to thiol oxidation and cysteine proteases activation. In isolated mitochondria, HTI derivatives promoted mitochondrial permeabilization by different mechanisms. The inhibition of BCL-2 by venetoclax enhanced the HTI-induced cytotoxicity. Regarding the inhibition of cysteine proteases type B of Leishmania mexicana, HTI 15 exhibited the most potent inhibitory activity through a linear non-competitive mechanism. These data highlight the therapeutic potential of 4-substituted quinolines as antitumor and antileishmanial drugs.

Silicon-assisted synthesis of new aminomethylenebisphosphonic acids with quinolines moieties

The convenient silicon-assisted synthesis of new aminomethylenebisphosphonic acids and their precursors was developed via unique methodology. So new aminomethylenebisphosphonic acids with quinolines moieties were obtained using suitable reaction of tris(trimethylsilyl) phosphite and N-formyl aminoquinolines catalyzed by trimethylsilyl triflate under mild conditions (20 °C). The initially formed intermediates – tetra (trimethylsilyl) aminomethylenebisphosphonates are transformed to target acids by methanolysis in high yields. The catalytic scheme of target substances formation is proposed and discussed in detail. The structures of aminomethylenebisphosphonic acids and their precursors with substituted quinoline moieties were confirmed by the 1H, 13C, 31P NMR spectra and high resolution mass spectra.

Crystal structure and Hirshfeld surface analysis of hexyl 1-hexyl-2-oxo-1,2-di-hydro-quinoline-4-carboxyl-ate.

The asymmetric unit of the title compound, C22H31NO3, comprises of one mol-ecule. The mol-ecule is not planar, with the carboxyl-ate ester group inclined by 33.47 (4)° to the heterocyclic ring. Individual mol-ecules are linked by aromaticC-H⋯Ocarbon-yl hydrogen bonds into chains running parallel to [001]. Slipped π-π stacking inter-actions between quinoline moieties link these chains into layers extending parallel to (100). Hirshfeld surface analysis, two-dimensional fingerprint plots and mol-ecular electrostatic potential surfaces were used to qu-antify the inter-molecular inter-actions present in the crystal, indicating that the most important contributions for the crystal packing are from H⋯H (72%), O⋯H/H⋯O (14.5%) and C⋯H/H⋯C (5.6%) inter-actions.

2-Chloro-7-methyl-3-((4-((p-tolyloxy)methyl)-1H-1,2,3-triazol-1-yl)methyl) quinoline: Crystal structure, hydrogen bonding and anti-bacterial activity

Crystal structure of a laboratory synthesized quinoline-triazole derivative 2-Chloro-7-methyl-3-((4-((p-tolyloxy)methyl)-1H-1,2,3-triazol-1-yl)methyl) quinoline (1) has been solved by X-ray powder diffraction technique. The overall molecular conformation of 1 is lying on three planes. The phenyl and quinoline moieties are linked to the triazole ring via alkoxy and methylene groups, respectively. The crystal packing in 1 is stabilized by C–H⋯N, C–H … π and π … π types of non-covalent molecular interactions, which ultimately assemble the molecules into two-dimensional supramolecular framework through formation of C11(9) chain. Analyses of Hirshfeld surface and 2D-fingerprint plots of the title compound indicate that the H⋯H, N⋯H and C⋯H contacts are responsible for almost 80% Hirshfeld surface contribution in 1. The molecular geometry, optimized by DFT calculation, agrees closely to that, obtained from crystallographic analysis. The HOMO-LUMO energy gap of 2.59 eV indicates a high kinetic stability of the title compound. Anti-bacterial activity of the synthesized compound 1, against different bacterial strains, shows a moderate result in comparison to the reference anti-bacterial drug molecule Amikacin.

Aaptolines A and B, Two New Quinoline Alkaloids from the Marine Sponge Aaptos aaptos.

Two new quinoline alkaloids, aaptolines A and B, were isolated from the marine sponge Aaptos aaptos. Their structures were determined by HR-ESI-MS data, NMR analysis, and X-ray crystallography. Structurally, aaptoline A is characterized as having a quinoline skeleton fused with a 1,4-dioxane motif at the C(7)-C(8) position, whereas aaptoline B possessed an intriguing 1H-pyrrolo[2,3-g]quinoline moiety. The cytotoxic assay of these compounds showed no cytotoxicity towards HepG2, A549, and PC9 cancer cell lines and had IC50 values greater than 20 μm.

Synthesis, antioxidant and anticholinesterase activities of novel quinoline‐aminophosphonate derivatives

AbstractA series of 20 novel α‐aminophosphonate derivatives bearing quinoline or quinolone moiety was designed and synthesized via Kabachnik‐Fields reaction in the presence of triethylammonium acetate as a solvent and catalyst under ultrasound irradiation. This procedure affords products in high yields and short reaction times. Molecular structures of the synthesized compounds 4a‐g and 5a‐m were confirmed using various spectroscopic methods. The antioxidant activity of these compounds was evaluated by eight complementary in vitro tests. The anticholinesterase activity (AChE, BChE) of these compounds were also evaluated. In addition, theoretical calculations of all compounds were investigated as corrosion inhibitors using density functional theory (DFT). The results revealed that 16 of these compounds exhibited high levels of antioxidant activities depending on the assay and that most compounds showed more potent inhibitory activities against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE).

Synthesis, Characterization and in vitro Antimicrobial Screening of Some Novel Series of 2-Azetidinone Derivatives Integrated with Quinoline, Pyrazole and Benzofuran Moieties

A series of 5-(benzofuran-2-yl)-N-(3-chloro-4-(2-(p-tolyloxy) substituted quinolin-3-yl)-2-oxoazetidin-1-yl)-1-phenyl-1H-pyrazole-3-carboxamide derivatives (4a-f) were synthesized with excellent yields by cyclocondensation reaction of 5-(benzofuran-2-yl)-N′-(2-(p-tolyloxy) substituted quinolin-3-yl)methylene)-1-phenyl-1H-pyrazole-3-carbohydrazide (3a-f) with chloroacetyl chloride in presence of triethylamine in DMF. One pot condensation of 5-(benzofuran-2-yl)-1-phenyl-1H-pyrazole-3-carbohydrazide (1) with 2-(p-tolyloxy) substituted quinoline-3-carbaldehyde (2a-f) in ethanol solvent in presence of catalytic amount of acetic acid gave intermediate compounds (3a-f). The structures of newly synthesized compounds have been substantiated through elemental analysis and spectral studies viz. 1H NMR, 13C NMR, IR and mass spectra. All the synthesized compounds were screened for their in vitro antibacterial activity against pathogenic bacteria such as S. aureus and E. coli at different concentrations.

Discovery of 1,6-naphthyridinone-based MET kinase inhibitor bearing quinoline moiety as promising antitumor drug candidate

A series of 1,6-naphthyridinone-based MET kinase inhibitors bearing quinoline moiety in block A were designed and synthesized based on the structures of Cabozantinib and our reported compound IV. Extensive SAR and DMPK studies led to the identification of 20j, a potent and orally bioavailable MET kinase inhibitor with favorable kinase selectivity. More importantly, 20j exhibited statistically significant tumor growth inhibition (Tumor growth inhibition/TGI of 131%, 4/6 partial regression/PR) in the U-87 MG xeograft model, which is superior to that of Cabozantinib (TGI of 97%, 2/6 PR), and significantly better than that of compound IV (TGI of 15%, 0/6 PR) at the same dose (12.5 mg/kg). Combined with favorable in vitro potency, kinase selectivity, pharmacokinetic profile and in vivo efficacy, the promising antitumor drug candidate 20j has subsequently advanced into preclinical research.

Structural analogues of quinoline alkaloids: Straightforward route to [1,3]dioxolo[4,5‐c]quinolines with antibacterial properties

AbstractCompounds bearing [1,3]dioxolo‐quinoline scaffolds have been found in quinoline‐based natural products; the only exception is the [1,3]dioxolo[4,5‐c]quinoline moiety with a rare occurrence in both natural and synthetic derivatives. In this article, we report the preparation of diversely substituted and functionalized [1,3]dioxolo[4,5‐c]quinolines using [1,3]dioxolo[4,5‐c]quinoline‐4‐carbaldehyde (DQC) as the common intermediate. DQC was synthesized on a large scale from anthranilic acid and chloroacetone as the starting materials, with the rearrangement of acetonyl‐anthranilate as the key step. The developed method allows for the simple preparation of [1,3]dioxolo[4,5‐c]quinolines with various C2 substituents on the quinoline scaffold. Additionally, the synthetic route was successfully applied to the preparation of 3‐hydroxyquinoline‐4(1H)‐ones. The target compounds were tested against representative Gram‐positive/negative bacteria, and two derivatives exhibited submicromolar minimum inhibitory concentrations against Micrococcus luteus.

The synthesis, crystal structure and Hirshfeld analysis of 4-(3,4-di-methyl-anilino)-N-(3,4-di-methyl-phen-yl)quinoline-3-carboxamide.

The structure of the title quinoline carboxamide derivative, C26H25N3O, is described. The quinoline moiety is not planar as a result of a slight puckering of the pyridine ring. The secondary amine has a slightly pyramidal geometry, certainly not planar. Both intra- and inter-molecular hydrogen bonds are present. Hirshfeld surface analysis and lattice energies were used to investigate the inter-molecular inter-actions.

Synthesis and Characterization of Novel 1,3,5-Thiadiazine Derivatives Integrated with Quinoline Moiety as Potent Antimicrobial Agents

An expeditious synthesis of series of novel 1,3,5-thiadiazine (5a-f) and (6a-f) derivatives have been described. These compounds were synthesized by reaction of 1-(N-((6-methyl-2-(p-tolyloxy)quinoline- 3-yl)methylene)carbamimidoyl)-3-arylthiourea (3a-b) derivatives with N-aryl isocyanodichloride (4a-c) in chloroform followed by basification with dilute NH4OH to give the target compounds 5a-f; which were acetylated further to afford six novel 1,3,5-thiadiazin-3-(6H)-yl)ethanone (6a-f) derivatives. Synthesis of intermediate compounds 3a-b was obtained by reacting 6-methyl-2-(p-tolyloxy)quinoline-3- carbaldehyde (2a) and 1-carbamimidoyl-3-aryllthiourea (1a-b) in chloroform. Structures of compounds 5a-f and 6a-f were established by FTIR, 1H & 13C NMR, mass spectra and further supported by elemental analysis. All synthesized compounds were investigated for their in vitro antimicrobial screening against a panel of pathogenic microorganism comprising S. aureus as Gram positive while E. coli, P. vulgaris, S. typhi as Gram-negative bacterial strains.

Inhibition of the photochromic behaviour of a 3,3-diphenyl-3H-pyrano[3,2-f]quinoline ligand by coordination to Ag(I) ions

The synthesis and characterisation of a photoresponsive 3,3-diphenyl-3H-pyrano[3,2-f]quinoline ligand which contains both quinoline and thiazole N-donor moieties is described. This ligand acts as a bidentate N-donor ligand and the solid-state structure of a Ag(I) complex is reported. Whereas the free ligand exhibits typical photochromic behaviour, coordination with Ag(I) results in complete inhibition of the photochromic response. However, excitation wavelength dependent emission spectra demonstrated an increase in fluorescence response of the new Ag(I) complex.

Ru(II)/Rh(III)-Catalyzed C(sp3)-C(sp3) Bond Formation through C(sp3)-H Activation: Selective Linear Alkylation of 8-Methylquinolines and Ketoximes with Olefins.

Herein, [RuCl2(p-cymene)]2/[Cp*RhIIICl2]2-catalyzed direct alkylation of C(sp3)-H bond of 8-methylquinolines with olefins (acrylates, styrenes, and aliphatic) is reported. The alkylation also proceeds with other conjugated systems such as malemides and α,β-unsaturated ketones. The reaction is highly regioselective, forms only a linear product, and tolerates a variety of functional groups on quinoline and olefin moieties. Control experiments, deuterium labeling, and kinetic studies have been carried out for preliminary understanding of the reaction pathway. The reaction possibly proceeds through five-membered metallacycle under redox-neutral condition. Diversification of alkylated product and late-stage functionalization of ketoxime derivatives of (-)-santonin have also been carried out to demonstrate the applicability of the developed method.

A quinoline-based fluorescent probe for selective detection and real-time monitoring of copper ions - a differential colorimetric approach.

A quinoline moiety was used as a building block for designing a probe for the selective detection of copper ions in a partially aqueous medium. We have developed a molecular sensing system which gives insight into the complex physiological and redox aspects of labile copper. The probe provides a colorimetric approach for distinguishing cuprous and cupric ions along with their simultaneous discrimination from other metal ions in the visible range of the spectrum. The chemosensor showed a remarkable fluorescence enhancement along with a significant bathochromic shift of about 35 nm. The detection limit of the probe was found to be 1.03 μM which is optimally favorable to be applied in real-time monitoring. Fabrication of paper strips with the probe was done to detect the presence of cuprous ions in the real sample. The value of the binding constant (1.37 × 104 M-1) suggests stable complex formation between the metal ion and the sensing probe. The photoluminescence and structural aspects of the chemosensor were characterized by using fluorescence, absorption, ESI-MS, and 1H NMR spectroscopy. Furthermore, the cytotoxic nature and bioimaging properties of the probe were interpreted in vitro on RAW 264.7 macrophage cell lines and peripheral blood mononuclear cells (PBMCs) respectively.

Design, synthesis and discovery of andrographolide derivatives against Zika virus infection

The Zika endemic established by imported and local transmission is of significant concern and effective anti-ZIKV drugs remain an urgent unmet need. As andrographolide was identified to be an inhibitor of DENV and CHIKV and the importance of quinoline structure against infectious diseases was considered, we are interested in studying its andrographolide derivatives with quinoline moiety against Zika virus infection. In addition to screening eight in-house derivatives of andrographolide, sixteen new derivatives were designed, synthesized and tested against Zika virus infection. Among these compounds, two most potent anti-Zika compounds of 19-acetylated 14α-(5′,7′-dichloro-8′-quinolyloxy) derivative 17b and 14β-(8′-quinolyloxy)-3,19- diol derivative 3 with the highest selectivity were discovered. The SAR analysis indicates that rational and optimal combined modification/s at 3-, 14-, or 19-positions can make derivatives less toxic and more potent against Zika infection, and both of 3 and 17b are suitable as leads for designing new generation of andrographolide derivatives with quinoline or its structure- and property-related moieties against Zika virus and other arboviruses.

Synthesis of quinoline functionalized fluorescent chemosensor for Cu (II), DFT studies and its application in imaging in living HEK 293 cells

New fluorescent probes having quinoline moiety have been successfully synthesized for the selective Cu2+ ions detection. These sensors show a favorable selectivity towards Cu2+ ion over a broad range of other common metal ions in DMSO/H2O (2:8, v/v) HEPES buffer solution (pH = 7.4), leading to remarkable fluorescence on-off response with very low Limit of Detection (LOD) value. The robust nature of the probes was shown by the detection of Cu2+ even after repeated rounds of the experiment. Moreover, the probe can be used to detect Cu2+ in real water samples with a high precision and good accuracy. The recognition mechanism of one representative probe towards Cu2+ has been properly inspected in details by High Resolution Mass Spectrometry (HRMS) and density functional theory (DFT) calculations. Besides, fluorescence imaging studies in HEK 293 cells of that probe is also indicating that the probe is low cytotoxic and offers good photophysical properties, suggesting that this fluorescent chemosensor can be easily used to track Cu2+ ion in cells.