Quinolines as potent 5-lipoxygenase inhibitors: synthesis and biological profile of L-746,530

AlCl3-Promoted Intramolecular Indolinone-Quinolone Rearrangement of Spiro[indoline-3,2'-quinoxaline]-2,3'-diones: Easy Access to Quinolino[3,4-b]quinoxalin-6-ones

A facile and direct intramolecular indolinone-quinolone rearrangement was developed for the synthesis of quinolino[3,4-b]quinoxalin-6-ones from spiro[indoline-3,2'-quinoxaline]-2,3'-diones, which are readily available with use of isatines, malononitrile, and 1,2-phenylenediamines under quite mild conditions. This efficient approach provides excellent yields and could potentially be used for the construction of a diverse library of quinolino[3,4-b]quinoxalin-6-ones for high-throughput screening in medicinal chemistry. The reaction mechanism is explored by extensive DFT calculations.

Green synthesis of quinazoline derivatives using a novel recyclable nano-catalyst of magnetic modified graphene oxide supported with copper

A new magnetic nano-catalyst system based on graphene oxide was designed and manufactured (GO@Fe3O4@3-chloropropyltrimethoxysilane@(Z)-N'-(2-hydroxybenzylidene)-4-(pyridin-4-yl)benzohydrazide@Cu(II)), and it was checked and confirmed by various analyzes such as FTIR, XRD, EDX, MAPPING, TGA/DSC, VSM and FESEM. This nano-catalyst was used in the three-component one-pot synthesis of quinazoline derivatives. The products were obtained using this efficient catalyst with high efficiency in short time and solvent-free conditions. Easy separation and acceptable recyclability are other advantages of this new nano-catalyst. Also, the catalyst can be recycled 4 times without a significant change in its efficiency.

Visible-light-driven radical Friedländer hetero-annulation of 2-aminoaryl ketone and α-methylene carbonyl compound via organic dye fluorescein through a single-electron transfer (SET) pathway

The discoveries recommend that the photoinduced conditions of fluorescein-determined go about as impetus for photochemically combining polysubstituted quinolines in ethanol at room temperature under air environment by means of revolutionary Friedländer hetero-annulation of 2-aminoaryl ketone and α-methylene carbonyl compound. This study lays out an original capability for photochemically orchestrating fluorescein. This non-metallic organic dye is economically accessible and modest, producing great outcomes, accelerating the cycle, and achieving a high compound economy. The turnover number (TON) and turnover recurrence (TOF) of polysubstituted quinolines have been determined. This cycle will likewise run on a gram scale, demonstrating the chance of modern applications.

Friedlӓnder's synthesis of quinolines as a pivotal step in the development of bioactive heterocyclic derivatives in the current era of medicinal chemistry

In the current scenario of medicinal chemistry, quinoline plays a pivotal role in the design of new heterocyclic compounds with several pharmacological properties, so the search for new synthetic methodologies and their application in drug discovery has been widely studied. So far, many procedures have been performed for the preparation of quinoline scaffolds, among which Friedländer quinoline synthesis plays an important role in obtaining these heterocycles. The Friedländer reaction involves condensation between 2-aminobenzaldehydes and keto-compounds. The quinoline nucleus, once obtained through the Friedländer synthesis, has been extensively modified so that these derivatives can exhibit a large number of biological activities such as anticancer, antimalarial, antimicrobial, antifungal, antituberculosis, and antileishmanial properties. In this work, the focus is on the applicability of the Friedländer reaction in the synthesis of various types of bioactive heterocyclic quinoline compounds, which to date has not been reported in the context of medicinal chemistry. The main part of this review selectively focuses on research from 2010 to date and will present highlights of the Friedländer quinoline synthesis procedures and findings to address biological and pharmacological activities.

Synthesis and antimalarial activity of 7-chloroquinoline-tethered sulfonamides and their [1,2,3]-triazole hybrids

Aim & background: Drugs with multiple bioactive moieties have the advantages of multiple modes of action and fewer chances of drug resistance. In continuation of our previous work of developing hybrid antimalarials, we present herein the synthesis and antimalarial activity of two different series of 7-chloroquinoline-sulfonamide hybrids. Materials & methods: The first series of compounds were synthesized by using p-dodecylbenzenesulfonic acid as a Bronsted acid catalyst in ethanol. The second series' compounds were synthesized by 1,3-dipolar cycloaddition of azides and alkynes under click reaction conditions. Results & conclusion: The majority of these compounds demonstrated noncytotoxicity and significant antimalarial activity against Plasmodium falciparum (3D7) with IC₅₀ values in the range of 1.49-13.49 μM. The most promising hybrids (12d, 13a and 13c) may be good starting points for next-generation antimalarials.

The development of Friedländer heteroannulation through a single electron transfer and energy transfer pathway using methylene blue (MB+)

The radical Friedländer hetero-annulation of 2-aminoaryl ketone and -methylene carbonyl compound was used to develop a green tandem approach for the metal-free synthesis of polysubstitutedquinolines. At room temperature in an ethanol solvent, photo-excited state functions generated from MB+ were used as single-electron transfer (SET) and energy transfer (EnT) catalysts, utilizing visible light as a renewable energy source in the air atmosphere. The purpose of this research is to increase the use of a nonmetal cationic dye that is both inexpensive and widely available. High yields, energy-effectiveness, high atom economy, time-saving features of the reaction, and operational simplicity, and the least amount of a catalyst are the benefits of this study. As a result, a wide range of ecological and long-term chemical properties are obtained. Polysubstitutedquinolines' turnover number (TON) and turnover frequency (TOF) have been calculated. Surprisingly, such cyclization can be accomplished on a gram scale, indicating that the process has industrial potential.

Cu(OAc)2 catalysed aerobic oxidation of aldehydes to nitriles under ligand-free conditions

An economically efficient ligand-free oxidative conversion of aldehydes to nitriles has been achieved using Cu(OAc)2 and NH4OAc as inexpensive materials of low toxicity in the presence of aerial oxygen as an eco-friendly oxidant.

Investigation of Antifungal Properties of Synthetic Dimethyl-4-Bromo-1-(Substituted Benzoyl) Pyrrolo[1,2-a] Quinoline-2,3-Dicarboxylates Analogues: Molecular Docking Studies and Conceptual DFT-Based Chemical Reactivity Descriptors and Pharmacokinetics Evaluation

Candida albicans, an opportunistic fungal pathogen, frequently colonizes immune-compromised patients and causes mild to severe systemic reactions. Only few antifungal drugs are currently in use for therapeutic treatment. However, evolution of a drug-resistant C. albicans fungal pathogen is of major concern in the treatment of patients, hence the clinical need for novel drug design and development. In this study, in vitro screening of novel putative pyrrolo[1,2-a]quinoline derivatives as the lead drug targets and in silico prediction of the binding potential of these lead molecules against C. albicans pathogenic proteins, such as secreted aspartic protease 3 (SAP3; 2H6T), surface protein β-glucanase (3N9K) and sterol 14-alpha demethylase (5TZ1), were carried out by molecular docking analyses. Further, biological activity-based QSAR and theoretical pharmacokinetic analysis were analyzed. Here, in vitro screening of novel analogue derivatives as drug targets against C. albicans showed inhibitory potential in the concentration of 0.4 µg for BQ-06, 07 and 08, 0.8 µg for BQ-01, 03, and 05, 1.6 µg for BQ-04 and 12.5 µg for BQ-02 in comparison to the standard antifungal drug fluconazole in the concentration of 30 µg. Further, in silico analysis of BQ-01, 03, 05 and 07 analogues docked on chimeric 2H6T, 3N9K and 5TZ1 revealed that these analogues show potential binding affinity, which is different from the therapeutic antifungal drug fluconazole. In addition, these molecules possess good drug-like properties based on the determination of conceptual Density Functional Theory (DFT)-based descriptors, QSAR and pharmacokinetics. Thus, the study offers significant insight into employing pyrrolo[1,2-a]quinoline analogues as novel antifungal agents against C. albicans that warrants further investigation.

Innovational combination of hetero-bifunctional N-PEG quinoline scaffolds derivatives with improved anticancer activity against breast and colon cancer cell lines and P-glycoprotein, cytochrome p450 enzyme activity prediction

Polyethylene glycol (PEG) is a polymer that is widely used as a carrier for drug delivery systems (DDS). A library of N-PEGylated quinoline derivatives of PEG molecular weight 200 was prepared rapidly after the activation of PEGs using maleic anhydride. Quinoline with a polymer backbone is essential as new material. PEG is a water-soluble nonionic polymer approved by food and drug organizations for medicine applications. Because of its nontoxic grapheme, it is widely utilized in numerous biochemical, cosmetic, pharmaceutical, and industrialized applications. The modern SwissADME is a web tool that stretches free admittance to a pool of hasty, yet solid, clarifying models for physicochemical properties, pharmacokinetics, and therapeutic science. The present facile synthetic strategy can be a practical approach for incorporating polymeric carriers conjugated with drug moieties, either in the backbone of the polymer or as a terminal and pendant group on the polymer chains.

Facile Synthesis of 6-Phenyl-6h-chromeno [4, 3-b] Quinoline Derivatives using NaHSO4@SiO2 Re-usable Catalyst and Their Antibacterial Activity Study Correlated by Molecular Docking Studies

Background:

Heterocyclic compounds containing heteroatoms (O, N and S) as part of five or six-membered cyclic moieties exhibited various potential applications, such as pharmaceutical drugs, agrochemical products and organic materials. Among many known heterocyclic moieties, quinoline and its derivatives are one of the privileged scaffolds found in many natural products. In general, quinoline derivatives could be prepared by utilizing ortho-substituted anilines and carbonyl compounds containing a reactive α-methylene group of well-known reaction routes like Friedlander synthesis, Niemantowski synthesis and Pfitzinger synthesis. Moreover, polysubstituted quinolones and their derivatives also had shown considerable interest in the fields of organic and pharmaceutical chemistry in recent years.

Objective:

The main objective of our research work is towards the design and synthesis of divergent biological-oriented, proactive analogues with potential pharmacological value inspired by the anti-tubercular activity of 2-phenylquinoline analogues. In this study, we have been interested in the design and synthesis of bioactive, 2, 4-diphenyl, 8-arylated quinoline analogues.

Methods:

6-phenyl-6h-chromeno [4, 3-b] quinoline derivatives were synthesized from 4-chloro-2- phenyl-2H-chromene-3-carbaldehyde and various substituted aromatic anilines as starting materials using sodium bisulfate embedded SiO2 re-usable catalyst. All these fifteen new compound structures confirmed by spectral data 1H & 13C NMR, Mass, CHN analysis etc. Furthermore, all these new compounds antibacterial activity strains recorded using the paper disc method. The compound molecular structures were designed using molecular docking study by utilizing the crystallographic parameters of S. Areus Murb protein.

Results:

A series of fifteen new quinoline derivatives synthesized in moderate to good yields using sodium bisulfate embedded SiO2 re-usable catalyst. The molecular structures of these newly synthesized compounds elucidated by the combination of spectral data along with the elemental analysis. These compounds antibacterial activity study have shown moderate to good activity against, Escherichia coli (Gram-negative) and Staphylococcus aureus (gram-positive) organisms. These antibacterial activity results were also a very good correlation with molecular docking studies.

Conclusion:

In this study, fifteen new quinoline derivatives synthesized and structures confirmed by spectral data. In fact, all the compounds have shown moderate to good antibacterial activity. In general, the compounds containing the electron donor group at R1 position (R1 = OMe) and the acceptor group at R2 positions (R2 = F or Cl) had shown good antibacterial activity. These antibacterial activity results were also a very good correlation with molecular docking studies showing strong binding energies with the highest value being, -12.45 Kcal mol-1 with S. aureus MurB receptor.

Advancements in the synthesis of fused tetracyclic quinoline derivatives

Fused tetracyclic systems containing a quinoline nucleus represent an important class of heterocyclic bioactive natural products and pharmaceuticals because of their significant and wide-spectrum biological properties. Several of these compounds have been obtained with diverse pharmacological and biological activities, such as antiplasmodial, antifungal, antibacterial, potent antiparasitic, antiproliferative, anti-tumor and anti-inflammatory activities. This information will be beneficial for medicinal chemists in the field of drug discovery to design and synthesize new fused tetracyclic quinolines as potent therapeutical agents. This review article provides a comprehensive report regarding the methods developed for the synthesis of fused tetracyclic quinolines reported so far (till October 2019). The article includes synthesis by one-pot domino reaction, microwave synthesis using a catalyst, using ionic liquids, photocatalytic synthesis (UV radiation), Pfitzinger reaction, I2-catalyzed cyclization reaction, Wittig reaction, cascade reaction, imino Diels-Alder reaction, Friedel-Crafts reaction, CDC reaction, solvent-free reactions and using small chiral organic molecules as catalysts. To the best of our knowledge, this is the first review focused on the synthesis of fused tetracyclic quinolines along with mechanistic aspects.

Cytotoxicity and Antimycobacterial Properties of Pyrrolo[1,2-a]quinoline Derivatives: Molecular Target Identification and Molecular Docking Studies

A series of ethyl 1-(substituted benzoyl)-5-methylpyrrolo[1,2-a]quinoline-3-carboxylates 4a–f and dimethyl 1-(substituted benzoyl)-5-methylpyrrolo[1,2-a]quinoline-2,3-dicarboxylates 4g–k have been synthesized and evaluated for their anti-tubercular (TB) activities against H37Rv (American Type Culture Collection (ATCC) strain 25177) and multidrug-resistant (MDR) strains of Mycobacterium tuberculosis by resazurin microplate assay (REMA). Molecular target identification for these compounds was also carried out by a computational approach. All test compounds exhibited anti-tuberculosis (TB) activity in the range of 8–128 µg/mL against H37Rv. The test compound dimethyl-1-(4-fluorobenzoyl)-5-methylpyrrolo[1,2-a]quinoline-2,3-dicarboxylate 4j emerged as the most promising anti-TB agent against H37Rv and multidrug-resistant strains of Mycobacterium tuberculosis at 8 and 16 µg/mL, respectively. In silico evaluation of pharmacokinetic properties indicated overall drug-likeness for most of the compounds. Docking studies were also carried out to investigate the binding affinities as well as interactions of these compounds with the target proteins.

MOF-5 as a highly efficient and recyclable catalyst for one pot synthesis of 2,4-disubstituted quinoline derivatives

An approach was developed for the synthesis of 2,4-disubstituted quinoline derivatives via a one pot three-component reaction of aromatic amines, aldehydes and alkynes catalyzed by MOF-5 under solvent-free conditions.

Synthesis of novel 1,10-phenanthroline derivatives and it used as probes for sensitive detection of Zn2+ and Cd2+ metal ions - Spectroscopic and theoretical approach

A novel class of unexpected 1,10-phenanthrolinederivatives were synthesized from 2,3-dihydroacridin-4(1H)-ones with 3-aminonaphthalen-2-carboxylic acid in presence of phosphorus oxychloride at 130°C and simple perceptive emission intensity increasing assay was developed effectively to detect the very low concentrations of Zn²⁺ and Cd²⁺ ions. Emission intensity of compounds 3(a-c) directly related to the concentrations of Zn²⁺ and Cd²⁺ ions was due to metal chelating enhanced fluorescence (CHEF) effect and also its further validated by fluorescence lifetime measurement. Furthermore, the sensing mechanism for compounds 3(a-c) of Zn²⁺ and Cd²⁺ were sustained by theoretical calculations. Computational analysis results reveals that compounds 3(a-c) are more interested in Zn²⁺ ions than that of Cd²⁺ ions, while, compound 3c is more interested with Zn²⁺ and Cd²⁺ ions than those of the rest of the compounds. In addition, this proposed detection analysis has the direct application for monitoring Zn²⁺ and Cd²⁺ concentrations in tap and drinking water samples.

A nickel catalyzed acceptorless dehydrogenative approach to quinolines

A general, efficient and environmentally benign, one-step synthesis of substituted quinoline derivatives was achieved by acceptorless dehydrogenative coupling of o-aminobenzylalcohols with ketones and secondary alcohols catalyzed by a cheap, earth abundant and easy to prepare macrocyclic nickel catalyst [Ni(MeTAA)].

A NbO type Cu(ii) metal-organic framework showing efficient catalytic activity in the Friedländer and Henry reactions

A three-dimensional NbO type porous metal-organic framework 1 containing both tertiary amine groups and paddle wheel dinuclear Cu₂(COO)₄ secondary building units as the active centre was synthesized at room temperature. The activated framework 1' can be used as an efficient heterogeneous catalyst for the synthesis of quinoline derivatives by the Friedländer reaction and for the synthesis of β-nitroalcohols by the Henry (nitroaldol) reaction. This MOF-based heterogeneous catalyst is easily recycled and reused further without losing its structural integrity and catalytic activity.