Convenient, two-step synthesis of 2-styrylquinolines: an application of the CAN-catalyzed vinylogous type-II Povarov reaction

Study and application of graphene oxide in the synthesis of 2,3-disubstituted quinolines via a Povarov multicomponent reaction and subsequent oxidation

The carbocatalyzed synthesis of 2,3-disubstituted quinolines is disclosed. This process involved a three-component Povarov reaction of anilines, aldehydes and electron-enriched enol ethers, which gave the substrate for the subsequent oxidation. Graphene oxide (GO) was exploited as a heterogeneous, metal-free and sustainable catalyst for both transformations. The multicomponent reaction proceeded under simple and mild reaction conditions, exhibited good functional group tolerance, and could be easily scaled up to the gram level. A selection of tetrahydroquinolines obtained was subsequently aromatized to quinolines. The multistep synthesis could also be performed as a one-pot procedure. Investigation of the real active sites of GO was carried out by performing control experiments and a by full characterization of the carbon material by X-ray photoelectron spectroscopy (XPS) and solid-state nuclear magnetic resonance (ssNMR).

The Povarov Reaction: A Versatile Method to Synthesize Tetrahydroquinolines, Quinolines and Julolidines

The multicomponent Povarov reaction represents a powerful approach for the construction of substances containing N-heterocyclic frameworks. By using the Povarov reaction, in addition to accessing tetrahydroquinolines, quinolines and julolidines in a single step, it is possible to form the following new bonds: two Csp 3–Csp 3 and one Csp 3–Nsp 3, two Csp 2–Csp 2 and one Csp 2–Nsp 2, and four Csp 3–Csp 3 and two Csp 3–Nsp 1, respectively. This short review discusses the main features of the Povarov reaction, including its mechanism, the reaction scope by employing different catalysts and substrates, as well as stereoselective versions.

1 Introduction

2 Mechanism of the Povarov Reaction

3 Tetrahydroquinolines

4 Quinolines

5 Julolidines

6 Concluding Remarks

Synthesis, delivery, and molecular docking of fused quinolines as inhibitor of Hepatitis A virus 3C proteinase

It is widely accepted that Hepatitis A virus (HAV) is responsible for liver failure and even death in older people and in people with other serious health issues; so, proposing new compounds with inhibitory activity can help to treated of these disease’s. In current study, a new class of quinolines is proposed with inhibitor activity of the HAV proteinase. So, in the first step, fused quinoline derivatives has been synthesized in short reaction time (12.0 min) and high efficiency yields (94%) in presence of 1-carboxymethyl-2,3-dimethylimidazolium iodide ([cmdmim]I) ionic liquid catalyst using a new method. In the following, chemical reactivity and inhibitory activity of synthesized quinolines were evaluated in density functional theory (DFT) framework and molecular docking methodologies. High global softness (0.67 eV), low HOMO_SWBNNT-LUMO_4a gap (4.78 eV), and more negative adsorption energy (− 87.9 kJ mol⁻¹) in these quinolines reveal that the 4a and 4b compounds have better delivery than other quinolines using SWBNNT as suitable carrier to target cells. Molecular docking shows that the best cavity of the HAV has − 134.2 kJ mol⁻¹ interaction energy involving bonding and non-bonding interactions. In fact, these interactions are between fused quinolines with especial geometries and sidechain flexibility amino acids residues inside the best binding site of the HAV, as hydrogen bonding, steric, and electrostatic interactions. So, these interactions imply that proposed fused quinolines have good inhibitor activity for the HAV.

Recent synthetic efforts in the preparation of 2-(3,4)-alkenyl (aryl) quinoline molecules towards anti-kinetoplastid agents

Leishmaniasis, Chagas disease and African sleeping sickness have been considered some of the most important tropical protozoan afflictions. As the number of drugs currently available to treat these human illnesses is severely limited and the majority has poor safety profiles and complicated administration schedules, actually there is an urgent need to develop new effective, safe and cost-effective drugs. Because quinoline alkaloids with antiprotozoal activity (quinine, chimanine, cryptolepine or huperzine groups) were historically and are still essential models for drug research to combat these parasitic infections, synthetic or semi-synthetic quinoline-based molecules are important for anti-kinetoplastid drug design approaches and synthetic methods of their preparation become a key task that is the central subject of this review. Its goal is to highlight the advances in the conventional and current syntheses of new 2-(3,4)-alkenyl (aryl) quinoline derivatives, which kill the most important kinetoplastid protozoa, - Leishmania and Trypanosoma and could be useful models for antileishmanial and antitrypanosomal research. An attempt has been made to present and discuss the more recent contributions in this field over the period 2015-2019, paying special attention to molecular design, synthetic efforts to new green reaction conditions for classical methods such as Skraup synthesis, Friedländer synthesis, Conrad-Limpach, Doebner-Miller, as well as contemporary methods like Gould-Jacobs, Meth-Cohn and Povarov reactions. This review includes brief general information on these neglected tropical diseases, their current chemotherapies, and primary natural models (quinoline alkaloids), suitable for development of anti-kinetoplastid quinoline-based agents. The main part of the review comprises critical discussion on the synthesis and chemistry of new quinolines diversely substituted by alkyl (alkenyl, aryl) fragments on the pyridine part of the quinoline skeleton, which could be considered interesting analogues of chimanine alkaloids. The methods described in this review were developed with the aim of overcoming the drawbacks of the traditional protocols using revolutionary precursors and strategies.

A general three-step one-pot synthesis of novel (E)-6-chloro-2-(aryl/hetarylvinyl)quinoline-3-carboxylic acids

In this work, a facile and general three-step one-pot synthesis of structurally new (E)-6-chloro-2-(aryl/hetarylvinyl)quinoline-3-carboxylic acid derivatives has been achieved from easily available ethyl 6-chloro-2-(chloromethyl) quinoline-3-carboxylate and aromatic or heteroaromatic aldehydes. This strategy features simple one-pot operation, tolerance of a wide range of substituents, and good yields. Moreover, these newly synthesized compounds belong to a new class of quinoline derivatives and could be good candidates for the development of more complex quinoline compounds for use in medicinal chemistry.

In(OTf)3-catalyzed synthesis of 2-styryl quinolines: scope and limitations of metal Lewis acids for tandem Friedländer annulation–Knoevenagel condensation

Investigation of metal Lewis acids for one-pot tandem Friedländer annulation–Knoevenagel condensation and exploration of In(OTf)₃for synthesis of 2-styryl quinolines.

Efficient synthesis of 2,4-disubstituted quinolines: calix[n]arene-catalyzed Povarov-hydrogen-transfer reaction cascade

A new calixarene-catalyzed cascade process, involving Povarov reaction and hydrogen transfer, for the synthesis of 2,4-disubstituted quinolines is described.

A Fluorescent Styrylquinoline with Combined Therapeutic and Diagnostic Activities against Alzheimer's and Prion Diseases

(E)-6-Methyl-4'-amino-2-styrylquinoline (3) is a small molecule with the proper features to potentially diagnose, deliver therapy and monitor response to therapy in protein misfolding diseases. These features include compound fluorescent emission in the NIR region and its ability to interact with both Aβ and prion fibrils, staining them with high selectivity. Styrylquinoline 3 also inhibits Aβ self-aggregation in vitro and prion replication in the submicromolar range in a cellular context. Furthermore, it is not toxic and is able to cross the blood brain barrier in vitro (PAMPA test).

New types of reactivity of α,β-unsaturated N,N-dimethylhydrazones: chemodivergent diastereoselective synthesis of functionalized tetrahydroquinolines and hexahydropyrrolo[3,2-b]indoles

The indium trichloride-catalyzed reaction between aromatic imines and α,β-unsaturated N,N-dimethylhydrazones in acetonitrile afforded 1,2,3,4-tetrahydroquinolines bearing a hydrazone function at C4 through a one-pot diastereoselective domino process that involves the formation of two C-C bonds and the controlled generation of two stereocenters, one of which is quaternary. This reaction constitutes the first example of an α,β-unsaturated dimethylhydrazone that behaves as a dienophile in a hetero Diels-Alder reaction. The related reaction between anilines, aromatic aldehydes, and methacrolein dimethylhydrazone in CHCl(3) with BF(3)⋅Et(2)O as catalyst afforded polysubstituted 1,2,3,3a,4,8b-hexahydropyrrolo[3,2-b]indoles as major products through a fully diastereoselective ABB'C four-component domino process that generates two cycles, three stereocenters, two C-C bonds, and two C-N bonds in a single operation.

Synthesis, Characterisation and Photoluminescent Properties of Quinoline Derivatives Containing both a Biphenyl Group and an α, β-Diarylacrylonitrile Unit

The synthesis of ( E)-2-(4-bromostyryl)quinoline involves an acid catalysed condensation of 2-methylquinoline and 4-bromobenzaldehyde. ( E)-4′-[(2-(Quinolin-2-yl)vinyl)]-(1,1′-biphenyl)-4-carbaldehyde has been synthesised from ( E)-2-(4-bromostyryl)quinoline and 4-formylphenylboronic acid via a Suzuki coupling reaction. A series of novel quinoline derivatives containing both a biphenyl group and an α, β-diarylacrylonitrile unit have been prepared by the base-catalysed condensation between ( E)-4′-[(2-(quinolin-2-yl)vinyl)]-(1,1′-biphenyl)-4-carbaldehyde and various arylacetonitriles. By contrast, the acid-catalysed condensation of the latter aldehyde with several aniline derivatives has been used to synthesise quinolines containing an imine group. These compounds, which have implications for the manufacture of organic light-emitting diodes, emit blue to green fluorescence with maximum emission peaks of 419–531 nm in solution and in the solid state under UV irradiation. Thermogravimetric analysis reveals their good thermal stability with a decomposition temperature range from 313 to 387°C.

Multicomponent reaction access to complex quinolines via oxidation of the Povarov adducts

The tetrahydroquinolines obtained through the Povarov multicomponent reaction have been oxidized to the corresponding quinoline, giving access to a single product through a two-step sequence. Several oxidizing agents were studied and manganese dioxide proved to be the reagent of choice, affording higher yields, cleaner reactions and practical protocols.

Synthesis and Photophysical Properties of Novel Fluorescent Quinoline-Based Aryl Substituted Styryl Systems

Synthesis of (E)-2-(4-bromostyryl)quinoline has been easily achieved by an acid catalysed condensation of 2-methylquinoline with 4-bromobenzaldehyde. Various boronic acid derivatives reacted with (E)-2-(4-bromostyryl)quinoline to afford a series of novel quinoline-based aryl substituted styryl derivatives by the catalysis of Pd(PPh3)4 at 85 °C in dimethoxyethane. The UV-Vis absorption and photoluminescent spectra of them in CH2Cl2 were investigated.