Synthesis Of Coumarins Research Articles

Molybdic acid immobilized on mesoporous MCM-41 coated on nano-Fe3O4: preparation, characterization, and its application for the synthesis of polysubstituted coumarins

In this study, Fe3O4@MCM-41-(CH2)3-OMoO3H as a new recyclable nanocatalyst was synthesized and characterized by FT-IR, X-ray diffraction patterns, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and vibrating sample magnetometer analysis. The performance ability of this novel magnetic heterogeneous catalyst was evaluated for the synthesis of coumarin derivatives by the one-pot reaction between aryl aldehydes, benzamide, and 5,7-dihydroxycoumarins. Fe3O4@MCM-41-(CH2)3-OMoO3H is a nontoxic and recoverable catalyst that provides an environmentally friendly reaction condition. This catalyst can be stored for a long times without a significant loss in its activity.

Synthesis of Three Bioactive Aromatic Compounds by Introducing Polyketide Synthase Genes into Engineered Escherichia coli.

Intermediates in aromatic amino acid biosynthesis can serve as substrates for the synthesis of bioactive compounds. In this study we used two intermediates in the shikimate pathway of Escherichia coli, chorismate and anthranilate, to synthesize three bioactive compounds: 4-hydroxycoumarin (4-HC), 2,4-dihydroxyquinoline (DHQ), and 4-hydroxy-1-methyl-2(1H)-quinolone (NMQ). We introduced genes for the synthesis of salicylic acid from chorismate to supply the substrate for 4-HC and the gene encoding N-methyltransferase for the synthesis of N-methylanthranilate from anthranilate. Polyketide synthases and coenzyme (Co)A ligases were tested to determine the optimal combination of genes for the synthesis of each compound. We also tested several constructs and identified the best one for increasing levels of endogenous substrates for chorismate, anthranilate, and malonyl-CoA. With the use of these strategies, 255.4 mg/L 4-HC, 753.7 mg/L DHQ, and 17.5 mg/L NMQ were synthesized. This work provides a basis for the synthesis of diverse coumarin and quinoline derivatives with potential medical applications.

Ultrasound Promoted Fabrication of CuO‐Graphene Oxide Nanocomposite for Facile Synthesis of Fluorescent Coumarin Based 1,4‐disubsituted 1,2,3‐triazoles in Aqueous Media

AbstractHerein, we report a highly efficient sonochemical synthesis of CuO‐graphene oxide nanocomposite and its application as a recyclable catalyst for copper catalyzed azide‐alkyne cycloaddition (CuAAC) reaction of 3‐azidocoumarin derivatives and various terminal alkynes for the robust synthesis of regioselective fluorescent 1,4‐disubsituted triazoles (3 a‐o). This protocol includes water as a clean medium, effectively low copper loading, operational simplicity, good to excellent yield (up to 97%) in lesser time (60 min) and diverse substrate scope. Easy catalyst separation from reaction media and its recycling up to nine consecutive cycles without appreciable loss in the product yield are other noteworthy features of this protocol. The optimized reaction conditions were then explored successfully to get 90% yield at gram scale level.

Chlorosulfonic Acid Supported Piperidine-4-carboxylic Acid (PPCA) Functionalized Fe3O4 Nanoparticles (Fe3O4-PPCA): The Efficient, Green and Reusable Nanocatalyst for the Synthesis of Pyrazolyl Coumarin Derivatives under Solvent-Free Conditions.

In this study, we developed a convenient methodology for the synthesis of coumarin linked to pyrazolines and pyrano [2,3-h] coumarins linked to 3-(1,5-diphenyl-4,5- dihydro-1H-pyrazol-3-yl)-chromen-2-one derivatives using Chlorosulfonic acid supported Piperidine-4-carboxylic acid (PPCA) functionalized Fe3O4 nanoparticles (Fe3O4-PPCA) catalyst. Fe3O4-PPCA was investigated as an efficient and magnetically recoverable Nanocatalyst for the one-pot synthesis of substituted coumarins from the reaction of coumarin with a variety of aromatic aldehydes in high to excellent yield at room temperature under solvent-free conditions. The magnetic nanocatalyst can be easily recovered by applying an external magnet device and reused for at least 10 reaction runs without considerable loss of reactivity. The advantages of this protocol are the use of commercially available materials, simple and an inexpensive procedure, easy separation, and an eco-friendly procedure, and it shows good reaction times, good to high yields, inexpensive and practicability procedure, and high efficiency.

Efficient atom-economic one-pot multicomponent synthesis of benzylpyrazolyl coumarins and novel pyrano[2,3-c]pyrazoles catalysed by 2-aminoethanesulfonic acid (taurine) as a bio-organic catalyst

The present work describes eco-friendly multicomponent protocol for the synthesis in excellent yields of structurally diverse benzylpyrazolyl coumarin 5 (a–s) involving the reaction of 4-hydroxycoumarin, ethyl acetoacetate, hydrazine hydrate/phenyl hydrazine hydrate and aldehydes, also novel pyrano[2,3-c]pyrazole derivatives 8 (a–k) integrated by isonicotinic acid hydrazide from reaction of aldehyde, ethyl acetoacetate, malononitrile with isoniazid, employing water as a reaction medium and 2-aminoethanesulfonic acid (taurine) as the catalyst. This new methodology endowed the advantages such as short reaction time, recovery of catalysts after catalytic reaction and reusing them without losing their activity and alleviate of operation.

L-Proline Derived Secondary Aminothiourea Organocatalyst for Synthesis of Coumarin Derived Trisubstituted Methanes: Rate Enhancement by Bifunctional Catalyst over Cooperative Catalysis

Although l-proline derived aminothioureas are being used as catalyst in asymmetric synthesis, their applications in multicomponent reactions are not yet reported in the literature. We report herein a l-proline derived secondary aminothiourea as a multifunctional catalyst in multicomponent reaction for synthesis of coumarin-based unsymmetrical trisubstituted methanes whose prototype has been found to be acetylcholinesterase inhibitor. The method requires low catalyst loading (5 mol%), very short reaction time (15–30 min) to give excellent yields. For the first time, it is observed that our bifunctional catalyst significantly increases the rate of conversion in comparison to that of two cooperative organocatalysts having similar catalytic sites. l-Proline derived secondary aminothiourea organocatalyst in multicomponent reaction: synthesis of coumarin derived trisubstituted methanes

Heterogeneously Catalyzed Pechmann Condensation Employing the Tailored Zn0.925Ti0.075O NPs: Synthesis of Coumarin

A novel heterogeneous catalytic method was developed for the synthesis of coumarin and its derivatives using the Ti(IV)-doped ZnO matrix forming catalyst Zn0.925Ti0.075O having a high surface area and good Lewis acidity. The catalyst shows high activity toward a broad spectrum of the substituted phenols with β-ketoesters such as ethyl acetoacetate, ethyl butyryl acetate, ethyl benzoyl acetate, and so forth in good yields over short reaction times during the synthesis of coumarins. The methodology was further extended for the synthesis of ayapin molecules. The catalyst also shows recycle activity up to seven cycles with very good stability.

Aryl alkynoates in the radical synthesis of coumarins

Radical reactions occupy a significant place in synthetic organic chemistry and significantly complement and expand modern approaches to the synthesis of substituted coumarins. This minireview summarizes various synthetic approaches to the construction of the coumarin system, based on radical cascade reactions starting with aryl alkynoates. The methods considered for constructing the coumarin system include cyclization reactions with the formation of two C–C bonds, as well as one C–C bond and C–P, C–S, C–Se, C–Hal bonds.

Zn(II)-Catalyzed One-Pot Synthesis of Coumarins from Ynamides and Salicylaldehydes.

A highly efficient and straightforward synthesis of diversely substituted coumarins from ynamides and salicylaldehydes in the presence of Zn(II) catalyst has been developed. The sulfonamide moiety of ynamides was successfully recycled in this process, serving as an effective traceless directing group for high regioselectivity in the bond-forming event. The advantages of this protocol are good functional group tolerance, broad substrate scope, simple and high-yielding reaction, recovery/reuse of the sulfonamides, low catalyst loading of inexpensive catalyst, and, by these merits, a more cost-effective and greener process.

Syntheses of ZnO with Different Morphologies: Catalytic Activity toward Coumarin Synthesis via the Knoevenagel Condensation Reaction.

Heterogeneous catalysts are preferred in fine chemical industries due to their easy recovery and reusability. Here, we report an easily scalable method of ZnO catalysts for coumarin synthesis. Nanocrystalline ZnO particles with diverse morphologies and crystallite sizes were prepared using different solvents. The change in morphology results in changes in band gaps, defects, basicity, and textural properties (surface areas, pore volumes, and pore sizes). The catalytic performances of the synthesized ZnO materials were tested using coumarin synthesis via the Knoevenagel condensation. The catalyst synthesized using methanol shows the highest activity and selectivity (conversion of 74%, selectivity of 94%) with a turnover number of 14.69. The increased activity of the ZnO synthesized in methanol is attributed to the combined effects of moderate basicity and relatively high textural properties of the sample.

ZnS nanoparticles immobilized on graphitic carbon nitride as a recyclable and environmentally friendly catalyst for synthesis of 3-cinnamoyl coumarins

Zinc oxide nanoparticles immobilized on a graphitic carbon nitride (ZnS NPs/g-C3N4) nanocomposite were applied as an organometallic recyclable catalyst in the synthesis of coumarin–chalcone hybrids through the Claisen–Schmidt condensation of different aromatic aldehydes and 3-acetyl coumarin. The nanocomposite increased the rate and facility of the aforementioned reaction and represented a strong influence in the green synthesis of different coumarin–chalcone derivatives. The nanocatalyst has been characterized by N2 adsorption–desorption, Fourier transform infrared spectroscopy, scanning electronic microscopy, powder X-ray diffraction and energy dispersive spectroscopy. Some advantages of this novel and sustainable approach are high yields of coumarin–chalcone compounds, short reaction times, environmentally benign, recoverability of ZnS NPs/g-C3N4 and reusability without important loss of catalytic activity.

Rapid synthesis of 4-alkynyl coumarins and tunable electronic properties of emission solvatochromic fluorophores

Novel fluorescent 4-alkynyl coumarins were rapidly and efficiently synthesized by Sonogashira coupling of readily accessible coumaryl triflates. The photophysical properties of the predominantly highly fluorescent compounds were experimentally studied by absorption and fluorescence spectroscopy and their electronic structure was rationalized by DFT and TD-DFT calculations using the PBEh1PBE functional. For certain consanguineous series structure-property relationships of the absorption and emission characteristics were established by Hammett-Taft correlations. Most interestingly, the energy levels of the underlying subchromophores can be electronically fine-tuned and addressed upon photonic excitation for placing donor substituents at the remote alkynyl terminus of the dyes.

Synthesis of methionine methyl ester-modified coumarin as the fluorescent-colorimetric chemosensor for selective detection Cu2+ with application in molecular logic gate.

A methionine methyl ester-modified coumarin derivative was designed and synthesized, which could discriminate Cu2+ from other metal ions in HEPES buffer (10 mM, pH 7.4)/CH3CN (40:60, V/V). The detection limit of WM toward Cu2+ was 1.84 × 10-7 M, which was lower than the concentration of Cu2+ in drinking water suggested by WHO and EPA. And the proposed coordination mode exhibiting the interaction between WM and Cu2+ was studied by UV-Vis, fluorescence spectrum, ESI-MS and FT-IR. Based on the fluorescent reversibility of WM, WM was considered as a molecular logic gate and molecular keypad lock. In addition, the test strips and the silica gel plates prepared from the solution of WM also demonstrate the favorable selectivity toward Cu2+.

A one-pot four-component domino protocol for the synthesis of indole and coumarin containing pyridine-3-carbonitrile derivatives

An efficient and simple protocol for the synthesis of a new class of diversely functionalized novel indole and coumarin containing pyridine-3-carbonitrile derivatives has been described through one-pot four-component condensation reaction of 3-(1H-indol-3-yl)-3-oxopropanenitrile, various aldehydes, 3-acetyl-2H-chromenones, and ammonium acetate in acetic acid conditions. The present new methodology offers several advantages such as short reaction time, easy experimental work-up, and good product yield, and endures the substrate diversity and operational simplicity under metal-free reaction conditions for the formation of C–C/C–N bonds.

Antioxidant Activity of Coumarine Compounds

Synthesis of coumarins, that were a structurally motivating antioxidant action, was finished in our article. Four components are condensed in the synthesis 4-hydroxycoumarin, 5,5-dimethyl-1,3-cyclohexanedione, and aromatic aldehydes, using tetrabutylammonium bromide (TBAB), diammonium hydrogen phosphate (DAHP), respectively to yield target compounds(1-4). The present methods have advantages, including one-pot synthesis, excellent yields, short reaction times, and easy isolation of product. All catalysts utilized in our study could be reused several times without losing their catalytic efficiency. The structures of the synthesized compounds were elucidating by spectro-scopically methods, Infrared Spectra FT-IR and 1H and 13C Nuclear/Magnetic/Resonance Spectra and elemental analysis techniques, melting point and thin layer chromatography. The scavenging activities of individual molecules were tested vs. stable free radical(1,1-Diphenyl-2-picrylhydrazyl (DPPH)), the results were compared to the Gallic acid. The results show that most of the compounds exhibited higher antioxidant activates than the standards in different concentration range. The highest efficiency scavenging activity was found for compound 2 (88.0±1%) followed by compounds 3 (83±0.5%).The component of the integrated mixes as cell reinforcements was likewise examined.

Microwave Assisted Synthesis of Coumarins: A Review From 2007 to 2018

Microwave Assisted Synthesis of Coumarins: A Review From 2007 to 2018

Synthesis and Biological Evaluation of Novel Coumarins with tert-Butyl and Terpene Substituents.

Coumarins with terpene and tert-butyl substituents were synthesized via Pechmann condensation reaction. New derivatives were investigated in different model system for the exhibition of antioxidant, radical scavenging and membrane-protective activities. It has been found that 4-methylcoumarin derivatives with monoterpene moieties exhibit high antioxidant activities. The most active and promising for further investigations is 5-hydroxy-6,8-diisobornyl-4-methylcoumarin, containing two isobornyl substituents on the benzopyran ring.

A Copper Halide Promoted Regioselective Halogenation of Coumarins Using N-Halosuccinimide as Halide Source

A safe, convenient, and regioselective synthesis of 3-halo coumarins using a metal halide (CuX2 alone or with ZnX2) promoted halogenation with N-halosuccinimide (NXS) as halide source is reported. The synthesis involved the steady in situ generation of highly reactive positive halogen (X+) by the coordination of copper or zinc with the N-halosuccinimide and subsequent electrophilic aromatic substitution of the electron-deficient coumarins. This procedure works well also for the halogenation of less electron-rich naphthoquinones, flavones, and methoxypsoralen in moderate to quantitative yields. This protocol features simple experimental conditions using readily available inexpensive reagents and provides a convenient approach to the chlorination or bromination of some useful heteroaromatic compounds.

An efficient light on-off one-pot method for the synthesis of 3-styryl coumarins from aryl alkynoates.

An efficient one-pot stepwise method to synthesize 3-styryl-4-arylcoumarins from simple alkynoates is demonstrated. On the basis of the control experiments, a possible mechanism involving light-driven radical cyclization and Pd-catalysed cross-coupling processes for this synthesis method is proposed. The results of X-ray analysis and spectroscopy experiments prove that the substituent effect has a significant influence on the absorption and emission properties of the synthesized 3-styryl coumarins.

Regioselective radical arylation: silver-mediated synthesis of 3-phosphorylated coumarins, quinolin-2(1H)-one and benzophosphole oxides.

A silver-mediated domino radical addition/cyclization reaction of diarylphosphine oxides with propynoic acid derivatives is described in this article. The reaction of diarylphosphine oxides with alkynoates or propynoic amide was regioselective, producing 3-phosphorylated coumarins and benzophosphole oxides in moderate to good isolated yield, respectively. The hydrogen bond between P[double bond, length as m-dash]O and N-H was proposed to assist the vinyl radical regioselective arylation process. The reaction conditions were also compatible with the conversion of dialkylphosphine oxides to 3-phosphorylated-coumarins and quinolin-2(1H)-one in good yields.