- N-(2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl)thiosemicarbazones of 6-alkoxy-2-oxo-2H-chromene-4-carbaldehydes: synthesis, evaluation of their antibacterial, anti-MRSA, antifungal activity, and docking study
-
Reaction of 6-alkoxy-2-oxo-2H-chromen-4-carbaldehydes with N-(2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl)thiosemicarbazide yielded corresponding thiosemicarbazones having 2H-chromen-2-one ring. In vitro evaluations showed that these 2H-chromen-2-one compounds exhibited remarkable antibacterial and antifungal activities against some typical bacteria and fungi. Representative compounds with MIC values of 0.78 ? 1.56 μg/mL were 6c, 6g (against S. aureus), 6a, 6f (against S. epidermidis) (Gram-positive bacterial strains), 6e, 6g (against E. coli), 6b, 6e (against K. pneumoniae), and 6d–f (against S. typhimurium) (Gram-negative bacterial strains). Almost all thiosemicarbazones 6a–g had no activity against Gram-positive bacterial strain B. subtilis at these MIC values. Some compounds had strong inhibitory activity against several bacteria, such as 6b (for K. pneumoniae and S. typhimurium), 6d, 6e (for E. coli, K. pneumoniae, and S. typhimurium), 6f (for S. aureus, E. coli, and S. typhimurium), and 6g (for B. subtilis, S. aureus, E. coli, and K. pneumoniae). Some compounds had remarkable inhibitory activity against three clinical MRSA isolates with MIC values of 0.78–6.25 μg/mL. Docking study showed that compound 6g is compatible with the active site of S. aureus DNA gyrase 2XCT, which suggested that the tested compounds inhibited the synthesis of this enzyme. [Figure not available: see fulltext.]
- Toan, Vu Ngoc,Thanh, Nguyen Dinh,Khuyen, Vu Hong,Tu, Luu Thi Cam,Tri, Nguyen Minh,Huong, Nguyen Thi Thu
-
-
Read Online
- N-Doped Carbon Wrapped Polyoxometalate Derived from POM-IL Hybrid: A Heterogeneous Catalyst for the Synthesis of Coumarin Derivatives under Solvent-Free Conditions
-
Vanadium substituted Keggin type polyoxometalate loaded N-doped carbon was prepared from polyoxometalate ionic liquid hybrid by carbonization process. The decomposition of organic part generates various functional groups leaving polyoxometalate part intact. The catalyst was characterized by elemental analysis, FTIR, MAS 13C NMR, XPS and electron microscopy studies. The presence of carboxylic acids, aromatic and hetero-aromatic groups in the catalyst was confirmed by 13C NMR. The high resolution C1s and O1s XPS analysis further confirmed the presence of these groups. Various oxidation states of nitrogen were confirmed by deconvoluted N1s XPS spectra. Pyridine adsorption study confirms the presence of Bronsted and Lewis acid sites in the catalyst. Layered structure of the catalyst was confirmed by HR TEM analysis. The hybrid material displayed excellent catalytic activity towards the synthesis of coumarin derivatives under solvent-free conditions.
- Ramalingam, Meenakshi,Mani, Chandhru,Manickam, Sundar,Srinivasalu, Kutti Rani
-
-
Read Online
- A highly selective chemosensor for naked-eye sensing of nanomolar Cu(II) in an aqueous medium
-
A novel highly selective and sensitive colorimetric chemosensor L for the detection of Cu2+ ion with a fast response time was designed and synthesized. Receptor L detected Cu2+ ion by changing its color from colorless to magenta in a semi-aqueous solution. The limit of detection for Cu2+ was calculated to be as low as 28 nM. The possible binding mode of compound L with Cu2+ ion was studied using the Job's method, HRMS, FTIR spectroscopy and 1H NMR spectroscopy titration. Importantly, test strips containing L were fabricated as a naked-eye indicator for Cu2+ ion in pure water samples.
- Qian, Yaao,Cao, Li,Jia, Chunman,Boamah, Peter Osei,Yang, Qiuyun,Liu, Chunling,Huang, Yan,Zhang, Qi
-
-
Read Online
- Synthesis of 6- and 7-alkoxy-4-methylcoumarins from corresponding hydroxy coumarins and their conversion into 6- and 7-alkoxy-4-formylcoumarin derivatives
-
Hydroxy derivatives of 4-methyl-2H-chromen-2-one were prepared from hydroquinone and resorcinol through their reaction with ethyl acetoacetate. These hydroxy coumarins were then converted into corresponding alkoxy derivatives by reaction with alkyl halides. The yields of 6- and 7-alkoxy-4-methylcoumarins 3a–i and 4a–i were 55?95%. Oxidation of these compounds by selenium dioxide under conventional and microwave-assisted heating conditions produced corresponding 4-formyl compounds 5b–h and 6b–h with yields of 40?67% and 90?93%, respectively. Several 6- and 7-alkoxy-4-methylcoumarins 3a–i, 4a–i and nearly all 6- and 7-alkoxy-4-formylcoumarins 5b–h, 6b–h are novel compounds.
- Ngoc Toan, Vu,Dinh Thanh, Nguyen
-
-
Read Online
- Synthesis and antiproliferative activity of 6,7-aryl/hetaryl coumarins
-
Two different series of novel analogs of 6,7-aryl/hetaryl coumarins 4a-4h and 8i-8l have been synthesized by using Suzuki-Miyara cross coupling reaction from 4-methyl-2-oxo-2H-chromen-7-yl trifluoro-methanesulfonate and 4-methyl-2-oxo-2H-chromen-6-yl trifluoromethanesulfonate in high yields (70-90%). All synthesized compounds were elucidated by means of IR, 1H NMR, 13C NMR, and MS spectra. The synthesized compounds were tested for antiproliferative activity against different human cancer cell lines (SiHa, MDAMB-231, and PANC-1) and some of products demonstrated the distinctive effect.
- Jayaprakash Rao,Yadaiah Goud,Hemasri,Jain, Nishant,Gabriella, Srujana
-
-
Read Online
- Novel thiazoline-coumarin hybrid compounds containing sugar moieties: synthesis, biological evaluation and molecular docking study as antiproliferative agents
-
A new series of 2,3-thiazoline-coumarin hybrid compounds that containedd-glucose andd-galactose moieties (4a-g) were synthesized and their cytotoxic activity was evaluated against breast adenocarcinoma (MCF-7), human liver cancer (HepG2), human cervical cancer (HeLa), human melanoma cancer (SK-Mel-2), and human lung cancer (LU-1) cells. To reveal their selectivity toward cancer cells, the compounds were also tested against the human fibroblast cell line MRC-5. The synthesized compounds exhibited potent cytotoxic activity against the tested cell lines with IC50values of 1.18-11.32, 1.91-9.81, 1.96-13.16, 1.35-16.12, and 2.12-15.92 μM (against MCF-7, HepG2, HeLa, SK-Mel-2, and LU-1 cells, respectively) compared with Sorafenib, doxorubicin, and 5-fluorouracil. Interestingly, compounds4a-gdisplayed selectivity toward cancer cell lines over MRC-5 (IC503.97-25.75 μM). The most active compounds, including4d,4e, and4f, also displayed potent inhibitory activity against EGFR and HER2 kinases (IC500.15-0.31 and 0.15-0.25 μM, respectively) compared with the standard drug Sorafenib (IC50= 0.11 and 0.13 μM, respectively). Molecular docking also showed that the hydrogen binding interactions often occurred between the CO lactone of the coumarin ring and appropriate amino acid residues, which played a key role in enhancing its potency against both enzymes.
- Ngoc Toan, Vu,Dinh Thanh, Nguyen
-
p. 10636 - 10653
(2021/06/27)
-
- A Reusable Column Method Using Glycopolymer-Functionalized Resins for Capture–Detection of Proteins and Escherichia coli
-
The use of glycopolymer-functionalized resins (Resin–Glc), as a solid support, in?column mode for bacterial/protein capture and quantification is explored. The Resin–Glc is synthesized?from commercially available chloromethylated polystyrene?resin and glycopolymer, and is characterized by fourier transform infrared spectroscopy, thermogravimetry, and elemental analysis. The percentage of glycopolymer functionalized on Resin–Glc is accounted to be 5 wt%. The ability of Resin–Glc to selectively capture lectin, Concanavalin A, over Peanut Agglutinin, reversibly, is demonstrated for six cycles of experiments. The bacterial sequestration study using SYBR (Synergy Brands, Inc.) Green I tagged?Escherichia coli/Staphylococcus aureus?reveals the ability of Resin–Glc to selectively capture?E. coli?over?S. aureus. The quantification of captured cells in the column is carried out by enzymatic colorimetric assay using methylumbelliferyl glucuronide?as the substrate. The?E. coli?capture studies reveal a consistent capture efficiency of 105?CFU (Colony Forming Units) g?1 over six cycles. Studies with spiked tap water samples show satisfactory results for?E. coli?cell densities ranging from 102 to 107?CFU mL?1. The method portrayed can serve as a basis for the development of a reusable solid support in capture and detection of proteins and bacteria.
- Ajish, Juby K.,Abraham, Hephziba Maria,Subramanian, Mahesh,Kumar, K. S. Ajish
-
-
- Recyclable cellulose nanocrystal supported Palladium nanoparticles as an efficient heterogeneous catalyst for the solvent-free synthesis of coumarin derivatives via von Pechmann condensation
-
2-Amino pyrimidine nanocellulose-supported Palladium nanoparticles (CNC-AMPD-Pd) as a novel bio supported nanocatalyst was prepared and characterized by ICP-AES, FT-IR, XRD, SEM, TEM, TGA and EDX techniques. The nanocatalyst demonstrated outstanding performance in Pechmann condensation between different substituted phenols and ethyl acetoacetate to obtain coumarin derivatives in good to excellent yields. The catalyst is easily recycled and reused without loss of the catalytic activity. The combined merits of reusable catalyst and solvent-free reaction conditions make the condensation with safe operation, no leaching of pd into environment, low pollution, rapid access to products and simple workup.
- Mirosanloo, Atieh,Zareyee, Daryoush,Khalilzadeh, Mohammad A.
-
-
- Cu (I) Catalyzed One Pot SN-Click Reactions of Halogenated Coumarins and 1-aza-coumarins
-
A one pot three component, copper catalyzed azide-alkyne cycloaddition reaction has been employed for the synthesis of bis-coumarinyl triazoles (A–D) using 4-chloro, 4-bromomethyl, 3-bromoacetyl and 4-bromomethyl-1-aza-coumarins (I–IV), sodium azide, and coumarin propargyl ethers (V–IX) in moderate yields.
- Revankar, Hrishikesh M.,Kulkarni, Manohar V.
-
p. 537 - 544
(2018/01/10)
-
- A green and convenient approach for the one-pot solvent-free synthesis of coumarins and β-amino carbonyl compounds using Lewis acid grafted sulfonated carbon@titania composite
-
Abstract: This paper reports an efficient protocol for the synthesis of coumarins via Pechmann reaction, and β-amino carbonyl compounds via aza-Michael reaction using catalytic amount of solid Lewis acid catalyst, C@TiO2–SO3–SbCl2. Six different catalysts were prepared by covalent immobilization of homogeneous Lewis acids onto sulfonated carbon@titania composite derived from amorphous carbon and nano-titania. Among various catalysts tested, C@TiO2–SO3–SbCl2 showed superior catalytic activity. The catalyst could be recycled without significant loss of its catalytic activity and demonstrated versatile catalysis for a wide range of substrates. Graphical abstract: [Figure not available: see fulltext.]
- Kour, Manmeet,Paul, Satya
-
p. 327 - 337
(2017/02/10)
-
- Acetamide Derivatives of Chromen-2-ones as Potent Cholinesterase Inhibitors
-
Alzheimer's disease (AD), a neurodegenerative disorder, is a serious medical issue worldwide with drastic social consequences. Inhibition of cholinesterase is one of the rational and effective approaches to retard the symptoms of AD and, hence, consistent efforts are being made to develop efficient anti-cholinesterase agents. In pursuit of this, a series of 19 acetamide derivatives of chromen-2-ones were synthesized and evaluated for their acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory potential. All the synthesized compounds exhibited significant anti-AChE and anti-BChE activity, with IC50 values in the range of 0.24–10.19 μM and 0.64–30.08 μM, respectively, using donepezil hydrochloride as the standard. Out of 19 compounds screened, 3 compounds, viz. 22, 40, and 43, caused 50% inhibition of AChE at 0.24, 0.25, and 0.25 μM, respectively. A kinetic study revealed them to be mixed-type inhibitors, binding with both the CAS and PAS sites of AChE. The above-selected compounds were found to be effective inhibitors of AChE-induced and self-mediated Aβ1–42 aggregation. ADMET predictions demonstrated that these compounds may possess suitable blood–brain barrier (BBB) permeability. Hemolytic assay results revealed that these compounds did not lyse human RBCs up to a thousand times of their IC50 value. MTT assays performed for the shortlisted compounds showed them to be negligibly toxic after 24 h of treatment with the SH-SY5Y neuroblastoma cells. These results provide insights for further optimization of the scaffolds for designing the next generation of compounds as lead cholinesterase inhibitors.
- Prasad, Suchita,Kumar, Bipul,Kumar, Shiv,Chand, Karam,Kamble, Shashank S.,Gautam, Hemant K.,Sharma, Sunil K.
-
-
- One-pot synthesis of coumarine derivatives using butylenebispyridinium hydrogen sulfate as novel ionic liquid catalyst
-
Pechmann condensation reaction of 3-hydroxyphenol and ethyl acetoacetate in the presence of 1,1′‐butylenebispyridinium hydrogen sulfate as an efficient, green, and recyclable catalyst produces 7-hydroxy-4-methylcoumarin in good yield under solvent-free conditions at room temperature. This catalyst has advantages such as the following: good to excellent yields, short reaction times, simplicity in operation, and easy workup procedure.
- Rezayati, Sobhan,Sheikholeslami-Farahani, Fatemeh,Rostami-Charati, Faramarz,Abad, Saeid Afshari Sharif
-
p. 4097 - 4107
(2016/07/06)
-
- Meglumine sulfate catalyzed solvent-free one-pot synthesis of coumarins under microwave and thermal conditions
-
A convenient method has been developed for the Pechmann reaction of phenols and β-keto esters catalyzed by meglumine sulfate. Solvent-free conditions, inexpensive catalyst, short reaction times, high yield, and ease of purification of the products are the advantages of this protocol. This novel catalytic system is expected to contribute to the development of more benign Pechmann condensation reactions of phenols with β-keto esters.
- Moradi, Leila,Rabiei, Khadijeh,Belali, Fateme
-
supporting information
p. 1283 - 1291
(2016/08/16)
-
- Synthesis and heterogeneous catalytic activity of covalently immobilized hexamine cation as a magnetically-recoverable nanocatalyst
-
Functionalized magnetic core-shell nanoparticles Fe3O4-SiO2-HMTA are prepared by co-precipitation method and characterized by SEM, TEM, FT-IR, XRD, and VSM. The particles are spherical with an average size of approximately 48 nm. The catalytic activity of these nanoparticles was tested in solvent-free synthesis of coumarin derivatives. The catalyst was readily recycled by the use of an external magnetic field and can be reused four times without significant loss of activity or mass.
- Kangari, Sahar,Yavari, Issa,Maasoumi, Bakhshali
-
p. 1771 - 1779
(2015/08/06)
-
- Sulfonated core-shell magnetic nanoparticle (Fe3O4@SiO2@PrSO3H) as a highly active and durable protonic acid catalyst; Synthesis of coumarin derivatives through pechmann reaction
-
Sulfonic acid supported silica coated magnetic nanoparticles (Fe3O4@SiO2@PrSO3H), was prepared by using low cost precursors and a facile immobilization technique. The final catalyst, which was characterized by XRD, FT-IR, vibrating sample magnetometer (VSM), TEM, and TGA techniques, was found to be an efficient and environmentally benign solid acid for the Pechmann condensation of substituted phenols with ethyl acetoacetate leading to the formation of coumarin derivatives. After the reaction, the catalyst could be effortlessly separated by external magnet and reused for 22 consecutive runs, without any significant loss in catalytic efficiency. The catalytic system presented offers a reusable strategy for the efficient synthesis of coumarin, simplicity in operation, and a green reaction profile by avoiding toxic conventional catalysts and solvents. Green earth and blue sky: Herein, we wish to disclose a simple bench top procedure for the synthesis of sulfonated core-shell magnetic nanoparticles (SMNPs) (Fe3O4@SiO2@PrSO3H) and discuss its performance as a very strong solid acid in the Pechmann condensation reaction.
- Esfahani, Farhad Kabiri,Zareyee, Daryoush,Yousefi, Reza
-
p. 3333 - 3337
(2015/04/16)
-
- Synthesis of substituted coumarins catalyzed by sawdust-SO3H. An efficient and environmentally benign solid acid catalyst under solvent-free conditions
-
The sulfonated sawdust (SD-SO3H) was easily prepared by treatment of sawdust, a biomass waste material, with chlorosulfonic acid and characterized by elemental analysis, SEM and TGA. The bio-degradable solid acid catalyst has been applied to the Pechmann condensation reaction of phenols with β-ketoesters for the synthesis of coumarin derivatives under solvent-free conditions. This environmentally benign and inexpensive method has such advantages as simplicity in operation, high yields, low catalyst loading and short reaction time. The catalyst can be efficiently recycled with insignificant loss of activity.
- Tahanpesar,Sarami
-
p. 2135 - 2140
(2015/10/29)
-
- Environmentally sustainable magnetic solid sulfonic acid: An efficient and reusable catalyst for the Pechmann reaction
-
Abstract An environmentally benign sulfonic acid nanocomposite based on Fe3O4@SiO2 core-shell magnetic nanoparticles, Fe3O4@SiO2@Et-PhSO3H, was prepared and the acidity and utility of the catalyst were explored for the synthesis of a diverse range of coumarin derivatives under solvent-free conditions. The catalyst shows potential for scale up in the synthesis of coumarins with high purity and was easily separated by using an external magnet. The recovered catalyst was reused in seven cycles without any significant loss of activity.
- Mobaraki, Akbar,Yasham, Shahriar,Movassagh, Barahman
-
supporting information
p. 1263 - 1268
(2015/06/02)
-
- Synthesis and photooxygenation of linear and angular furocoumarin derivatives as a hydroxyl radical source: Psoralen, pseudopsoralen, isopseudopsoralen, and allopsoralen
-
Synthesis of linear and angular furocoumarins with new skeleton structure of potential photobiological feature interest was carried out through Williamson reaction of hydroxycoumarins with 3-chloro-2-butanone followed by cyclization with polyphosphoric acid or by heating in a strongly alkaline solution. The photooxygenation reactions of synthesized furocoumarins were performed in chloroform and in the presence of tetraphenylporphyrin as singlet oxygen sensitizer (1O2). The photooxygenation reactions afforded the photocleaved product through [2 + 2] cycloaddition and the photooxygenated products through ene reaction and [4 + 2] cycloaddition. The photoproducts were isolated and fully characterized by spectral analyses.
- Elgogary, Sameh Ramadan,Hashem, Neveen Mohamed,Khodeir, Mohamed Nabeel
-
p. 506 - 512
(2015/03/30)
-
- Quaternary ammonium and amido derivatives of pyranochromenones and chromenones: Synthesis and antimicrobial activity evaluation
-
Infectious diseases and the development of their resistance to antimicrobial agents are alarming issues worldwide and consistent efforts are being made to develop efficient antimicrobial agents. In this perspective, a series of novel ammonium and amide derivatives of pyranocoumarin and coumarin were synthesized and evaluated for their antimicrobial activity. Among them, six compounds exhibited significant activity against gram-positive bacteria Bacillus cereus (MTCC 430) and Bacillus subtilis (MTCC 121) and a gram-negative bacterium Pseudomonas aeruginosa (MTCC 741). The compound N,N,N-triethyl-10-(4,8,8-trimethyl-2-oxo-2,6,7,8-tetrahydropyrano[3,2-g]chromen-10-yloxy)decan-1-aminium bromide (16) exhibited the highest antibacterial activity with MIC value of 5 μg/ml in MDA. Compounds 17 and 18 exhibited modest antifungal activity with MIC of 6.25 μg/ml against Trichophyton rubrum (clinical isolate) in MDA. Haemolytic assay results demonstrated that three out of six compounds were safe at their respective MIC values. These results provide insights for further optimization of the scaffolds for designing the next generation of compounds as lead antimicrobial agents.
- Prasad, Suchita,Kumar, Shiv,Kumar, Bipul,Singh, Abhishek Kumar,Gautam, Hemant K.,Sharma, Sunil K.
-
p. 2297 - 2313
(2015/02/19)
-
- Use of a highly efficient and recyclable solid-phase catalyst based on nanocrystalline titania for the pechmann condensation
-
Nanocrystalline titania-based sulfonic acid was used as an efficient and reusable catalyst for the synthesis of coumarins. The clean, mild acidity condition, the quantitative yields of products, the short reaction time, and the low reaction temperature are attractive features of this method, making it suitable for heat- or acid-sensitive substrates, particularly in drug synthesis. In practice, this method affords an advantageous combination of satisfactory yields, easy product isolation and purification.
- Atghia, Seyyed Vahid,Beigbaghlou, Somayyeh Sarvi
-
p. 1155 - 1159
(2015/02/05)
-
- Recyclable CMK-5 supported sulfonic acid as an environmentally benign catalyst for solvent-free one-pot construction of coumarin through Pechmann condensation
-
Sulfonic acid modified nanostructured CMK-5 is used as an alternative to conventional acid catalysts in the von Pechmann condensation of a neat mixture of substituted phenols with ethyl acetoacetate leading to the formation of coumarin derivatives at 130 °C. In comparison, CMK-5-SO3H showed a greater activity than some other homogeneous and heterogeneous catalysts. Additionally, the catalyst is reused repeatedly for 6 reaction cycles without any evidence of loss of activity, confirming the stability of the covalent bonding of acidic centers. The methodology presented offers reusable strategy for the efficient synthesis of coumarin, simplicity in operation, and green aspects by avoiding toxic conventional catalysts and solvents.
- Zareyee, Daryoush,Serehneh, Mahshad
-
-
- Diazabicyclo[2.2.2]octane stabilized on Fe3O4 as catalysts for synthesis of coumarin under solvent-free conditions
-
Fe3O4-diazabicyclo[2.2.2]octane (Fe3O 4-DABCO) magnetic nanoparticles (MNPs) catalyst was readily prepared from inexpensive starting materials in aqueous media which catalyzed the synthesis of coumarin. FTIR spectroscopy, X-ray diffraction, transmission electron micrographs were employed to characterize the properties of the synthesized Fe3O4-DABCO MNPs. High catalytic activity and ease of recovery from the reaction mixture using external magnet, and several reuse times without significant losses in performance are additional eco-friendly attributes of this catalytic system.
- Nasseri, Mohammad Ali,Sadeghzadeh, Seyed Mohsen
-
-
- Coumarins: Facile and expeditious synthesis via keggin-type heteropolycompounds under solvent-free condition
-
Different Keggin-type heteropolycompounds were used in Pechmann reaction to obtain biologically active coumarins. Effect of solvent, catalyst loading, and molar ratios of substrates was studied to introduce the best reaction condition. The optimized reaction condition was extended to Pechmann reaction of methylacetoacetate with various monohydric and polyhydric phenols. This rapid procedure afforded structurally diverse coumarins with high to excellent yields. Short reaction times, simple work-up, and mild reaction conditions were advantages of this method. The optimized catalysts were reusable for four runs.
- Rafiee, Ezzat,Fakhri, Akram,Joshaghani, Mohammad
-
p. 1121 - 1128
(2013/10/21)
-
- Solvent free synthesis of coumarins using environment friendly solid acid catalysts
-
Solid acid catalysts, ZrPW (Zirconium(IV) Phosphotungstate) and 12-TPA/ZrO2 [12-Tungstophosphoric acid (12-TPA) supported onto ZrO2] have been synthesized. The catalysts have been characterized for chemical stability, elemental analysis by ICP-AES, TGA, FTIR, SEM, EDX, XRD, surface area (BET) and surface acidity (NH3-TPD). The performance of these materials as solid acid catalysts has been explored by studying Pechmann condensation as a model reaction, wherein phenols have been treated with methyl acetoacetate to give coumarins, under solvent free conditions using conventional heating as well as microwave heating. Catalytic activity of both the solid acid catalysts have been compared and correlated with surface properties of the materials.
- Ghodke, Shrinivas,Chudasama, Uma
-
p. 219 - 226
(2013/03/28)
-
- Br?nsted-acidic imidazolium ionic liquid [bmim(SO 3H)][OTf]: A mild catalyst for highly efficient synthesis of coumarins
-
The use of Br?nsted-acidic imidazolium ionic liquid [bmim(SO 3H)][OTf] as a catalyst for the high yielding synthesis of a wide variety of coumarins under mild conditions via Pechmann condensation has been demonstrated. This method is simple and has benefits from the easy way to isolate coumarins in good yields. In comparison with the classical Pechmann condensation, this new method consistently has the advantage of high yields and good purity.
- Haldorai, Yuvaraj,Kalkhambkar, Rajesh G.,Shim, Jae-Jin
-
p. 9379 - 9383
(2013/11/19)
-
- A green, efficient and recyclable poly(4-vinylpyridine)-supported copper iodide catalyst for the synthesis of coumarin derivatives under solvent-free conditions
-
Poly(4-vinylpyridine)-supported copper iodide is reported as a green, efficient and recyclable catalyst for the synthesis of coumarin derivatives by the Pechmann reaction under solvent-free conditions. This catalyst can be recovered by simple filtration and recycled up to eight consecutive runs without any loss of their efficiency.
- Albadi, Jalal,Shirini, Farhad,Abasi, Jafar,Armand, Nezam,Motaharizadeh, Tayebeh
-
p. 407 - 411
(2013/07/05)
-
- Synthesis of coumarins and 2,3-dihydroquinazolin-4(1H)-ones using trichloroacetic acid as a catalyst
-
Trichloroacetic acid was used as an efficient catalyst for the synthesis of coumarins from phenols and β-ketoesters and in an efficient synthesis of 2,3-dihydroquinazolin-4(H)-ones through the condensation of 2-aminobenzamide with aldehydes or ketones under solvent-free conditions. The remarkable advantages offered by this method are short reaction times, simple procedure, and an easy work-up without using any chromatographic methods.
- Karimi-Jaberi, Zahed,Zarei, Leila
-
p. 178 - 183
(2013/06/27)
-
- Sequential photo-oxidation of methanol to methyl formate on TiO 2(110)
-
Methyl formate is produced from the photo-oxidation of methanol on preoxidized TiO2(110). We demonstrate that two consecutive photo-oxidation steps lead to methyl formate using mass spectrometry and scanning tunneling microscopy. The first step in methanol oxidation is formation of methoxy by the thermal dissociation of the O-H bond to yield adsorbed CH3O and water. Formaldehyde is produced via hole-mediated oxidation of adsorbed methoxy in the first photochemical step. Next, transient HCO is made photochemically from formaldehyde. The HCO couples with residual methoxy on the surface to yield methyl formate. Exposure of the titania surface to O 2 is required for these photo-oxidation steps in order to heal surface and near-surface defects that can serve as hole traps. Notably, residual O adatoms are not required for photochemical production of methyl formate or formaldehyde. All O adatoms react thermally with methanol to form methoxy and gaseous water at rt, leaving a surface devoid of O adatoms. The mechanism provides insight into the photochemistry of TiO2 and suggests general synthetic pathways that are the result of the ability to activate both alkoxides and aldehydes using photons.
- Phillips, Katherine R.,Jensen, Stephen C.,Baron, Martin,Li, Shao-Chun,Friend, Cynthia M.
-
supporting information
p. 574 - 577
(2013/03/14)
-
- Polyvinylpolypyrrolidone-bound boron trifluoride (PVPP-BF3); A mild and efficient catalyst for synthesis of 4-metyl coumarins via the Pechmann reaction
-
Polyvinylpolypyrrolidone-supported boron trifluoride has been studied for synthesis of 4-methyl coumarin by the Pechmann reaction. The reaction proceeded smoothly with hydroxyl phenols and ethyl acetoacetate in good yields in ethanol at reflux conditions. The polyvinylpolypyrrolidone-boron trifluoride complex is a non-corrosive and stable solid catalyst elevated Lewis acid property.
- Mokhtary, Masoud,Najafizadeh, Faranak
-
experimental part
p. 530 - 532
(2012/08/08)
-
- Microwave-induced one-pot synthesis of coumarins using potassium dihydrogen phosphate as a catalyst under solvent-free condition
-
Potassium dihydrogen phosphate was found to be an efficient catalyst for the Pechmann condensation of phenols with ethyl acetoacetate, leading to the formation of coumarins under microwave-irradiation and solvent-free condition. This procedure offers several advantages, including the low loading of catalysts, high yields, clean reactions, short reaction time for the synthesis of coumarins.
- Niralwad, Kirti S.,Shingate, Bapurao B.,Shingare, Murlidhar S.
-
experimental part
p. 486 - 489
(2011/09/16)
-
- Periodic mesoporous silica chloride (PMSCl) as an efficient and recyclable catalyst for the Pechmann reaction
-
Periodic mesoporous silica chloride (PMSCl) with 2D P6mm hexagonal structure which can be prepared by a simple procedure is reported to act as an efficient and recyclable catalyst for the conversion of a variety of phenols into their corresponding coumarins through Pechmann reaction. The reactions were conducted under solvent-free conditions in good to excellent yields.
- Karimi, Babak,Behzadnia, Hesam
-
experimental part
p. 1432 - 1436
(2012/07/31)
-
- Lipase catalysed substituted coumarins with antioxidant activity
-
Lipase has been employed as a green catalyst to esterify 7- and 6-hydroxy-4-methyl-coumarin with different fatty and acetic acid. The esterified coumarins have been evaluated for antioxidant activities using DPPH and ABTS assays, among them 3a and 5a are known as active antioxidants.
- Kidwai, Mazaahir,Poddar, Vaishali,Poddar, Roona
-
experimental part
p. 715 - 720
(2011/07/08)
-
- Design of a highly efficient and water-tolerant sulfonic acid nanoreactor based on tunable ordered porous silica for the von Pechmann reaction
-
(Figure Presented) Among a number of different sulfonic acid nanoreactors prepared, 5 having both acidic sites and phenyl groups located inside the mesochannels of SBA-15 was shown to be the most active and reusable catalyst in the von Pechmann reaction. The mesochannels, and covalently anchored organic groups, provide a synergistic means of an efficient approach of the reactants to acidic sites, enough space for the subsequent cyclization, and suitable hydrophobicity to drive out the water byproduct.
- Karimi, Babak,Zareyee, Daryoush
-
supporting information; experimental part
p. 3989 - 3992
(2009/06/18)
-
- Structural insights into hydroxycoumarin-induced apoptosis in U-937 cells
-
In the present study, we sought to establish the effect of diverse structural-related hydroxycoumarins on the proliferation, cytotoxicity, and induction of apoptosis in promonocytic leukemic cells (U-937). The dihydroxylated coumarins, 7,8-dihydroxy-coumarin and esculetin, induced DNA fragmentation as well as characteristic morphological changes of programmed cell death in U-937 cells. With the aim to perform a structure-activity relationship study, the correlation between the physicochemical properties of the molecules and their pro-apoptotic activity was carried out. Results showed that the presence of two adjacent phenolic hydroxyl groups was the most important factor in terms of the SAR. The exposure of leukemic cells to 7,8-dihydroxy-coumarin evoked a phenoxyl radical generation that was detected by electron spin resonance spectroscopy. The present study suggests that reactive oxygen species generation plays a critical role in dihydroxycoumarin-induced apoptosis in U-937 cells. These findings further suggest that these compounds may have a potential therapeutic role in the treatment of hematological malignancies.
- Riveiro, Maria E.,Moglioni, Albertina,Vazquez, Ramiro,Gomez, Natalia,Facorro, Graciela,Piehl, Lidia,de Celis, Emilio Rubin,Shayo, Carina,Davio, Carlos
-
p. 2665 - 2675
(2008/09/21)
-
- Fries rearrangement of aryl formates: A mechanistic study by means of 1H, 2H, and 11B NMR spectroscopy and DFT calculations
-
(Figure Presented) 1H, 2H, and 11B NMR spectroscopy has been used to study the mechanism of the Fries rearrangement of aryl formates promoted by boron trichloride by monitoring both the substrate and the Lewis acid. DFT calculations were employed to investigate the energetics of several reaction paths and to calculate NMR chemical shifts of key intermediates and products. After the formation of a 1:1 substrate - Lewis acid adduct, the rearrangement proceeds in two steps, beginning with the cleavage of the ester bond and the release of formyl chloride in situ, which, in turn, acts as a formylating agent, introducing an aldehydic functionality into the aromatic ring. The high regioselectivity (only the ortho product is obtained) is also accounted for by the proposed intermolecular, Lewis acid-assisted mechanism.
- Bagno, Alessandro,Kantlehner, Willi,Kress, Ralf,Saielli, Giacomo,Stoyanov, Edmont
-
p. 9331 - 9340
(2007/10/03)
-
- Mild and efficient deprotection of allyl ethers of phenols and hydroxycoumarins using a palladium on charcoal catalyst and ammonium formate
-
An efficient procedure for the cleavage of allyl phenyl ethers and allyl coumarinyl ethers using a catalytic amount of 10% Pd/C in combination with ammonium formate is described. Allyl ethers of phenols are deprotected in preference to those of alcohols and this method is compatible with several reducible functional groups such as CHO, COCH3, CO2Et and NHCOCH3.
- Ganguly, Nemai C.,Dutta, Sanjoy,Datta, Mrityunjoy
-
p. 5807 - 5810
(2007/10/03)
-
- Gallium triiodide-catalyzed organic reaction: A convenient procedure for the synthesis of coumarins
-
Gallium triiodide, which was generated in situ by the reaction of gallium metal and iodine, was used as an efficient catalyst in the Pechmann condensation of phenols with ethyl acetoacetate, leading to the formation of coumarins. The reaction proceeded in dichloromethane at room temperature with good to excellent yields. Copyright Taylor & Francis, Inc.
- Sun, Peipei,Hu, Zhixin
-
p. 1875 - 1880
(2007/10/03)
-
- Synthesis of novel amino and acetyl amino-4-methylcoumarins and evaluation of their antioxidant activity
-
The six novel 4-methylcoumarins bearing different functionalities such as amino, hydroxy, N-acetyl, acetoxy and nitro have been synthesized and confirmed on the basis of their spectral data (1H-, 13C-NMR, UV, IR and EI mass). They were examined for the first time for their effect on NADPH dependent liver microsomal lipid peroxidation in vitro, and the results were compared with other model 4-methylcoumarin derivatives to establish the structure-activity relationship. Our studies demonstrated that amino group is an effective substitute for the hydroxyl group for antioxidant property and produced a dramatic inhibition of lipid peroxidation. Ortho dihydroxy and ortho hydroxy-amino coumarins were found to possess highest antioxidant and radical scavenging activities.
- Tyagi, Yogesh K.,Kumar, Ajit,Raj, Hanumantharao G.,Vohra, Parag,Gupta, Garima,Kumari, Ranju,Kumar, Pankaj,Gupta, Rajinder K.
-
p. 413 - 420
(2007/10/03)
-
- Catalytic transfer hydrogenation reactions of PEG-bound succinyl esters
-
Various substrates bound to polyethylene glycol (PEG) through succinyl ester linkages were cleaved under catalytic transfer hydrogenation conditions. The substrates with unsaturated functions also underwent hydrogenation. The protocol was found to be suit
- Kumar, H. M. Sampath,Chakravarthy, Pawan,Sawant, Sanghapal D.,Singh, Parvinder Pal,Shesha Rao,Yadav
-
p. 3591 - 3593
(2007/10/03)
-
- Synthesis of coumarins via a Pechmann condensation using heterogeneous catalysts
-
The synthesis of coumarins via a Pechmann condensation involving the reaction between phenols and ethyl acetoacetate has been carried out using two heterogeneous catalysts, NaHSO4.SiO2 and silica chloride under solvent free conditions, thus avoiding acidic waste.
- Das, Biswanath,Venkateswarlu, Katta,Mahender, Gurram,Holla, Harish
-
p. 836 - 837
(2007/10/03)
-
- A solvent-free synthesis of coumarins using a Wells-Dawson heteropolyacid as catalyst
-
Seventeen examples are resolved, most of them in good to excellent yields, using the cheap WD catalyst. Substituted coumarins are synthesized from phenols and β-ketoesters by the Pechmann reaction, using a Wells-Dawson heteropolyacid (H6P2W18O62? 24H2O) as catalyst by a solvent-free procedure. This one requires low reaction times, 130°C temperature and as little as 1 mol % of Wells-Dawson acid, obtaining good to excellent yields of coumarins. The catalyst showed to be reusable with no differences in the yields. The results are compared with those of the reactions performed in toluene solution. The presented synthetic procedure is a convenient, clean and fast alternative for synthesizing 4-substituted coumarins (17 examples).
- Romanelli,Bennardi,Ruiz,Baronetti,Thomas,Autino
-
p. 8935 - 8939
(2007/10/03)
-
- Acceleration of the Pechmann Reaction by Microwave Irradiation: Application to the Preparation of Coumarins
-
Substituted coumarins are synthesised from methyl acetoacetate and substituted phenols using microwaves in excellent yields.
- Singh, Vasundhara,Singh, Jasvinder,Kaur, Kanwal Preet,Kad, Goverdhan L.
-
-
- Steric Course of Ketopantoate Hydroxymethyltransferase in E. coli
-
The conversion of α-ketoisovaleric acid (α-KIVA) to ketopantoate by the 5,10-methylenetetrahydrofolate-dependent enzyme ketopantoate hydroxymethyltransferase (KHMT) in E. coli has been shown to proceed in a retention mode at the β-position of α-KIVA. 5,10-methylenetetrahydrofolate formed in vivo by serine hydroxymethyltransferase (SHMT) from stereospecifically deuterated (3S-d1) serine was converted by KHMT into an ca. 3:1 ratio of deuterated ketopantoates with the 4S isomer predominating.The results indicate that KHMT and SHMT have the same overall steric course in E. coli.
- Aberhart, D. John,Russell, David J.
-
p. 4902 - 4906
(2007/10/02)
-