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1.
Chem Commun (Camb) ; 56(13): 2012-2015, 2020 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-31961351

RESUMO

Here, we describe one simple Ir/hydrosilane catalytic system for chemoselective isomerization of 2-substituted allylic ethers. This facile strategy shows high efficiency towards a variety of substrates, including derivatives from bioactive molecules. The substituent at the α position of the olefins is supposed to be critical in retarding the alkene hydrosilylation process and leading the reaction to go through the isomerization pathway.


Assuntos
Éteres/química , Irídio/química , Silanos/química , Alcenos/química , Catálise , Complexos de Coordenação/química , Isomerismo
2.
J Agric Food Chem ; 67(43): 11893-11900, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31542926

RESUMO

To explore a novel fungicide effectively against cucumber downy mildew (CDM), a series of new arylpyrazole containing pyrimidine ether derivatives were designed and synthesized by employing the intermediate derivatization method (IDM). The structures of synthesized compounds were identified by 1H NMR, 13C NMR, elemental analyses, MS, and X-ray diffraction. Bioassays demonstrated that some of the title compounds exhibited excellent fungicidal activities against CDM. Especially, compound 7 (EC50 = 1.22 mg/L) displayed significantly higher bioactivity than that of commercial fungicides diflumetorim and flumorph and nearly equal effect to that of cyazofamid. The relationship between the structure and fungicidal activity of the synthesized compounds was discussed as well. The study showed that compound 7 was a promising fungicide candidate for further development.


Assuntos
Éteres/química , Fungicidas Industriais/síntese química , Fungicidas Industriais/farmacologia , Pirimidinas/química , Cucumis sativus/microbiologia , Desenho de Drogas , Éteres/farmacologia , Fungicidas Industriais/química , Estrutura Molecular , Oomicetos/efeitos dos fármacos , Doenças das Plantas/microbiologia , Pirimidinas/farmacologia , Relação Estrutura-Atividade , Difração de Raios X
3.
Pharmacol Rev ; 71(4): 450-466, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31471460

RESUMO

Despite continuous clinical use for more than 170 years, the mechanism of general anesthetics has not been completely characterized. In this review, we focus on the role of voltage-gated sodium channels in the sedative-hypnotic actions of halogenated ethers, describing the history of anesthetic mechanisms research, the basic neurobiology and pharmacology of voltage-gated sodium channels, and the evidence for a mechanistic interaction between halogenated ethers and sodium channels in the induction of unconsciousness. We conclude with a more integrative perspective of how voltage-gated sodium channels might provide a critical link between molecular actions of the halogenated ethers and the more distributed network-level effects associated with the anesthetized state across species.


Assuntos
Éteres/farmacologia , Inconsciência/induzido quimicamente , Inconsciência/metabolismo , Canais de Sódio Disparados por Voltagem/metabolismo , Animais , Éteres/química , Humanos , Hidrocarbonetos Halogenados/química , Hidrocarbonetos Halogenados/farmacologia , Hipnóticos e Sedativos/química , Hipnóticos e Sedativos/farmacologia
4.
Chem Pharm Bull (Tokyo) ; 67(8): 872-876, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31366835

RESUMO

A gold-catalyzed introduction of various terminal alkynes to acetals was investigated. Extensive optimization of the reaction conditions revealed that thermally stable cationic gold catalysts bearing bulky ligands such as 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene 3-1H-benzo[d][1,2,3]triazolyl gold trifluoromethanesulfonate (IPrAu(BTZ-H)OTf) were particularly suitable for the reaction. Additionally, significant solvent effects were observed. Ether solvents such as tetrahydrofuran (THF), cyclo pentyl methyl ether (CPME), and 1,4-dioxane were effective for the reaction. Studies on the scope of substrates and alkynes indicated that various alkynes and acetals were feasible to provide a wide range of propargylic ethers.


Assuntos
Acetais/química , Alquinos/química , Éteres/síntese química , Ouro/química , Alquinos/síntese química , Éteres/química , Estrutura Molecular
5.
Talanta ; 205: 120070, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31450480

RESUMO

Pd0-mediated Tsuji-Trost reaction is a practical strategy to design fluorescent probes for carbon monoxide (CO) sensing, and in such reaction CO can reduce Pd2+ to Pd0 in-situ and remove allyl groups on fluorophores. In most of these probes, esters are commonly used to link allyl on fluorophores. We found that the ester groups could be hydrolyzed by esterase activity of fetal bovine serum (FBS), while FBS is a requisite in cell culture, and the hydrolysis could interfere the Pd0-mediated Tsuji-Trost reaction. In this study, we synthesized a fluorescent probe (Cou-CO) using allyl ether as reaction site rather than allyl ester. Cou-CO is non-fluorescence, and could react with CO under the presence of Pd0 to form Cou with strong fluorescence, and the maximum excitation and emission wavelengths of Cou are 464 nm and 495 nm respectively. Cou-CO shows excellent selectivity to CO and could avoid the effect of FBS with the limit of detection for CO is 78 nm. Finally, Cou-CO was successfully applied for imaging of CO in living cells.


Assuntos
Compostos Alílicos/química , Monóxido de Carbono/análise , Ésteres/química , Éteres/química , Corantes Fluorescentes/química , Imagem Molecular/métodos , Compostos Alílicos/síntese química , Compostos Alílicos/toxicidade , Monóxido de Carbono/química , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/toxicidade , Células HeLa , Humanos , Limite de Detecção , Cebolas/química , Sensibilidade e Especificidade , Soroalbumina Bovina/química
6.
Molecules ; 24(13)2019 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-31288408

RESUMO

Demand for the development of novel polymers derived from biomass that can replace petroleum resources has been increasing. In this study, biomass-derived isosorbide was used as a monomer in the polymerization of poly(arylene ether ketone)s, and its synthetic characteristics were investigated. As a phase-transfer catalyst, crown ether has increased the weight-average molecular weight of polymers over 100 kg/mol by improving the reaction efficiency of isosorbide and minimizing the effect of moisture. By controlling the experimental parameters such as halogen monomer, polymerization solvent, time, and temperature, the optimal conditions were found to be fluorine-type monomer, dimethyl sulfoxide, 24 h, and 155 °C, respectively. Biomass contents from isosorbide-based polymers were determined by nuclear magnetic resonance and accelerator mass spectroscopy. The synthesized polymer resulted in a high molecular weight that enabled the preparation of transparent polymer films by the solution casting method despite its weak thermal degradation stability compared to aromatic polysulfone. The melt injection molding process was enabled by the addition of plasticizer. The tensile properties were comparable or superior to those of commercial petrochemical specimens of similar molecular weight. Interestingly, the prepared specimens exhibited a significantly lower coefficient of thermal expansion at high temperatures over 150 °C compared to polysulfone.


Assuntos
Biomassa , Isossorbida/análogos & derivados , Isossorbida/química , Cetonas/química , Plásticos/química , Catálise , Éteres/química , Temperatura Alta , Peso Molecular , Sulfonas/química
7.
Int J Biol Macromol ; 136: 540-546, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31216448

RESUMO

Water-soluble kraft lignin-based polyoxyethylene ether (KL-PEG), synthesized from the black liquor of kraft pulping and PEG, was used to improve the enzymatic hydrolysis efficiency of dilute acid pretreated (DA-pretreated) Eucalyptus hardwood and cellulase stability. The physicochemical properties of KL-PEG polymer such as solubility, surface tension, charge and aggregation behavior in the solution were first studied. KL-PEG could enhance the enzymatic hydrolysis of Avicel and DA-pretreated Eucalyptus from 63.6% and 58.3% to 78.5% and 93.8%, respectively. The enzymatic activity of cellulase after the enzymatic hydrolysis of Avicel and DA-pretreated Eucalyptus for 72 h remained approximately 84% and 44% in the presence of KL-PEG polymer. KL-PEG could improve the stability and longevity of the cellulase, facilitate the recovery and save the amount of cellulase. The efficient utilization of the pulping black liquor lignin was of great significance to alleviate the pressure brought by the shortage of petrochemical resources, and build an energy-saving and low-carbon society.


Assuntos
Biomassa , Celulase/metabolismo , Éteres/química , Lignina/química , Lignina/metabolismo , Polietilenoglicóis/química , Madeira/química , Fenômenos Químicos , Estabilidade Enzimática , Eucalyptus/química , Hidrólise , Hypocrea/enzimologia
8.
Molecules ; 24(12)2019 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-31234296

RESUMO

A cross-coupling reaction of allylic aryl ethers with arylmagnesium reagents was investigated using ß-aminoketonato- and ß-diketiminato-based pincer-type nickel(II) complexes as catalysts. An ß-aminoketonato nickel(II) complex bearing a diphenylphosphino group as a third donor effectively catalyzed the reaction to afford the target cross-coupled products, allylbenzene derivatives, in high yield. The regioselective reaction of a variety of substituted cinnamyl ethers proceeded to give the corresponding linear products. In contrast, α- and γ-alkyl substituted allylic ethers afforded a mixture of the linear and branched products. These results indicated that the coupling reaction proceeded via a π-allyl nickel intermediate.


Assuntos
Catálise , Éteres/química , Magnésio/química , Indicadores e Reagentes/química , Estrutura Molecular , Níquel/química , Estereoisomerismo
9.
Spectrochim Acta A Mol Biomol Spectrosc ; 222: 117239, 2019 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-31202031

RESUMO

A novel fluorescent graft conjugated polymer (poly (2, 5-bis (Polyethylene glycol oxybutyrate)-1, 4-phenylethynylene-alt-1, 4-phenyleneethynylene, PPE-OB-PEG) has been designed and synthesized for the determination of aristolochic acid (AA). The detection conditions and detection characters of PPE-OB-PEG were systematically explored in this work. The fluorescence intensity of PPE-OB-PEG changes with the different concentration of AA. PPE-OB-PEG has a good linear range towards AA from 1.00 × 10-7 to 8.00 × 10-5 mol L-1 and the limit of detection (LOD) is 3.00 × 10-8 mol L-1 (S/N = 3). PPE-OB-PEG have been applied to detect AA in traditional Chinese medicine samples and the results are satisfactory. The experimental results show that PPE-OB-PEG can be used as a fluorescence probe for rapid and sensitive detection of AA.


Assuntos
Alquinos/química , Ácidos Aristolóquicos/análise , Medicamentos de Ervas Chinesas/química , Éteres/química , Corantes Fluorescentes/química , Polietilenoglicóis/química , Espectrometria de Fluorescência/economia , Espectrometria de Fluorescência/métodos , Fatores de Tempo
10.
J Sep Sci ; 42(14): 2418-2425, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31074562

RESUMO

A simple and fast method named microfunnel-filter-based emulsification microextraction is introduced for an efficient determination of some organophosphorus pesticides including diazinon, malathion, and chlorpyrifos in the environmental samples including the river, sea, and well water. This method is based upon the dispersion of a low-toxicity organic solvent (dihexyl ether), as the extractant, in a high volume of an aqueous sample solution (45 mL). It is implemented without a centrifugation step, and using a syringe filter and a micro-funnel, the phase separation and transfer of the enriched analytes to the gas chromatograph are simply achieved. By filtration of the extractant phase, a suitable sample clean-up is obtained, and the total extraction time is just a few minutes. The factors influencing the extraction efficiency are optimized, and under the optimal conditions, the proposed method provides a good linearity (in the range of 15-1500 ng/mL (R2  > 0.996). A high enrichment factor is obtained (in the range of 306-342), and the method provides low limits of detection and quantification (in the ranges of 4-8 and 15-25 ng/mL, respectively).


Assuntos
Éteres/química , Microextração em Fase Líquida , Compostos Organofosforados/análise , Praguicidas/análise , Poluentes Químicos da Água/análise , Cromatografia Gasosa , Emulsões/química , Solventes/química
11.
J Chromatogr A ; 1602: 206-216, 2019 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-31133423

RESUMO

Adsorptive membrane-based chromatography can provide the high separation efficiency common to column chromatography but at a lower working pressure. Herein, a novel membrane chromatography system for lithium isotope adsorptive separation is reported. It uses polysulfone-graft-4'-aminobenzo-15-crown-5-ether (PSf-g-AB15C5) porous membranes (0.52 mmol/g of immobilization crown ether, average pore size of 62.7 nm, porosity of 80.4%) as a stationary phase packed in a chromatography column (Ø 25 × 100 mm). Furthermore, a four-stage tandem membrane chromatography system was designed to enhance lithium isotope separation performance. The partial eluate from the former column was used as the feed solution for the next stage. Results show that the flow rate of the eluent could reach 18 mL/h owing to the lower internal diffusion resistance of membranes. Meanwhile, adsorption isotherms and adsorption kinetics show that Li+ adsorption was an exothermic and spontaneous process. The surface diffusion, multilayer adsorption and ion-pore electrostatic interaction between Li+ and the crown ether groups on the membranes played a key role in the separation of 7Li+ and 6Li+ by membrane chromatography. The separation factor obtained from the single-stage membrane chromatography was up to 1.0232. The abundances of 7Li+ and 6Li+ gradually increased with an increase in the elution stages. The relative abundances of 7Li+ and 6Li+ obtained from the four-stage tandem membrane chromatography increased by 0.26% (from 92.40 to 92.66%) and 0.2% (from 7.60 to 7.80%), respectively. In conclusion, our current research opens a new avenue for the simultaneous enrichment of 7Li+ and 6Li+ during lithium isotope adsorptive separation.


Assuntos
Técnicas de Química Analítica/métodos , Cromatografia , Éteres/química , Isótopos/isolamento & purificação , Lítio/isolamento & purificação , Adsorção , Difusão , Isótopos/química , Cinética , Lítio/química , Membranas Artificiais , Porosidade
12.
Molecules ; 24(9)2019 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-31064088

RESUMO

Flavonoids are well-characterized polyphenolic compounds with pharmacological and therapeutic activities. However, most flavonoids have not been developed into clinical drugs, due to poor bioavailability. Herein, we report a strategy to increase the drugability of flavonoids by constructing C(sp2)-O bonds and stereo- as well as regioselective alkenylation of hydroxyl groups of flavonoids with ethyl-2,3-butadienoate allenes. Twenty-three modified flavonoid derivatives were designed, synthesized, and evaluated for their anti-cancer activities. The results showed that compounds 4b, 4c, 4e, 5e, and 6b exhibited better in vitro inhibitory activity against several cancer cell lines than their precursors. Preliminary structure-activity relationship studies indicated that, in most of the cancer cell lines evaluated, the substitution on position 7 was essential for increasing cytotoxicity. The results of this study might facilitate the preparation or late-stage modification of complex flavonoids as anti-cancer drug candidates.


Assuntos
Antineoplásicos/síntese química , Antineoplásicos/uso terapêutico , Éteres/química , Flavonoides/síntese química , Flavonoides/uso terapêutico , Alcadienos/química , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Desenho de Drogas , Humanos , Estrutura Molecular , Estereoisomerismo , Relação Estrutura-Atividade
13.
J Enzyme Inhib Med Chem ; 34(1): 999-1009, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31072143

RESUMO

This study explored the possible bioactive ingredients and target protein of Rostellularia procumbens (L.) Nees. The results of optical turbidimetry revealed that the ethyl acetate extraction obtained from R. procumbens (L.) Nees could inhibit platelet aggregation. Gene chip was used to investigate differentially expressed genes. According to the results of the gene chip, the targets of compounds isolated from the ethyl acetate extraction were predicted by network pharmacology. Computational studies revealed that chinensinaphthol methyl ether and neojusticin B may target the integrin αIIbß3 protein. The results of Prometheus NT.48 and microscale thermophoresis suggested that the molecular interactions between the two compounds with purified integrin αIIbß3 protein in the optimal test conditions were coherent with the docking results. To our best knowledge, this is the first report to state that chinensinaphthol methyl ether and neojusticin B target the integrin αIIbß3 protein.


Assuntos
Acanthaceae/química , Derivados de Benzeno/farmacologia , Dioxolanos/farmacologia , Éteres/farmacologia , Lignanas/farmacologia , Inibidores da Agregação de Plaquetas/farmacologia , Derivados de Benzeno/química , Derivados de Benzeno/isolamento & purificação , Dioxolanos/química , Dioxolanos/isolamento & purificação , Relação Dose-Resposta a Droga , Éteres/química , Éteres/isolamento & purificação , Humanos , Lignanas/química , Lignanas/isolamento & purificação , Agregação Plaquetária/efeitos dos fármacos , Inibidores da Agregação de Plaquetas/química , Inibidores da Agregação de Plaquetas/isolamento & purificação , Testes de Função Plaquetária , Relação Estrutura-Atividade
14.
Chem Commun (Camb) ; 55(42): 5930-5933, 2019 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-31049491

RESUMO

Fluorescent macromolecules were developed for intracellular labeling in live cells. Coupling rigid rod phenyleneethynylene trimers with flexible amphiphilic diamines via the imine-bond formation chemistry yielded rigid-flexible [2+2] macromolecules showing nucleic acid selectivity and nontoxicity in live cells.


Assuntos
Alquinos/química , Éteres/química , Compostos Macrocíclicos/química , Ácidos Nucleicos/química , Polímeros/química , Células HeLa , Humanos , Espectroscopia de Prótons por Ressonância Magnética
15.
Org Lett ; 21(10): 3610-3614, 2019 05 17.
Artigo em Inglês | MEDLINE | ID: mdl-31033299

RESUMO

An expedient synthesis of tetrahydroindoles and tetrahydrocyclopenta[ b]pyrroles, highlighted by Brønsted acid catalyzed formal [2 + 2 + 1] annulation reaction, is reported. Using three readily accessible reaction components, i.e., an electrophilic species in silyloxyallyl cations and two distinct nucleophiles in silylenol ethers and amines, our chemistry enables the assembly and functionalization of these biologically important N-heterocycles in a highly modular manner.


Assuntos
Aminas/química , Éteres/química , Indóis/síntese química , Pirróis/síntese química , Catálise , Indóis/química , Estrutura Molecular , Pirróis/química
16.
Chem Pharm Bull (Tokyo) ; 67(6): 587-593, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-30944268

RESUMO

Formylations of fluorine-containing aromatic compounds with dichloromethyl alkyl ethers have been investigated. Dichloromethyl propyl ether and dichloromethyl butyl ether have been applied for the formylation of fluorine-containing anisoles to give the corresponding aldehydes in good yields. Application of these ethers is preferable to that of methyl ether, which is prepared from volatile methyl formate. Reaction of fluorine-containing phenols with these dichloromethyl alkyl ethers did not give salicylaldehyde derivatives, leading instead to corresponding aryl formates in high yields. A plausible mechanism is discussed.


Assuntos
Éter Bisclorometílico/química , Flúor/química , Aldeídos/química , Derivados de Benzeno/química , Éteres/química , Ácidos de Lewis/química
17.
Soft Matter ; 15(13): 2884-2896, 2019 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-30849134

RESUMO

Copper has a strong bactericidal effect against multi-drug resistant pathogens and polyethers are known for their resistance to biofilm formation. Herein, we combined Cu nanoparticles (NPs) and a polyether plasma polymer in the form of nanocomposite thin films and studied whether both effects can be coupled. Cu NPs were produced by magnetron sputtering via the aggregation in a cool buffer gas whereas polyether layers were synthesized by Plasma-Assisted Vapor Phase Deposition with poly(ethylene oxide) (PEO) used as a precursor. In situ specific heat spectroscopy and XPS analysis revealed the formation of a modified polymer layer around the NPs which propagates on the scale of a few nanometers from the Cu NP/polymer interface and then transforms into a bulk polymer phase. The chemical composition of the modified layer is found to be ether-deficient due to the catalytic influence of copper whereas the bulk polymer phase exhibits the chemical composition close to the original PEO. Two cooperative glass transition phenomena are revealed that belong to the modified polymer layer and the bulk phase. The former is characterized by constrained mobility of polymer segments which manifests itself via a 30 K increase of dynamic glass transition temperature. Furthermore, the modified layer is characterized by the heterogeneous structure which results in higher fragility of this layer as compared to the bulk phase. The Cu NPs/polyether thin films exhibit reduced protein adsorption; however, the constrained segmental dynamics leads to the deterioration of the non-fouling properties for ultra-thin polyether coatings. The films are found to have a bactericidal effect against multi-drug resistant Gram-positive Methicillin-Resistant Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa.


Assuntos
Antibacterianos/química , Cobre/química , Éteres/química , Nanopartículas Metálicas/química , Polímeros/química , Adsorção , Antibacterianos/administração & dosagem , Cobre/administração & dosagem , Éteres/administração & dosagem , Nanopartículas Metálicas/administração & dosagem , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Nanocompostos/administração & dosagem , Nanocompostos/química , Polímeros/administração & dosagem , Pseudomonas aeruginosa/efeitos dos fármacos , Soroalbumina Bovina/química
18.
Chemosphere ; 226: 132-139, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30925405

RESUMO

Hydroxylated bromodiphenyl ethers (OH-BDEs) can arise from monooxygenation of anthropogenic BDEs or through natural biosynthetic processes in marine organisms, and several OH-BDEs have been shown to be toxic. OH-BDEs are expected to form sulfate and glucuronide conjugates that are readily excreted, however there is little information on these pathways. We examined the human hepatic glucuronidation and sulfonation of 6-OH-BDE47, 2-OH-BDE68, 4-OH-BDE68 and 2-OH-6'methoxy-BDE68. Human liver microsomes and cytosol were from de-identified female and male donors aged 31 to 75 under an exempt protocol. Recombinant human SULT1A1, 1B1, 1E1 and 2A1 enzymes were prepared from bacterial expression systems. Sulfonation and glucuronidation of each OH-BDE were studied using radiolabeled co-substrates, 3'phosphoadenosine-5'phospho-35S-sulfate or uridine diphospho-ß-D-14C-glucuronic acid in order to quantify the sulfated or glucuronidated products. The OH-BDEs studied were more efficiently glucuronidated than sulfonated. Of the compounds studied, 2-OH-BDE68 was the most readily conjugated, and exhibited an efficiency (Vmax/KM) of glucuronidation of 0.274 ±â€¯0.125 mL/min/mg protein, mean ±â€¯S.D., n = 3, while that for sulfonation was 0.179 ±â€¯0.030 mL/min/mg protein. For both pathways, all Km values were in the low µM range. Studies with human SULT enzymes showed that sulfonation of these four substrates was readily catalyzed by SULT1B1 and SULT1E1. Much lower activity was found with SULT1A1 and SULT2A1. Assuming that the glucuronide and sulfate conjugates are non-toxic and readily excreted, as is the case for most such conjugates, these studies suggest that OH-BDEs should not accumulate in people to the same extent as the parent BDEs.


Assuntos
Éteres/química , Glucuronídeos/química , Fígado/metabolismo , Bifenil Polibromatos/química , Sulfatos/química , Adulto , Idoso , Citosol/química , Feminino , Humanos , Hidroxilação , Fígado/ultraestrutura , Masculino , Microssomos Hepáticos/metabolismo , Pessoa de Meia-Idade
19.
ChemSusChem ; 12(13): 3152-3158, 2019 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-30848531

RESUMO

Tertiary allylic alcohols were conveniently converted into either (Z)- or (E)-configured α,ß-unsaturated γ-amino acids by treatment with secondary amines under Pd catalysis at ambient conditions. The key to control the stereochemical course of these formal allylic aminations was the presence of a suitable diphosphine ligand, with dppp [1,3-bis(diphenylphosphino)propane, L12] providing high yields and selectivities for the (Z) isomers, whereas the bis[(2-diphenylphosphino)phenyl]ether (DPEPhos) derivative L1' allowed for selective formation of the corresponding (E) isomeric products. This ligand-controlled, stereodivergent protocol thus shows promise for the stereoselective preparation of allylic amine products from a common substrate precursor.


Assuntos
Aminoácidos/química , Paládio/química , Propanóis/química , Aminação , Catálise , Éteres/química , Ligantes , Fosfinas/química , Estereoisomerismo
20.
Methods Mol Biol ; 1954: 25-35, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30864121

RESUMO

Capsular polysaccharides are a dominant class of antigens from bacteria, both pathogenic and symbiotic or commensal. With the rise of awareness for the influence of the microbiota over immune system development and immune homeostasis, analysis of the antigens is more important than ever. Here we describe a method for the isolation of capsular polysaccharide from gram-negative bacteria, with the purification of polysaccharide from the commensal bacterium Bacteroides fragilis serving as an example. The method efficiently removes all detectable endotoxins and other lipid components, proteins, and nucleic acids, providing a source of capsular polysaccharide for immunologic study.


Assuntos
Cápsulas Bacterianas/química , Bacteroides fragilis/química , Fracionamento Químico/instrumentação , Polissacarídeos Bacterianos/isolamento & purificação , Infecções por Bacteroides/microbiologia , Fracionamento Químico/métodos , Precipitação Química , Cromatografia/métodos , Eletroforese em Gel de Poliacrilamida/métodos , Desenho de Equipamento , Éteres/química , Humanos , Fenóis/química , Polissacarídeos Bacterianos/química
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