PDF superior Halogenation of pyridinium N (2' pyridyl)aminide: an easy synthesis of halo 2 aminopyridines

Halogenation of pyridinium N (2' pyridyl)aminide: an easy synthesis of halo 2 aminopyridines

Halogenation of pyridinium N (2' pyridyl)aminide: an easy synthesis of halo 2 aminopyridines

Method A: To a solution of Pyridinium N-2’-pyridylaminide 1 1 mmol in dichloromethane 5 mL stirred at -20°C a solution of the corresponding NXS 1 mmol in the same solvent 10 mL was added[r]

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Pyridinium N 2´ pyridylaminide: synthesis of 3 aryl 2 aminopyridines through an intramolecular radical process

Pyridinium N 2´ pyridylaminide: synthesis of 3 aryl 2 aminopyridines through an intramolecular radical process

interested in the chemistry of pyridinium N-2 0 -pyridylami- nide, 1a (Scheme 1), a stable heterocyclic betaine, that has a p-deficient pyridinium fragment attached to a p-excessive 2-iminopyridine moiety. This compound has proven to be a versatile scaffold in a wide range of transformations. Thus, for example, the preparation of 3-or 3,5-halogenated 2-alkyl aminopyridines from 1a can be carried out by an easy and selective halogenation at the iminopyridine moiety (for supply, for example 1b, Scheme 1), followed by regio- selective N-alkylation at the aminide nitrogen and final reduction of NN bond. 3
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Pyridinium N (2' azinyl)aminides: Regioselective synthesis of 2 alkylaminoazines

Pyridinium N (2' azinyl)aminides: Regioselective synthesis of 2 alkylaminoazines

regioselective. 7,8 The metalation, however, might not be quantitative. As an alternative, activation of the exocyclic amino group facilitates deprotonation, and regioselective alkylation. Thus, N-acyl-aminopyridines 6 have been deprotonated with sodium amide and alkylated with methyl iodide, 9,10 yielding the 2-methylaminopyridines by hydroly- sis. With other alkyl halides, obtained yields were lower. A similar procedure has been described using alcohols in the Mitsunobu reaction. 11 Alternative methods have been reported based on the easy reduction of aromatic aldimines, using heterocyclic fragments as leaving groups. Two-step
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An easy preparation of pyridinium N heteroarylaminides

An easy preparation of pyridinium N heteroarylaminides

The synthesis of N-aminide intermediates 5 has been traditionally performed by attack of the corresponding 2-heteroaryl hydrazine 2 to 2,4-dinitrophenyl pyridinium chloride 1 (see Scheme 1) generating the hydrazone 3, which is again closed to a pyridinium derivative by acid catalysis, to produce the salt 4 and from there, by treatment with base, the N-aminides were obtained. This method, adapted from the scheme described by Beyer 11 is suitable

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Synthesis and characterization of nanowires and micromotors for electrochemical sensing and biosensing in microfluidic analytical systems

Synthesis and characterization of nanowires and micromotors for electrochemical sensing and biosensing in microfluidic analytical systems

When the potential of the NWs is combined with the selectivity and sensitivity of biomolecules, the power of these hybrid structures becomes enhanced. These biosensors are increasing their relevance in the last years and different MNWs have been employed as immobilization surface for biomolecules. Conceptually speaking, and as we have already stated in the introduction, in biosensing, NWs present not only all the electronic advantages previously mentioned, moreover they permit an oriented functionalization of its surface. Biological systems can be very complex and sometimes, to work properly, they need several biomolecules in intimate proximity. As NWs can be made with fragments of different metals, a differentiated and oriented biofunctionalization of the NWs can be performed, developing a selective functionalization strategy for each NW’s metal-fragment. This characteristic permits to co-immobilizate on the same NWs different biomolecules, mimicking nature’s pattern. Not only MNWs are applied in biosensing. PPy is a conducting polymer with excellent characteristics for biosensing due to its high conductivity and electrochemical activity; moreover PPy shows biocompatibility being a perfect candidate for developing this kind of biosensors.
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KNbO3 as Photocatalyst for Hydrogen Production

KNbO3 as Photocatalyst for Hydrogen Production

KN nanometric powders were obtained using different synthesis methods, which showed values of bandgap energies within the spectrum of visible light and showed photocatalytic properties for the dissociation of the water molecule. The KN-3 synthesized material showed the highest hydrogen production, compared to the KN-c (commercial) and synthesized KN-1 and KN-2 samples. Based on the results obtained in this study the photocatalytic decomposition of water may be a promising alternative for the production of hydrogen using as niobates materials as water splitting photocatalysts.
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Strategies to Fabricate Polypeptide Based Structures via Ring Opening Polymerization of N Carboxyanhydrides

Strategies to Fabricate Polypeptide Based Structures via Ring Opening Polymerization of N Carboxyanhydrides

Figure 2. The mechanism proposed for the “Fuchs-Farthing” method [22–24]. (A) N-carboxyanhydrides (NCAs) formation by reaction with phosgene and (B) Formation of NCA and acidic decomposition. The purification process for the NCA monomers involves washing NCA solutions with water or aqueous sodium bicarbonate at 0 °C in order to remove residual HCl. Subsequently, the monomer is rapidly dried [28]. While, this methodology is still widely employed, further improvements have been later reported. For instance, hydrochloride scavengers like pinene and limonene were proved effective in preventing by-product formation. This methodology reported by Smeets et al. was demonstrated to be particularly well adapted for the synthesis of L -leucine NCA (Leu-NCA) [29]. A more recent improvement in the purification process was reported recently by Deming et al. [30]. They used a rapid and general method i.e., flash column chromatography. This technique was effective at removing all common impurities from NCAs and was found to work for a variety of NCAs, including those synthesized using different routes as well as those bearing either hydrophilic or hydrophobic side chains (especially interesting for those that cannot be recrystallized).
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N (pyridylmethyl)azinium salts: precursors of pyridyl stabilized azinium N ylides

N (pyridylmethyl)azinium salts: precursors of pyridyl stabilized azinium N ylides

was added and the mixture was stirred at room temperature, The aqueous layer was extracted with dichloromethane over Na$O,.. The combined organic extracts were dried.[r]

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Novel fast random search clustering approach for mixing matrix identification in MIMO linear blind inverse problems with sparse inputs

Novel fast random search clustering approach for mixing matrix identification in MIMO linear blind inverse problems with sparse inputs

Therefore, even though many clustering algorithms have been proposed for the estimation of the mixing matrix for sparse inputs, there is still a need for simple, effective and robust techniques that can deal with a potentially large number of outputs. In particular, clustering in the angular domain, where noise may be reduced due to the compressive nature of the arctan function required for angle calculation, has not been fully exploited yet. Most of the angular clustering techniques proposed so far [9-11] focus on the two outputs case, and cannot be easily extended to a higher number of outputs. The only angular clustering approach theoretically valid for an arbitrary number of outputs is the one proposed in [21], which is based on hyperspherical coordinates and one-dimensional projections of the higher dimensional angular vector. Unfortunately, the expo- nential increase in complexity with the dimension of the problem limits its applicability to a reduced number of inputs and outputs (e.g. three outputs and four inputs [21]).
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An extension of best $L^2$ local approximation

An extension of best $L^2$ local approximation

The problem of best local approximation was formally introduced and studied in a paper by Chui, Shisha and Smith [2]. However, the initiation of this could be dated back to results of J. L. Walsh [7], who proved that the Taylor polynomial of an analytic function f over a domain is the limit of the net of best polynomial approximations of a given degree, by shrinking the domain to a single point. In [6] this problem was considered when f is L 2 differentiable of order q −1 at x

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Análisis estadísticos de superestructuras en el Universo /

Análisis estadísticos de superestructuras en el Universo /

errores en la masa. Esto se entiende f´acilmente en t´erminos de la forma exponencial de la funci´on de masa para halos de esas masas. Hay muchos m´as halos de baja masa que de alta masa. Por consiguiente, al aplicar una perturbaci´on en la masa del halo correspondiente a una distribuci´on sim´etrica de error, hay una transferencia de halos desde los bines con masas m´as bajas hacia los bines con masas m´as altas. Este efecto es acrecentado por la peque˜na sobres- tima sistem´atica en la masa del halo debida al algoritmo del 2PIGG. Las funciones de masa anal´ıticas, representadas por las curvas de colores tal como indica cada gr´afico, est´an en buen acuerdo con la funci´on de masa sin perturbar, excepto para el caso de la teor´ıa de Press & Schechter, la cual predice muy pocos halos masivos. Esta discrepancia ya se not´o en trabajos previos (ver por ejemplo, Efstathiou et al. 1988). Finalmente, notamos que hay una reduc- ci´on importante en la abundancia de halos de una dada masa en la cosmolog´ıa L-BASICC II, con respecto a la cosmolog´ıa L-BASICC, como puede verse claramente comparando los resultados de las simulaciones con los modelos anal´ıticos en la Figura 5.2, los cuales son las mismas en cada panel.
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Future virialized structures: an analysis of superstructures in the SDSS DR7

Future virialized structures: an analysis of superstructures in the SDSS DR7

also allowed them to compare superclusters derived from different samples of clusters. They find that both types of clusters generate superstructures that represent the large-scale structure in a similar way. Also, they find that X-ray clusters not belonging to superclus- ters surround the Southern and Northern Local supervoids or are located in filaments between superclusters. Although the authors find a strong signal indicating that the fraction of X-ray clusters in superclusters increases with supercluster richness, there is no correlation between the X-ray luminosity of clusters and their host supercluster richness, quantified as the number of member clusters. Einasto et al. (2007b) return to the problem of defining the largest isolated structures in the universe and use data from the 2dFGRS (Colless et al. 2001) to assemble a catalogue of superclusters. The authors find that the most effective method to perform a superclus- ter search is the density field method which consists in obtaining a smoothed luminosity density field in redshift space from the galaxy catalogue. The luminosity, on large scales, is supposed to follow the distribution of matter, provided that a convenient smoothing kernel is used. In their work, Einasto et al. (2007b) use an Epanechnikov kernel and assert that the best results in the identification method are obtained when a kernel size of 8 h − 1 Mpc is used. Einasto et al.
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Nucleoside 2'-Deoxyribosyltransferase from psychrophilic bacterium bacillus psychrosaccharolyticus - Preparation of an immobilized biocatalyst for the enzymatic synthesis of therapeutic nucleosides

Nucleoside 2'-Deoxyribosyltransferase from psychrophilic bacterium bacillus psychrosaccharolyticus - Preparation of an immobilized biocatalyst for the enzymatic synthesis of therapeutic nucleosides

The optimization of an enzyme-catalyzed synthesis of nucleoside analogs usually includes the evaluation of enzyme stability in non-physiological condition. In particular, the presence of water-miscible organic co-solvents has been evaluated, since solubility of halogenated bases and their 2'-deoxyribonucleosides counterparts can be improved in such conditions [35]. Therefore, stability of free and immobilized BpNDT was studied in the presence of dimethylformamide (DMF), which is one of the most commonly used solvents for nucleoside synthesis. As depicted in Figure 3, residual activity of the free enzyme was maintained for at least 48 h in presence of 20% DMF, whereas the derivative obtained by adsorption on PEI coated carrier was completely unstable, losing almost all the activity after only 2 h. This detrimental effect, which may be related to a change in enzyme microenvironment exerted by the PEI, is progressively attenuated by increasing the oxidation degree of the aldehyde-dextran used in the post immobilization cross-linking process. In particular, the best stability was obtained using dextrane oxidized at 70% as probable consequence of a stabilization of the 3D structure of the enzyme. This immobilized biocatalyst, hereafter abbreviated as PA9BpNDT, was selected for further characterization and application in the synthesis of trifluridine.
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Stomach content analyses of the threadfin anglerfish Lophiodes spilurus (Lophiiformes:
 Lophiidae) associated with deepwater shrimp fisheries from the central Pacific of Costa Rica

Stomach content analyses of the threadfin anglerfish Lophiodes spilurus (Lophiiformes: Lophiidae) associated with deepwater shrimp fisheries from the central Pacific of Costa Rica

Stomach contents of deepwater fishes along the tropical Eastern Pacific have been poorly studied. The present study revealed that the diet composition of L. spilurus includes a high diversity of food items, but that this diver- sity of prey was restricted to just two major taxa, teleost fish and crustaceans. Although we found evidence of an ontogenetic diet shift between small-intermediate and large-size L. spilurus, due to the low number of individuals with full stomachs and unequal sample sizes among size-classes, any conclusion should be made with caution. A more detailed study of the diet, as well as further research into other aspects of the ecology and feeding behavior can provide more information of this benthic predator and its role in the trophic dynamic of deepwater ecosystems.
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Synthesis and anti-inflammatory activity of 2-{[3-(trifluoromethyl) phenyl] amino} N, N'-bis (aryl) pyridine-3-carboximidamide

Synthesis and anti-inflammatory activity of 2-{[3-(trifluoromethyl) phenyl] amino} N, N'-bis (aryl) pyridine-3-carboximidamide

SUMMARY. A novel compounds of 2-{[3-(trifluoromethyl) phenyl] amino} N, N’-bis (aryl) pyridine-3-carbox- imidamide ( PJS1-PJS6 ) were synthesized by condensation of niflumic acid with aromatic amines using most re- active Lewis reagent: polyphosphoric acid trimethyl silyl ester (PPSE). These compounds were characterized by IR, 1 H-NMR, HRMS-FAB and elemental analysis and evaluated for anti-inflammatory activity using car-

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2. SYNTHESIS OF THE ANTI-CANCER CARBOPLATIN OXIDIZED, AND
      STUDY OF ITS INTERACTIONS WITH N-BASES BY CYCLIC
    VOLTAMMETRY.

2. SYNTHESIS OF THE ANTI-CANCER CARBOPLATIN OXIDIZED, AND STUDY OF ITS INTERACTIONS WITH N-BASES BY CYCLIC VOLTAMMETRY.

CBDCAOX libre. Estos cambios muy significativos indican la formación del aducto CBDCAOX-timina estable. En esta interacción la transferencia de electrones ocurrió en una mezcla homogénea entre el CBDCAOX y timina. La interacción de CBDCAOX con adenina muestra un cambio en potencial de 14 mV y en corriente de 0,6 µA, los cuales indican que existe una interacción muy débil, [1, 2, 10]. La interacción con citosina no muestra un cambio en potencial y en corriente de 2,2 µA, y con guanina un cambio en potencial de 0,3 mV y en corriente de 0,2 µA estos resultados indican que no hubo interacción con estas bases. El porcentaje de interacción en potencial confirma que la interacción de CBDCAOX con timina fue de 37,6%, con guanina 0,05%, con citosina 0,0% y con adenina 2,2%. Estos resultados indican que el fármaco sintetizado tiene mayor afinidad solamente por timina. Para medir la magnitud de la interacción entre el CBDCAOX y BASES se consideraron la forma y el desplazamiento de las señales de reducción de los aductos [1, 2, 10, 11].
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Quantification of Nitrous Oxide Emissions in soils of Chihuahua Mexico

Quantification of Nitrous Oxide Emissions in soils of Chihuahua Mexico

horizons to that of from 0 to 15 cm in all soil classifications, both sand and clay. In the deeper soil horizons, from 0 to 1 m, concentration values of nitrous oxide were almost imperceptible. Nitrous oxide concentrations differed significantly (p<0.05) between Horizons 1 and 2. Multiple regression analysis revealed that N 2 O concentration increases with temperature and

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4. SYNTHESIS OF THE NEW 4’-
      HYDROXY-3’-(3-METHYL-2-
      BUTENYL)CHALCONE
      BY MICROWAVE-ASSISTED
      CONDENSATION OF 4-HYDROXY-3-
      (3’-METHYL-2’-BUTENYL)
      ACETOPHENONE ISOLATED FROM
      SENECIO GRAVEOLENS AND
    BENZALDE

4. SYNTHESIS OF THE NEW 4’- HYDROXY-3’-(3-METHYL-2- BUTENYL)CHALCONE BY MICROWAVE-ASSISTED CONDENSATION OF 4-HYDROXY-3- (3’-METHYL-2’-BUTENYL) ACETOPHENONE ISOLATED FROM SENECIO GRAVEOLENS AND BENZALDEHYDE

ABSTRACT In this article we report the synthesis of a new chalcone, 4’-hydroxy-3’-3-methyl-2-butenylchalcone 2, from the organic condensation assisted by microwave irradiation of benzald[r]

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Regioselective formation of
[2 (η5 cyclopentadienyl) 2 fluorenylpropane] titanium complexes:
precursors, synthesis, structure and reactivity

Regioselective formation of [2 (η5 cyclopentadienyl) 2 fluorenylpropane] titanium complexes: precursors, synthesis, structure and reactivity

[25]. All non-hydrogen atoms were refined anisotropi- cally and the hydrogen atoms were positioned geomet- rically and refined by using a riding model. Crystallographic data (excluding structure factors) for the structure reported in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication no. CCDC-100428. Copies of the data can be obtained free of charge on applica- tion to The Director, CCDC, 12 Union Road, Cam- bridge CB2 1EZ (UK), (Fax: +44 1223 336033; e-mail: deposit@chemcrys.cam.ac.uk).

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Suzuki reaction on pyridinium N haloheteroarylaminides: regioselective synthesis of 3,5 disubstituted 2 aminopyrazines

Suzuki reaction on pyridinium N haloheteroarylaminides: regioselective synthesis of 3,5 disubstituted 2 aminopyrazines

In both cases, the course of the reaction was followed by TLC, HPLC and/or 1 H NMR spectroscopy. Once the starting material had been consumed, the system was allowed to reach room temperature, the mixture was filtered through Celite or silica gel and washed with acetonitrile until colour was no lon- ger observed in the filtrate. The combined filtrates were eva- porated to dryness. The crude product was purified by flash chromatography on a silica gel column, with ethanol as the mobile phase, and recrystallized from a suitable solvent. Com- pound 3l was isolated as a yellow oil, while compounds 3a, 3c, 3g, 4c, 4e and 5ae5e were transformed into the corresponding hydrobromides before purification.
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