- Stable and rigid DTPA-like paramagnetic tags suitable for in vitro and in situ protein NMR analysis
-
Organic synthesis of a ligand with high binding affinities for paramagnetic lanthanide ions is an effective way of generating paramagnetic effects on proteins. These paramagnetic effects manifested in high-resolution NMR spectroscopy are valuable dynamic and structural restraints of proteins and protein–ligand complexes. A paramagnetic tag generally contains a metal chelating moiety and a reactive group for protein modification. Herein we report two new DTPA-like tags, 4PS-PyDTTA and 4PS-6M-PyDTTA that can be site-specifically attached to a protein with a stable thioether bond. Both protein-tag adducts form stable lanthanide complexes, of which the binding affinities and paramagnetic tensors are tunable with respect to the 6-methyl group in pyridine. Paramagnetic relaxation enhancement (PRE) effects of Gd(III) complex on protein-tag adducts were evaluated in comparison with pseudocontact shift (PCS), and the results indicated that both 4PS-PyDTTA and 4PS-6M-PyDTTA tags are rigid and present high-quality PREs that are crucially important in elucidation of the dynamics and interactions of proteins and protein-ligand complexes. We also show that these two tags are suitable for in-situ protein NMR analysis.
- Chen, Jia-Liang,Zhao, Yu,Gong, Yan-Jun,Pan, Bin-Bin,Wang, Xiao,Su, Xun-Cheng
-
-
Read Online
- Novel nevirapine-like inhibitors with improved activity against NNRTI-resistant HIV: 8-Heteroarylthiomethyldipyridodiazepinone derivatives
-
A series of 8-heteroarylthiomethyldipyridodiazepinone derivatives were prepared and evaluated for their antiviral profile against wild type virus and the important K103N/Y181C mutant as an indicator for broad activity. 2,6-Dimethylpyridine derivative 16 was found to have a good pharmacokinetic profile in spite of poor metabolic stability in rat liver microsomes.
- Yoakim,Bonneau,Deziel,Doyon,Duan,Guse,Landry,Malenfant,Naud,Ogilvie,O'Meara,Plante,Simoneau,Thavonekham,Boes,Cordingley
-
-
Read Online
- Electronic influence of substitution on the pyridine ring within NNN pincer-type molecules
-
Pincer molecules are of increasing interest due to the modular nature of modification and range of reactivity observed when coordinated to metal ions. A subset within the family of pincer molecules use a pyridine group to bridge the outer two arms as well as provide a N-donor atom for metal binding. While the arm appendages have been studied extensively, little research has been conducted on the electronic effects of the central, substituted pyridine systems. Therefore, a series of NNN pincer-type ligands with substitution on the 4-position of the pyridine ring with -OH, -OBn, -H, -Cl, and -NO2 functional groups were synthesized and characterized through NMR spectroscopy and ESI-HRMS. Each pincer was metalated with Cu(ii) salts and evaluated through X-ray diffraction analysis, cyclic voltammetry, and density functional theory analysis. The results indicate that the relatively unstudied -OBn group demonstrates both electron-withdrawing (XRD bond lengths) and electron-donating (NMR spectroscopy) properties. The -NO2 pincer ligand shows a redox event within experimental windows evaluated, in contrast to the other congeners studied. In addition, electron-donating groups increase the electron density around the Cu(ii) center based on DFT studies and cyclic voltammetry. These findings can be applied to other pyridine-based pincer systems when considering ligand design and warrants future characterization of 4-position substituted pyridines.
- Burnett, Marianne E.,Green, Kayla N.,Schwartz, Timothy M.
-
-
Read Online
- N-oxidation of 2-substituted pyridines and quinolines by dimethyldioxirane: Kinetics and steric effects
-
The oxidation of 2-substituted pyridines and selected N-containing aromatic heterocycles by dimethyldioxirane (1) produced the corresponding N-oxides as the sole products, quantitatively in most cases. The second order rate constants for N-oxidation by 1 in dried acetone at 23°C were determined for a series of 2-substituted pyridines 2-10, quinolines 11-14 and isoquinolines 15,16. An excellent correlation of log k2 with Taft (σ*) constants was obtained for 2-substituted pyridines (R = Me, Et, Prn, Pr i, 3-pentyl) with the exception of the data for 2-f-butylpyridine. The results for the substituted quinolines and isoquinolines followed the same trends observed with the pyridines. Steric effects due to 2-substitution and periinteractions can substantially reduce reactivity. The results provide insights into the geometrical requirements for N-oxidation by dimethyldioxirane.
- Winkeljohn, W. Rucks,Leggett-Robinson, Pamela,Peets, Monique R.,Strekowski, Lucjan,Vasquez, Pedro C.,Baumstark
-
-
Read Online
- Kinetic assay of the michael addition-like thiol-ene reaction and insight into protein bioconjugation
-
The chemical modification of proteins is a valuable technique in understanding the functions, interactions, and dynamics of proteins. Reactivity and selectivity are key issues in current chemical modification of proteins. The Michael addition-like thiol-ene reaction is a useful tool that can be used to tag proteins with high selectivity for the solvent-exposed thiol groups of proteins. To obtain insight into the bioconjugation of proteins with this method, a kinetic analysis was performed. New vinyl-substituted pyridine derivatives were designed and synthesized. The reactivity of these vinyl tags with L-cysteine was evaluated by UV absorption and high-resolution NMR spectroscopy. The results show that protonation of pyridine plays a key role in the overall reaction rates. The kinetic parameters were assessed in protein modification. The different reactivities of these vinyl tags with solvent-exposed cysteine is valuable information in the selective labeling of proteins with multiple functional groups. Tag! You're it! The Michael addition-like thiol-ene reaction between a pyridine-substituted vinyl group and the thiol of L-cysteine is evaluated by kinetic assay. Diverse reaction rates between different vinyl tags and free thiols are assessed, and the determined reactivity offers valuable information on protein bioconjugation.
- Ma, Fei-He,Chen, Jia-Liang,Li, Qing-Feng,Zuo, Hui-Hui,Huang, Feng,Su, Xun-Cheng
-
-
Read Online
- Single-armed phenylsulfonated pyridine derivative of DOTA is rigid and stable paramagnetic tag in protein analysis
-
Single-armed DOTA-like phenylsulfonated pyridine derivatives are rigid and stable paramagnetic tags for site-specific labeling of proteins. Their reactions with a solvent-exposed protein thiol group generate a stable C-S bond and produce one single paramagnetic species in solution NMR. The generated large paramagnetic effects yield valuable long-range structural restraints for proteins.
- Yang, Feng,Wang, Xiao,Pan, Bin-Bin,Su, Xun-Cheng
-
-
Read Online
- The oxidation of pyridines catalyzed by surfactant-encapsulated polyoxometalate [(C18H37)2(CH3) 2N]8[HBW11O39] with the temperature-responsive property of solubility
-
Temperature-responsive characterization of solubility based on a surfactant-encapsulated polyoxometalate ([(C18H37) 2(CH3)2N]8[HBW11O 39]) in tert-butyl alcohol was described and used in catalytic oxidation of pyridines. The catalyst could be recovered and reused several times by controlling the temperature.
- Zhao, Wei,Yang, Chunxia,Ding, Yong,Ma, Baochun
-
-
Read Online
- Effect of intermolecular = C-H···O interaction on the crystal structure and vibrational properties of 2,6-dimethyl-4-nitropyridine N-oxide
-
The crystal structure of 2,6-dimethyl-4-nitropyridine N-oxide (DMNPO) has been determined at ambient temperature. The compound crystallizes as a monoclinic structure, space group P2/n, with 12 molecules per unit cell. The unit cell contains three non-equivalent formula units. The nitro group is not coplanar with the pyridine ring. Through a system of =C-H···O hydrogen bonds the molecules are arranged into a two-dimensional network of layers parallel to the axc plane. The IR and Raman spectra, measured in the 3500-100 cm-1 region at ambient temperature, are correlated with X-ray structural data. The assignment of IR and Raman bands is given. The appearance of characteristic vibrational features in the spectra of this compound and the observed shifts of the =C-H and N-O IR active stretching modes, when the sample is dissolved in CCl4, is discussed in terms of the relatively strong =C-H···O hydrogen bonds present in this crystal.
- Hanuza,MacZka,Waskowska,Oganowski,Ban-Oganowska,Lutz,Van Der Maas
-
-
Read Online
- Method for preparing sulfone and N-oxygen compound by using green and efficient oxidation system
-
The invention discloses a method for preparing sulfone and N-oxygen compound by using a green and efficient oxidation system. The method comprises the following steps of: by using a tertiary amine compound or aromatic thioether or fatty thioether compound as a raw material, H2O2 as an oxidant, methanol as a reaction solvent and potassium carbonate as an alkali, introducing sulfuryl fluoride 5O2F2gas as an accelerator; performing stirring at room temperature under a sealed condition for oxidation reaction; and after finishing the reaction, filtering to remove solid potassium carbonate, dryingto remove water, filtering to obtain a crude product, and finally carrying out column chromatography separation to obtain a pure product. Tertiary amine is oxidized into an N-oxygen compound, and thethioether is oxidized into sulfone. According to the method, the sulfuryl fluoride (SO2F2) which is very cheap and easy to obtain is used as the reaction promoter, green and environment-friendly hydrogen peroxide (H2O2) is used as an oxidizing agent, and so that the yield of the reaction is generally high; after the reaction, byproducts are only water and inorganic salts (SO4 and F) whichare easy to remove and free of pollution, and the green and efficient oxidation system can be realized, and therefore, the method is suitable for large-scale industrial production.
- -
-
Paragraph 0045-0047
(2021/01/29)
-
- SO2F2-mediated oxidation of primary and tertiary amines with 30% aqueous H2O2 solution
-
A highly efficient and selective oxidation of primary and tertiary amines employing SO2F2/H2O2/base system was described. Anilines were converted to the corresponding azoxybenzenes, while primary benzylamines were transformed into nitriles and secondary benzylamines were rearranged to amides. For tertiary amine substrates quinolines, isoquinolines and pyridines, their oxidation products were the corresponding N-oxides. The reaction conditions are very mild and just involve SO2F2, amines, 30% aqueous H2O2 solution, and inorganic base at room temperature. One unique advantage is that this oxidation system is just composed of inexpensive inorganic compounds without the use of any metal and organic compounds.
- Liao, Xudong,Zhou, Yi,Ai, Chengmei,Ye, Cuijiao,Chen, Guanghui,Yan, Zhaohua,Lin, Sen
-
supporting information
(2021/11/01)
-
- From Pyridine- N-oxides to 2-Functionalized Pyridines through Pyridyl Phosphonium Salts: An Umpolung Strategy
-
The reactions of pyridine-N-oxides with Ph3P under the developed conditions provide an unprecedented route to (pyridine-2-yl)phosphonium salts. Upon activation with DABCO, these salts readily serve as functionalized 2-pyridyl nucleophile equivalents. This umpolung strategy allows for the selective C2 functionalization of the pyridine ring with electrophiles, avoiding the generation and use of unstable organometallic reagents. The protocol operates at ambient temperature and tolerates sensitive functional groups, enabling the synthesis of otherwise challenging compounds.
- Bugaenko, Dmitry I.,Yurovskaya, Marina A.,Karchava, Alexander V.
-
supporting information
p. 6099 - 6104
(2021/08/03)
-
- Methyl Scanning and Revised Binding Mode of 2-Pralidoxime, an Antidote for Nerve Agent Poisoning
-
Organophosphorus nerve agents (OPNAs) inhibit acetylcholinesterase (AChE) and, despite the Chemical Weapons Convention arms control treaty, continue to represent a threat to both military personnel and civilians. 2-Pralidoxime (2-PAM) is currently the only therapeutic countermeasure approved by the United States Food and Drug Administration for treating OPNA poisoning. However, 2-PAM is not centrally active due to its hydrophilicity and resulting poor blood-brain barrier permeability; hence, these deficiencies warrant the development of more hydrophobic analogs. Specifically, gaps exist in previously published structure activity relationship (SAR) studies for 2-PAM, thereby making it difficult to rationally design novel analogs that are concomitantly more permeable and more efficacious. In this study, we methodically performed a methyl scan on the core pyridinium of 2-PAM to identify ring positions that could tolerate both additional steric bulk and hydrophobicity. Subsequently, SAR-guided molecular docking was used to rationalize hydropathically feasible binding modes for 2-PAM and the reported derivatives. Overall, the data presented herein provide new insights that may facilitate the rational design of more efficacious 2-PAM analogs.
- Gambino, Adriana,Burnett, James C.,Koide, Kazunori
-
supporting information
p. 1893 - 1898
(2020/02/06)
-
- ANALOGS OF 2-PRALIDOXIME AS ANTIDOTES AGAINST ORGANOPHOSPHORUS NERVE AGENTS
-
Provided herein are compounds useful in treating exposure to an organophosphorus compound, such as a nerve agent, pesticide, or, generally, an acetylcholinesterase inhibitor, such as sarin. Compositions, e.g. pharmaceutical compositions or dosage forms, comprising the compounds also are provided herein. Methods of treating a patient exposed to a nerve agent, pesticide, or, generally, an acetylcholinesterase inhibitor, e.g., an organophosphorus compound, such as sarin, also are provided.
- -
-
Paragraph 00119
(2020/02/23)
-
- The M?CPbA?NH3(G) system: A safe and scalable alternative for the manufacture of (substituted) pyridine and quinoline N?oxides?
-
An improved, safe, and scalable isolation process for (substituted) pyridine and quinoline N-oxides in quantitative yields along with high purities using the m-CPBA?NH3(g) system is described. The safety was assessed by reaction calorimetry and differential scanning calorimetry studies for possible hazards during the conversion and isolation steps. Careful interpretation of the data substantiated the safety and scalability. The process flow is simplified to meet the industrial requirements of safety, cost-effectiveness, and utility minimization. The reaction was safely demonstrated at a 2.5 kg scale.
- Palav, Amey,Misal, Balu,Ernolla, Anilkumar,Parab, Vinod,Waske, Prashant,Khandekar, Dileep,Chaudhary, Vinay,Chaturbhuj, Ganesh
-
supporting information
p. 244 - 251
(2019/03/17)
-
- Metal- and base-free regioselective thiolation of the methyl C(sp3)-H bond in 2-picoline: N -oxides
-
A one-pot, two-step synthesis of pyridine-2-ylmethyl thioethers is developed through a TFAA-mediated [3,3]-sigmatropic rearrangement of pyridine N-oxides and TBAB-catalyzed direct conversion of trifluoroacetates into thioethers under metal- and base-free conditions. This methodology enables thiolation of the unactivated methyl C(sp3)-H bond in 2-picolines with thiols. Remarkable features of the method include high regioselectivity, step- and atom-economy, mild conditions, simple operation, wide substrate scope and scalability. Furthermore, the method has been successfully applied to the synthesis of omeprazole sulfide and rabeprazole sulfide without the need for TBAB catalysis. A comprehensive green chemistry metrics analysis indicated that this method is much more efficient and greener than the reported synthesis of rabeprazole sulfide.
- Wang, Dong,Liu, Zhenlin,Wang, Zhentao,Ma, Xinyue,Yu, Peng
-
supporting information
p. 157 - 163
(2019/01/11)
-
- NEW COMPOUNDS AND USES THEREOF FOR DETECTION OF TARGET MOLECULES IN A SAMPLE
-
The present invention relates to new profluorophores and conjugates thereof and their use for the detection of target molecule in a sample, in particular nucleic acid target molecules. The invention relates to new profluorophores and new fluorophores and methods of use thereof particularly useful in the fields of diagnostics and quality control.
- -
-
Page/Page column 26; 30
(2018/04/27)
-
- Preparation and purification method of toxic impurity DCAL of clopidol
-
The invention relates to a preparation and purification method of toxic impurity DCAL of clopidol and belongs to the technical field of preparation of standard medicine products. The preparation and purification method comprises the following steps: firstly carrying out chlorination reaction, i.e., dissolving a solvent and 2,6-dimethyl-4-aminopyridine; then slowly adding a chlorinating agent to carry out chlorination; after reaction is finished, carrying out neutralization and water washing, concentration and crystallization, filtering or direct neutralization and filtering on reaction liquidto obtain a crude DCAL product; purifying the crude DCAL product, adding a mixed solvent of ethanol and ethyl acetate into the crude DCAL product, stirring for dissolving, dripping petroleum ether toprecipitate solids, filtering, carrying out concentration, cooling and precipitation on filtrate, then filtering, and drying solids to obtain a pure DCAL product. The preparation and purification method has the beneficial effects that the reaction temperature is low, the reaction time is short, the side products in reaction are fewer, and the product is easily purified, so that convenience is brought for preparing impurity reference products of the veterinary-drug clopidol.
- -
-
Paragraph 0022
(2018/04/03)
-
- Visible-Light-Induced C2 Alkylation of Pyridine N-Oxides
-
A photoredox catalytic method has been developed for the direct C2 alkylation of pyridine N-oxides. This reaction is compatible with a range of synthetically relevant functional groups for providing efficient synthesis of a variety of C2-alkylated pyridine N-oxides under mild conditions. Mechanistic studies are consistent with the generation of a radical intermediate along the reaction pathway.
- Zhang, Wen-Man,Dai, Jian-Jun,Xu, Jun,Xu, Hua-Jian
-
p. 2059 - 2066
(2017/02/26)
-
- A pyridine nitrogen oxide high-efficient, multi-phase catalytic preparation method
-
The invention discloses a high efficient heterogeneous catalytic preparation method of pyridine oxynitride. In the provided preparation method, mono-substituted or poly-substituted pyridines or pyridine derivatives are taken as the primary raw materials, titanium dioxide loaded on tungsten (WO3/TiO2) is taken as the catalyst, hydrogen peroxide is taken as the oxidizing agent, and reactions are carried out in a water solution at a room temperature so as to obtain the target product. Compared with the prior art, the preparation method has the following advantages: (1) the provided oxidation method, no acetic acid is used, and thus the requirements on equipment are greatly reduced; (2) a heterogeneous catalytic method is adopted to prepare pyridine oxynitride, the catalyst can be separated from the reaction system through simple filtration or centrifugation, and the operation is convenient; (3) titanium dioxide loaded on tungsten is taken as the catalyst, pyridine oxynitride is prepared by one step in a water solution at a room temperature, the reaction conditions are mild, and the pollution to the environment is little.
- -
-
Paragraph 0146; 0151; 0152
(2017/08/25)
-
- Generic tags for Mn(II) and Gd(III) spin labels for distance measurements in proteins
-
High-affinity chelating tags for Gd(iii) and Mn(ii) ions that provide valuable high-resolution distance restraints for biomolecules were used as spin labels for double electron-electron resonance (DEER) measurements. The availability of a generic tag that can bind both metal ions and provide a narrow and predictable distance distribution for both ions is attractive owing to their different EPR-related characteristics. Herein we introduced two paramagnetic tags, 4PSPyMTA and 4PSPyNPDA, which are conjugated to cysteine residues through a stable thioether bond, forming a short and, depending on the metal ion coordination mode, a rigid tether with the protein. These tags exhibit high affinity for both Mn(ii) and Gd(iii) ions. The DEER performance of the 4PSPyMTA and 4PSPyNPDA tags, in complex with Gd(iii) or Mn(ii), was evaluated for three double cysteine mutants of ubiquitin, and the Gd(iii)-Gd(iii) and Mn(ii)-Mn(ii) distance distributions they generated were compared. All three Gd(iii) complexes of the ubiquitin-PyMTA and ubiquitin-PyNPDA conjugates produced similar and expected distance distributions. In contrast, significant variations in the maxima and widths of the distance distributions were observed for the Mn(ii) analogs. Furthermore, whereas PyNPDA-Gd(iii) and PyNPDA-Mn(ii) delivered similar distance distributions, appreciable differences were observed for two mutants with PyMTA, with the Mn(ii) analog exhibiting a broader distance distribution and shorter distances. ELDOR (electron-electron double resonance)-detected NMR measurements revealed some distribution in the Mn(ii) coordination environment for the protein conjugates of both tags but not for the free tags. The broader distance distributions generated by 4PSPyMTA-Mn(ii), as compared with Gd(iii), were attributed to the distributed location of the Mn(ii) ion within the PyMTA chelate owing to its smaller size and lower coordination number that leave the pyridine nitrogen uncoordinated. Accordingly, in terms of distance resolution, 4PSPyNPDA can serve as an effective generic tag for Gd(iii) and Mn(ii), whereas 4PSPyMTA is efficient for Gd(iii) only. This comparison between Gd(iii) and Mn(ii) suggests that PyMTA model compounds may not predict sufficiently well the performance of PyMTA-Mn(ii) as a tag for high-resolution distance measurements in proteins because the protein environment can influence its coordination mode.
- Yang, Yin,Gong, Yan-Jun,Litvinov, Aleksei,Liu, Hong-Kai,Yang, Feng,Su, Xun-Cheng,Goldfarb, Daniella
-
p. 26944 - 26956
(2017/10/19)
-
- A 6 - methyl - 2 - pyridyl methanol preparation method
-
The invention discloses a preparation method of 6-methyl-2-pyridyl methanol and belongs to the field of organic chemical synthesis, solving the problems of poor selectivity, abundant byproducts, low yield and environment pollution in the prior art. The preparation method of 6-methyl-2-pyridyl methanol comprises the following steps: carrying out high-selectivity oxidization on 2,6-dimethyl pyridine based on 2,6-dimethyl pyridine and glacial acetic acid which serve as raw materials in the presence of tungsten oxide and hydrogen peroxide which serve as catalysts, introducing an acetyl group into an alpha position of a pyridine ring, then carrying out alpha-carbon electronic transfer rearrangement to generate 6-methyl-2-pyridyl ethyl formate, subsequently carrying out hydrolysis to generate 6-methyl-2-pyridyl methanol, then carrying out extraction and distillation to obtain high-purity 6-methyl-2-pyridyl methanol. The preparation method of 6-methyl-2-pyridyl methanol can fully accord with the synthesis requirements of medical manufacturing enterprises, has the advantages of high selectivity, few byproducts, high product yield and low production cost, is mild in reaction conditions and is suitable for industrial production.
- -
-
Paragraph 0029-0033; 0038-0042; 0047-0051; 0056-0060
(2017/08/25)
-
- Catalyst-free and selective oxidation of pyridine derivatives and tertiary amines to corresponding N-oxides with 1,2-diphenyl-1,1,2,2-tetrahydroperoxyethane
-
The catalyst-free oxidation of various pyridine derivatives and tertiary amines to their corresponding N-oxides with 1,1,2,2-tetrahydroperoxy-1,2-diphenylethane as an efficient oxidant has been developed. The methodology proved to tolerate a number of functional groups. The reactions proceeded smoothly under solvent-free and mild conditions at room temperature. All the products were easily extracted from the reaction mixtures in excellent yields. Graphical abstract: The catalyst-free oxidation of various pyridine derivatives and tertiary amines to their corresponding N-oxides with 1,1,2,2-tetrahydroperoxy-1,2-diphenylethane as an efficient oxidant has been developed. The methodology proved to tolerate a number of functional groups. The reactions proceeded smoothly under solvent-free and mild conditions at room temperature. All the products were easily extracted from the reaction mixtures in excellent yields.
- Azarifar, Davood,Mahmoudi, Boshra
-
p. 645 - 651
(2016/02/19)
-
- DTTA paramagnetic probe for protein labeling
-
The invention discloses a DTTA paramagnetic probe for protein paramagnetic labeling. The chemical name of the paramagnetic probe is 4-phenylsulfonyl-6-methyl-2-[N, N-bis(ethylenediamine)aminomethyl]pyridine-N', N', N'', N''-tetraacetic acid, and the chemical structural formula is shown as the specification. The probe has eight coordination sites, contains four carboxyl groups, three nitrogen atoms and one pyridine nitrogen, and achieves rigid connection by means of nucleophilic substitution reaction between para-position phenylsulfonyl of pyridine ring and protein sulfhydryl in an aqueous solution. The DTTA paramagnetic probe for protein paramagnetic labeling provided by the invention can be directly used for protein labeling. The probe provided by the invention has eight coordination sites, contains four carboxyl groups, three nitrogen atoms and one pyridine nitrogen, achieves rigid connection through reaction of phenylsulfonyl and protein sulfhydryl, has the advantages of high denticity, good chelating properties (a plurality of coordination sites), single conformation, and good water solubility, and can be directly used for protein labeling.
- -
-
Paragraph 0053; 0054
(2017/08/25)
-
- A lipase-glucose oxidase system for the efficient oxidation of: N -heteroaromatic compounds and tertiary amines
-
In this work, a lipase-glucose oxidase system has been designed and proven to be an efficient system for the oxidation of N-heteroaromatic compounds and tertiary amines. This dual-enzyme system not only displays environmental friendliness, but also demonstrates its huge potential in industrial applications.
- Yang, Fengjuan,Zhang, Xiaowen,Li, Fengxi,Wang, Zhi,Wang, Lei
-
supporting information
p. 3518 - 3521
(2016/07/06)
-
- Metal-free methylation of a pyridine N-oxide C-H bond by using peroxides
-
Metal-free methylation of a pyridine N-oxide C-H bond was developed using peroxide as a methyl reagent under neat conditions. Pyridine N-oxide derivatives with various groups (e.g., Cl, NO2, and OCH3) were all suitable substrates, and the desired products were obtained in moderate to excellent yields under standard conditions. Moreover, the methylation can be performed with a good yield on the gram-scale experiment. Tentative mechanistic studies show that the methylation is a classical radical process.
- Li, Gang,Yang, Suling,Lv, Bingjie,Han, Qingqing,Ma, Xingxing,Sun, Kai,Wang, Zhiyong,Zhao, Feng,Lv, Yunhe,Wu, Hankui
-
p. 11184 - 11188
(2015/11/27)
-
- Facile Immobilization of a Lewis Acid Polyoxometalate onto Layered Double Hydroxides for Highly Efficient N-Oxidation of Pyridine-Based Derivatives and Denitrogenation
-
N-Oxides are a class of highly important compounds that are used widely as synthetic intermediates. In this paper, we demonstrate for the first time the use of a polyoxometalate-based composite material as a highly efficient heterogeneous catalyst for the N-oxidation of pyridines and its derivatives in the presence of H2O2 at room temperature. The composite was prepared by the intercalation of the [La(PW11O39)2]11- anion into a layered double hydroxide (LDH) modified with tris(hydroxymethyl)aminomethane (Tris). Additionally, the Tris-LDH-La(PW11)2-based catalyst has been employed for the denitrogenation of a model oil mixture in the presence of 1-butyl-3-methylimidazolium tetrafluoroborate and H2O2. Denitrogenation can be achieved in 40 min at 75 C. Finally, the heterogeneous catalyst can be recovered easily and reused at least 10 times without a measurable decrease of the catalytic activity and disintegration of the Tris-LDH-La(PW11)2 structure. Between the sheets: We demonstrate for the first time the use of a polyoxometalate-based composite material as a highly efficient heterogeneous catalyst for the N-oxidation of pyridines and its derivatives in the presence of H2O2 at room temperature. The composite is prepared by the intercalation of the [La(PW11O39)2]11- anion into a layered double hydroxide modified with tris(hydroxymethyl)aminomethane.
- Liu, Kai,Yao, Zhixiao,Miras, Haralampos N.,Song, Yu-Fei
-
p. 3903 - 3910
(2016/01/26)
-
- Catalytic system for pyridine oxidation to N-oxides under mild conditions based on polyoxomolybdate
-
A reusable and effective catalytic system has been developed for oxidation of pyridines catalyzed by Keplerate polyoxomolybdate ({Mo132}) at room temperature. Pyridine compounds could be oxidized in high yields under mild conditions.
- Yang, Chunxia,Zhao, Wei,Cheng, Zhiguo,Luo, Baomin,Bi, Dongqin
-
p. 36809 - 36812
(2015/05/05)
-
- Selective photosensitization through an and logic response: Optimization of the pH and glutathione response of activatable photosensitizers
-
A series of pH and GSH responsive photosensitizers were designed and synthesized. pKa values were optimized by adjusting the inductive contribution of substituents to reach a pH range (6.0-7.4) relevant to the tumour microenvironment. pH-Activatable behaviour and redox mediated release of the quencher from the PS by GSH allow the construction of an AND logic operator for selective photodynamic action in aqueous solutions.
- Erbas-Cakmak, Sundus,Cakmak, Fatma Pir,Topel, Seda Demirel,Uyar, Taha Bilal,Akkaya, Engin U.
-
supporting information
p. 12258 - 12261
(2015/07/27)
-
- Green and reusable synthetic procedure for pyridine N-oxides catalyzed by a lacunary polyoxometalate
-
A lacunary Keggin polyoxometalate of K8[BW11O39H] · 13H2O was used as an effective and reusable catalyst for pyridine oxidation. Good yields of pyridine N-oxides were obtained in this catalytic system with hydrogen peroxide in water under mild conditions. Taylor and Francis Group, LLC.
- Zhao, Wei,Wang, Xing,Yang, Chunxia
-
p. 150 - 160
(2013/11/06)
-
- 2,2,2-Trifluoroacetophenone as an organocatalyst for the oxidation of tertiary amines and azines to N-oxides
-
A cheap, mild and environmentally friendly oxidation of tertiary amines and azines to the corresponding Noxides is reported by using polyfluoroalkyl ketones as efficient organocatalysts. 2,2,2-Trifluoroacetophenone was identified as the optimum catalyst for the oxidation of aliphatic tertiary amines and azines. This oxidation is chemoselective and proceeds in high-to-quantitative yields utilizing 10 mol% of the catalyst and H2O2 as the oxidant.
- Limnios, Dimitris,Kokotos, Christoforos G.
-
supporting information
p. 559 - 563
(2014/04/03)
-
- A green catalytic procedure for oxidation of pyridines catalyzed by a lacunary polyoxometalate in water at room temperature
-
A green and reusable catalytic procedure for oxidation of pyridines to N-oxides was developed. High yields of heterocyclic N-oxides were obtained when catalyzed by Δ-Na8HPW9O34 in water at room temperature. The catalyst used in the system could be recovered and reused several times without obvious loss of activity.
- Zhao, Wei,Yang, Chunxia
-
supporting information
p. 1867 - 1870
(2013/10/08)
-
- The oxidation of pyridine and alcohol using the Keggin-type lacunary polytungstophosphate as a temperature-controlled phase transfer catalyst
-
A novel temperature-controlled phase transfer catalyst of [(C 18H37)2(CH3)2N] 7[PW11O39] has been developed for the oxidation of pyridines and alcohols with hydrogen peroxide. The reactions were conducted in 1,4-dioxane, and high yields of the corresponding heterocyclic N-oxides and ketones were obtained under relative mild conditions. The catalyst could be easily recovered and reused after reaction with cooling. There was no discernable loss in activity and selectivity after several reaction cycles.
- Ding, Yong,Zhao, Wei
-
experimental part
p. 45 - 51
(2011/04/24)
-
- Mild and recyclable catalytic oxidation of pyridines to N-oxides with H2O2 in water mediated by a vanadium-substituted polyoxometalate
-
A vanadium-substituted polyoxometalate, K6[PW9V 3O40]·4H2O, was used as a recyclable and effective catalyst for the oxidation of pyridines. The reactions were successfully conducted in water under mild conditions. The catalyst could be easily recovered and reused.
- Ding, Yong,Zhao, Wei,Song, Wenfeng,Zhang, Zhenxin,Ma, Baochun
-
supporting information; experimental part
p. 1486 - 1489
(2011/08/03)
-
- Novel late transition metal catalysts based on iron: Synthesis, structures and ethylene polymerization
-
In this article we reported synthesis, characterization and ethylene polymerization behavior of two new late transition metal 2,6-bis(imino)pyridine catalysts based on iron(II) possessing different substituents of NO2 (catalyst b) and OMe (catalyst c) at the para position of the pyridine ring. Theoretical study exhibited more positive charge on the central metal of the catalyst b, leading to higher activity offset by lower thermal stability and life time.
- Zohuri, Gholam Hossein,Seyedi, Seyed Mohammad,Sandaroos, Reza,Damavandi, Saman,Mohammadi, Ali
-
experimental part
p. 160 - 166
(2011/10/03)
-
- Chiral amine-imine ligands based on trans-2,5-disubstituted pyrrolidines and their application in the palladium-catalyzed allylic alkylation
-
A series of amine-imine bidentate ligands based on a trans-2,5-disubstituted pyrrolidine and pyridine moieties have been prepared. The use of these ligands in the palladium-catalyzed allylic alkylation reaction of rac-(E)-1,3-diphenylprop-2-enyl acetate is reported. The results suggest that these ligands are good catalyst precursors for the reaction. Electronic modification on the pyridine ring of the ligands does not have a significant effect on the enantioselectivity of the reaction but does on the reaction rate, while structural modification on either the pyridine or the pyrrolidine moiety affords dramatic changes on the outcome of the stereochemistry. Evidence from various studies suggested that during the palladium-catalyzed allylic alkylation reaction, nucleophilic attack onto the 1,3-diphenylallyl moiety in the transition state occurs mainly trans to the pyridine ring of the less stable conformation of the palladium complexes.
- Chen, Hongfeng,Sweet, James A.,Lam, Kin-Chung,Rheingold, Arnold L.,McGrath, Dominic V.
-
scheme or table
p. 1672 - 1682
(2009/12/04)
-
- A safe, convenient and efficient method for the preparation of heterocyclic N-oxides using urea·hydrogen peroxide
-
A novel, convenient, and high-yielding method has been developed for the preparation of heterocyclic N-oxides. The reaction uses the urea·hydrogen peroxide addition complex as a peroxide source for the in situ generation of trifluoroperacetic acid. The advantages of this method are easy handling of a stable, solid oxidant; high yields and simple removal of excess reagents and by-products.
- Rong, Dawen,Phillips, Victoria A.,Rubio, Ramón Sánchez,ángeles Castro, Ma,Wheelhouse, Richard T.
-
scheme or table
p. 6933 - 6935
(2009/04/07)
-
- Equilibrium of acyl transfer between pyridine N-oxides and their acylonium salts
-
Transfer of acyl groups from N-acyloxypyridinium salts to pyridine N-oxides in acetonitrile was studied. The equilibrium constants of acyl exchange were determined. These quantities vary in the range covering eight orders of magnitude, depending on the st
- Rubachenko,Schroeder,Chotii,Kovalenko,Red'ko,Lenska
-
p. 1241 - 1246
(2008/12/22)
-
- NEW ISOTHIAZOLOQUINOLONES AND RELATED COMPOUNDS AS ANTI-INFECTIVE AGENTS
-
The invention provides certain compounds and salts of Formula I and Formula II:which possess antimicrobial activity. The invention also provides novel synthetic intermediatesuseful in making compounds of Formula I and Formula II. The variables A1, R2, R3, R5, R6, R7, A8, and Rg are defined herein. Certain compounds of Formula I and Formula II disclosed herein are potent and selective inhibitors of bacterial DNA synthesis and bacterial replication. The invention also provides antimicrobial compositions, including pharmaceutical compositions, containing one or more compounds of Formula I or Formula II and one or more carriers, excipients, or diluents. Such compositions may contain a compound of Formula I or Formula II as the only active agent or may contain a combination of a compound of Formula I or Formula II and one or more other active agents. The invention also provides methods for treating microbial infections in animals.
- -
-
Page/Page column 59; 60
(2008/06/13)
-
- ISOTHIAZOLOQUINOLONES AND RELATED COMPOUNDS AS ANTI-INFECTIVE AGENTS
-
The invention provides compounds and salts of Formula (I) and Formula (II): which possess antimicrobial activity. The invention also provides novel synthetic intermediates useful in making compounds of Formula (I) and Formula (II). The variables A1, R2, R3, R5, R6, R7, A8 and R9 are defined herein. Certain compounds of Formula (I) and Formula (II) disclosed herein are potent and selective inhibitors of bacterial DNA synthesis and bacterial replication. The invention also provides antimicrobial compositions, including pharmaceutical compositions, containing one or more compounds of Formula (I) or Formula (II) and one or more carriers, excipients, or diluents. Such compositions may contain a compound of Formula (I) or Formula (II) as the only active agent or may contain a combination of a compound of Formula (I) or Formula (II) and one or more other active agents. The invention also provides methods for treating microbial infections in animals.
- -
-
Page/Page column 62
(2010/02/11)
-
- Aqueous biphasic oxidation: A water-soluble polyoxometalate catalyst for selective oxidation of various functional groups with hydrogen peroxide
-
A "sandwich" type polyoxometalate, Na12[(WZn 3(H2O)2][(ZnW9O34) 2], was used as an oxidation catalyst in aqueous biphasic reaction media to effect oxidation of alcohols, diols, pyridine derivatives, amines and aniline derivatives with hydrogen peroxide. The catalyst was shown by 183W NMR to be stable in aqueous solutions in the presence of H 2O2 and showed only minimal non-productive decomposition of the oxidant. Secondary alcohols were selectively oxidized to ketones, while primary alcohols tended to be oxidized to the corresponding carboxylic acids, although secondary alcohols were selectively oxidized in the presence of primary alcohols. Vicinal diols yielded carbon-carbon bond cleavage products in very high yields. Pyridine derivatives were oxidized to the respective TV-oxides, but strongly electron-withdrawing moieties inhibited the oxidation reaction. Primary amines were oxidized to the oximes, but significantly hydrolyzed in situ. Aniline derivatives were oxidized to the corresponding azoxy or nitro products depending on the substitution pattern in the aromatic ring. Catalyst recovery and recycle was demonstrated.
- Sloboda-Rozner, Dorit,Witte, Peter,Alsters, Paul L.,Neumann, Ronny
-
p. 339 - 345
(2007/10/03)
-
- A Simple and Efficient Method for the Preparation of Heterocyclic N-Oxide
-
Pyridine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2,4-dimethylpyridine, 2,6-dimethylpyridine, quinoline, isoquinoline and 2-chloropyridine are readily oxidized to their N-oxides with a solution of trichloroisocyanuric acid, acetic acid, sodium acetate and water in acetonitrile and methylene dichloride in 78%-90% yields.
- Zhong, Ping,Guo, Sheng-Rong,Song, Cai-Sheng
-
p. 247 - 253
(2007/10/03)
-
- The Kinetics and Mechanism of the Reaction of Pyridine-N-Oxides with Alkyl Halides
-
The kinetics of formation of N-alkoxypyridinium salts and their decomposition to the starting reagents in acetonitrile at 25°C is studied. The decomposition of the salts takes place only in the ion pair. Similar mechanism of proton and methyl group transfer in reactions with participation of pyridines and pyridine-N-oxides was demonstrated noted.
- Matveev,Koblik,Popov,Savelova,Matvienko
-
p. 271 - 275
(2007/10/03)
-
- Hydroxymethylation and carbamoylation of di- and tetramethylpyridines using radical substitution (minisci) reactions
-
Reaction of hydroxymethyl radicals with N-methoxy 2,4- and 2,6- dimethylpyridinium salts gave 2,4,6-substituted hydroxymethylpyridines. Similar reactions with 2,3,5,6-tetramethylpyridine and derivatives failed, however 4-substitution could be achieved using a carbamoyl radical.
- Amrollahi Biyouki, Mohammad A.,Smith, Robin A. J.,Bedford, Jennifer J.,Leader, John P.
-
p. 3817 - 3825
(2007/10/03)
-
- On the preparation of amine N-oxides by using dioxiranes
-
The reaction of heterocyclic aromatic amines, anilines and tertiary amines with dimethyldioxirane (DMD) was examined. Treatment of heterocyclic aromatic amines and anilines with a slight excess of DMD at 0°C afforded the corresponding N-oxides in quantitative conversion yields. In addition, the oxidation was chemoselective in the presence of carbon-carbon double bonds. On the other hand, most of the tertiary amines assayed did afford also quantitative yields of the corresponding N. oxides, although reaction conditions, in particular regarding the amount of DMD required, depended on each substrate. Additional studies carried out on selected substrates suggested that certain N-oxides derived from tertiary amines deactivate DMD.
- Ferrer, Marta,Sanchez-Baeza, Francisco,Messeguer, Angel
-
p. 15877 - 15888
(2007/10/03)
-
- Process for stabilizing percarboxylic acid
-
Disclosed is a process for stabilizing a percarboxylic acid characterized in that the percarboxylic acid is mixed with at least one pyridine derivative selected from the group consisting of picoline, ethylpyridine, conyrine, lutidine and N-oxide thereof.
- -
-
-
- FURTHER FUNCTIONAL GROUP OXIDATIONS USING SODIUM PERBORATE
-
Sodium perborate in acetic acid is an effective reagent for the oxidation of aromatic aldehydes to carboxylic acids, iodoarenes to (diacetoxyiodo)arenes, azines to N-oxides, and various types of sulfur heterocycles to S,S-dioxides.Nitriles are unaffected by the reagent in acetic acid, but undergo smooth hydration to amides when aqueous methanol is employed as solvent.
- McKillop, Alexander,Kemp, Duncan
-
p. 3299 - 3306
(2007/10/02)
-
- Enamine Rearangement of Pyridinium Salts: Part VIII - Effect of Nucleophilic Reagent on Pyridinium Salts
-
N-Methoxy-2-methyl-(IIa) and N-methoxy-2,6-dimethyl-pyridinium salts (IIb) undergo ring opening and recyclization reactions when heated with methylammonium silphite to give N-methyl-aniline (IVa) and N-methyl-m-toluidine (IVb), respectively.
- Fadda, A. A.,Khalil, A. M.,Elmorsy, S. S.,El-Habbal, M. M.
-
p. 266 - 268
(2007/10/02)
-