- Au(I)-Catalyzed Oxidative Functionalization of Yndiamides
-
Yndiamides, underexplored cousins of ynamides, offer rich synthetic potential as doubly nitrogenated two carbon building blocks. Here we report a gold-catalyzed oxidative functionalization of yndiamides to access unnatural amino acid derivatives, using a wide range of nucleophiles as a source of the amino acid side chain. The transformation proceeds under mild conditions, is highly functional group tolerant, and displays excellent regioselectivity through subtle steric differentiation of the yndiamide nitrogen atom substituents.
- Tong, Zixuan,Garry, Olivia L.,Smith, Philip J.,Jiang, Yubo,Mansfield, Steven J.,Anderson, Edward A.
-
supporting information
p. 4888 - 4892
(2021/06/28)
-
- 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)
-
- Recyclable anhydride catalyst for H2O2 oxidation:: N -oxidation of pyridine derivatives
-
The catalytic efficiency and recyclability of poly(maleic anhydride-alt-1-octadecene) (Od-MA) and poly(maleic anhydride-alt-1-isobutylene) (Bu-MA) were evaluated for use in the development of a metal-free, reusable catalyst for the oxidation of pyridines to pyridine N-oxides in the presence of H2O2. The Od-MA catalyst was easily recovered via filtration with recovery yields exceeding 99.8%. The catalyst retained its activity after multiple uses and did not require any treatment for reuse. The Od-MA and H2O2 catalytic system described herein is eco-friendly, operationally simple, and cost-effective; thus, it is industrially applicable. Od-MA and H2O2 could potentially be used in place of percarboxylic acid as an oxidant in a wide range of oxidation reactions.
- Gajeles, Ghellyn,Kim, Se Mi,Lee, Kyung-Koo,Lee, Sang Hee,Yoo, Jong-Cheol
-
p. 9165 - 9171
(2020/03/13)
-
- Method for catalyzing vitamin A isomerization with ruthenium catalyst
-
The invention provides a method for catalyzing vitamin A isomer conversion with a ruthenium catalyst. According to the method, a ruthenium compound is used as a catalyst, various vitamin A cis-isomerswith low biological activity can be converted into all-trans-isomers with high biological activity in a high proportion in the presence of an auxiliary agent, and the cis-isomers comprise 9-cis-isomers, 11-cis-isomers and 13-cis-isomers. The method has the characteristics of cheap and easily available catalyst, less catalyst dosage, mild reaction conditions, low reaction cost, high isomerizationefficiency and the like.
- -
-
Paragraph 0050; 0053-0054
(2020/04/22)
-
- Preparation method of 2-chloro-4-aminopyridine
-
The invention belongs to the field of organic synthesis, and particularly relates to a preparation method of 2-chloro-4-aminopyridine. The preparation method comprises the following steps: (1) using 2-chloropyridine as a raw material and chloroform as a solvent, and generating 2-chloropyridine oxide under the action of m-chloroperoxybenzoic acid; (2) reacting 2-chloropyridine oxide with a mixed acid composed of concentrated nitric acid and concentrated sulfuric acid to generate 2-chloro-4-nitropyridine oxynitride; and (3) reducing 2-chloro-4-nitropyridine oxynitride into 2-chloro-4-aminopyridine. The method has the beneficial effects that the reaction conditions are mild, the operation is easy, the post-treatment is simple, the scale-up production is easy, the method is very suitable for industrial production; the catalytic effect is good, the yield is high; the raw materials are cheap, and the production cost is low.
- -
-
Paragraph 0016; 0019; 0020; 0023; 0024; 0028; 0029
(2020/05/05)
-
- Visible-Light-Mediated C-H Alkylation of Pyridine Derivatives
-
We report herein a visible-light-mediated C-H alkylation of pyridine derivatives that proceeds by simple combination of a large variety of N-alkoxypyridinium ions with alkanes in the presence of 2 mol % of fac-Ir(ppy)3 under blue illumination. The mild reaction conditions together with the high group functional tolerance make of this process a useful synthetic platform for the construction of structurally strained heterocycles. Detailed mechanistic investigations, including density functional theory calculations and quantum yield measurement, allowed us to understand factors controlling the reactivity and the selectivity of the reaction.
- Rammal, Fatima,Gao, Di,Boujnah, Sondes,Gaumont, Annie-Claude,Hussein, Aqeel A.,Lakhdar, Sami
-
supporting information
p. 7671 - 7675
(2020/10/09)
-
- Reaction of Pyridine-N-Oxides with Tertiary sp2-N-Nucleophiles: An Efficient Synthesis of Precursors for N-(Pyrid-2-yl)-Substituted N-Heterocyclic Carbenes
-
N-(Pyrid-2-yl)-substituted azolium and pyridinium salts, precursors for hybrid NHC-containing ligands, were obtained with excellent regioselectivity, employing a deoxygenative CH-functionalization of pyridine-N-oxides with substituted imidazoles, thiazoles, and pyridine. Unlike the traditional SNAr-based methods, this approach provides high yields for substrates bearing substituents of different electronic nature. The utility of azolium and pyridinium salts thus prepared was also highlighted by the synthesis of pyridyl-substituted imidazolyl-2-thione, benzodiazepine as well as 2-aminopyridines.
- Bugaenko, Dmitry I.,Karchava, Alexander V.,Yurovskaya, Marina A.
-
supporting information
p. 5777 - 5782
(2020/12/01)
-
- A 2 - chloro -4 - aminopyridine preparation method
-
The invention belongs to the field of organic synthesis, in particular relates to a 2 - chloro - 4 - aminopyridine preparation method, comprises the following steps: (1) to 2 - chloro pyridine as raw materials, chloroform as solvent, under the action of the meta-chloroperoxybenzoic acid to produce 2 - chloro pyridine oxide; (2) 2 - chloro pyridine oxide by the concentrated nitric acid in concentrated sulfuric acid the acid produced by the reaction of a 2 - chloro - 4 - nitro pyridine nitrogen oxides; (3) 2 - chloro - 4 - nitro pyridine nitrogen oxide reduction is 2 - chloro - 4 - aminopyridine. The beneficial effect of the invention is: mild reaction conditions, is easy to operate, after treatment is simple, and easy to enlarge production, is extremely suitable for industrial production; good catalytic effect, high yield; low prices of raw materials, the production cost is low.
- -
-
Paragraph 0016; 0019; 0020; 0023; 0024; 0028; 0029
(2019/05/28)
-
- Strategic Approach on N-Oxides in Gold Catalysis – A Case Study
-
An extensive kinetic study of selected key reactions of (oxidative) gold catalysis concentrates on the decrease of the catalytic activity due to inhibition of the gold(I) catalyst caused by pyridine derivatives that are obtained as by-products if N-oxides are applied as oxygen donors. The choice of the examined pyridine derivatives and their corresponding N-oxides has been made regardless of their commercial availability; particular attention has been paid to the practical benefit which up to now has been neglected in most of the reaction screenings. The test reactions were monitored by GC and 1H NMR spectroscopy. The received reaction constants provide information concerning a correlation between the electronic structure of the heterocycle and the catalytic activity. Based on the collected kinetic data, it was possible to develop a basic set of three N-oxides which have to be taken into account in further oxidative gold(I)-catalyzed reactions. (Figure presented.).
- Schie?l, Jasmin,Stein, Philipp M.,Stirn, Judith,Emler, Kirsten,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
-
supporting information
p. 725 - 738
(2018/10/20)
-
- A Biocatalytic Synthesis of Heteroaromatic N-Oxides by Whole Cells of Escherichia coli Expressing the Multicomponent, Soluble Di-Iron Monooxygenase (SDIMO) PmlABCDEF
-
Aromatic N-oxides (ArN?OX) are desirable biologically active compounds with a potential for application in pharmacy and agriculture industries. As biocatalysis is making a great impact in organic synthesis, there is still a lack of efficient and convenient enzyme-based techniques for the production of aromatic N-oxides. In this study, a recombinant soluble di-iron monooxygenase (SDIMO) PmlABCDEF overexpressed in Escherichia coli was showed to produce various aromatic N-oxides. Out of 98 tested N-heterocycles, seventy were converted to the corresponding N-oxides without any side oxidation products. This whole-cell biocatalyst showed a high activity towards pyridines, pyrazines, and pyrimidines. It was also capable of oxidizing bulky N-heterocycles with two or even three aromatic rings. Being entirely biocatalytic, our approach provides an environmentally friendly and mild method for the production of aromatic N-oxides avoiding the use of strong oxidants, organometallic catalysts, undesirable solvents, or other environment unfriendly reagents. (Figure presented.).
- Petkevi?ius, Vytautas,Vaitekūnas, Justas,Taurait?, Daiva,Stankevi?iūt?, Jonita,?arlauskas, Jonas,??nas, Narimantas,Me?kys, Rolandas
-
supporting information
p. 2456 - 2465
(2019/01/25)
-
- Synthesis method of zinc pyrithione
-
The invention discloses a synthesis method of zinc pyrithione, and belongs to the field of organic synthesis. According to the synthesis method, 2-chloropyridine is used as a raw material; a final product is obtained through three steps of reactions of nitrogen oxidation, sulfhydrylation and salt formation. The synthesis method is simple in step and convenient to operate and further, the content of an obtained product is high.
- -
-
Paragraph 0033; 0034; 0035; 0036; 0037; 0038; 0039; 0040
(2018/04/02)
-
- A high-quality zinc pyrithione synthetic method (by machine translation)
-
The invention discloses a high-quality zinc pyrithione synthetic method, in order to 2 - chloro pyridine as raw materials, through catalytic oxidation, then the thiolation reaction to obtain the pyridine sulfur [...] solution; pyridine sulfur [...] solution by reduced pressure distillation, separating out the sodium chloride solid salt; thermal insulation filtering, to obtain the pyridine sulfur [...] filtrate, - 10 - 10 °C low-temperature crystallization; filtering, to obtain the pyridine sulfur [...] solid and containing pyridine sulfur [...] filtrate, filtrate circulation process for preparing pyridine sulfur [...] solid; pyridine sulfur [...] solid preparation into the pyridine sulfur [...] solution with the water-soluble zinc salt reaction to obtain the zinc pyrithione product. The method of the invention the process is simple, easy to operate, the prepared product has high purity, the whiteness is good good stability; at the same time the synthesis process has reduced the three waste generation, environmental protection, and is favorable for industrial production. (by machine translation)
- -
-
Paragraph 0028; 0031; 0032
(2018/09/11)
-
- Synthesis method of zinc pyrithione
-
The invention discloses a synthesis method of zinc pyrithione. The method comprises the following steps: (1) nitrogen oxidation of 2-chloropyridine: adding 2-chloropyridine, a solvent and a catalyst into a reactor, dropwise adding hydrogen peroxide for reacting, and after the reacting, filtering to obtain a 2-chloropyridine nitrogen oxide solution; (2) sulfhydrylation: adding a sulfhydrylation reagent into the reactor, dropwise adding the 2-chloropyridine nitrogen oxide solution, and after the reacting, adjusting the pH value, and decolorizing with active carbon to obtain a 2-chloropyridine nitrogen oxide mercapto sodium salt solution; and (3) chelation to obtain salt: adding a zinc salt solution into the reactor, dropwise adding the 2-chloropyridine nitrogen oxide mercapto sodium salt solution, and after the reacting, filtering, washing the filter cake with deionized water, and drying to obtain zinc pyrithione. In the zinc pyrithione prepared by the method disclosed by the invention, the total yield is increased to 92%, and the product purity is increased to over 98%; the nitrogen oxidation reaction yield is increased to over 97%, and the catalyst can be regenerated for use; and moreover, the whole process is simple to operate and generates relatively few three wastes.
- -
-
Paragraph 0043; 0044; 0049
(2017/06/02)
-
- 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 0061; 0065; 0066; 0067
(2017/08/25)
-
- Hydroheteroarylation of Unactivated Alkenes Using N-Methoxyheteroarenium Salts
-
We report the first reductive coupling of unactivated alkenes with N-methoxy pyridazinium, imidazolium, quinolinium, and isoquinolinium salts under hydrogen atom transfer (HAT) conditions, and an expanded scope for the coupling of alkenes with N-methoxy pyridinium salts. N-Methoxy pyridazinium, imidazolium, quinolinium, and isoquinolinium salts are accessible in 1-2 steps from the commercial arenes or arene N-oxides (25-99%). N-Methoxy imidazolium salts are accessible in three steps from commercial amines (50-85%). In total 36 discrete methoxyheteroarenium salts bearing electron-donating, electron-withdrawing, alkyl, aryl, halogen, and haloalkyl substituents were prepared (several in multigram quantities) and coupled with 38 different alkenes. The transformations proceed under neutral conditions at ambient temperature, provide monoalkylation products exclusively, and form a single alkene addition regioisomer. Preparatively useful and complementary site selectivities in the addition of secondary and tertiary radicals to pyidinium salts are documented: harder secondary radicals favor C-2 addition (2->10:1), while softer tertiary radicals favor bond formation to C-4 (4.7->29:1). A diene possessing a 1,2-disubstituted and 2,2-disubstituted alkene undergoes hydropyridylation at the latter exclusively (61%) suggesting useful site selectivities can be obtained in polyene substrates. The methoxypyridinium salts can also be employed in dehydrogenative arylation, borono-Minisci, and tandem arylation processes. Mechanistic studies support the involvement of a radical process.
- Ma, Xiaoshen,Dang, Hester,Rose, John A.,Rablen, Paul,Herzon, Seth B.
-
supporting information
p. 5998 - 6007
(2017/05/04)
-
- Discovery of New Potential Anti-Infective Compounds Based on Carbonic Anhydrase Inhibitors by Rational Target-Focused Repurposing Approaches
-
In academia, compound recycling represents an alternative drug discovery strategy to identify new pharmaceutical targets from a library of chemical compounds available in house. Herein we report the application of a rational target-based drug-repurposing approach to find diverse applications for our in-house collection of compounds. The carbonic anhydrase (CA, EC 4.2.1.1) metalloenzyme superfamily was identified as a potential target of our compounds. The combination of a thoroughly validated docking screening protocol, together with in vitro assays against various CA families and isoforms, allowed us to identify two unprecedented chemotypes as CA inhibitors. The identified compounds have the capacity to preferentially bind pathogenic (bacterial/protozoan) CAs over human isoforms and represent excellent hits for further optimization in hit-to-lead campaigns.
- Annunziato, Giannamaria,Angeli, Andrea,D'Alba, Francesca,Bruno, Agostino,Pieroni, Marco,Vullo, Daniela,De Luca, Viviana,Capasso, Clemente,Supuran, Claudiu T.,Costantino, Gabriele
-
p. 1904 - 1914
(2016/10/12)
-
- Solvent- and halide-free synthesis of pyridine-2-yl substituted ureas through facile C-H functionalization of pyridine: N -oxides
-
A novel solvent- and halide-free atom-economical synthesis of practically useful pyridine-2-yl substituted ureas utilizes easily accessible or commercially available pyridine N-oxides (PyO) and dialkylcyanamides. The observed C-H functionalization of PyO is suitable for the good-to-high yielding synthesis of a wide range of pyridine-2-yl substituted ureas featuring electron donating and electron withdrawing, sensitive, or even fugitive functional groups at any position of the pyridine ring (63-92%; 19 examples). In the cases of 3-substituted PyO, the C-H functionalization occurs regioselectively providing a route for facile generation of ureas bearing a 5-substituted pyridine-2-yl moiety.
- Rassadin, Valentin A.,Zimin, Dmitry P.,Raskil'dina, Gulnara Z.,Ivanov, Alexander Yu.,Boyarskiy, Vadim P.,Zlotskii, Semen S.,Kukushkin, Vadim Yu.
-
supporting information
p. 6630 - 6636
(2018/03/01)
-
- 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)
-
- Base free regioselective synthesis of α-triazolylazine derivatives
-
A regioselective α-heteroarylation followed by deoxygenation towards the synthesis of variety of azine triazole from simple azine N-oxides derivatives and N-tosyl-1,2,3-triazoles has been described. The reaction is metal free and base free with shorter reaction time, high yields and a broad substrate scope.
- Harisha, Mysore Bhyrappa,Nagaraj, Muthupandi,Muthusubramanian, Shanmugam,Bhuvanesh, Nattamai
-
p. 58118 - 58124
(2016/07/06)
-
- Design and synthesis of purine analogues as highly specific ligands for FcyB, a ubiquitous fungal nucleobase transporter
-
In the course of our study on fungal purine transporters, a number of new 3-deazapurine analogues have been rationally designed, based on the interaction of purine substrates with the Aspergillus nidulans FcyB carrier, and synthesized following an effective synthetic procedure. Certain derivatives have been found to specifically inhibit FcyB-mediated [3H]-adenine uptake. Molecular simulations have been performed, suggesting that all active compounds interact with FcyB through the formation of hydrogen bonds with Asn163, while the insertion of hydrophobic fragments at position 9 and N6 of 3-deazaadenine enhanced the inhibition.
- Lougiakis, Nikolaos,Gavriil, Efthymios-Spyridon,Kairis, Markelos,Sioupouli, Georgia,Lambrinidis, George,Benaki, Dimitra,Krypotou, Emilia,Mikros, Emmanuel,Marakos, Panagiotis,Pouli, Nicole,Diallinas, George
-
p. 5941 - 5952
(2016/11/09)
-
- 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
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p. 3903 - 3910
(2016/01/26)
-
- Trichloroacetonitrile-hydrogen peroxide: A simple and efficient system for the selective oxidation of tertiary and secondary amines
-
A variety of tertiary and secondary amines were efficiently oxidized to their corresponding N-oxides and nitrones, respectively, using the trichloroacetonitrile-hydrogen peroxide system. The in situ generated trichloromethylperoxyimidic acid is the active reagent for the oxidation processes.
- Nikbakht, Fatemeh,Heydari, Akbar
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p. 2513 - 2516
(2014/05/06)
-
- 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)
-
- Oxidation of alcohols and pyridines by a water-soluble polyoxometalate with hydrogen peroxide
-
A water-soluble catalyst based on a silicotungstate polyoxometalate, K 8[β-SiW11O39] · 14H2O, was developed for the oxidation of pyridines and alcohols with hydrogen peroxide. The reactions were carried out in water, and good yields of the corresponding heterocyclic N-oxides and ketones were obtained under relatively mild conditions. The catalyst could be easily recovered by extraction with ethyl acetate and reused several times. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications to view the free supplemental file.
- Zhang, Zhenxin,Zhu, Qianqian,Ding, Yong
-
supporting information
p. 1211 - 1218
(2013/03/29)
-
- 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
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p. 2614 - 2618
(2013/09/12)
-
- 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)
-
- 2- [ (2-SUBSTITUTED) -IND0LIZIN-3-YL] -2-OXO-ACETAMIDE DERIVATIVES AS ANTIFUNGAL AGENTS
-
The invention provides compounds of formula (I), and pharmaceutically acceptable salts thereof wherein: Rl, R2, R3, R4, R5, R6, R7, X and X1 are as defined herein. These compounds are useful in the manufacture of medicaments for use in the prevention or treatment of a fungal disease. Compounds of formula (I), and agriculturally acceptable salts thereof, may also be used as agricultural fungicides.
- -
-
Page/Page column 112
(2008/12/05)
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- Keratin dyeing compounds, keratin dyeing compositions containing them, and use thereof
-
Compositions for the oxidative dyeing of keratin fibers, comprising a medium suitable for dyeing and at least one N-oxides of six-membered rings with one or two nitrogen atoms keratin dyeing compound. A method for oxidative dyeing of keratin fibers, comprising applying such compositions in the presence of an oxidizing agent, for a period sufficient to develop the desired coloration.
- -
-
Page/Page column 9
(2008/06/13)
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- The Reaction of Acetic Acid 2-Selenoxo-2H-pyridin-1-yl Esters with Benzynes: A Convenient Route to Benzo[b]seleno[2,3-b]pyridines
-
Benzyne and its 3,4,5,6-tetraphenyl, 3- and 4-methyl, 3-methoxy and 4,5-difluoro derivatives react with acetic acid 2-selenoxo-2H-pyridin-1-yl esters 4a-e to give benzo[b]seleno[2,3-b]pyridines 10-15 in modest yields. The benzynes were generated by one or more of the following methods: diazotization of anthranilic acids 5a-g with isoamyl nitrate; mild thermal decomposition of 2-diazoniobenzenecarboxylate hydrochlorides 6a-d; treatment of (phenyl)[o-(trimethylsilyl)phenyl]iodonium triflate (7) with tetrabutylammonium fluoride; and treatment of 2-trimethylsilylphenyl triflates 8a-c with cesium fluoride. In all the reactions, the corresponding 2-(methylselenenyl)pyridines 16a-d were also obtained suggesting that these reactions may involve selenium addition to benzyne via a SET (single electron transfer).
- Rao, U. Narasimha,Sathunuru, Ramadas,Maguire, John A.,Biehl, Ed
-
-
- 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
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p. 247 - 253
(2007/10/03)
-
- Stabilised 2,3-pyridyne reactive intermediates of exceptional dienophilicity
-
The enhanced dienophilicity of 4-methoxy, 4-aryloxy and 4-thiophenoxy analogues 6-9 of 2,3-pyridyne (2) relative to 2 itself is reported. The regioselective lithiation of 4-alkoxy-(22, 23 and 25) and 4-thiophenoxy-2- chloropyridme (24) at low temperatures, followed by elimination of lithium chloride affords 4-alkoxy- and 4-thiophenoxypyridynes, which can be trapped in situ in a [4+2] cycloaddition reaction with furan to give endoxides 28-31 in moderate to good yields (25-58%). In contrast, precursors with a hydrogen (18) or methyl (12) substituent at C-4 give no evidence for pyridyne formation under these conditions. Attempts to generate 6-isopropoxy-2,3-pyridyne (10) from the low-temperature lithiation of 2-chloro-6-isopropoxypyridine were unsuccessful due to the instability of the 2-chloro-6-isopropoxy-5-lithiopyridine. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Connon, Stephen J.,Hegarty, Anthony F.
-
p. 3477 - 3483
(2007/10/03)
-
- Aqueous biphasic oxidation: A water-soluble polyoxometalate catalyst for selective oxidation of various functional groups with hydrogen peroxide
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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
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p. 339 - 345
(2007/10/03)
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- Method for producing 2-halopyridine-n-oxide
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The present invention concerns a process for the preparation of 2-halopyridine N-oxide by reaction of 2-halopyridine with hydrogen peroxide in aqueous solution in the presence of an acid anhydride as catalyst in which, according to the invention, as catalyst there is used an anhydride of the formula I whereby the aromatic rings can be substituted by alkyl groups or halogens or can be anellated with a further aromatic ring.
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- An efficient synthesis of heterocyclic N-oxides over molecular sieve catalyst
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Heterocyclic N-oxides have been synthesized in very high yields over redox molecular sieve catalysts in the presence of H2O2.
- Prasad, M. Ramakrishna,Kamalakar, G.,Madhavi, G.,Kulkarni, S. J.,Raghavan, K. V.
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p. 1577 - 1578
(2007/10/03)
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- Synthesis of the analogue nucleoside 3-deaza-2'-deoxycytidine and its template activity with DNA polymerase
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A new synthesis of the nucleoside analogue 3-deaza-2'-deoxycytidine is described. The N3-nitrogen of dC is involved in the central hydrogen bond of a dG-dC base pair. The relative importance of hydrogen bonding as a controlling factor in the activity of DNA polymerase is examined by studying both duplex stability and template effects for this dc3C nucleoside. Duplexes containing dG-dc3C base pairs were strongly destabilized while templates containing the analogue nucleoside were found to incorporate only the complementary dG triphosphate, similar to observations with templates containing the native 2'-deoxycytidine.
- Searls, Tim,McLaughlin, Larry W.
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p. 11985 - 11996
(2007/10/03)
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- Tertiary amine oxidation using HOF-CH3CN: A novel synthesis of N-oxides
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HOF·CH3CN, probably the best oxygen transfer agent organic chemistry has to offer, is easily made by bubbling diluted fluorine (10-15%) through aqueous acetonitrile solution. Used as formed without any isolation or purification, it reacts with various tertiary amines such as pyridine derivatives, polyaromatic nitrogen containing compounds and aliphatic and alicyclic ones to form the corresponding N-oxides. When two nitrogen atoms are present it is possible to make both the N-monoxides and the N,N-dioxides. The reaction times are short (a few minutes), conditions are very mild (0-25 °C) and the yields range from good to excellent (70-95%).
- Dayan, Sharon,Moshe, Kol,Rozen, Shlomo
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p. 1427 - 1430
(2007/10/03)
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- Alkyl transfer with retention and inversion of configuration: Reexamination of a putative [1s,4s] sigmatropic rearrangement
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The thermal rearrangement of 2-alkoxypyridine-1-oxides to 1-alkoxy-2-pyridones, which has been reported to proceed by an intramolecular [1s,4s] sigmatropic migration of the alkyl group with retention of configuration and first-order kinetics, has been reexamined. The intramolecular barriers have been computed to be at least 20 kcal mol-1 higher than the reported experimental barriers. An alternative bimolecular mechanism, discovered computationally, has been confirmed by a variety of experiments including crossover studies, determination of solvent effects and secondary H/D isotope effects, and new kinetic and stereochemical studies. In the new mechanism there is an initial intermolecular transfer of the alkyl group, with inversion of configuration, to the N-oxide. Depending on the nature of the alkyl group and the solvent, this is followed by a second transfer, also with inversion of configuration, of one of the alkyl groups of the cationic intermediate to one of the oxygens of the anionic intermediate. The product is then formed either without crossover, by a double inversion of one alkyl group, or with crossover by two single inversions of different alkyl groups. The proposed intermediates of this mechanism can be synthesized; they react to form a 1-alkoxy-2-pyridone at room temperature.
- Wolfe, Saul,Yang, Kiyull,Weinberg, Noham,Shi, Zheng,Hsieh, Yih-Huang,Sharma, Rajendra Dev,Ro, Stephen,Kim, Chan-Kyung
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p. 886 - 902
(2007/10/03)
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- Structural and vibrational investigation of 2-amino-4-nitropyridine crystal
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The X-ray structure of 2-amino-4-nitropyridine was determined at room temperature. The crystal belongs to the P2(I)/c space group of the monoclinic system (Z = 4, a = 6.7290(10), b = 10.946(2), c = 9.060(2) A, β = 100.03(3) deg) and is built of layers parallel to the (102) crystallographic plane. The molecules in the layer are joined into centrosymmetric dimers by two N-H···N hydrogen bonds (N···N distance = 3.011(3) A), which form rings of C(i) symmetry. The other N-H bonds of the amino groups are involved in N-H···O hydrogen bonds with the oxygen atoms of the nitro groups (N···O distance = 3.054(3) A). These hydrogen bonds join the dimers into an infinite plane. The powder IR and Raman spectra (4000-80 cm-1) were measured for normal and deuterated crystals and are discussed with respect to the crystal structure. The N-H stretching vibrations behave as the stretching vibrations of two almost independent hydrogen bonds. Strong A(g)-A(u)-type splitting is observed for the stretching vibrations of the N-H···N type hydrogen bonds.
- Oszust,Talik,Pietraszko,Marchewka,Baran
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- Synthesis of 'A' Ring Isomazole Oxypropanolamines via Hydrolysis of 1H-Imidazopyridine Oxazolidin-2-ones
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The hydrolysis of oxazolidin-2-one 15, under forcing conditions, gives the oxypropanolamine 7 and 4,5-dihydro-1H-imidazopyridin-4-ones (17-19) and may occur by a BAL mechanism, involving intramolecular nucleophilic attack by pyridyl nitrogen.
- Barraclough, Paul,Gillam, Janet,King, W. Richard,Nebbs, Malcolm S.,Vine, Susan J.
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p. 1359 - 1376
(2007/10/03)
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- An Excellent Method for the Mild and Safe Oxidation of N-Heteroaromatic Compounds and Tertiary Amines
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Selective, mild and safe N-oxidation of N-heteroaromatic compounds and tertiary amines affording high product yields was achieved by using the H2O2-urea/phthalic anhydride system. Key Words: N-Oxidation / Hydrogen peroxide / Urea / Phthalic anhydride
- Kaczmarek, Lukasz,Balicki, Roman,Nantka-Namirski, Pawel
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p. 1965 - 1966
(2007/10/02)
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- Chemistry of Mercaptopyridines and Related Ligands. Part 3. Novel Examples of Copper(II)-Tertiary Phosphine Complexes stabilized by 1-Hydroxypyridine-2-thione
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reaction of 1-hydroxypyridine-2-thione (C5H5NOS) with copper(II) chloride dihydrate gave an insoluble dirty yellow compound of stoichiometry, 1 which is ESR active.Similar reaction with copper(II) bromide gave the ESR-active green compound 7.Reactions of 1 and 7 with tertiary phosphines gave mixed-ligand complexes of stoichiometry CuX(C5H4NOS)Ln , all of which are ESR active.The latter complexes represent the first novel examples of air- and moisture-stable copper(II)-tertiary phopshine complexes in which Cu(II) is bonded to one halogen, one oxygen, one sulfur and two phosphorus atoms.
- Lobana, Tarlok S.,Bhatia, Paramjit K.
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p. 1407 - 1410
(2007/10/02)
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- Periselectivity between the and Thermal Sigmatropic Rearrangements of 2-Allyloxypyridine N-Oxides
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Thermal rearrangement of 2-allyloxypyridine N-oxides (4a-c) yields N-allyloxy-2-pyridones (5a-c) and 3-allyl-N-hydroxy-2-pyridones (6a-c).These transformations are shown to be regiospecific and on this basis it is proposed that the reactions involve concerted and sigmatropic rearrangements.Supporting evidence based on solvent effects, temperature effects, and substituent effects is given.
- Alker, David,Ollis, W. David,Shahriari-Zavareh, Hooshang
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p. 1623 - 1630
(2007/10/02)
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- Pyridinylurea N-oxide compounds and agricultural uses
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Pyridinylurea N-oxides of the formula STR1 and acid addition salts thereof; wherein R is cycloalkyl (C3 -C8), alkenyl (C3 -C8), or an alkyl (C1 -C6) group optionally substituted with halogen, hydroxy, cycloalkyl (C3 -C8) alkoxy (C1 -C6), dialkyl (C1 -C6)amino or phenyl; R1 is hydrogen or alkyl (C1 -C6); R and R1 together with the nitrogen atom of the NRR1 group optionally define a nonaromatic heterocycle containing 4 to 6 ring carbon atoms; each X independently is halogen, alkyl (C1 -C6), haloalkyl (C1 -C6), alkoxy (C1 -C6), hydroxy, 2-pyridinyl, alkyl(C1 -C6)thio or alkyl (C1 -C6)sulfonyl; A is 1 to 4; and wherein the NHCONRR1 group is bonded to the pyridinyl ring in the 3- or 4-position. The compounds are useful in agriculture as plant growth regulators.
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- Oxidation Reactions Using Magnesium Monoperphthalate: A Comparison with m-Chloroperoxybenzoic Acid
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Magnesium monoperphthalate hexahydrate (MMPP), a newly developed reagent with high stability at ambient temperatures, has been shown to oxidise a wide range of substrates under mild conditions: the substrates include alkenes, ketones, sulphides and sulphoxides, pyridine, and dipotassium p-tolylpentafluorosilicate.
- Brougham, Paul,Cooper, Mark S.,Cummerson, David A.,Heaney, Harry,Thompson, Nicola
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p. 1015 - 1017
(2007/10/02)
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- SOLVENT AND TEMPERATURE DEPENDENT REGIOSELECTIVE REACTIONS BETWEEN 2-CHLORO-6-CYANOPYRIDINE AND ALIPHATIC ALCOHOLS
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Reaction of 2-chloro-6-cyanopyridine with aliphatic mono- and di-alcohols or ethylene glycols affords, depending on the reaction conditions, alkoxypyridines or imino ester pyridines or a mixture of both types of compounds.It is suggested that the product distribution is determined by the stability of an imidate anion formed as an intermediate.An improved synthesis of 2-chloro-6-cyanopyridine is also described.
- Elman, Bjoern
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p. 4941 - 4948
(2007/10/02)
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- Reactions of N-Heteroaromatic Bases with Nitrous Acid. Part 6. Kinetics of the Nitrosation of 2- and 4-Methylaminpprridine and their 1-Oxide Derivates
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The nitrosation of 2- and 4-methylaminopyridine and their 1-oxide derivates in 0.002-5.00 M-perchoric acid is of first order in a both the amine and nitrous acid.The respective nitrosamines formed are easily denitrosated under the experimental conditions.The rate coefficients of the nitrosation increase with an increase in the concenration of perchloric acid and sodium perchlorate.In perchloric acid solution whose ionic strength is maintained constant by the addition of sodium perchlorate the rate coefficients of the nitrosation of 2- and 4-methylaminopyridine only show rectilinear dependence on the h0 parameter of the medium.The nitrosation of 2- and 4-methylaminopyridine proceeds mainly by the interaction of the nitrous acidium ion with the protonated form of these amines whilst the nitrosation of 2- and 4-methylaminopyridine 1-oxide proceeds by the simultaneous interaction of the nitrous acidium ion with the protonated and the free form of both amines.The nitrous acidium ion seems to show a distinct discrimination in its reaction with free form of the amines as evidenced by a rectilinear relationship between the rate coefficient of ther nitrosation and their Ka values.The protonated amine 1-oxides react faster than the protonated amines when the hydroxy-group is in para-position with respect to the amino-group and therefore not involved in hydrogen bonding with it.The nitrosation of free and the protonated amines involves an initial interaction between the nitrosating agent and the heteroaromatic nucleus.The present results show that the formation of the respective N-nitroso-derivate is the rate-determining stage of the diazotisation of the N-heteroaromatic amines over the whole of the acid range examined. pKa Values are recorded.
- Kalatzis, Evangelos,Papadopoulos, Panayiotis
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p. 239 - 247
(2007/10/02)
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