- CONTROLLED, REGIOSPECIFIC OXIDATION OF PYRIDINE CARBOXYLIC ACIDS AND ESTERS WITH ELEMENTAL FLUORINE
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Pyridine carboxylic acid salts or esters in water or water-acetonitrile mixtures were treated with elemental fluorine to give the corresponding 2-pyridones.
- Puy, Michael Van Der,Nalewajek, David,Wicks, Gene E.
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Read Online
- LACTAM/LACTIM TAUTOMERIC INTERCONVERSION MECHANISM OF 2-PYRIDONE IN AQUEOUS SOLUTION
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By means of the CNDO/2 method, the participation of a water molecule in the process of interconversion from the form lactam to lactim is rationalised.
- Lledos, A.,Bertran, J.
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Read Online
- Clean protocol for deoxygenation of epoxides to alkenes: Via catalytic hydrogenation using gold
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The epoxidation of olefin as a strategy to protect carbon-carbon double bonds is a well-known procedure in organic synthesis, however the reverse reaction, deprotection/deoxygenation of epoxides is much less developed, despite its potential utility for the synthesis of substituted olefins. Here, we disclose a clean protocol for the selective deprotection of epoxides, by combining commercially available organophosphorus ligands and gold nanoparticles (Au NP). Besides being successfully applied in the deoxygenation of epoxides, the discovered catalytic system also enables the selective reduction N-oxides and sulfoxides using molecular hydrogen as reductant. The Au NP catalyst combined with triethylphosphite P(OEt)3 is remarkably more reactive than solely Au NPs. The method is not only a complementary Au-catalyzed reductive reaction under mild conditions, but also an effective procedure for selective reductions of a wide range of valuable molecules that would be either synthetically inconvenient or even difficult to access by alternative synthetic protocols or by using classical transition metal catalysts. This journal is
- Fiorio, Jhonatan L.,Rossi, Liane M.
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p. 312 - 318
(2021/01/29)
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- Electrochemical-induced hydroxylation of aryl halides in the presence of Et3N in water
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A thorough study of mild and environmentally friendly electrochemical-induced hydroxylation of aryl halides without a catalyst is presented. The best protocol consists of hydroxylation of different aryl iodides and aryl bromides by water solution in the presence of Et3N under air, affording the target phenols in good isolated yields. Moreover, aryl chlorides were successfully employed as substrates. This methodology also provides a direct pathway for the formation of deoxyphomalone, which displayed a significant anti-proliferation effect.
- Ke, Fang,Lin, Chen,Lin, Mei,Long, Hua,Wu, Mei,Yang, Li,Zhuang, Qinglong
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supporting information
p. 6417 - 6421
(2021/08/03)
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- Ni-Catalyzed Aryl Sulfide Synthesis through an Aryl Exchange Reaction
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A Ni-catalyzed aryl sulfide synthesis through an aryl exchange reaction between aryl sulfides and a variety of aryl electrophiles was developed. By using 2-pyridyl sulfide as a sulfide donor, this reaction achieved the synthesis of aryl sulfides without using odorous and toxic thiols. The use of a Ni/dcypt catalyst capable of cleaving and forming aryl-S bonds was important for the aryl exchange reaction between 2-pyridyl sulfides and aryl electrophiles, which include aromatic esters, arenol derivatives, and aryl halides. Mechanistic studies revealed that Ni/dcypt can simultaneously undergo oxidative additions of aryl sulfides and aromatic esters, followed by ligand exchange between the generated aryl-Ni-SR and aryl-Ni-OAr species to furnish aryl exchanged compounds.
- Isshiki, Ryota,Kurosawa, Miki B.,Muto, Kei,Yamaguchi, Junichiro
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p. 10333 - 10340
(2021/07/21)
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- Reactions of 1,2,4-Oxadiazole[4,5-a]piridinium Salts with Alcohols: the Synthesis of Alkoxybutadienyl 1,2,4-Oxadiazoles
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1,2,4-Oxadiazole[4,5-a]piridinium salts add alcohols and alkoxides to undergo electrocyclic ring opening affording alkoxybutadienyl 1,2,4-oxadiazole derivatives. The pyridinium salts represent a special class of Zincke salts that are prone to rearrange to give alkoxybutadienyl 1,2,4-oxadiazoles when treated with suitable nucleophiles or, alternatively, to give pyridones in the presence of bicarbonate. The pivotal tuning of the experimental conditions leads to a straightforward synthesis of valuable 1,2,4-oxadiazole derivatives. The mechanism is also discussed in the light of previous observations.
- Moiola, Mattia,Leusciatti, Marco,Quadrelli, Paolo
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p. 195 - 199
(2020/03/06)
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- Catalytic Reductions Without External Hydrogen Gas: Broad Scope Hydrogenations with Tetrahydroxydiboron and a Tertiary Amine
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Facile reduction of aryl halides with a combination of 5% Pd/C, B2(OH)4, and 4-methylmorpholine is reported. Aryl bromides, iodides, and chlorides were efficiently reduced. Aryl dihalides containing two different halogen atoms underwent selective reduction: I over Br and Cl, and Br over Cl. Beyond these, aryl triflates were efficiently reduced. This combination was broadly general, effectuating reductions of benzylic halides and ethers, alkenes, alkynes, aldehydes, and azides, as well as for N-Cbz deprotection. A cyano group was unaffected, but a nitro group and a ketone underwent reduction to a low extent. When B2(OD)4 was used for aryl halide reduction, a significant amount of deuteriation occurred. However, H atom incorporation competed and increased in slower reactions. 4-Methylmorpholine was identified as a possible source of H atoms in this, but a combination of only 4-methylmorpholine and Pd/C did not result in reduction. Hydrogen gas has been observed to form with this reagent combination. Experiments aimed at understanding the chemistry led to the proposal of a plausible mechanism and to the identification of N,N-bis(methyl-d3)pyridin-4-amine (DMAP-d6) and B2(OD)4 as an effective combination for full aromatic deuteriation. (Figure presented.).
- Korvinson, Kirill A.,Akula, Hari K.,Malinchak, Casina T.,Sebastian, Dellamol,Wei, Wei,Khandaker, Tashrique A.,Andrzejewska, Magdalena R.,Zajc, Barbara,Lakshman, Mahesh K.
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supporting information
p. 166 - 176
(2020/01/02)
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- Application of quebrachitol in hydrolysis reaction of copper-catalyzed aryl halide
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The invention belongs to the technical field of drug synthesis, and provides application of quebrachitol in a hydrolysis reaction of a copper-catalyzed aryl halide. According to the hydrolysis reaction, copper serves as a catalyst, quebrachitol serves as a ligand, and the hydrolysis reaction is carried out on the aryl halide. The invention further provides a catalytic system of the hydrolysis reaction of the aryl halide. The reaction system comprises the copper catalyst, the quebrachitol, alkali and water, and the system is environmentally friendly and is suitable for industrial application.
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Paragraph 0096-0098
(2019/07/16)
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- Chemoselective Demethylation of Methoxypyridine
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A chemoselective demethylation method for various methoxypyridine derivatives has been developed. Treatment of 4-methoxypyridine with L-selectride in THF for 2 h at reflux temperature afforded 4-hydroxypyridine in good yield; no reaction to anisole occurred. The utility of our method was demonstrated by the efficient synthesis of the metabolic substances of the antiulcer agent omeprazole. Chemoselective demethylation at the site of 3,5-dimethyl-4-methoxypyridine in the presence of 4-methoxybenzimidazole was achieved.
- Makino, Kosho,Hasegawa, Yumi,Inoue, Takahide,Araki, Koji,Tabata, Hidetsugu,Oshitari, Tetsuta,Ito, Kiyomi,Natsugari, Hideaki,Takahashi, Hideyo
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p. 951 - 954
(2019/05/10)
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- Preparation method of 2-hydroxypyridine
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The invention relates to the field of pharmaceutical synthesis, and discloses a preparation method of 2-hydroxy pyridine, and 3,5,6-trichloro pyridinol as a raw material is subjected to reduction dechlorination under palladium/carbon catalysis in ammonium formate to obtain the 2-hydroxy pyridine. The method has the advantages of cheap and easily available raw materials, mild reaction conditions, high yield, simple post-treatment, less three wastes, recyclable catalyst, low production cost, low equipment requirement, and the method is a rapid way for small-batch production.
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Paragraph 0023-0025
(2019/07/04)
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- An Improved Rapid and Mild Deoxygenation of Amine N-oxides
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An improved mild and selective method for the deoxygenation of a variety of amine N-oxides has been carried out in the presence of silica gel under mild conditions at room temperature to afford corresponding amines in relatively good yields without purification. The reaction is tolerant of a variety of functional groups such as hydroxyl, ester, acid, carbonyl, and cyano groups, as well as halogens. This method would be of great utility to synthesize various pyridines and amines easily.
- Rajesh
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p. 486 - 491
(2017/12/29)
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- HETEROCYCLIC COMPOUNDS WITH MICROBIOCIDAL PROPERTIES
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The present disclosure relates to a compound of Formula I, wherein the substituents T, A, W, R2, n, Z, G, Z1 and J are as defined in the description.
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Page/Page column 107
(2018/11/22)
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- Photoreductive Removal of O-Benzyl Groups from Oxyarene N-Heterocycles Assisted by O-Pyridine-pyridone Tautomerism
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Facile photoreductive protocols have been developed to remove benzyl O-protective groups from oxyarene N-heterocycles at positions capable for 2-/4-O-pyridine-2-/4-pyridone tautomerism. Blue light irradiation, a [Ru] or [Ir] photocatalyst, and ascorbic acid in a water-acetonitrile solution debenzylates a variety of aryl N-heterocycles cleanly and selectively. Ascorbic acid has two functions in the reaction. On the one hand, it protonates the N-heterocycles that reduces their reduction potentials notably and on the other hand it acts as a sacrificial reductant. Reduction potentials and free energy barriers calculated at the CPCM-B3LYP/6-31+G? level can predict the reactivities of the studied substrates.
- Todorov, Aleksandar R.,Wirtanen, Tom,Helaja, Juho
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p. 13756 - 13767
(2017/12/26)
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- Iridium-catalysed hydrosilylation of cyclopropanes: Via regioselective carbon-carbon bond cleavage
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While cyclopropanes have been explored as synthetically valuable building blocks, their transformation without conjugated substituents or directly substituted heteroatoms remains challenging. The current study describes the iridium-catalysed ring-opening hydrosilylation of cyclopropanes. A nitrogen-based directing group was found to control the reactivity of iridium active species as well as the regiochemistry of carbon-carbon bond cleavage and hydrosilylation.
- Murai, Masahito,Nishiyama, Atsushi,Nishinaka, Naoki,Morita, Haruka,Takai, Kazuhiko
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supporting information
p. 9281 - 9284
(2017/08/21)
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- A catalytic oxidation fragrant boron class compound preparing phenol method (by machine translation)
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The invention discloses a method for catalytic oxidation of phenolic compounds fragrant boron class compound synthesis method, the flux in the solvent in the aqueous solution, under the action of alkali, adding hydrazine hydrate or acid hydrazides catalyst, catalytic oxidation fragrant boron class compound directly for the preparation of phenolic compound. The invention of the method of preparation of the phenol compound, the catalyst is a cheap hydrazine hydrate or hydrazine compound, the oxidizing agent is atmospheric pressure of air or oxygen, the reaction does not need good and activeness metal catalyst, is extensive and stable substrate, substrate-sensitive functional group compatibility good and wide range of application. In the optimized under the reaction conditions, the yield of the target product separation up to 99%. (by machine translation)
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Paragraph 0073; 0075; 0076
(2017/08/08)
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- A Novel Convenient Synthesis of Pyridinyl and Quinolinyl Triflates and Tosylates via One-Pot Diazotization of Aminopyridines and Aminoquinolines in Solution
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The first effective and simple method for the direct one-pot transformation of 2-, 3-, and 4-aminopyridines, 2,6-diaminopyridines, and 2-aminoquinoline into the corresponding pyridinyl and quinolinyl trifluoromethanesulfonates and tosylates in solvents was developed. The procedure involves diazotization of the heterocyclic amines with sodium nitrite in mixed hexane-DMSO or hexane-DMF solutions in the presence of trifluoromethanesulfonic acid or p-toluenesulfonic acid.
- Kassanova, Assiya Zh.,Krasnokutskaya, Elena A.,Beisembai, Perizat S.,Filimonov, Victor D.
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p. 256 - 262
(2016/01/15)
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- Rhodium-catalyzed borylation of aryl 2-pyridyl ethers through cleavage of the carbon-oxygen bond: Borylative removal of the directing group
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The rhodium-catalyzed reaction of aryl 2-pyridyl ethers with a diboron reagent results in the formation of arylboronic acid derivatives via activation of the C(aryl)-O bonds. The straightforward synthesis of 1,2-disubstituted arenes was enabled through catalytic ortho C-H bond functionalization directed by the 2-pyridyloxy group followed by substitution of this group with a boryl group. Several control experiments revealed that the presence of a sp2 nitrogen atom at the 2-position of the substrate and the use of a boron-based reagent were crucial for the activation of the relatively inert C(aryl)-O bond of aryl 2-pyridyl ethers.
- Kinuta, Hirotaka,Tobisu, Mamoru,Chatani, Naoto
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p. 1593 - 1600
(2015/03/05)
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- Continuous-flow synthesis of functionalized phenols by aerobic oxidation of grignard reagents
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Phenols are important compounds in chemical industry. An economical and green approach to phenol preparation by the direct oxidation of aryl Grignard reagents using compressed air in continuous gas-liquid segmented flow systems is described. The process tolerates a broad range of functional groups, including oxidation-sensitive functionalities such as alkenes, amines, and thioethers. By integrating a benzyne-mediated in-line generation of arylmagnesium intermediates with the aerobic oxidation, a facile three-step, one-flow process, capable of preparing 2-functionalized phenols in a modular fashion, is established. Putting on airs: Aerobic oxidation of (hetero)aryl Grignard reagents using compressed air proceeds with a gas-liquid continuous-flow system, thus enabling preparation of fucntionalized phenols. By integrating an in-line generation of ArMgBr intermediates with the aerobic oxidation, ortho-functionalized phenols can be assembled. The method demonstrates good functional-group (FG) compatibility, mild reaction conditions, and short reaction times.
- He, Zhi,Jamison, Timothy F.
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supporting information
p. 3353 - 3357
(2014/04/03)
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- Tosvinyl and besvinyl as protecting groups of imides, azinones, nucleosides, sultams, and lactams. Catalytic conjugate additions to tosylacetylene
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The use of the 2-(4-methylphenylsulfonyl)-ethenyl (tosvinyl, Tsv) group for the protection of the NH group of a series of imides, azinones (including AZT), inosines, and cyclic sulfonamides has been examined. The Tsvprotected derivatives are obtained in excellent yields by conjugate addition to tosylacetylene (ethynyl p-tolyl sulfone). The stereochemistry of the double bond can be controlled at will: with only 1 mol % of Et3N or with catalytic amounts of NaH, the Z stereoisomers are generated almost exclusively, while the E isomers are obtained using a stoichiometric amount of DMAP. Analogous phenylsulfonylvinyl-protected groups (with the besvinyl or Bsv group instead of Tsv) are obtained stereospecifically by reaction with (Z)- or (E)-bis(phenylsulfonyl)ethene. For lactams and oxazolidinones, this last method is much better. The Tsv and Bsv groups are stable in the presence of non-nucleophilic bases and to acids. They can be removed highly effectively via a conjugate addition-elimination mechanism using pyrrolidine or sodium dodecanethiolate as nucleophiles.
- Petit, Elena,Bosch, Llus,Font, Joan,Mola, Laura,Costa, Anna M.,Vilarrasa, Jaume
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p. 8826 - 8834
(2015/01/08)
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- Molecular products from the thermal degradation of glutamic acid
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The thermal behavior of glutamic acid was investigated in N2 and 4% O2 in N2 under flow reactor conditions at a constant residence time of 0.2 s, within a total pyrolysis time of 3 min at 1 atm. The identification of the main pyrolysis products has been reported. Accordingly, the principal products for pyrolysis in order of decreasing abundance were succinimide, pyrrole, acetonitrile, and 2-pyrrolidone. For oxidative pyrolysis, the main products were succinimide, propiolactone, ethanol, and hydrogen cyanide. Whereas benzene, toluene, and a few low molecular weight hydrocarbons (propene, propane, 1-butene, and 2-butene) were detected during pyrolysis, no polycyclic aromatic hydrocarbons (PAHs) were detected. Oxidative pyrolysis yielded low molecular weight hydrocarbon products in trace amounts. The mechanistic channels describing the formation of the major product succinimide have been explored. The detection of succinimide (major product) and maleimide (minor product) from the thermal decomposition of glutamic acid has been reported for the first time in this study. Toxicological implications of some reaction products (HCN, acetonitrile, and acyrolnitrile), which are believed to form during heat treatment of food, tobacco burning, and drug processing, have been discussed in relation to the thermal degradation of glutamic acid.
- Kibet, Joshua K.,Khachatryan, Lavrent,Dellinger, Barry
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p. 7696 - 7704
(2013/09/02)
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- Development of peptidomimetic boronates as proteasome inhibitors
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Proteasome inhibition has emerged over the past decade as an effective therapeutic approach for the treatment of hematologic malignancies. It is a multicatalytic complex, whose proteolytic activity relies in three types of subunits: chymotrypsin-like (β5), trypsin-like (β2) and caspase-like (β1). Most important for the development of effective antitumor agents is the inhibition of the β5 subunits. In this context, the dipeptide boronate bortezomib (Velcade) represents the first proteasome inhibitor approved by the FDA and the lead compound in drug discovery. This paper describes the synthesis and biological evaluation of a series of conformationally constrained pseudopeptide boronates (1-3) structurally related to bortezomib. The synthesized compounds showed a promising inhibitory profile by blocking primarily the chymotrypsin-like activity of the proteasome with Ki values in submicromolar/micromolar range. These compounds also resulted quite selective since no significant inhibition was recorded in the test against bovine pancreatic α-chymotrypsin. The obtained results were rationalized by means of docking experiments based on a model of the crystal structure of bortezomib bound to the yeast 20S proteasome providing essential insights for further optimization of this class of inhibitors.
- Micale, Nicola,Ettari, Roberta,Lavecchia, Antonio,Di Giovanni, Carmen,Scarbaci, Kety,Troiano, Valeria,Grasso, Silvana,Novellino, Ettore,Schirmeister, Tanja,Zappalà, Maria
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- Reduction of sulfoxides and pyridine-N-oxides over iron powder with water as hydrogen source promoted by carbon dioxide
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A green process was developed for efficient reduction of sulfoxides and pyridine-N-oxides using the iron powder in the presence of H2O- CO2 to sulfides and pyridines, respectively. Notably, H2O is employed as the terminal hydrogen source, and CO2 could enhance hydrogen generation through in situ formation of carbonic acid. Thus carbonic acid offers simple neutralization by depressurizing CO2 and the system can eliminate unwanted byproducts. The high generality and chemo-selectivity of this protocol were demonstrated by the scope of substrates, in which chlorine, vinyl group and benzene ring can be tolerated.
- Ma, Ran,Liu, An-Hua,Huang, Cheng-Bin,Li, Xue-Dong,He, Liang-Nian
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supporting information
p. 1274 - 1279
(2013/06/05)
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- Pd2dba3/Bippyphos: A robust catalyst system for the hydroxylation of aryl halides with broad substrate scope
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A mixture of tris(dibenzylideneacetone)dipalladium(0) (Pd 2dba3) and 5-(di-tert-butylphosphino)-1′,3′, 5′-triphenyl-1′H-[1,4′]bipyrazole (Bippyphos) is shown to be a robust and efficient catalyst system for the hydroxylation of structurally diverse (hetero)aryl halides under mild conditions and with broad substrate scope. Included in this reactivity survey is the successful synthesis of substituted benzofurans and related heteroatomic derivatives, which are formed via the hydroxylation of 2-haloalkynylarenes. Notably, a significant number of the reactions reported herein proceed at room temperature, and we have demonstrated that it is possible to conduct reactions on the benchtop under air using unpurified solvents with negligible loss in reactivity versus related transformations conducted under inert atmosphere conditions. We also report herein the first crystallographically characterized (Bippyphos)Pd(II) complex, which confirms the ability of this synthetically useful ligand to adopt a bidentate binding motif in a manner similar to Buchwald's biarylphosphine ligand class. Copyright
- Lavery, Christopher B.,Rotta-Loria, Nicolas L.,McDonald, Robert,Stradiotto, Mark
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supporting information
p. 981 - 987
(2013/05/08)
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- The spontaneous hydrolysis of 2-pyridyl phosphate is a good model for the special mechanism for the hydrolysis of phosphate monoester monoanions
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The microscopic pKa of the pyridine N of the phosphate monoester 2-pyridyl phosphate (MPP) is 2.76, significantly higher than that expected for the leaving group (RO) oxygen of a typical monoester ROPO3 =. This favours the prototropic equilibrium considered to be the key step in the rapid hydrolysis of a typical monoester, and the observed rate of hydrolysis of the monoanion MPP- is shown to be close to that expected for the protomer MPP+=, with neutral 2-pyridone as the leaving group. Copyright 2013 John Wiley & Sons, Ltd. The prototropic equilibrium is a key step in the hydrolysis of monoester MPP-, allowing neutral 2-pyridone to be the leaving group from MPP+=. Copyright
- Medeiros, Michelle,Manfredi, Alex M.,Kirby, Anthony J.,Nome, Faruk
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p. 1044 - 1047
(2014/01/06)
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- Nucleophile-catalyzed additions to activated triple bonds. protection of lactams, imides, and nucleosides with MocVinyl and related groups
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Additions of lactams, imides, (S)-4-benzyl-1,3-oxazolidin-2-one, 2-pyridone, pyrimidine-2,4-diones (AZT derivatives), or inosines to the electron-deficient triple bonds of methyl propynoate, tert-butyl propynoate, 3-butyn-2-one, N-propynoylmorpholine, or
- Mola, Laura,Font, Joan,Bosch, Lluis,Caner, Joaquim,Costa, Anna M.,Etxebarria-Jardi, Gorka,Pineda, Oriol,De Vicente, David,Vilarrasa, Jaume
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p. 5832 - 5842
(2013/07/26)
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- Ir(I)-catalyzed synthesis of N-substituted pyridones from 2-alkoxypyridines via C-O bond cleavage
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A cationic Ir(I) complex-catalyzed O-to-N-alkyl migration in 2-alkoxypyridines bearing a secondary alkyl group on the oxygen atom by C-O bond cleavage is described. The present transformation gave various N-alkylpyridones in moderate to good yields. The addition of sodium acetate played a key role in suppressing β-hydrogen elimination.
- Pan, Shiguang,Ryu, Naoto,Shibata, Takanori
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supporting information
p. 1902 - 1905
(2013/06/04)
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- Intramolecular general base catalysis in the hydrolysis of a phosphate diester. calculational guidance to a choice of mechanism
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Notwithstanding its half-life of 70 years at 25 C, the spontaneous hydrolysis of the anion of di-2-pyridyl phosphate (DPP) is thousands of times faster (ca. 3000 at 100 C, over 10000-fold at 25 C) than expected for a diester with leaving groups of pKa 9.09. The kinetic parameters do not permit a conclusive choice between five possible mechanisms considered, but the combination of kinetics and calculational evidence supports a single-step, concerted, SN2(P) mechanism involving the attack of solvent water on phosphorus assisted by intramolecular catalysis by a (weakly basic) pyridine nitrogen acting as a general base. Catalysis is relatively efficient for this mechanism, with an estimated effective molarity (EM) of the general base of >15 M, consistent with the absence of catalysis by typical buffers. Further new results confirm that varying the nonleaving group has minimal effect on the rate of spontaneous diester hydrolysis, in striking contrast to the major effect on the corresponding reaction of triesters: though protonation of one nitrogen of DPP- increases the rate of hydrolysis by 6 orders of magnitude, in line with expectation.
- Kirby, Anthony J.,Medeiros, Michelle,Mora, José R.,Oliveira, Pedro S. M.,Amer, Almahdi,Williams, Nicholas H.,Nome, Faruk
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p. 1343 - 1353
(2013/03/28)
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- Expanding the scope of silane-mediated hydrodehalogenation reactions
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A palladium-catalysed, silane-mediated hydrodehalogenation (HDH) reaction with increased substrate scope has been developed. Whereas previous attempts to reduce carboxylic acid or phenol-containing aryl halides using silane-based HDH conditions failed, the current protocol allows efficient access to the reduced products. Chemoselective HDH in the presence of sensitive functional groups is also presented.
- Noonan, Gary M.,Hayter, Barry R.,Campbell, Andrew D.,Gorman, Timothy W.,Partridge, Benjamin E.,Lamont, Gill M.
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p. 4518 - 4521
(2013/08/23)
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- A kinetic study on aminolysis of benzyl 2-pyridyl thionocarbonate and t-butyl 2-pyridyl thionocarbonate: Effects of polarizability and steric hindrance on reactivity and reaction mechanism
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Second-order rate constants kN have been measured for reactions of benzyl 2-pyridyl thionocarbonate (4b) and t-butyl 2-pyridyl thionocarbonate (5b) with a series of cyclic secondary amines in MeCN at 25.0 ± 0.1 °C. The kN values for the reactions of 4b and 5b have been compared with those reported previously for the corresponding reactions of benzyl 2-pyridyl carbonate (4a) and t-butyl 2-pyridyl carbonate (5a) to investigate the effect of changing the electrophilic center from C=O to C=S on reactivity and reaction mechanism. The thiono compound 4b is more reactive than its oxygen analogue 4a. The Bronsted-type plots for the reactions of 4a and 4b are linear with βnuc = 0.57 and 0.37, respectively. The reactions of 4a were previously reported to proceed through a concerted mechanism, while those of 4b in this study have been concluded to proceed through a stepwise mechanism with formation of an intermediate being the rate-determining step on the basis of the βnuc value of 0.37. Enhanced polarizability upon changing the C=O in 4a by C=S has been suggested to be responsible for the reactivity order and the contrasting reaction mechanisms. In contrast, the reactivity of 5a and 5b is similar, but they are much less reactive than 4a and 4b. Furthermore, the reactions of 5a and 5b have been concluded to proceed through the same mechanism (i.e., a concerted mechanism) on the basis of linear Bronsted-type plots with βnuc = 0.45 or 0.47. It has been concluded that the strong steric hindrance exerted by the t-Bu in 5a and 5b causes a decrease in their reactivity and forces the reactions to proceed through a concerted mechanism.
- Kim, Min-Young,Bae, Ae Ri,Um, Ik-Hwan
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p. 2325 - 2329
(2013/09/24)
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- Use of the graebe-ullmann reaction in the synthesis of 8-methyl-γ- carboline and isomeric aromatic aza-γ-carbolines
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Two variants of the Graebe-Ullmann reaction were used to obtain 8-methyl-5H-pyrido[4,3-b]indole (8-methyl-γ-carboline) and the conditions for this reaction were optimized. The feasibility of using this method was studied for the synthesis of a series of isomeric aromatic aza-γ- carbolines from the corresponding 1-(pyridyl)-1H-1,2,3-triazolo[4,5-c]pyridines under thermal and microwave irradiation conditions.
- Alekseev,Kurkin,Yurovskaya
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p. 1235 - 1250
(2013/03/13)
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- Au(III)-catalyzed tandem amination - Hydration of alkynes: Synthesis of α-(N -2-pyridonyl)ketones
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A new Au(III)-catalyzed tandem amination - hydration reaction has been discovered, leading to the formation of α-(N-2-pyridonyl)ketones and heterocyclic analogues in good to excellent yields (14 examples, 48 - 90%). This reaction demonstrates the unusual use of a heterocyclic sp2 nitrogen nucleophile in a gold-catalyzed 6-endo-dig cyclization. The tandem process allows rapid access to α-(N-2-pyridonyl)ketones, making them a convenient building block for the synthesis of more complex N-alkyl pyridone targets.
- Romero, Nathan A.,Klepser, Benjamin M.,Anderson, Carolyn E.
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supporting information; experimental part
p. 874 - 877
(2012/05/05)
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- Efficient and selective demethylation of heteroaryl methyl ethers in the presence of aryl methyl ethers
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A new and efficient method for the demethylation of 6-membered aza-heterocyclic methyl ethers is described using lithium chloride and para-toluenesulfonic acid. This process is chemoselective for aza-heterocyclic methyl ethers in the presence of aryl methyl ethers.
- Soni, Ajay,Dutt, Akhilesh,Sattigeri, Viswajanani,Cliffe, Ian A.
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scheme or table
p. 1852 - 1857
(2011/06/20)
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- Non-standard nucleoside analogs with reduced epimerization
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This invention relates to nucleoside, nucleotide, and oligonucleotide analogs that incorporate non-standard nucleobase analogs, defined to be those that present a pattern of hydrogen bonds to a paired nucleobase analog in a complementary strand that is different from the pattern presented by adenine, guanine, cytosine, and thymine. The invention is specifically concerned with compositions of matter that present the donor-donor-acceptor, donor-acceptor-donor, and acceptor-donor-donor non-standard hydrogen bonding patterns on pyrimidine analogs, where nucleoside analogs bearing these pyrimidine analogs do not epimerize as easily as those known in the art. The heterocycles on these nucleoside analogs are diaminopyridines and aminopyridones that have electron withdrawing groups attached to the position analogous to the 5-position of the ring in standard pyrimidines, including nitro, cyano, and carboxylic acid derivatives.
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- Activating water: Important effects of non-leaving groups on the hydrolysis of phosphate triesters
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The high rate of spontaneous hydrolysis of tris-2-pyridyl phosphate (TPP) is explained by the activating effects of the non-leaving ("spectator" ) groups on P-OAr cleavage, and not by intramolecular catalysis. Previous work on phosphate-transfer reactions has concentrated on the contributions to reactivity of the nucleophile and the leaving group, but our results make clear that the effects of the non-leaving groups on phosphorus can be equally significant. Rate measurements for three series of phosphate triesters showed that sensitivities to the non-leaving groups are substantial for spontaneous hydrolysis reactions, although significantly smaller for reactions with good nucleophiles. There are clear differences between triaryl and dialkyl aryl triesters in sensitivities to leaving and non-leaving groups with the more reactive triaryl systems showing lower values for both βLG and βNLG. Intramolecular catalysis of the hydrolysis of TPP by the neighbouring pyridine nitrogens is insignificant, primarily because of their low basicity.
- Kirby, Anthony J.,Medeiros, Michelle,Oliveira, Pedro S. M.,Orth, Elisa S.,Brandao, Tiago A. S.,Wanderlind, Eduardo H.,Amer, Almahdi,Williams, Nicholas H.,Nome, Faruk
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supporting information; experimental part
p. 14996 - 15004
(2012/02/03)
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- Heterocyclic antiviral compounds
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Compounds having the formula I wherein R1, R2, R3, R4a, R4b, R4c, R5, R6, R9 and n are as defined herein are Hepatitis C virus NS5b polymerase inhibitors. Also disclosed are compositions and methods for treating an HCV infection and inhibiting HCV replication.
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- HETEROCYCLIC ANTIVIRAL COMPOUNDS
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Compounds having the formula I wherein R1, R2, R3a, R3b, R3c, R4, R5 and p are as defined herein are Hepatitis C virus NS5b polymerase inhibitors. Also disclosed are compositions and methods for treating an HCV infection and inhibiting HCV replication.
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- Lithium pipecolinate as a facile and efficient ligand for copper-catalyzed hydroxylation of aryl halides in water
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Direct hydroxylation of a wide scope of aryl halides was catalyzed by a combination of CuI and lithium pipecolinate in water with yields up to 92%.
- Jing, Linhai,Wei, Jiangtao,Zhou, Li,Huang, Zhiyong,Li, Zhengkai,Zhou, Xiangge
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supporting information; experimental part
p. 4767 - 4769
(2010/09/03)
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- NOVEL AROMATIC COMPOUND AND POLYARYLENE COPOLYMER HAVING NITROGEN-CONTAINING HETEROCYCLE INCLUDING SULFONIC ACID GROUP IN SIDE CHAIN
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Provided is a solid polymer electrolyte having increased heat resistance and high proton conductivity and a proton conductive membrane composed of the electrolyte. Also provided is a copolymer having a sulfonic acid group. The copolymer includes a repeating unit represented by Formula (1): (in the formula, Y denotes at least one kind of structure selected from the group consisting of —CO—, —SO2—, —SO—, —CONH—, —COO—, —(CF2)l— (l is an integer of 1 to 10), and —C(CF3)2—; W denotes at least one kind of structure selected from the group consisting of a direct bond, —CO—, —SO2—, —SO—, —CONH—, —COO—, —(CF2)l— (l is an integer of 1 to 10), —C(CF3)2—, —O—, and —S—; Z denotes a direct bond or at least one kind of structure selected from the group consisting of —(CH2)l—(l is an integer of 1 to 10), —C(CH3)2—, —O—, —S—, —CO—, and —SO2—; R30 denotes a nitrogen-containing aromatic ring having a substituent represented by —SO3H, —O(CH2)hSO3H, or —O(CF2)hSO3H (h is an integer of 1 to 12); p is an integer of 0 to 10; q is an integer of 0 to 10; r is an integer of 1 to 5; and k is an integer of 0 to 4).
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- Copper-catalyzed direct preparation of phenols from aryl halides
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A method for direct preparation of phenols from aryl halides using microwave heating is reported. A catalyst system comprising a simple copper salt and a diamine ligand is used, together with tripotassium phosphate as base and water as the solvent. Heating at 180 °C for 30 min allows for the conversion of a range of aryl bromides and iodides to the corresponding phenols. Aryl chlorides prove less reactive.
- Mehmood, Arshad,Leadbeater, Nicholas E.
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experimental part
p. 64 - 66
(2011/01/12)
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- Difluoromethyl 2-pyridyl sulfone: A new gem-difluoroolefination reagent for aldehydes and ketones
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Chemical equation presented Difluoromethyl 2-pyridyl sulfone, a previously unknown compound, was found to act as a novel and efficient gem-difluoroolefination reagent for both aldehydes and ketones. It was found that the fluorinated sulfinate intermediate in the reaction is relatively stable, which can be observed by 19F NMR and trapped with CH 3l.
- Zhao, Yanchuan,Huang, Weizhou,Zhu, Lingui,Hu, Jinbo
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supporting information; experimental part
p. 1444 - 1447
(2010/06/20)
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- A kinetic study on aminolysis of 2-pyridyl X-substituted benzoates: Effect of changing leaving group from 4-nitrophenolate to 2-pyridinolate on reactivity and mechanism
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Second-order rate constants (kN) have been measured spectrophotometrically for nucleophilic substitution reactions of 2-pyridyl X-substituted benzoates 8a-e with a series of alicyclic secondary amines in H2O at 25.0 ± 0.1 °C. The kN values for the reactions of 8a-e are slightly smaller than the corresponding reactions of 4-nitrophenyl X-substituted benzoates 1a-e (e.g., kN 1a-e/kN8a-e = 1.1 3.1), although 2-pyridinolate in 8a-e is ca. 4.5 pKa units more basic than 4-nitrophenolate in 1a-e. The Bronsted-type plot for the aminolysis of 8c (X = H) is linear with βnuc = 0.77 and R2 = 0.991 (Figure 1), which is typical for reactions reported previously to proceed through a stepwise mechanism with breakdown of a zwitterionic tetrahedral intermediate T± being the rate-determining step (RDS), e.g., aminolysis of 4-nitrophenyl benzoate 1c. The Hammett plot for the reactions of 8a-e with piperidine consists of two intersecting straight lines (Figure 2), i.e., ρ = 1.71 for substrates possessing an electron-donating group (EDG) while ρ = 0.86 for those bearing an electron-withdrawing group (EWG). Traditionally, such a nonlinear Hammett plot has been interpreted as a change in RDS upon changing substituent X in the benzoyl moiety. However, it has been proposed that the nonlinear Hammett is not due to a change in RDS since the corresponding Yukawa-Tsuno plot exhibits excellent linear correlation with ρ = 0.85 and r = 0.62 (R2 = 0.995, Figure 3). Stabilization of substrates 8a-e in the ground state has been concluded to be responsible for the nonlinear Hammett plot.
- Lee, Jong Pal,Bae, Ae Ri,Im, Li-Ra,Um, Ik-Hwan
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experimental part
p. 3588 - 3592
(2011/10/02)
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- NOVEL PIPERAZINE DERIVATIVES AS INHIBITORS OF STEAROYL-CoA DESATURASE
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The present invention relates to piperazine derivatives that act as inhibitors of stearoyl-CoA desaturase. The invention also relates to methods of preparing the compounds, compositions containing the compounds, and to methods of treatment using the compounds.
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Page/Page column 31
(2009/10/01)
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- Photolabile N-hydroxypyrid-2(1H)-one derivatives of guanine nucleosides: A new method for independent guanine radical generation
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One-electron oxidized guanine is an important reactive intermediate in the formation of oxidatively generated damage in DNA and a variety of methods have been utilized for the abstraction of a single electron from the guanine moiety. In this study, an alt
- Kaloudis, Panagiotis,Paris, Cecilia,Vrantza, Despoina,Encinas, Susana,Perez-Ruiz, Raul,Miranda, Miguel A.,Gimisis, Thanasis
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supporting information; experimental part
p. 4965 - 4972
(2010/02/16)
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- Mechanism of the triplet-sensitized photolysis of 1-[1-(1-naphthyl)ethoxy]-2-pyridone and related derivatives
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On irradiation at 366 nm in the presence of benzophenone, the title 2-pyridone derivatives (1) in nitrogen-saturated acetonitrile underwent sensitized decomposition to give arylaldehyde and 2-methoxypyridine in addition to the expected N-O bond cleavage p
- Watanabe, Asako,Matsushita, Maya,Masuda, Aya,Igarashi, Tetsutaro,Sakurai, Tadamitsu
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experimental part
p. 2431 - 2437
(2010/04/25)
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- Pyridinium N-heteroarylaminides: synthesis of N-heteroarylpolyamines
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The synthesis of a set of new N-heteroarylpolyamines is reported. A multiple and regioselective alkylation on the exo nitrogen of pyridinium N-(heteroaryl)aminides with several polybromo compounds, followed by a clean N-N bond reduction of the corresponding pyridinium salts, provides an easy and general method to obtain the title compounds.
- Castillo, Rafael R.,Córdoba, Marta,Izquierdo, M. Luisa,Alvarez-Builla, Julio
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scheme or table
p. 9782 - 9790
(2010/02/27)
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- Synthesis and rearrangement of quinone-embedded epoxycyclopentenones: A new avenue to pyranonaphthoquinones and indenopyranones
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The epoxyquinones (e.g., 24), readily assembled in one step from the quinols (e.g., 27) by a simplified version of the Dowd oxidation, are shown to undergo rearrangement to pyranonaphthoquinones (e.g., 28) and their ring contracted homologues (e.g., 29) on flash vacuum pyrolysis at 450 °C and 0.01 Torr. The rearrangement has been demonstrated to be useful for a regiospecific synthesis of lambertellin (3). Similarly, the masked aziridinocyclopentanone 9 rearranges to 2-pyridone (37).
- De Saroj,Ghorai, Sujit K.,Mal, Dipakranjan
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body text
p. 1598 - 1604
(2009/07/17)
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- Activating water: Efficient intramolecular general base catalysis of the hydrolysis of a phosphate triester
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We have identified the first highly efficient intramolecular general base catalysis (IGBC) of a hydrolysis reaction, in a system where two general bases are available to assist the attack of the same nucleophilic water molecule. The suggested mechanism, a
- Kirby, Anthony J.,Medeiros, Michelle,Oliveira, Pedro S.M.,Brandao, Tiago A.S.,Nome, Faruk
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experimental part
p. 8475 - 8479
(2010/07/14)
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- Catalytic deoxygenation of pyridine N-oxides with N-fused porphyrin rhenium complexes
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Deoxygenation reactions of pyridine N-oxide derivatives catalyzed by N-fused porphyrin rhenium(VII) trioxo complexes are developed, affording the corresponding pyridine derivatives in quantitative yields with excellent turnover numbers up to 340,000.
- Toganoh, Motoki,Fujino, Keitaro,Ikeda, Shinya,Furuta, Hiroyuki
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p. 1488 - 1491
(2008/09/18)
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- Synthesis and molecular structure of 1-(2-pyridyloxy)silatrane
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1-(2-Pyridyloxy)silatrane was synthesized by trans-etherification of 1-ethoxysilatrane with 2-hydroxypyridine as well as by the reaction of the latter with tetraethoxysilane and triethanolamine. Its structure was established by the XRD analysis of a single crystal, and in solution using the methods of 1H, 13C, 29Si NMR and IR spectroscopy.
- Voronkov,Zelbst,Bolgova, Yu. I.,Trofimova,Albanov,Chipanina,Aksamentova,Korlyukov,Antipin, M. Yu.
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body text
p. 2333 - 2338
(2009/05/30)
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- Functional mimicry of carboxypeptidase A by a combination of transition state stabilization and a defined orientation of catalytic moieties in molecularly imprinted polymers
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An artificial model for the natural enzyme carboxypeptidase A has been constructed by molecular imprinting in synthetic polymers. The tetrahedral transition state analogues (TSAs 4 and 5) for the carbonate hydrolysis have been designed as templates to allow incorporation of the main catalytic elements, an amidinium group and a Zn2+ or Cu2+ center, in a defined orientation in the transition state imprinted active site. The complexation of the functional monomer and the template in presence of Cu2+ through stoichiometric noncovalent interaction was established on the basis of 1H NMR studies and potentiometric titration. The Cu2+ center was introduced into the imprinted cavity during polymerization or by substitution of Zn2+ in Zn2+ imprinted polymers. The direct introduction displayed obvious advantages in promoting catalytic efficiency. With substrates exhibiting a very similar structure to the template, an extraordinarily high enhancement of the rate of catalyzed to uncatalyzed reaction (Kcat/kuncat) of 105-fold was observed. If two amidinium moieties are introduced in proximity to one Cu 2+ center in the imprinted cavity by complexation of the functional monomer 3 with the template 5, the imprinted catalysts exhibited even higher activities and efficiencies for the carbonate hydrolysis with k cat/Kuncat as high as 410 000. These are by far the highest values obtained for molecularly imprinted catalysts, and they are also considerably higher compared to catalytic antibodies. Our kinetic studies and competitive inhibition experiments with the TSA template showed a clear indication of a very efficient imprinting procedure. In addition, this demonstrates the important role of the transition state stabilization during the catalysis of this reaction.
- Liu, Jun-Qiu,Wulff, Guenter
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experimental part
p. 8044 - 8054
(2009/02/01)
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- Hydrogen peroxide promoted hydroxylation of haloarenes and heteroarenes
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Addition of aqueous hydrogen peroxide significantly accelerates the substitution reactions of hydroxide salts with haloarenes bearing electron withdrawing substituents. A similar effect is observed in the reactions of hydroxide salts with halogenated heteroarenes. Reactions are carried out in water or water-THF at ambient temperature or at 50-60 °C.
- Cantrell Jr., William R.,Bauta, William E.,Engles, Tracy
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p. 4249 - 4251
(2007/10/03)
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- Pyridinones to treat and prevent bacterial infections
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Novel pyridinones and their derivatives which are effective in treating or preventing Gram-negative bacterial infections are provided. The pyridinones are stable and easily derivatized; the methods by which these derivatizations occur is described. Two regioselective and functional group tolerant methods for the synthesis of the novel pyridinones are also provided. One such synthetic method involves reacting an imine and a Meldrum's acid derivative in solution. The other synthetic method is a solid phase synthesis of the pyridinones in which an imine is prepared bound to a solid support and a Meldrum's acid derivative is reacted with the imine. Novel imine intermediates useful in the solid phase and solution methods of synthesizing the pyridionones are also described.
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