- Nanoreactor of MOF-Derived Yolk-Shell Co@C-N: Precisely Controllable Structure and Enhanced Catalytic Activity
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Hollow yolk-shell nanoreactors are of great interest in heterogeneous catalysis owing to their improved mass transfer ability and stability. Here, we report a facile and straight route to synthesize a highly efficient and recyclable yolk-shell Co@C-N nanoreactor with controllable properties by the direct thermolysis of a hollow Zn/Co-ZIF precursor. Based on systematical optimization of the pyrolysis temperature and the shell-thickness of Zn/Co-ZIFs, we could completely anchor and stabilize uniform Co nanoparticles (NPs) in the hollow yolk, accommodated by the Co-ZIF derived N-doped carbon nanosheets. This nanosheet-assembled yolk was further confined by a permeable and robust N-doped carbon (C-N) shell to protect the Co NPs against leaching and also enabled the reaction to take place in the hollow void. Consequently, the optimal yolk-shell Co@C-N nanoreactor showed a significantly enhanced catalytic activity for the aqueous oxidation of alcohols, yielding >99% conversion under atmospheric air and base-free conditions, which was much higher than that of the solid counterparts derived from pure ZIF-67 and solid core-shell ZIF-67@ZIF-8 precursors (with 14% and 59% conversion under the same reaction condition, respectively). The enhanced catalytic activity should be attributed to the yolk-shell structure that could facilitate the transport of reactant/product and the strong interaction between the Co NPs and N-doped carbon nanosheet to afford positive synergistic effects. Moreover, this catalyst also showed good recyclability, magnetically reusability, and general applicability for a broad substrate scope, further highlighting the structure superiority of our yolk-shell nanoreactor. This strategy might open an avenue to synthesize various hollow yolk-shell nanoreactors with controllable structures and enhanced catalytic performances.
- Chen, Huirong,Shen, Kui,Mao, Qing,Chen, Junying,Li, Yingwei
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- Microwave Assisted Improved Synthesis of 6-Formylpterin and Other Heterocyclic Mono- and Di-aldehydes
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2-Pivaloylamino-6-formylpterin (1a) and a series of other important heterocyclic aldehydes (2a, 3a, 4a, 6a, and 7a) have been synthesized in good yield by microwave assisted selenium dioxide oxidation. Interestingly, 2-methylpyrazine gives 2-pyrazinecarboxylic acid (5a) under the similar condition.
- Goswami, Shyamaprosad,Adak, Avijit Kumar
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- Aerobic oxidation of primary alcohols catalyzed by copper complexes of 1,10-phenanthroline-derived ligands
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Five copper complexes [(L1)2Cu(H2O)] (ClO4)2 (1), [(L1)Cu(H2O) 3](ClO4)2 (1a), [(L3) 2Cu(H2O)](ClO4)2 (2), [(L 5)2Cu(H2O)](ClO4)2 (3) and [(L6)2Cu](ClO4) (4) (where L1 = 1,10-phenanthroline, L3 = 1,10-phenanthroline-5,6-dione, L 5 = 1,10-phenanthrolinefuroxan and L6 = 2,9-dimethyl-1,10-phenanthrolinefuroxan), and in situ prepared copper complexes of 2,9-dimethyl-1,10-phenanthroline (L2) or 2,9-dimethyl-1,10- phenanthrolinedione (L4) were used for aerial oxidation of primary alcohols to the corresponding aldehydes under ambient conditions. The copper catalysts have been found to catalyze a series of primary alcohols including one secondary alcohol with moderate turnover numbers and selectivity towards primary alcohols. Copper(ii) complexes 1 (or 1a) and 2 were found to be the better catalysts among all other systems explored in this study. A copper(ii)-superoxo species is implicated to initiate the oxidation reaction. Structural and electronic factors of 1,10-phenanthroline-based ligands affecting the catalytic results for aerial oxidation of alcohols are discussed.
- Das, Oindrila,Paine, Tapan Kanti
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- Mild and convenient oxidation of aromatic heterocyclic primary alcohols by 4-acetylamino-2,2,6,6-tetramethylpiperidine-1-oxoammonium perchlorate
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Hydroxymethyl substituted aromatic heterocycles, including pyridines, furans, and thiophenes, are oxidized to the corresponding aldehydes in excellent yields by 4-acetylamino-2,2,6,6-tetramethylpiperidine-1- oxoammonium perchlorate (1) with minimal workup.
- Kernag, Casey A.,Bobbitt, James M.,McGrath, Dominic V.
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- Methyl Scanning and Revised Binding Mode of 2-Pralidoxime, an Antidote for Nerve Agent Poisoning
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Organophosphorus nerve agents (OPNAs) inhibit acetylcholinesterase (AChE) and, despite the Chemical Weapons Convention arms control treaty, continue to represent a threat to both military personnel and civilians. 2-Pralidoxime (2-PAM) is currently the only therapeutic countermeasure approved by the United States Food and Drug Administration for treating OPNA poisoning. However, 2-PAM is not centrally active due to its hydrophilicity and resulting poor blood-brain barrier permeability; hence, these deficiencies warrant the development of more hydrophobic analogs. Specifically, gaps exist in previously published structure activity relationship (SAR) studies for 2-PAM, thereby making it difficult to rationally design novel analogs that are concomitantly more permeable and more efficacious. In this study, we methodically performed a methyl scan on the core pyridinium of 2-PAM to identify ring positions that could tolerate both additional steric bulk and hydrophobicity. Subsequently, SAR-guided molecular docking was used to rationalize hydropathically feasible binding modes for 2-PAM and the reported derivatives. Overall, the data presented herein provide new insights that may facilitate the rational design of more efficacious 2-PAM analogs.
- Gambino, Adriana,Burnett, James C.,Koide, Kazunori
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supporting information
p. 1893 - 1898
(2020/02/06)
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- ANALOGS OF 2-PRALIDOXIME AS ANTIDOTES AGAINST ORGANOPHOSPHORUS NERVE AGENTS
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Provided herein are compounds useful in treating exposure to an organophosphorus compound, such as a nerve agent, pesticide, or, generally, an acetylcholinesterase inhibitor, such as sarin. Compositions, e.g. pharmaceutical compositions or dosage forms, comprising the compounds also are provided herein. Methods of treating a patient exposed to a nerve agent, pesticide, or, generally, an acetylcholinesterase inhibitor, e.g., an organophosphorus compound, such as sarin, also are provided.
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Paragraph 00121
(2020/02/23)
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- Effect of substituent in pyridine-2-carbaldehydes on their heterocyclization to 1,2,4-triazines and 1,2,4-triazine 4-oxides
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A series of substituted pyridine-2-carbaldehydes were brought into heterocyclization with isonitrosoacetophenone hydrazones, followed by aromatization by the action of oxidants or by dehydration in boiling acetic acid. As a result, substituted 3-(pyridin-2-yl)-1,2,4-triazines or 3-(pyridin-2-yl)-1,2,4-triazine 4-oxides were formed. 6-Formylpyridine-2-carbonitrile failed to undergo heterocyclization, 6-methylpyridine-2-carbaldehyde and methyl 6-formylpyridine-3-carboxylate can be converted to both 1,2,4-triazine and 1,2,4-triazine 4-oxide derivative, and only 1,2,4-triazine 4 oxides were obtained from 6-bromopyridine-2-carbaldehyde and 6-formyl-3-phenylpyridine-2-carbonitrile. Convenient procedures were proposed for the synthesis of some initial pyridinecarbaldehydes.
- Krinochkin,Kopchuk,Chepchugov,Kovalev,Zyryanov,Rusinov,Chupakhin
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p. 963 - 970
(2017/09/07)
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- Acceptorless dehydrogenation of alcohols on a diruthenium(II,II) platform
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The diruthenium(II,II) complex [Ru2(L1)(OAc)3]Cl (1), spanned by a naphthyridine-diimine ligand and bridged by three acetates, has been synthesized. The catalytic efficacy of complex 1 has been evaluated for the acceptorless dehydrogenation (AD) of alcohols and for the dehydrogenative coupling reactions of alcohols with Wittig reagents. The diruthenium(II,II) complex is an excellent catalyst for AD of a diverse range of alcohols, and it is shown to be particularly effective for the conversion of primary alcohols to the corresponding aldehydes without undesired side products such as esters. Triphenylphosphonium ylides in a one-pot reaction with alcohols afforded the corresponding olefins in high yields with excellent E selectivity. The liberated dihydrogen gas was identified and measured to be 1 equiv with respect to alcohol. Deuteration studies with PhCD2OH revealed the absence of isotope scrambling in the product, indicating the involvement of a Ru-monohydride intermediate. Kinetic studies and DFT calculations suggest a low-energy bimetallic β-hydride elimination pathway where rate-limiting intramolecular proton transfer from alcohol to metal-bound hydride constitutes the dehydrogenation step. The general utility of metal-metal bonded compounds for alcohol AD and subsequent coupling reactions is demonstrated here.
- Dutta, Indranil,Sarbajna, Abir,Pandey, Pragati,Rahaman, S. M. Wahidur,Singh, Kuldeep,Bera, Jitendra K.
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p. 1505 - 1513
(2016/06/09)
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- Manganese oxide promoted liquid-phase aerobic oxidative amidation of methylarenes to monoamides using ammonia surrogates
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In the presence of amorphous MnO2, various methylarenes (even with two or more methyl groups) could be selectively converted into the corresponding primary monoamides in moderate to high yields. The observed catalysis was truly heterogeneous, and the retrieved amorphous MnO2 catalyst could be reused without an appreciable loss of its catalytic performance. Copyright
- Wang, Ye,Yamaguchi, Kazuya,Mizuno, Noritaka
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supporting information; experimental part
p. 7250 - 7253
(2012/08/28)
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- Synthesis, structures of (aminopyridine)nickel complexes and their use for catalytic ethylene polymerization
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A series of α-aminopyridines in the form of (2,6-C6H 3N)(R1)(CHR2NR3R4) (R1 = R2 = H R3 = H R4 = iPr (L1a), R4 = tBu (L1b), R4 = Ph (L1c), R4 = 2,6-Me2C6H3 (L1d), R4 = 2,6-iPr2C6H3 (L1e), R1 = R2 = H R3 = R4 = Et (L1f), R1 = H R2 = Me R3 = H R4 = iPr (L2a), R4 = Ph (L2c), R4 = 2,6-Me 2C6H3 (L2d), R4 = 2,6- iPr2C6H3 (L2e), R1 = Me R2 = H R3 = H R4 = 2,6-iPr 2C6H3 (L3e)) and β-aminopyridines in the form of (2-C6H4N)(CH2CH2NR 1R2) (R1 = H R2 = iPr (4a), R2 = tBu (L4b), R1 = R2 = Et (L4f)) have been prepared. Their corresponding halonickel complexes 1a-4f are synthesized by ligand substitution from (DME)NiBr2 and the molecular structures are characterized. Four types of coordination modes include four-coordinate mononuclear species with one ligand, five-coordinate mononuclear species with two ligands, five-coordinate dinuclear species with two ligands, and a six-coordinate polymeric framework were determined by X-ray crystallography. Using methylaluminoxanes (MAO) as the activator, the nickel complexes can catalyze ethylene polymerization under moderate pressure and ambient temperature. The activity reaches 105 g PE mol-1 Ni h. The PE products with high branching and high crystallinity have M n ~ 103 with PDI 2.
- Lin, Ya-Chi,Yu, Kuo-Hsuan,Lin, Ya-Fan,Lee, Gene-Hsiang,Wang, Yu,Liu, Shiuh-Tzung,Chen, Jwu-Ting
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experimental part
p. 6661 - 6670
(2012/08/08)
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- Synthesis of optically active imidazopyridinium salts and the corresponding NHCs
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A convergent synthesis of chiral imidazo-[1,5-a]-pyridinium salts is described by facile introduction of a stereogenic center via the N2 substituent. Conversion of these optically active salts to the corresponding N-heterocyclic carbenes (NHCs) and their trapping with sulfur followed by optical activity measurements are discussed.
- Schmidt, Michael A.,Movassaghi, Mohammad
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p. 101 - 104
(2007/10/03)
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- Oxidation of benzylic alcohols with I2/K2CO 3/tert-butanol: Formation of aldehydes or dimeric esters
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Oxidation of a series of aromatic and heteroaromatic benzylic alcohols with molecular iodine in tert-butanol in the presence of potassium carbonate has been studied. Oxidation of most benzylic alcohols affords the corresponding aldehydes in reasonable yields. The reaction has been shown to be compatible with amino, formyl, methylthio groups and thiophene ring in the molecule. Oxidation of the electron-poor benzylic alcohols such as nitrobenzyl alcohols and (benzimidazol-2-yl)methanol results in the formation of the corresponding dimeric esters.
- Tumkevicius,Navickas,Dailide
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p. 1377 - 1383
(2007/10/03)
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- Process for producing heterocyclic aldehyde
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The present invention provides a process for preparing a heterocyclic aldehyde by oxidizing a heterocyclic alcohol with high selectivity and high yield. Specifically, the heterocyclic aldehyde is prepared by reacting a heterocyclic compound having at least one hydroxymethyl group bonded to a carbon atom of a heterocyclic ring with a hypohalogenous acid salt in the presence of a base to oxidize the hydroxymethyl group, wherein reaction is conducted in the co-presence of a 2,2,6,6-tetramethylpiperidine-1-oxyl derivative having at least two 2,2,6,6-tetramethylpiperidine-1-oxyl-4-yl groups.
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Page/Page column 11
(2008/06/13)
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- Potentially tridentate hydrazonic ligands in the synthesis of methyl and acetyl palladium(II) complexes
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Potentially tridentate hydrazonic ligands of the type HNNO have been used in the synthesis of some methyl palladium(II) complexes. Depending on the applied experimental conditions two different kinds of complexes are obtained. Thus, the reactions between HL1-HL5 and (COD)PdMeCl in diethyl ether led to the formation of bidentate methyl complexes of the type Pd(HNN)MeCl (1-5), where the ligands maintain a neutral character. However, in the presence of a base such as Et3N or NaOMe, the ligands are deprotonated with the consequent formation of tridentate methyl complexes of the type Pd(NNO)Me (7-10). In solution, complexes 1-5 tend to lose the hydrazonic proton with elimination of methane and formation of a tridentate chloride complex Pd(NNO)Cl (6); this tendency can be correlated with the acidity of the free ligands, which has been determined. On bubbling carbon monoxide through solutions of 1-5, the corresponding acetyl complexes Pd(HNN)[C(O)Me]Cl (11-15) are formed, in which both the cis and trans isomers are present. Their molar ratio is rationalised from the results of a molecular modelling study on the basis of electronic considerations. A remarkably different reactivity has been found in the carbonylation of the tridentate complexes 7-10: they decompose rapidly and quantitatively to palladium black and an organic product corresponding to the ligand with an acetyl group bonded to the hydrazonic nitrogen. The X-ray structures of a methyl complex (3) and its corresponding acetyl (13) derivative have been determined.
- Pelagatti, Paolo,Carcelli, Mauro,Franchi, Francesca,Pelizzi, Corrado,Bacchi, Alessia,Fochi, Andrea,Fruehauf, Hans-Werner,Goubitz, Kees,Vrieze, Kees
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p. 463 - 475
(2007/10/03)
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- Isoquinoline compound melanocortin receptor ligands and methods of using same
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The invention relates to melanocortin receptor ligands and methods of using the ligands to alter or regulate the activity of a melanocortin receptor. The invention further relates to tetrahydroisoquinoline aromatic amines that function as melanocortin receptor ligands and as agents for controlling cytokine-regulated physiologic processes and pathologies, and combinatorial libraries thereof.
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- REACTIVITY OF METHYL DERIVATIVES OF NITROGENOUS HETEROCYCLES IN VAPOR-PHASE CATALYTIC OXIDATION
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A study has been made of the reactivity of methylpyridines, methylpyrazines, and methylquinolines in oxidation in the vapor phase in the presence of β-VO(PO3)2.Relationships have been found between the overall reaction rates of heterocyclic compounds and the charge on the ring nitrogen, and between the partial oxidation rate and the charge on the ring carbon atom adjacent to the methyl group.The partial oxidation rate of methylpyridines is given to a first approximation by the Hammett-type expression lnWa = -3.5 + 4.6 Σ?, with a correlation coefficient of 0.93.
- Leitis, L. Ya.,Skolmeistere, R. A.,Golender, L. O.,Yansone, D. P.,Meksh, P. A.,Shimanskaya, M. V.
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- Triazolopyridines. Part 6. Ring Opening Reactions of Triazolopyridines
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The triazole ring in 1,2,3-triazolo-pyridines and -quinolines, and in 1,2,3-triazoloisoquinolines can be opened with loss of nitrogen.The reagents described are bromine, aqueous sulphuric acid, glacial acetic acid, and selenium dioxide; the products from the triazolopyridines are dibromomethyl, hydroxymethyl, acetoxymethyl, and acyl derivatives of pyridine.The generality of the reactions is discussed.The first reported reaction in which the six-membered ring of a 1,2,3-triazolopyridine is opened, by hydride reduction, gives a triazolylbutadiene.
- Jones, Gurnos,Mouat, Deborah J.,Tonkinson, Daryl J.
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p. 2719 - 2724
(2007/10/02)
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