- Weak Links to Differentiate Weak Bonds: Size-Selective Response of π-Conjugated Macrocycle Gels to Ammonium Ions
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Molecular-level host-guest interactions can drive gel-to-sol phase transitions of the bulk material. Using supramolecular gels constructed from π-conjugated aza-crown macrocycles, we have investigated the effects of guest chemical structures on the kinetics of gel disassembly. While ammonium ions bind only weakly to the individual macrocycles in solution, gel-to-sol transitions of self-assembled macrocycles occur readily under ambient conditions. This net signal amplification process was monitored conveniently by time-dependent spectroscopic studies to reveal a straightforward correlation between the response rate and shape/size of the guest species. Well-designed weak links thus respond to subtle differences in weak bonds and translate them into visually discernible macroscopic signaling events.
- Kang, Suk-Il,Lee, Milim,Lee, Dongwhan
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Read Online
- Pd-Catalyzed Decarboxylative Ortho-Halogenation of Aryl Carboxylic Acids with Sodium Halide NaX Using Carboxyl as a Traceless Directing Group
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A highly regioselective Pd-catalyzed carboxyl directed decarboxylative ortho-C-H halogenation of cheap o-nitrobenzoic acids with NaX (X = I, Br) under aerobic conditions has been established. The utility of the method has been demonstrated by the gram-scale reaction and derivatization of the product. Experimental results have confirmed Pd and Bi played critical roles in the transformation and indicated the transformation might proceed via 2-halo-6-nitrobenzoic acid derivative intermediate.
- Fu, Zhengjiang,Jiang, Yongqing,Wang, Shuiliang,Song, Yuanyuan,Guo, Shengmei,Cai, Hu
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supporting information
p. 3003 - 3007
(2019/05/10)
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- Sulfonamide compound and medical applications thereof
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The invention discloses a compound containing a sulfonamide structure, a preparation method thereof, and medical applications of the compound, and more specifically discloses the compound with a structure represented by formula I, and a pharmaceutically acceptable salt or a prodrug or a solvate thereof. The compound is used for tumor treatment through inhibiting ATP-citrate lyase.
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Paragraph 0044-0047
(2019/02/13)
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- Mechanistic study on iodine-catalyzed aromatic bromination of aryl ethers by N-Bromosuccinimide
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Although iodine-catalyzed reaction has rapid advances in recent years, examples on iodine-catalyzed bromination are rare and the mechanism of these reactions remains unclear. Herein, we reported an I2-catalyzed aromatic bromination of aryl ethers by NBS and presented the details of the mechanistic study including kinetic study and the study of kinetic isotope effects. The study revealed that the reaction was actually catalyzed by IBr formed in the induction period, and the rate-determining step was the HBr-elimination of the Wheland intermediate assisted by IBr.
- Pramanick, Pranab Kumar,Hou, Zhen-Lin,Yao, Bo
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p. 7105 - 7114
(2017/11/27)
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- TUBULIN BINDING AGENTS
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The invention provides combretastatin A-4 like compounds that are modified to have enhanced tubulin binding activity and in some embodiments the ability to promote accumulation in the vasculature undergoing angiogenesis (homing activity). The compounds are based on the combretastatin A-4 skeletal structure having a tubulin-binding pharmacophore comprising two fused rings (A and B rings) in which the B ring is substituted with (a) an aromatic ring structure (C ring) and (b) a second substituent/functional group that comes off the B ring. The aromatic ring structure is typically a six membered ring phenolic or aniline structure, or may also be a fused ring structure such as a substituted or unsubstituted naphthalene. The second substituent on the B ring may for example be a substituent which has been found to provide enhanced tubulin binding activity (for example a carbonyl group), or may be a substituent that facilitates functionalisation of the B ring (for example an hydroxyl or amine group), or it may be a binding agent for a target that is preferentially expressed on vasculature undergoing angiogenesis, and not expressed on quiescent vasculature.
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Paragraph 0625; 0626; 0627; 0628; 0629; 0630; 0631
(2015/02/18)
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- Synthesis and biological evaluation of enantiomerically pure cyclopropyl analogues of combretastatin A4
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To evaluate the influence of stereochemistry on biological activities of cis-cyclopropyl combretastatin A4 (CA4) analogues, we have prepared several cyclopropyl compounds in their pure enantiomeric forms. The key reactions in our synthesis are the cyclopropanation of a (Z)-alkenylboron compound bearing a chiral auxiliary, and the cross-coupling of both enantiomeric cyclopropyl trifluoroborate salts with aryl and olefinic halides. Three pairs of cis-cyclopropyl CA4 analogues were evaluated for their potential antivascular activities. The diarylcyclopropyl compounds with SR-configuration (-)-1b, (-)-2b and the cyclopropylvinyl enantiomer (+)-3a with RR-configuration were the most potent tubulin polymerization inhibitors. A correlation was noted between anti-tubulin activity and rounding up activity of endothelial cells. The cytotoxic activity on B16 melanoma cells was in the submicromolar range for most compounds, but unlike the anti-tubulin activity, there was no difference in cytotoxic activity between racemic and enantiomerically pure forms for the three series of compounds. Molecular docking studies within the colchicine binding site of tubulin were in good agreement with the tubulin polymerization inhibitory data and confirmed the importance of the configuration of the synthesized cis-cyclopropyl CA4 analogues for potential antivascular activities.
- Ty, Nancy,Pontikis, Renée,Chabot, Guy G.,Devillers, Emmanuelle,Quentin, Lionel,Bourg, Stéphane,Florent, Jean-Claude
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p. 1357 - 1366
(2013/03/29)
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- Aromatic nitration with bismuth nitrate in ionic liquids and in molecular solvents: A comparative study of Bi(NO3)3·5H 2O/[bmim][PF6] and Bi(NO3)3· 5H2O/1,2-DCE systems
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A suspension of bismuth nitrate pentahydrate (BN) in [bmim][PF6] or [bmim][BF4] imidazolium ionic liquid (IL) is an effective reagent for ring nitration of activated aromatics under mild conditions without the need for external promoters. Nitration can also be effected in 1,2-DCE, MeCN, or MeNO2 without additives. Nitration of activated arenes (anisole, toluene, ethylbenzene, cumene, p-xylene, mesitylene, durene, and 1,3-dimethoxybenzene) is considerably faster (time to completion) in BN/[bmim][PF6] relative to BN/1,2-DCE and there are also differences in isomer distributions (for anisole, toluene, and ethylbenzene). With introduction of strongly deactivating substituents (-CHO; -MeCO; -NO 2) the BN/IL system is no longer active but reactions still proceed with BN/1,2-DCE in reasonable yields. The ready availability and low cost of BN, simple operation, and absence of promoters, coupled to recycling and reuse of the IL, provide an attractive alternative to classical nitration methods for activated arenes. Switching from Bi(NO3)3·5H 2O/[bmim][PF6] to Bi(NO3)3· 5H2O/1,2-DCE increases the scope of the substrates that can be nitrated.
- Jacoway, Jonathan,Kumar, G. G. K. S. Narayana,Laali, Kenneth K.
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p. 6782 - 6785,4
(2012/12/12)
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- N-Phenyloxamide derivatives
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A compound represented by the following general formula (I) or a salt thereof, or a hydrate thereof or a solvate thereof having an inhibitory action against plasminogen activator inhibitor-1 (PAI-1): wherein R1 represents a C6-10 aryl group; or a C6-10 aryl group substituted with a group or groups selected from the group consisting of a halogen atom, cyano group, nitro group, a C1-6 alkyl group, a halogenated C1-6 alkyl group, a C1-6 alkoxy group, a halogenated C1-6 alkoxy group and a C1-6 alkylsulfanyl group, R2 represents a C6-10 aryl group; or a C6-10 aryl group substituted with a group or groups selected from the group consisting of a halogen atom, hydroxy group, a C1-6 alkyl group, a halogenated C1-6 alkyl group, a C1-6 alkoxy group, a halogenated C1-6 alkoxy group, a C1-6 alkylsulfanyl group and phenyl group, X represents a single bond or oxygen atom, Z represents a phenylene group or a substituted phenylene group, m represents 0 or 1.
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Page/Page column 71
(2008/12/08)
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- Supported bismuth(III) nitrate on silica sulfuric acid as useful reagent for nitration of aromatic compounds under solvent-free conditions
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A number of aromatic compounds were nitrated to the corresponding nitroaromatic derivatives with the use of supported bismuth(III) nitrate on silica sulfuric acid under solvent-free conditions.
- Hajipour,Zarei,Ruoho
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p. 1493 - 1495
(2007/10/03)
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- Selective nitration of aromatic compounds with bismuth subnitrate and thionyl chloride
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Bismuth subnitrate/thionyl chloride have been found to be an efficient combination of reagents for nitration of a wide range of aromatic compounds in dichloromethane. Phenols, in particular, were easily mononitrated and dinitrated with the reagents by controlling the stoichiometry.
- Muathen, Hussni A.
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p. 593 - 598
(2007/10/03)
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- Aromatic allylation via diazotization: Metal-free C-C bond formation
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A new method for the synthesis of allyl aromatic compounds not involving any metal-containing reagent or catalyst has been developed. Arylamines substituted with a large number of different substituents were converted via diazotizative deamination with tert-butyl nitrite in allyl bromide and acetonitrile to the corresponding allyl aromatic compounds. The allylation reaction was found to be suitable for larger scale synthesis due to short reaction times, a nonextractive workup, and robustness toward moisture, air, and type of solvent.
- Ek, Fredrik,Axelsson, Oskar,Wistrand, Lars-Goeran,Frejd, Torbjoern
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p. 6376 - 6381
(2007/10/03)
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- Convenient Nitration of Anisole and its Derivatives using an NO-O2 System
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Anisole and its derivatives are regioselectively nitrated by use of nitrogen monoxide-molecular dioxygen mixed gas under mild conditions.
- Mizuno, Kazuhiko,Tamai, Toshiyuki,Hashida, Isao,Otsuji, Yoshio,Inoue, Hiroo
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p. 284 - 285
(2007/10/03)
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- 13C NMR Spectra of Substituted o-Nitroanisoles and n-Butyl o-Nitrophenyl Ethers
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13C NMR analyses of substituted o-nitroanisoles and n-butyl o-nitrophenyl ethers are reported. Key Words: 13C NMR - o-Nitroanisoles - n-Butyl o-nitrophenyl ethers
- Zeegers, Petrus J.,Thompson, Malcolm J.
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p. 497 - 499
(2007/10/02)
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- SYNTHESIS OF 4-NITRO-1,2,3-TRIAZOLES
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Preparative methods were studied for the synthesis of 4-nitro-1,2,3-triazole and its N-oxide by the nitration of 2-phenyl-substituted triazoles followed by elimination of the nitrophenyl fragment, which can be successfully removed when it contains two nitro groups.
- Vereshchagin, L. I.,Nikitin, V. M.,Meshcheryakov, V. I.,Gareev, G. A.,Kirillova, L. P.,Shul'gina, V. M.
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p. 1574 - 1577
(2007/10/02)
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- ipso Nitration in p-halophenyl ethers
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Addition of nitronium ion ipso to halogen occurs on nitration of the p-haloanisoles in acetic anhydride at -60 deg C.In the cases of p-fluoro- and p-chloro-anisole, addition of the nitronium ion is reversible and only small amounts of ipso products are obtained.With p-bromoanisole nitrodebromination occurs.When p-halophenyl ethers containing a trapping substituent, e.g., 2-(4-chlorophenoxy)-2-methylpropanoic acid, are used as substrates, substantial amounts of the spiro diene with nitro ipso to halogen, e.g., 3,3-dimethyl-8-chloro-8-nitro-1,4-dioxaspirodeca-6,9-dien-2-one, can be isolated.The results demonstrate that extensive ipso attack at the halogen-substituted position is general in the nitration of p-halophenyl ethers.Key words: ipso nitration, ether, diene, p-haloanisole.
- Clewley, Robin G.,Fischer, Alfred,Henderson, George N.
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p. 1472 - 1479
(2007/10/02)
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- Theoretical Calculations of Chemical Interactions. Part 4. Aromatic Nucleophilic Substitutions and SN2 Reactions of 4- and 6-Substituted 2-Nitroanisoles
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The reactions of 4-R- and 6-R-2-nitroanisoles (R=Me, Br) in neat cyclohexylamine and piperidine have been studied.The reactions with cyclohexylamine lead to the respective aromatic nucleophilic substitution products while the reactions with piperidine mainly yield the substituted nitrophenols.It was found that 6-R-2-nitroanisoles react faster than the respective 4-R-2-nitroanisoles.The absence of the expected primary steric effect is thought to be due to the spatial arrangement of the methoxide group, which adopts a conformation perpendicular to the ring plane when it is surrounded by two ortho-substituents.CNDO and INDO calculations for different conformations of the substrates give support to this assumption.
- Nudelman, N. Sbarbati,Palleros, Daniel R.
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p. 805 - 810
(2007/10/02)
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