- Host-guest complexation behavior of resorcinarenes with tetraalkylammonium ions and N-methylpyridinium ions in methanol: The effect of bulky hydrophobic substituents at the extra-annular positions
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The host-guest interaction of C-methylresorcin[4]arene and its derivative having four tert-butylsulfanylmethyl groups at the extra-annular positions was studied by 1H NMR spectroscopy in CD3OD. Based on the association constants (Ka) and the complexation-induced NMR shifts (CIS), it was concluded that the bulky substituents create a deep cavity with a narrow entrance and improve the size and shape selectivity. Copyright Taylor & Francis Group, LLC.
- Morikawa, Osamu,Yamaguchi, Hiroshi,Katsube, Yoshiko,Abe, Kazuyuki,Kobayashi, Kazuhiro,Konishi, Hisatoshi
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Read Online
- Palladium-Catalyzed Direct Arylation of Alkylpyridine via Activated N-Methylpyridinium Salts
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An efficient Pd-catalyzed arylation of alkylpyridine based on the pyridinium activation strategy has been developed for synthesis of mixed aryl alkylpyridines. It was found that (1) the N-methyl group in the pyridinium salts acted as a transient activator and could be automatically departed after the reaction, (2) CuBr was an indispensable additive for achieving the C6-selective arylation, (3) the α-branched alkyl chain on the alkylpyridine greatly increased the yield of the product. Deuterium labelling experiment revealed that in the case of the α-branched alkylpyridine, the presence of CuBr completely inhibited the H/D exchange at the benzylic position and thus enabled the selective arylation at the C6 position. This protocol demonstrates a broad substrate scope, and with respect to both the aryl iodides and the α-branched alkylpyridine, the desired mixed aryl alkylpyridines were obtained in generally good to excellent yields.
- Chen, Xue,Li, Wen-Jing,Li, Shun,Tang, Juan,Du, Xi,Zheng, Xue-Li,Yuan, Mao-Lin,Fu, Hai-Yan,Li, Rui-Xiang,Chen, Hua
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p. 622 - 632
(2019/12/30)
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- Regioselective Direct C-H Trifluoromethylation of Pyridine
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A highly efficient and regioselective direct C-H trifluoromethylation of pyridine based on an N-methylpyridine quaternary ammonium activation strategy has been developed. A variety of trifluoromethylpyridines can be obtained in good yield and excellent re
- Yang, Xiao,Sun, Rui,Li, Shun,Zheng, Xueli,Yuan, Maolin,Xu, Bin,Jiang, Weidong,Chen, Hua,Fu, Haiyan,Li, Ruixiang
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supporting information
p. 7108 - 7112
(2020/10/02)
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- Preparation and in vitro evaluation of monoquaternary inhibitors of brain cholinesterases
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Acetylcholinesterase inhibitors are currently of high interest due to the many reasons. Among them, Alzheimer's disease drugs are of great interest. In this study, eleven monoquaternary pyridinium salts substituted by different groups (electron donors and
- Jun, Daniel,Paar, Martin,Binder, Jiri,Marek, Jan,Pohanka, Miroslav,Stodulka, Petr,Kuca, Kamil
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scheme or table
p. 500 - 503
(2010/04/23)
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- Menschutkin Reactions of Bicyclic Aliphatic Amines and of Pyridine Derivatives with Methyl Iodide. Extended Broensted Treatments and Isokinetic Relationships in Acetonitrile-Methanol
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The rate constants, activation parameters for the Menschutkin reactions for five bases with methyl iodide, and the enthalpies of solution for the relevant species of the reactions have been determined in acetonitrile-methanol.The bases are quinuclidine, 1,4-diazabicyclooctane, and 4-cyano-, 4-t-butyl-, and 4-dimethylamino-pyridine.The coefficients of empirical energy correlations defined in terms of 'more physical' energies, extended Broensted treatments, αphys' and isokinetic temperatures, βphys' have been determined for these reactions.Discussion is provided on the physical meaning of these coefficients in relation to the characteristics of the activated complex.
- Kondo, Yasuhiko,Uematsu, Ryoichi,Nakamura, Yoshinobu,Kusabayashi, Shigekazu
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p. 1219 - 1224
(2007/10/02)
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- Empirical Analysis on the Constituent Terms of Transfer Enthalpies. Quarternary Ammonium Ions in Acetonitrile-Methanol Mixtures.
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Through an empirical analysis of transfer enthalpies in acetonitrile-methanol mixtures using ten quaternary ammonium ions, an equation which expresses the behaviour of the transfer enthalpy as a function of solvent composition has been derived: .On the basis of this equation it is suggested that the transfer enthalpy includes at least three types of interaction, a protophobic interaction, an electrostatic interaction and another interaction, presumably a specific interaction such as dipole-dipole or acid-base association.
- Kondo, Yasuhiko,Uematsu, Ryoichi,Nakamura, Yoshinobu,Kusabayashi, Shigekazu
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p. 111 - 116
(2007/10/02)
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