- Ruthenium-catalyzed ring-closing metathesis accelerated by long-range steric effect
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Ruthenium-based metathesis catalysts with a N-heterocyclic carbene ligand bearing 2,3,4,5-tetraphenylphenyl moieties (1-TPPh and 1-TPPh*) are developed. The highly active catalyst system has been realized in THF by the combination of 1-TPPh* and CuCl as a phosphine scavenger. The Royal Society of Chemistry 2011.
- Fujihara, Tetsuaki,Tomike, Yoshikazu,Ohtake, Toshiyuki,Terao, Jun,Tsuji, Yasushi
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p. 9699 - 9701
(2011/10/08)
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- Straightforward synthesis of novel biphenyl-based macrobicyclic azathioethers
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The synthesis and characterization of two new macrobicyclic azathioether ligands are reported. The biphenyl-based compounds were prepared by traditional organic reactions and cyclization methods. The identity of one compound was confirmed by X-ray crystallography. Georg Thieme Verlag Stuttgart.
- Gregor, Thomas,Weise, Christian F.,Lozan, Vasile,Kersting, Berthold
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p. 3706 - 3712
(2008/09/19)
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- NITROGENOUS HETEROCYCLIC DERIVATIVE HAVING 2,6-DISUBSTITUTED STYRYL
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The invention provides a novel nitrogen-containing heterocyclic derivative having 2,6-disubstituted styryl and a pharmaceutically acceptable salt thereof, and a pharmaceutical composition comprising the nitrogen-containing heterocyclic derivative and a pharmaceutically acceptable salt thereof, in particular, a pharmaceutical composition effective as a sodium channel inhibitor, having an excellent analgesic action especially on neuropathic pain with minimized side effects.
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Page/Page column 14
(2010/02/14)
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- Triplet diphenylcarbenes protected by o-aryl groups
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Diphenyldiazomethanes (2a-N2) having phenyl groups at the ortho positions were prepared and the corresponding diphenylcarbenes (2a) photolytically generated from them were characterized not only by the traditional product analysis method but also by ESR and UV/vis spectroscopy in a rigid organic matrix at low temperature and in laser flash photolysis in solution at room temperature. Product analysis indicated that fluorenes 4a are formed almost exclusively. Fluorene is most likely produced by the attack of singlet carbene 12a on an ortho carbon of the phenyl substituent to generate isofluorene, followed by 1,5-H shift. Irradiation of 2a-N2 in a 2-methyltetrahydrofuran (2-MTHF) matrix at 77 K gave ESR signals ascribable to triplet carbenes (32a). UV/vis spectra of 32a were obtained by irradiating 2a-N2 under identical conditions. However, laser flash photolysis (LFP) of 2a-N2 in degassed benzene at room temperature showed transient absorption bands completely different from those observed in photolysis in the 2-MTHF matrix at 77 K. The transient band decayed in first-order with a rate constant of 7.6 × 104 s -1, which was not retarded by deuterium substitution of o-phenyl hydrogens. Essentially the same transient band was observed in LFP of fluorene 4a. The LFP of 2a-N2 in nondegassed benzene gave transient absorption bands ascribable to triplet carbene 32a and the corresponding carbonyl oxide. The quenching rate constant of 32a by oxygen and the lifetime of 32a in the absence of oxygen were estimated by plotting the observed pseudo-first-order rate constant of the formation of the carbonyl oxide against the concentration of oxygen. They were 1.9 × 107 M-1s-1 and 16 μs, respectively. Similar studies with diphenyldiazomethanes having a series of substituents (4-Ph, 3,5-(CF 3)2, and 2-F) on the ortfto-phenyl rings gave essentially identical results, indicating that those substituents exhibit little effect on overall reaction pathway. From those studies, it is suggested that triplet carbenes 32 are also trapped by the ortho-phenyl ring to give eventually fluorenes.
- Monguchi, Kyoko,Itoh, Tetsuji,Hirai, Katsuyki,Tomioka, Hideo
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p. 11900 - 11913
(2007/10/03)
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