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Yuji Ogawa Motoji Wakida Hideharu Ishida Makoto Kiso Akira Hasegawa 《Journal of carbohydrate chemistry》2013,32(3):433-446
Abstract To investigate the biological influence of the 2-(acyloxy)tetradecanoyl and 2-hydroxyacyl groups in the nonreducing-sugar subunit analogs of lipid A, a novel series of 3-(O-[(2RS)-2-acyloxytetradecanoyl]-2-deoxy-2-[(2RS)-2-hydroxytetradecanamido]-4-O-phosphono-d-glucoses (10a-d), 3-O-[(2RS)-2-acyloxytetradecanoyl]-2-deoxy-2-[(3R)-3-hydroxytetradecanamido]-4-O-phosphono-d-glucoses (19a-d), and 2-deoxy-2-[(2RS)-2-hydroxyacyl]amino-4-O-phosphono-3-O-[(3R)-3-tetradecanoyloxytetradecanoyl]-d-glucoses (23e-h) were systematically synthesized. 相似文献
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Abstract Optical absorption bands and epr spectra of NaCl: Mn++ X-irradiated at liquid nitrogen and room temperature are studied. Manganese epr spectra are divided into three classes, based on the value of hyperfme splitting constants. It is shown that the epr spectra with the hyperhe splitting constants of around 250 × 10-4, 80 × 10?4 and 20 × 10?4 cm?1 are caused by Mn+, Mn++ and Mn9, respectively. Formation of several manganese centers by X-irradiation is discussed. It is suggested that optical absorption bands at 410 and 440 nm are caused by MnO at the lattice site and that the MnO center which gives an epr spectrum with A = 15. 5 × 10?4 cm?1 is associated with a Mn0 center which is not at a substitutional site. 相似文献
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K Yoshikawa K Matsuchika K Takahashi M Tanaka S Arihara H C Chang J D Wang 《Chemical & pharmaceutical bulletin》1999,47(6):798-804
The structural elucidation of eleven new related polyoxypregnane glycosides, gymnepregosides G (1), H (2), I (3), J (4), K (5), L (6), M (7), N (8), O (9), P (10) and Q (11), from the roots of Gymnema alternifolium (Asclepiadaceae) was achieved by a detailed study of 1H- and 13C-NMR spectral data and chemical means. The results obtained for new compounds, 1-11, show that they are (20S)-pregn-6-ene-3 beta,5 alpha,8 beta,12 beta,14 beta,17 beta,20-heptaol 3-O-glycosides, and all the sugars at C-3 are beta(i-->4)-linked. Some of them possess benzoyl, (E)- and (Z)-cin-namoyl, and tigloyl residues as the ester linkages located at C-12 and/or C-20 of the aglycone. 相似文献
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An enantiomeric pair of the fully unprotected AB-ring systems of sesbanimide A (1), a potent antitumor alkaloid, was efficiently synthesized from readily available D- and L-xylose. Examination on their antitumor activity clearly disclosed that the AB-ring system only made a small contribution to the notable cytotoxicity of 1. 相似文献
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Tsutomu Takeichi Motoji Arihara Michihiro Ishimori Teiji Ttsuruta 《Tetrahedron》1980,36(23):3391-3398
Optically active chloromethyloxirane was obtained from 1,3-dichloro-2-propanol by a process of asymmetric synthesis. The highest enantiomenc excess (e. e. ) of chloromethyloxirane that could be obtained was 67%, using Co(II) (3,5-Cl,Cl-sal)2(S-CHXDA) and K2CO3 as the catalyst and base, respectively. For purpose of comparison, asymmetric cyclizations of racemic 2,3-dichloro-1-propanol and 2-chloro-1-propanol were examined; optically active chloromethyloxirane and methyloxirane were obtained according to kinetic resolution mechanisms, although the optical purities of oxiranes formed were not so high. The mechanisms for the asymmetric reactions were investigated by circular dichroism and absorption spectroscopies. It was found that the cobalt (salen) type complex forms a new complex with alkali metal carbonate, similarly to the function of crown ether. The substrate interacts with the newly formed chiral complex, followed by cylization to give optically active oxiranes. 相似文献
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Arihara S Umeyama A Bando S Imoto S Ono M Yoshikawa K 《Chemical & pharmaceutical bulletin》2004,52(4):463-465
Three new sesquiterpenes, (4S)-2,6,10-bisaboratrien-4-ol-1-one (1), 1,8-epoxy-1(6),2,4,7,10-bisaborapenta-en-4-ol (2), and 1-methoxy-4-cadinene (3) have been isolated from the black heartwood of Cryptomeria japonica. Compounds 1 and 2 were designated sugikurojinols A and B, respectively, and the structures of compounds 1-3 were established by extensive NMR experiments. Compounds 1 and 2 were also examined for antibacterial activity against Staphylococcus aureus and Escherichia coli, and for termiticidal activity against Coptotermes formosanus SHIRAKI. 相似文献
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Kazuki Arihara Fusao Kitamura Takeo Ohsaka Koichi Tokuda 《Journal of Electroanalytical Chemistry》2001,510(1-2)
The spectro-electrochemical behavior of carbonate and bicarbonate ions at the Au(111) electrode surface was studied using the infrared reflection absorption spectroscopy (IRAS). An absorption band caused by the adsorbed carbonate ions was observed in the wavenumber region of 1425–1511 cm−1 both in Na2CO3 and NaHCO3 solutions. It was concluded that the adsorbed carbonate ions co-ordinate with the electrode surface in the unidentate state with their symmetry axis normal to the substrate. This orientation is retained in the whole potential region where carbonate ions adsorb on the electrode surface in contrast to the behavior of the carbonate ions adsorbed on the Pt(111) electrode surface. 相似文献