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131.
Muranaka A Okuda M Kobayashi N Somers K Ceulemans A 《Journal of the American Chemical Society》2004,126(14):4596-4604
Oxo-titanium phthalocyanine (TiOPc) derivatives of catechin and hematoxylin (natural ortho-diol type chiral compounds) have been prepared and characterized by spectral and chromatographic techniques. It is demonstrated that the TiOPc unit is an excellent template for chiral recognition through its isolated Q-transitions. The formation of a helical dimeric complex with hematoxylin induces strong CD-activity in the Q-band region. Ab initio geometry optimizations were combined with a Kuhn-Kirkwood coupled-oscillator mechanism to obtain the absolute configuration of hematoxylin. In addition, it is shown that the described chiroptical recognition method is sensitive to slight conformational changes. 相似文献
132.
Kobayashi J Sekiguchi M Shimamoto S Shigemori H Ishiyama H Ohsaki A 《The Journal of organic chemistry》2002,67(18):6449-6455
Three novel quaternary indole alkaloids with an unprecedented 1-azoniatricyclo[4.3.3.0(1,5)]undecane moiety, subincanadines A-C (1-3), as well as two new indole alkaloids with a 1-azabicyclo[5.2.2]undecane moiety, subincanadines D (4) and E (5), and a new indole alkaloid with a 1-azabicyclo[4.3.1]decane moiety, subincanadine F (6), have been isolated from the barks of Aspidosperma subincanum Mart, and the structures of 1-6 and the stereochemistry of 1-3 were elucidated by spectroscopic data and chemical means. 相似文献
133.
The stereoselective synthesis of the two segments 3 and 4 of macrolactin A 1 is described. Macrolactin A is a 24-membered polyene macrolide antibiotic, which is of interest due to a strong activity against B16-F10 murine tumor cell and HIV-1 virus. The key step of the synthesis is the 1,2-migration reaction of a (diene)Fe(CO)3 complex with a introduction of the thiol group to construct the unstable (E,Z)-conjugated dienic moiety (C8-C11). 相似文献
134.
Ayako Torikai Teruyuki Hattori Takuji Eguchi 《Journal of polymer science. Part A, Polymer chemistry》1995,33(11):1867-1871
Polymethylmethacrylate (PMMA) containing benzophenone (BP) was photo-irradiated with monochromatic radiation of wavelength 260–360 nm using the Okazaki Large Spec-trograph (OLS). On irradiation of PMMA films containing BP in air, the sensitized main-chain scission and photocrosslinking of PMMA took place simultaneously. These reactions are dependent on irradiation wavelength. The threshold wavelength for both reactions is found to be ca. 380 nm. The number of main-chain scission and amount of gel increased with the increase of BP concentration in PMMA. Photosensitized main-chain scission favors the irradiation of radiation at ca. 280 nm and photocrosslinking takes place efficiently with the exposure of 340 nm radiation. A possible mechanism for photosensitized reaction is proposed. © 1995 John Wiley & Sons, Inc. 相似文献
135.
A novel synthetic basic resolving agent, cis-1-aminobenz[f]indan-2-ol (ABI), was rationally designed by introducing effective CH/pi interaction sites to cis-1-aminoindan-2-ol (AI), whose chiral recognition ability has been reported from our laboratory. ABI was applicable to a wide variety of racemic arylalkanoic acids and showed moderate to excellent chiral recognition ability, which was obviously higher than that of AI. The fundamental and important role of CH/pi interactions, such as tunable CH(sp(2))/pi and CH(sp(3))/pi interactions, in the chiral recognition by ABI was revealed by X-ray crystallographic study. 相似文献
136.
Aoki S Ye Y Higuchi K Takashima A Tanaka Y Kitagawa I Kobayashi M 《Chemical & pharmaceutical bulletin》2001,49(10):1372-1374
Two novel aplysinopsin-type indole alkaloids, 1 and 2, and three known indole alkaloids were isolated from the marine sponge Hyrtios erecta. These compounds exhibited selective inhibitory activity against the neuronal isozyme of nitric oxide synthase (nNOS). Furthermore, new quinolone 7 was also isolated from the same marine sponge. The chemical structures of these new compounds were elucidated on the basis of spectroscopic analysis. 相似文献
137.
Tsuda M Izui N Shimbo K Sato M Fukushi E Kawabata J Katsumata K Horiguchi T Kobayashi J 《The Journal of organic chemistry》2003,68(13):5339-5345
A novel cytotoxic 16-membered macrodiolide, amphidinolide X (1), has been isolated from a marine dinoflagellate Amphidinium sp. (strain Y-42). The gross structure of 1 was elucidated on the basis of spectroscopic data including one-bond and long-range (13)C-(13)C correlations. The relative and absolute stereochemistries were determined by combined analyses of NOESY data and (1)H-(1)H and (1)H-(13)C coupling constants of 1 and NMR data of the degradation products. Amphidinolide X (1) is the first macrodiolide consisting of polyketide-derived diacid and diol units from natural sources. The biosynthetic origins of 1 were investigated by means of feeding experiments with (13)C-labeled acetates. 相似文献
138.
Marlin Opałło Nagao Kobayashi Tetsuo Osa 《Journal of inclusion phenomena and macrocyclic chemistry》1989,7(4):413-422
The complexation of 2,3-anthracenedicarboxylate (ADC) by- and-cyclodextrins in water containing an organic solvent has been studied by induced circular dichroism. It has been shown that an increase of organic solvent ratio causes the degradation of the 1:1 ADC:-CD complex and the liberation of one guest molecule from the 2:1 ADC:-CD complex in water. The higher the hydrophobicity of the cosolvent, the weaker the complexation of ADC by-CD. 相似文献
139.
Uchida K Saito M Murakami A Kobayashi T Nakamura S Irie M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(2):534-542
A photochromic polymer film containing three different diarylethene derivatives, that is, 1,2-bis(3,5-dimethyl-2-thienyl)perfluorocyclopentene (1), 1,2-bis(2,5-dimethyl-3-thienyl)perfluorocyclopentene (2), and 1,2-bis(2-methyl-5-phenyl-3-thienyl)perfluorocyclopentene (3) was prepared. Upon UV irradiation, the three derivatives changed to their closed-ring isomers having different colors, yellow, red, and blue. They showed different spectra not only in UV/Vis region but also in the IR spectral region. Upon irradiation with visible light of appropriate wavelengths, each closed-ring isomer was selectively bleached, and three bits eight states recording was performed. The eight states could be read out nondestructively by using IR light of appropriate wavenumbers. 相似文献
140.
Fujitani T Nakamura I Kobayashi Y Takahashi A Haneda M Hamada H 《The journal of physical chemistry. B》2005,109(37):17603-17607
Adsorption and reactions of NO on clean and CO-precovered Ir(111) were investigated by means of X-ray photoelectron spectroscopy (XPS), high-resolution electron energy loss spectroscopy (HR-EELS), infrared reflection absorption spectroscopy (IRAS), and temperature-programmed desorption (TPD). Two NO adsorption states, indicative of fcc-hollow sites and atop sites, were present on the Ir(111) surface at saturation coverage. NO adsorbed on hollow sites dissociated to Na and Oa at temperatures above 283 K. The dissociated Na desorbed to form N2 by recombination of Na at 574 K and by a disproportionation reaction between atop-NO and Na at 471 K. Preadsorbed CO inhibited the adsorption of NO on atop sites, whereas adsorption on hollow sites was not affected by the coexistence of CO. The adsorbed CO reacted with dissociated Oa and desorbed as CO2 at 574 K. 相似文献