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991.
Miura T Nakashima K Tada N Itoh A 《Chemical communications (Cambridge, England)》2011,47(6):1875-1877
Oxidation of alcohols in the presence of a catalytic amount of fluorous IBX and Oxone as a co-oxidant resulted in the corresponding carbonyl compounds in good to high yields. The fluorous IBX is readily recovered as insoluble fluorous IBA from the reaction mixture by simple filtration, and can be reused without significant loss of the catalytic activity. 相似文献
992.
Emission spectra, quantum yields and decays of the fast emission component of s-triazine vapor following excitation into various vibronic levels in S1 are reported. A monotonic increase of the radiative decay constant with increasing excitation energy suggests that a singlet electronic state higher than S1 should participate in the fluorescence emission. 相似文献
993.
Tsuyoshi Miura Kie ImaiHikaru Kasuga Mariko InaNorihiro Tada Nobuyuki ImaiAkichika Itoh 《Tetrahedron》2011,67(34):6340-6346
Fluorous organocatalyst 3 promotes direct asymmetric aldol reactions of ketones with aldehydes in brine, leading to the synthesis of the corresponding anti-aldol products in high yields with up to 96% ee. Fluorous organocatalyst 3 is easily recovered by solid-phase extraction using fluorous silica gel and can be reused up to five times without purification. 相似文献
994.
Folic acid models, 1,3-dimethyl-6-(N-acylarylamino)methyllumazines 9 , were synthesized from 6-bromomethyl-1,3-dimethyllumazine ( 6 ), which was derived from 5,6-diamino-1,3-dimethyluracil ( 1 ) by the condensation with 1,3-dihydroxyacetone, followed by bromination. The bromide 6 was also prepared by the cycloaddition between 3,6,8-trioxo-5,7-dimethyl-5,6,7,8-tetrahydro-3H-pyrimido[5,4-c][1,2,5]oxadiazine ( 4 ) and 1-propenyl trimethylsilyl ether followed by bromination. The folic acid models 9 were also directly synthesized from the oxadiazine 4 and 3-(N-acylaryl)amino-1-propenyl trimethylsilyl ether 8 by cycloaddition. 相似文献
995.
996.
Stereoselective synthesis of (25S)-25-hydroxyvitamin D3 26,23-lactone () is described starting from C-22 steroidal aldehyde and (S)-citramalic acid. The spectral properties of the compound are almost identical with those of the natural product. 相似文献
997.
In order to elucidate the mechanism of deoxyribonucleic acid (DNA) strand breaks caused by 9-anilino-acridine DNA intercalators, the antitumor activity of L1210, P388 and the reduction-oxidation (redox) reaction of 9-anilinoacridines were studied. The redox reaction induced by two electrons causing structural changes in quinone diimines of 9-anilinoacridines is believed to be an important factor in DNA strand breaks and was examined by means of temperature-dependent nuclear magnetic resonance and cyclic voltammetry. The redox reaction of 9-anilinoacridines is induced by the effect of a low-energy electron transfer from the acridine to the aniline ring. We propose that the redox reaction plays an important role in the DNA strand cleavage of 9-anilinoacridine when it is intercalated into double-strand DNA. 相似文献
998.
Koji Kano Hiroaki Kitagishi Shigeki Tanaka 《Journal of inclusion phenomena and macrocyclic chemistry》2006,56(1-2):69-74
The structure of a carbon monoxide adduct (CO-hemoCD) of a 1:1 complex of 5,10,15,20-tetrakis(4-sulfonatophenyl)porphinato iron(II) (Fe(II)TPPS) and an O-methylated β-cyclodextrin dimer having a pyridine linker (1) has been determined by means of NMR spectroscopy and molecular mechanics (MM) calculation. The results indicate the structure as that the sulfonatophenyl groups at the 5- and 15-positions of Fe(II)TPPS are incorporated into two cyclodextrin cavities of 1 to form a 1:1 inclusion complex (hemoCD), whose Fe(II) center is coordinated by a carbon monoxide (CO) molecule. CO-hemoCD possesses a C
2v symmetrical nature that is supported by MM calculation. The energy minimized structure of CO-hemoCD suggests that the CO–Fe(II) part is significantly covered by two cyclodextrin moieties resulting in a cage effect in CO binding phenomenon. Other spectroscopic results of relating complexes also support the structure of hemoCD deduced from the results concerning CO-hemoCD. 相似文献
999.
Kitayama A Yoshizaki H Ohmiya Y Ueda H Nagamune T 《Photochemistry and photobiology》2003,77(3):333-338
The thermal instability and pH-sensitive spectral property of firefly luciferase have hampered its use as a sensitive multicolor luminescent label or bioluminescent resonance energy transfer donor. With the intention of improving the thermostability of a previously found firefly Hotaria parvula luciferase mutant with minor pH-sensitive spectral change (V368A), further mutation (E356R) was introduced by taking a reportedly stabilized mutant of Photinus pyralis luciferase into account. The double mutant E356R/V368A showed significantly improved thermostability because > 90% activity remained after incubation for 1 h at 45 degrees C, with its specific activity being maintained. Unlike the wild type or V368A, E356R/V368A showed no change in the emission maximum of 568 nm even at pH 6.3, also implying a mutual relationship between thermostability and the proportion of yellow-green luminescent peak under acidic condition. 相似文献
1000.
Y Fujimoto Y Watanabe M Aragane H Tada Y Simamori M Uchida M Ozaki K Igarashi S Hirose 《Chemical & pharmaceutical bulletin》1983,31(8):2940-2943