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71.
Akira Ohnuma Tomohiro Nagata Kenichi Komura Hiromune Ando Hideharu Ishihara Mamoru Koketsu 《Journal of heterocyclic chemistry》2015,52(2):513-517
Various 2H‐5,6‐dihydroselenine derivatives were synthesized by the reaction of α‐alkoxy carbonylselenoacetamides with α,β‐unsaturated ketones in the presence of BF3•Et2O. 相似文献
72.
Hayashi Y Regnier T Nishiguchi S Sydnes MO Hashimoto D Hasegawa J Katoh T Kajimoto T Shiozuka M Matsuda R Node M Kiso Y 《Chemical communications (Cambridge, England)》2008,(20):2379-2381
Herein, we describe an efficient strategy for the total synthesis of (+)-negamycin using commercially available achiral N-Boc-2-aminoacetaldehyde as starting material with 42% overall yield for a limited number of steps. 相似文献
73.
Kohki Fujikawa Tomohiro Nohara Hiromune Ando Hideharu Ishida Makoto Kiso 《Tetrahedron letters》2010,51(7):1126-5815
A cyclic glucosyl ceramide (GlcCer) acceptor has been developed as a versatile building block for the synthesis of complex ganglioside. A macrocyclic GlcCer acceptor, which was the product of intramolecular glycosylation between glucose and ceramide, exhibited high reactivity during the coupling reactions with a variety of complex oligosaccharyl donors, thereby furnishing the corresponding ganglioside frameworks in high yields. 相似文献
74.
The anatomical locations of three components of insect photoperiodism--the photoperiodic photoreceptor, photoperiodic clock and hormonal effector--are summarized and compared between species. Among photoperiodic photoreceptors, either the retinal or extraretinal types or both are operative, and there is no general relationship between phylogeny and photoreceptor type. The photoperiodic clock comprises time measurement and counter systems. Currently, it is generally accepted that circadian oscillators are involved in the photoperiodic clock. Several recent studies have raised the possibility that timeless, a circadian clock gene, plays a role in the photoperiodic clock in flies. The dorsal protocerebrum has been identified as an important region regulating the endocrine system for adult, pupal and embryonic diapause controlled by photoperiod. In the blow fly Protophormia terraenovae, neural connections between circadian clock neurons and indispensable neurons in the pars lateralis for diapause induction in the dorsal protocerebrum have been demonstrated. This neural network may provide the access needed to investigate the neural components of the photoperiodic clock. 相似文献
75.
Yoshiya T Taniguchi A Sohma Y Fukao F Nakamura S Abe N Ito N Skwarczynski M Kimura T Hayashi Y Kiso Y 《Organic & biomolecular chemistry》2007,5(11):1720-1730
The O-acyl isopeptide method has recently received attention as an efficient synthetic method for peptides. Herein, forty kinds of "O-acyl isodipeptide unit" Boc-Ser/Thr(Fmoc-Xaa)-OH (1-40) were effectively synthesized in two-steps without epimerization. The O-acyl isodipeptide units are important building blocks to enable the routine use of the O-acyl isopeptide method. 相似文献
76.
77.
T Hirokawa H Takemi Y Kiso R Takiyama M Morio K Fujii H Kikuchi 《Journal of chromatography. A》1984,305(2):429-437
Experimentally determined optimum separation conditions for a metabolite of anaesthetic halothane in urine, trifluoroacetic acid, were assessed by means of computer simulation of the isotachophoretic steady-state. The simulation confirmed that urinary acids and trifluoroacetic acid can be separated in the limited pH range of 3.5-3.7 buffered by beta-alanine, as far as the pH dependence of effective mobility is utilized. The separated fraction of the trifluoroacetic acid zone was identified by mass spectrometry. The simulated coefficient of the calibration curve agreed well with the observed value. 相似文献
78.
Saito Y Nakao Y Imaizumi M Takeichi T Kiso Y Jinno K 《Fresenius' Journal of Analytical Chemistry》2000,368(7):641-643
A novel "fiber-in-tube" configuration has been applied to the extraction tube of solid phase microextraction (SPME), and the direct coupling of the extraction process to liquid chromatography (LC) has been accomplished for the analysis of n-butylphthalate in wastewater. By using this fiber-in-tube SPME/LC system the preconcentration factor for the phthalate was about 160 with 20 min extraction and no interference peak was observed in the chromatogram. The results also showed the potential applications of this fiber-in-tube SPME/LC for the analysis of sub-ppb level (i.e., lower than 1 ng/mL) of various organic analytes in aqueous sample matrix without a large solvent consumption during the preconcentration process. 相似文献
79.
Hideharu Mori Masato Sawada Tomohiro Higuchi Koichi Hasebe Nobuo Otsuka Minoru Terano 《Macromolecular rapid communications》1999,20(5):245-250
The surface atomic structure of MgCl2 crystalline particles and MgCl2‐supported Ziegler catalysts was observed by means of high resolution transmission electron microscopy. Step‐terrace surface structures, characteristic of the structure of the MgCl2 crystal, are found in the observed images of MgCl2 particles. The observation of the structure of MgCl2‐supported Ziegler catalysts shows that the MgCl2 crystals are severely deformed by the processes of catalyst preparation. Due to the preparation procedure used the structure of the catalyst changes from crystalline to amorphous. 相似文献
80.
Akira Hasegawa Minoru Morita Hideharu Ishida Makoto Kiso 《Journal of carbohydrate chemistry》2013,32(4):579-588
Abstract Various types of the O-protected derivatives and the 9-bromo analogs of methyl [2-(trimethylsilyl)ethyl 5-acetamido-3,5-dideoxy-D-glycero-α-D-galacto-2-nonulopyranosid]onate were synthesized from methyl [2-(trimethyl-silyl)ethyl 5-acetamido-4,7-di-O-acetyl-3,5-dideoxy-D-glycero-α-D-galacto-2-nonulopyranosid]onate (1) or methyl [2-(trimethylsilyl)ethyl 5-acetamido-8,9-di-O-isopropylidene-D-glycero-α-D-galacto-2-nonulopyranosid]onate (3). 相似文献