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61.
Isao Kadota Takayuki Kishi Yuka Fujisawa Yuji Yamagami Hiroyoshi Takamura 《Tetrahedron letters》2010,51(30):3960-5853
A convenient method for the stereoselective construction of angular methyl group of fuzed cyclic ethers is described. Reactions of mixed thioacetals with Me2Zn/Zn(OTf)2 afforded the corresponding methylated products in good yields. Various protective groups such as MOM ether, benzylidene acetal, TBS ether, and pivaloyl group were stable under the reaction conditions. 相似文献
62.
Isao Yamaguchi Ayaka Kado Hiroki Fukumoto Moriyuki Sato 《European Polymer Journal》2010,46(5):1119-1130
Reactions of N-(2,4-dinitrophenyl)-4-arylpyridinium chlorides (aryl (Ar) = phenyl and 4-pyridyl) with piperazines caused the ring opening of the pyridinium ring and yielded polymers that consisted of 5-piperazinium-3-aryl-penta-2,4-dienylideneammonium chloride units [N(CH(R)CH2)2N+(Cl−)CHCHC(Ar)CHCH, RH, Me, and phenyl]. However, the same reactions occurring in the presence of piperidine yielded oligomers that consisted of 5-piperazinium-3-aryl-penta-2,4-dienylideneammonium chloride units having piperidine and/or piperazine rings at both ends. 1H NMR spectra suggested that π-electrons of the penta-2,4-dienylideneammonium group of the polymers and the oligomers were delocalized. UV-vis measurements revealed that the π-conjugation system expanded along the polymer and oligomer chains due to the orbital interaction between electrons on the two nitrogen atoms of the piperazinium ring. Conversion of the piperazinium ring from the boat form to the chair form caused decrease in the π-conjugation length. The rate constants of the conversion of the oligomers depended on their chain lengths. The surface of pellets that were molded from the polymers and oligomers exhibited metallic luster. These polymers and oligomers underwent electrochemical oxidation in solution. 相似文献
63.
Takeshi Kumazawa Koichi Saeki Isao Yanagisawa Seisaku Uchigasaki Chika Hasegawa Hiroshi Seno Osamu Suzuki Keizo Sato 《Analytical and bioanalytical chemistry》2009,394(4):1161-1170
This paper describes a fully automated on-line method combining in-tube solid-phase microextraction (SPME) in which sample
clean-up and enrichment are conducted through an open tubular fused-silica capillary column and high-performance liquid chromatography
(HPLC)/tandem mass spectrometry (MS/MS) detection for the determination of six butyrophenone derivatives (moperone, floropipamide,
haloperidol, spiroperidol, bromperidol, and pimozide) in human plasma samples. The six butyrophenones were extracted by repeatedly
aspirating and dispensing plasma sample solutions on a DB-17 capillary column (60 cm × 0.32 mm i.d., film thickness 0.25 μm).
The analytes retained on the inner surface of the capillary column were then eluted into an acetonitrile-rich mobile phase
using a gradient separation technique. Extraction efficiencies ranged from 12.7% to 31.8% for moperone, spiroperidol, and
pimozide, and from 1.08% to 4.86% for floropipamide, haloperidol, and bromperidol. The regression equations for all compounds
showed excellent linearity, ranging from 0.05 to 50 ng/0.1 mL of plasma, except for moperone and spiroperidol (0.01 to 50 ng/0.1 mL).
The limits of detection and quantification in plasma for each drug were 0.03–0.2 and 0.1–0.5 ng/mL, respectively. The intra-
and inter-day coefficients of variation for all compounds in plasma were not greater than 13.7%. 相似文献
64.
Nakamura H Abe Y Koizumi R Suzuki K Mogi Y Hirayama T Karube I 《Analytica chimica acta》2007,602(1):94-100
A new chemiluminescence biochemical oxygen demand (BODCL) determining method was studied by employing redox reaction between quinone and Baker's yeast. The measurement was carried out by utilizing luminol chemiluminescence (CL) reaction catalyzed by ferricyanide with oxidized quinone of menadione, and Saccharomyces cerevisiae using a batch-type luminometer. In this study, dimethyl sulfoxide was used as a solvent for menadione. After optimization of the measuring conditions, the CL response to hydrogen peroxide in the incubation mixture had a linear response between 0.1 and 100 μM H2O2 (r2 = 0.9999, 8 points, n = 3, average of relative standard deviation; R.S.D.av = 4.22%). Next, a practical relationship between the BODCL response and the glucose glutamic acid concentration was obtained over a range of 11-220 mg O2 L−1 (6 points, n = 3, R.S.D.av 3.71%) with a detection limit of 5.5 mg O2 L−1 when using a reaction mixture and incubating for only 5 min. Subsequently, the characterization of this method was studied. First, the BODCL responses to 16 pure organic substances were examined. Second, the influences of chloride ions, artificial seawater, and heavy metal ions on the BODCL response were investigated. Real sample measurements using river water were performed. Finally, BODCL responses were obtained for at least 8 days when the S. cerevisiae suspension was stored at 4 °C (response reduction, 69.9%; R.S.D. for 5 testing days, 18.7%). BODCL responses after 8 days and 24 days were decreased to 69.9% and 35.8%, respectively, from their original values (R.S.D. for 8 days involving 5 testing days, 18.7%). 相似文献
65.
This paper describes the preparation, characterization, mechanical properties and thermal stability of layered silicate nanocomposites based on poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHB-co-PHH, known as NodaxTM). The dispersed phases were organically modified montmorillonites (clay 20A and clay 25A), mica, and talc, and they were introduced by solution mixing. Wide-angle X-ray scattering results and transmission electron microscopy (TEM) images confirmed that these two clays were intercalated and finely distributed in the NodaxTM matrix. This type of layered filler led to remarkable improvements in mechanical properties even at very low loadings. Minimizing aggregation was more of a problem in the case of the mica and the talc, at least in this particular matrix. In some cases, these layered fillers slightly decreased the thermal stability of the NodaxTM. 相似文献
66.
Prof. Dr. Hiroyoshi Takamura Takayuki Fujiwara Yohei Kawakubo Prof. Dr. Isao Kadota Prof. Dr. Daisuke Uemura 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(6):1979-1983
Stereoselective and streamlined synthesis of the proposed C79–C104 fragment 2 of symbiodinolide ( 1 ), a polyol marine natural product with a molecular weight of 2860, was achieved. In the synthetic route, the proposed C79–C104 fragment 2 was synthesized by utilizing a Julia–Kocienski olefination and subsequent Sharpless asymmetric dihydroxylation as key transformations in a convergent manner. Detailed comparison of the 13C NMR chemical shifts between the natural product and the synthetic C79–C104 fragment 2 revealed that the stereostructure at the C91–C99 carbon chain moiety of symbiodinolide ( 1 ) should be reinvestigated. 相似文献
67.
Stereodivergent Synthesis and Stereochemical Reassignment of the C79–C104 Fragment of Symbiodinolide
Prof. Dr. Hiroyoshi Takamura Takayuki Fujiwara Yohei Kawakubo Prof. Dr. Isao Kadota Prof. Dr. Daisuke Uemura 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(6):1984-1996
We have synthesized eight possible diastereoisomers 3 a – h of the C79–C97 fragment of symbiodinolide ( 1 ) in a stereodivergent manner by utilizing a dithiane addition to the aldehyde as a key step. Comparison of the 13C NMR chemical shifts of the natural product 1 and the synthetic products 3 a – h indicated that the relative stereostructure of this fragment in symbiodinolide ( 1 ) is that represented in 3 a or f . We have stereodivergently synthesized eight possible diastereoisomers of the C94–C104 fragment 4 a – h , and we have compared their 13C NMR chemical shifts with those of the natural product, which established the relative stereochemistry of this fragment to be that described in diastereoisomers 4 a or e . By combining the stereostructural outcomes of the C79–C97 and C94–C104 fragments, we have proposed four candidate compounds of the C79–C104 fragment 2 a – d . We also synthesized diastereoisomers 2 a and b ( 2 a in the preceding article; Chem. Eur. J. 2015 , DOI: 10.1002/chem.201503880) by a Julia–Kocienski olefination and diastereoisomers 2 c and d by a Wittig reaction. By comparing the 13C NMR chemical shifts of natural symbiodinolide ( 1 ) with those of the synthetic products 2 a – d , we have reassigned the stereostructure of the C79–C104 fragment of natural product 1 to be that depicted in diastereoisomer 2 b . 相似文献
68.
Saito Y Bag SS Kusakabe Y Nagai C Matsumoto K Mizuno E Kodate S Suzuka I Saito I 《Chemical communications (Cambridge, England)》2007,(21):2133-2135
A novel FRET based strategy for DNA sequence analysis utilising base-discriminating fluorescence (BDF) nucleoside, (Py)U/(2-Ant)U, as donor in the dual-labelled oligonucleotide probe is reported; a selective/specific emission from acceptor, was observed upon excitation at the donor, only when the opposite base of the "smart" fluorescently labeled BDF nucleoside, (Py)U/(2-Ant)U, is adenine on the complementary target sequence. 相似文献
69.
Nagamitsu T Takano D Marumoto K Fukuda T Furuya K Otoguro K Takeda K Kuwajima I Harigaya Y Omura S 《The Journal of organic chemistry》2007,72(8):2744-2756
The total synthesis of borrelidin has been achieved. The best feature of our synthetic route is macrocyclization at C11-C12 for the construction of an 18-membered ring after esterification between two segments. A detailed examination of the macrocyclization led us to the samarium(II) iodide-mediated intramolecular Reformatsky-type reaction as the most efficient synthetic approach. The two key segments were synthesized through regioselective methylation, directed hydrogenation, stereoselective Reformatsky-type reaction, and MgBr2.Et2O-mediated chelation-controlled allylation. 相似文献
70.
A convergent synthesis of the key synthetic intermediate of hemibrevetoxin B was achieved via the intramolecular allylation of an α-chloroacetoxy ether and subsequent ring-closing metathesis. 相似文献