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181.
Enantioselective Denitrogenative Annulation of 1H‐Tetrazoles with Styrenes Catalyzed by Rhodium
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Takayuki Nakamuro Kohei Hagiwara Dr. Tomoya Miura Prof. Dr. Masahiro Murakami 《Angewandte Chemie (International ed. in English)》2018,57(19):5497-5500
Sulfonylation of 1H‐tetrazoles with triflic anhydride in the presence of chiral rhodium(II) carboxylate dimers causes denitrogenation to generate α‐azo rhodium(II) carbenoid species as new types of donor/acceptor carbenoids, which then readily react with styrenes to afford 3,5‐diaryl‐2‐pyrazolines with a high degree of enantioselectivity. 相似文献
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Miyuki Hagiwara Toru Tagawa Hideo Amemiya Kunio Araki Isao Shinohara Tsutomu Kagiya 《Journal of polymer science. Part A, Polymer chemistry》1976,14(9):2167-2172
Thermal decomposition of polymer peroxide radicals formed in γ-irradiated polytetrafluoroethylene, ~CF2CF(OO·)CF2~ (radical I) and ~CF2CF2(OO~) (radical II), was studied by mass spectral analysis of the gas evolved in comparison with their photolysis with ultraviolet light. In the thermal decomposition of radicals I and II, CO2 was the most abundant component, with smaller amount of CO, CF2O, and gases present. In the photolysis, CO instead of CO2 was the most abundant in the case of radical I, while in the case of radical II, CO2 was again the main product. When a labeled polymer peroxide radical, ~CF2CF(18O-18O·)CF2~, was treated with heat or ultraviolet light, C18O16O was detected as a main component. In the treatment with ultraviolet light, a large amount of C18O comparable to that of C18O16O was also obtained. The mechanism of main-chain scission of radicals I and II is discussed. 相似文献
187.
Voltammetric response of phenylboronic acid monolayer-modified gold electrode to sugars. 总被引:1,自引:0,他引:1
Shigehiro Takahashi Yoshitomo Kashiwagi Tomonori Hoshi Jun-ichi Anzai 《Analytical sciences》2004,20(5):757-759
The surface of a gold (Au) disk electrode was modified with a self-assembled monolayer consisting of phenylboronic acid moiety to fabricate a voltammetric sensor sensitive to sugars. The modified Au electrode exhibited a voltammetric response to sugars in the presence of Fe(CN)6(3-) ion in the sample solution at neutral pH. The peak current of the cyclic voltammograms decreased depending on the type and concentration of sugars. The dynamic range of the electrode is 3 - 100 mM for glucose and mannose and 1 - 30 mM for fructose. The sugar sensor can be used repeatedly after rinsing in 10 mM acetate buffer (pH 4.5). 相似文献
188.
M Hagiwara E Ohuchi K Hongo M Oki M Nakano M Amemiya T Morikawa K Kobashi 《Chemical & pharmaceutical bulletin》1990,38(5):1369-1372
The pharmacological activities of synthetic human CCK-33, in which a tyrosine molecule was sulfated by arylsulfotransferase, were investigated in the rat and the guinea-pig. The activities were compared with those of non-sulfated CCK-33 (CCK-33NS), CCK-8 and CCK-4. CCK-33 was about 100 fold more potent than non-sulfated CCK-33(CCK-33NS) but was about 20 fold less potent than CCK-8 in the contraction of the isolated gallbladder of the guinea-pig. In rat pancreatic secretion, intravenous CCK-33 and CCK-8 showed almost the same activity. The potency of each was about 1000 fold more than the individual potency of CCK-33NS, non-sulfated CCK-8 (CCK-8NS) and CCK4. There were no significant differences in gastric acid stimulatory activities among CCK-33, CCK-8, CCK-4, but the activities of CCK-33NS and CCK-8NS were less than those of CCK-33 and CCK-8, respectively. CCK-33 and CCK-8 produced a reduction in the intake of powder chow in doses of 10(-8) and 3 x 10(-8) mol/kg i.p., but CCK-33NS, CCK-8NS and CCK-4 did not. In conclusion, the activities of synthetic human CCK-33 are almost the same as those of CCK-8 on exocrine pancreatic secretion, gastric acid secretion and food intake, but less than CCK-8 on isolated gallbladder contraction. 相似文献
189.
Daisuke Sasaki Yasushi Okada Toshiki Hagiwara Takashi Sawaguchi 《Polymer Degradation and Stability》2007,92(2):271-279
It was found that telechelic isotactic oligo(1-butene) and telechelic oligo(propylene-ran-1-butene) could be isolated as nonvolatile oligomers from polymer residues resulting from the thermal degradation of isotactic poly(1-butene) and poly(propylene-ran-1-butene), respectively. Their structures were determined by 1H and 13C NMR with attention being paid to their reactive end groups. The maximum average number of terminal vinylidene groups per molecule (fTVD) was 1.8, indicating that about 80 mol% were α,ω-diene oligomers having two terminal vinylidene groups. This useful new telechelic oligomer had a lower polydispersity than the original polymer, in spite of its lower molecular weight and Tm. The composition of end groups of nonvolatile oligomers obtained by thermal degradation of poly(propylene-ran-1-butene) could be explained by the differences in bond dissociation energy and activation energy of elementary reactions during thermal degradation, based on the monomer composition of the original polymer. 相似文献
190.
Miyuki Hagiwara Hiroshi Mitsui Sueo Machi Tsutomu Kagiya 《Journal of polymer science. Part A, Polymer chemistry》1968,6(3):609-621
The γ-radiation-induced polymerization of ethylene with the use of liquid carbon dioxide as a solvent, was studied from the viewpoint of kinetics. The polymerization was carried out at conversions less than 10% under the pressure ranging from 100 to 400 kg./cm.2, dose rates 1.3 × 104?1.6 × 105 rad/hr., and temperatures of 20–90°C. The concentration of carbon dioxide varied up to 84.1 mole-%. The polymerization rate and the polymer molecular weight were observed to increase with reaction time. This observation, however, becomes less pronounced with increasing concentration of carbon dioxide and with rising temperature. The exponents of the pressure and the dose rate were determined to be 2.3 and 0.85 for the rate, and 2.0 and ?0.20 for the molecular weight, respectively. From the kinetic considerations for these results, the effect of carbon dioxide on the initiation and termination reaction in the polymerization was evaluated. 相似文献