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991.
Hiromichi Tanaka Hiroyuki Hayakawa Kikoh Obi Tadashi Miyasaka 《Tetrahedron letters》1985,26(50):6229-6232
Phenylthio group in the C-6 or C-5 position of uracil moiety can be removed by radical mediated stannylation with tributyltin hydride followed by protonolysis, providing a new route to 5-substituted uridines. 相似文献
992.
Takahashi S Hishinuma N Koshino H Nakata T 《The Journal of organic chemistry》2005,70(24):10162-10165
[reaction: see text] A new synthesis of epoxyketone 22 is described that is a key intermediate in Barton's synthesis of ovalicin (2), a powerful anti-angiogenetic inhibitor. The key process for the construction of 22 was ring-closing metathesis of olefins 11 and 12 obtained from 2,3:5,6-di-O-isopropylidene-alpha-D-mannofuranose (4) and regioselective desilylation of tri-TES ether 19. Furthermore, an alternative stereoselective route from 22 into 2 has also been developed, and the overall yield of 2 from 4 was 10.0%. 相似文献
993.
Four possible diastereomers of a functionalized 1,3-dimethyl-2-hydroxy unit were synthesized based on the stereoselective reduction of various acyclic ketones (i.e. reduction of β-keto ester, β-hydroxy ketone, α-hydroxy ketone, and α-silyloxy ketone) and the regioselective ring opening of epoxide by 1,3-dithiane anion. 相似文献
994.
Kiyoshi Kawatsura Hiroyoshi Kageyama Ryohei Takahashi Dai Hamaguchi Shigeyoshi Arai Yasushi Aoki Shunya Yamamoto Hidefumi Takeshita Hiroshi Naramoto Tadashi Kambara Masaki Oura Yasuyuki Kanai Yohko Awaya 《Radiation Physics and Chemistry》1997,49(6):617-622
High resolution L X-ray emission spectra of Cu have been measured by 0.75 MeV/u H, He, and F, 0.73 MeV/u Ar, 0.64 MeV/u Si, and 0.073 MeV/u Si ion impacts with a crystal spectrometer. The X-ray transition energies in the Cu target for Lι, Lη, L1,2, Lβ1, and Lβ3,4 diagram lines induced by H ion impact are determined, which are in good agreement with those given in the reference by Bearden (Rev. Mod. Phys. 39, 78, 1967). The X-ray spectra produced by F, Si, and Ar ions have complicated structures due to multiple L and M shell vacancy production. The L1,2 and Lβ1 emission spectra for H and He ions are compared with the calculated ones based on the multiconfiguration Dirac-Fock method. The origin of the broadening of the L1,2 line to the lower energy for H ion impact is attributed to one 2p plus one 3d electron vacancy production. 相似文献
995.
Sohda KY Minematsu T Hashimoto T Suzumura K Funatsu M Suzuki K Imai H Usui T Kamimura H 《Chemical & pharmaceutical bulletin》2004,52(11):1322-1325
Zonampanel monohydrate (YM872) has a potent and selective antagonistic effect on the glutamate receptor subtype, alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor. Metabolic fingerprinting in rat urine after a single intravenous administration of (14)C-labeled YM872 ((14)C-YM872) revealed the presence of two metabolites, R1 and R2. The two metabolites were semi-purified by preparative HPLC from rat urine after a single intravenous administration of non-labeled YM872, and their structures were elucidated by various instrumental analyses involving LC-NMR. The results showed that R1 and R2 have a hydroxyamino group and an amino group at the C-7 position of the quinoxalinedione skeleton, respectively. Therefore, the proposed metabolic pathway of YM872 in rats involves the reduction of the nitro group to a hydroxyamino group and then subsequent reduction to an amino group. 相似文献
996.
Isao Ishigaki Akihiko Ito Tadashi Iwai Koichiro Hayashi 《Journal of polymer science. Part A, Polymer chemistry》1972,10(7):1883-1893
Studies on the composition of copolymers obtained by the radiation-induced solid-state postpolymerization of trioxane with 1,3-dioxolane have been carried out. Gas-chromatographic analysis of the reaction mixtures showed that most of the 1,3-dioxolane disappears rapidly from the reaction system in an early stage of polymerization, and that the fraction of ethylene oxide units in the copolymer chain [E] decreases markedly with increasing polymer yield. This finding was confirmed by NMR spectra of the copolymer. DSC thermograms of the copolymer indicated that the relationship between the melting point and the average composition of copolymers prepared in this study differed from that found for copolymers in which comonomer units are distributed statistically in the polymer chain. It was suggested that the copolymer formed by the radiation-induced solid-state postpolymerization of trioxane–1,3-dioxolane is characterized by a heterogeneous distribution of ethylene oxide units in the copolymer chain. It was also found that, in the radiation-induced solid-state postpolymerization of trioxane–1,3-dioxolane, the amount of tetraoxane formation increased linearly with increasing polymer yield. Although it is extremely small compared with that obtained in solution polymerization, it is slightly larger in the trioxane–1,3-dioxolane system than in the trioxane system. 相似文献
997.
Chikamoto Y Hirotsu M Yamaguchi T Yoshimura T Konno T 《Dalton transactions (Cambridge, England : 2003)》2004,(21):3654-3661
The reaction of fac(S)-[Co(aet)(3)](aet = aminoethanethiolate) with [PdCl(4)](2-) in a 2:1 ratio in water gave an S-bridged Co(III)Pd(II)Co(III) trinuclear complex composed of two mer(S)-[Co(aet)(3)] units, [Pd[Co(aet)(3)](2)](2+)([1](2+)). In [1](2+), each of the two mer(S)-[Co(aet)(3)] units is bound to a square-planar Pd(II) ion through two of three thiolato groups, leaving two non-bridging thiolato groups at the terminal. Of two geometrical forms, syn and anti, possible for [Pd[Co(aet)(3)](2)](2+), which arise from the difference in arrangement of two terminal non-bridging thiolato groups, [1](2+) afforded only the syn form. A similar reaction of fac(S)-[Co(aet)(3)] with [PtCl(4)](2-) or trans-[PtCl(2)(NH(3))(2)] produced an analogous Co(III)Pt(II)Co(III) trinuclear complex, [Pt[Co(aet)(3)](2)](2+)([2](2+)), but both the syn and anti forms were formed for [2](2+). Complexes [1](2+) and syn- and anti-[2](2+), which exclusively exist as a racemic(DeltaDelta/LambdaLambda) form, were successfully optically resolved with use of [Sb(2)(R,R-tartrato)(2)](2-) as the resolving agent. The reaction of syn-[2](2+) with [AuCl[S(CH(2)CH(2)OH)(2)]] led to the formation of an S-bridged Co(III)(4)Pt(II)(2)Au(I)(2) octanuclear metallacycle, [Au(2)[Pt[Co(aet)(3)](2)](2)](6+)([3](6+)), while the corresponding reaction of anti-[2](2+) afforded a different product ([[4](3+)](n)) that is assumed to have a polymeric structure in [[Au[Pt[Co(aet)(3)](2)]](3+)](n). 相似文献
998.
Tetsuo Okada Teruji Tsuji Tadahiko Tsushima Tadashi Yoshida Shinzo Matsuura 《Journal of heterocyclic chemistry》1991,28(4):1061-1065
A new synthetic method was developed to obtain two novel tricyclic quinolonecarboxylic acids, 9-fluoro-3-methylene-10-(4-methylpiperazin-1-yl)-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylic acid ( 2 ) and its 1-thia congener 3 . The method involves the key intermediate of an oxetane derivative and its cleavage with acids. Evaluation of the antibacterial activities showed that 2 and 3 are excellent against both Gram-positive and Gram-negative organisms in vitro, being comparable to or only slightly less effective than Ofloxacin. In experimental systemic infections in mice, compound 2 showed distinctly higher activity than Ofloxacin, especially against infection caused by Escherichia coli. 相似文献
999.
With the aim of obtaining comprehensive information on the selection of synthetic adsorbents for industrial applications, effect of pore and chemical structure of industrial-grade synthetic adsorbents on adsorption capacity of several pharmaceutical compounds was investigated. For relatively low molecular mass compounds, such as cephalexin, berberine chloride and tetracycline hydrochloride, surface area per unit volume of polystyrenic adsorbents dominated the equilibrium adsorption capacity. On the contrary, effect of pore size of the polystyrenic adsorbents on the equilibrium adsorption capacity was observed for relatively high molecular mass compounds, such as rifampicin, Vitamin B12 and insulin. Polystyrenic adsorbent with high surface area and small pore size showed small adsorption capacity for relatively high molecular mass compounds, whereas polystyrenic adsorbent with relatively small surface area but with large pore size showed large adsorption capacity. Effect of chemical structure on the equilibrium adsorption capacity of several pharmaceutical compounds was also studied among polystyrenic, modified polystyrenic and polymethacrylic adsorbents. The modified polystyrenic adsorbent showed larger adsorption capacity for all compounds tested in this study due to enhanced hydrophobicity. The polymethacrylic adsorbent possessed high adsorption capacity for rifampicin and insulin, but it showed lower adsorption capacity for the other compounds studied. This result may be attributed to hydrogen bonding playing major role for the adsorption of compounds on polymethacrylic adsorbent. Furthermore, column adsorption experiments were operated to estimate the effect of pore characteristics of the polystyrenic adsorbents on dynamic adsorption behavior, and it is found that both surface area and pore size of the polystyrenic adsorbents significantly affect the dynamic adsorption capacity as well as flow rate. 相似文献
1000.
Takayoshi Kimura Takanori Matsushita Tadashi Kamiyama 《Journal of solution chemistry》2004,33(6-7):875-886
The enthalpies of solution of aliphatic compounds [{aliphatic amine, H(CH2) n NH2, n = 3 to 10}, aliphatic benzene {H(CH2) n C6H5, n = 0 to 8}, and alkane {H(CH2) n H, n = 6 to 10}] in dimethyl sulfoxide have been measured at 298.15 K in the low concentration range from x = 5 × 10?6 to x = 0.002. The partial molar enthalpies at infinite dilution of each aliphatic compound were determined and were found to increase linearly with increasing number of methylene groups. The enthalpic group contribution of methylene, phenyl, methyl, hydroxyl, nitrile, and amine in aliphatic compounds were 1.55, 2.65, 3.81, ?2.55, ?3.71, and ?4.43 kJ-mol?1, respectively. 相似文献