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91.
Konoike T Matsumura K Yorifuji T Shinomoto S Ide Y Ohya T 《The Journal of organic chemistry》2002,67(22):7741-7749
A practical multikilogram-scale synthesis of enantiomerically pure S-1255 (1), a potent and orally active ET(A) receptor antagonist, is described. Utilizing readily available starting materials and reagents, the entire sequence of reactions starting from 2,5-dihydroxyacetophenone 8 proceeded under mild conditions to give 1 in an excellent chemical yield (8 steps, 41% overall yield) and in a high enantiopurity (98% ee). The crucial step of the synthesis is a dynamic resolution of key intermediate 16. (R)-Methoxy acid (R)-16 having 97-99% ee was obtained in 83-84% yield from racemic 16 as a crystalline (1S,2R)-(+)-norephedrine or (+)-cinchonine salt by the dynamic resolution comprising concurrent crystallization and in situ racemization. A mechanism of the dynamic resolution through a ring-opened zwitterionic intermediate is discussed. In the final synthetic step, an effective carbon-carbon bond formation between the C4 carbon and the p-anisyl group was accomplished by a conjugate addition-elimination reaction of Grignard reagent 3 to (R)-16 to give 1 having 98% ee. Owing to high efficiencies of functional group transformations, carbon-carbon bond formations, and the dynamic resolution, the synthesis required no chromatographic purification and was amenable to a multikilogram-scale preparation. Several kilograms of 1 for clinical trials were successfully prepared by this process. 相似文献
92.
Koji Oshita Mitsuko Oshima Yunhua Gao Kyue-Hyung Lee Shoji Motomizu 《Analytica chimica acta》2003,480(2):239-249
A chitosan resin derivatized with serine moiety (serine-type chitosan) was newly developed by using the cross-linked chitosan as a base material. The adsorption behavior of trace amounts of metal ions on the serine-type chitosan resin was systematically examined by packing it in a mini-column, passing a metal solution through it and measuring metal ions in the effluent by ICP-MS. The resin could adsorb a number of metal cations at pH from neutral to alkaline region, and several oxoanionic metals at acidic pH region by an anion exchange mechanism. Uranium and Cu could be adsorbed selectively at pH from acidic to alkaline region by a chelating mechanism; U could be adsorbed quantitatively even at pH 3–4. Uranium adsorbed on the resin was easily eluted with 1 M nitric acid: the preconcentration (5-, 10-, 50- and 100-fold) of U was possible. The column treatment method was used prior to the ICP-MS measurement of U in natural river, sea and tap waters; R.S.D. were 2.63, 1.13 and 1.37%, respectively. Uranium in tap water could be determined by 10-fold preconcentration: analytical result was 1.46±0.02 ppt. The resin also was applied to the recovery of U in sea water: the recovery tests for artificial and natural sea water were 97.1 and 93.0%, respectively. 相似文献
93.
Monitoring the removal of carbonate from alkali metal hydroxide (MOH, M = K, Na) solutions with calcium oxide (CaO) was studied using a newly developed method for the determination of trace amounts of total carbonate (TC) in alkaline solutions based on a flow injection (FI) technique coupled with a gas diffusion system. The optimized conditions of the FI system were as follows: the flow rate of each carrier, reaction solution (H2SO4) and receptor solution (Cresol Red, pH 8.9) was 0.25 ml min(-1), the sample size was 0.1 ml and the concentration of H2SO4 in the reaction solution was 0.09 M. The limit of detection of TC by the proposed method was 4 x 10(-7) M. The removal efficiency of carbonate was affected by the amount of CaO added, the shaking time of the solutions and the concentration of MOH. For 1 M NaOH and KOH solution, the removal efficiency of carbonate was about 99% and the concentration of residual carbonate was 4 x 10(-5) and 1.2 X 10(-4) M, respectively, when the amount of CaO added was 2 g l(-1) and the shaking time was 16 h. 相似文献
94.
Mitsuru Ueda Toshiyuki Suzuki Yoshio Imai Charles U. Pittman Easley Wallace 《Journal of polymer science. Part A, Polymer chemistry》1983,21(10):2997-3008
The kinetics of cyanomethyl methacrylate (CyMA) homopolymerization was investigated in acetonitrile with azobisisobutyronitrile as initiator. The rate of polymerization Rp was expressed by Rp = k[AIBN]0.49[CyMA]1.2 and the overall activation energy was calculated as 72.3 kJ/mol. Kinetic constants for CyMA polymerization were obtained as follows: kp/k = 0.10 L1/2s?1/2; 2fkd = 1.57 × 10?5s?. The relative reactivity ratios of CyMA(M2) copolymerization with styrene (r1 = 0.15, r2 = 0.29) and methyl methacrylate (r1 = 0.43, r2 = 0.75) in acetonitrile were obtained. Applying the Q-e scheme (in styrene copolymerization) led to Q = 1.64 and e = 0.98. The glass transition temperature Tg of poly(CyMA) was observed to be 91°C by thermomechanical analysis. Thermogravimetry of poly(CyMA) showed a 10% weight loss at 265°C in air. 相似文献
95.
Inumaru K Kasahara T Yasui M Yamanaka S 《Chemical communications (Cambridge, England)》2005,(16):2131-2133
Well-crystallised TiO2 particles (P-25, 20-30 nm in diameter) were directly incorporated into surfactant-templated mesoporous silica particles (pore diameter: 2.7 nm), and the composite material with a high TiO2 content (60 wt%) showed molecular selective and enhanced photocatalysis for decomposition of 4-nonylphenol. 相似文献
96.
We have investigated the static and dynamic structures of nonionic surfactant micelles, a C(12)E(8)/water binary system, during the disorder-order transition using small angle x-ray scattering, static light scattering, and dynamic light scattering techniques. In the disordered phase, the micelles have spherical shape and intermicellar interactions are governed by the hard core and weak long ranged attractive potentials. With increase of the micellar concentration, the disordered micelles transform to the three characteristic ordered micellar phases, a hexagonally close packed lattice, a body centered cubic lattice, and an A15 lattice having area-minimizing structure. The stability of these phases is well explained by balance of a close packing rule and a minimal-area rule proposed by Ziherl and Kamien [Phys. Rev. Lett. 85, 3528 (2000)]. The role of hydrodynamic interactions in surfactant micellar solutions was compared with that in hard sphere colloidal particle suspensions. 相似文献
97.
Imai M Tanaka M Tanaka K Yamamoto Y Imai-Ogata N Shimowatari M Nagumo S Kawahara N Suemune H 《The Journal of organic chemistry》2004,69(4):1144-1150
Intermolecular hydroacylation between salicylaldehydes 1, 26-40 and 1,4-penta- or 1,5-hexadienes 4-13 by Rh-catalyst proceeded under mild reaction conditions to give a mixture of iso- and normal-hydroacylated products 14-25, 41-55, and 57-60. In the hydroacylation reaction, chelation of both salicylaldehyde and diene to the Rh-complex plays a crucial role. The ratio of iso- and normal-hydroacylated products could be regulated by the addition of salicylic acid or amines. The effects of various Rh-complexes, solvents, and additives were examined, and the plausible mechanisms of the catalytic cycle were proposed on the basis of the deuterium-labeling salicylaldehyde experiments. 相似文献
98.
Ken-ichi Sato Shoji AkaiToshiyuki Hiroshima Hidenori AokiMayumi Sakuma Ken-ju Suzuki 《Tetrahedron letters》2003,44(17):3513-3516
The chemoenzymatic synthesis of 13C-labeled sialic acid (NeuAc) and 3-deoxy-d-glycero-d-galacto-2-nonulosonic acid (KDN) as useful molecular probes for studying the conformation of sialyl or KDN oligosaccharides attached to proteins was performed by using [6-13C]-ManNAc, [6-13C]-Man and [3-13C]-pyruvic acid sodium salt. In the synthesis of the compounds, 5,6-anhydro intermediates were found to easily provide not only 6-13C-labeled but also 5-, and 6-modified NeuAc and KDN analogs. Furthermore, it was demonstrated that identical results are obtained by NMR for both [3,9-13C]-NeuAc and 1:1 mixtures of [3-13C]- and [9-13C]-NeuAc. 相似文献
99.
Masaru Yoneyama K. D. Athula Kuruppu Masa-Aki Kakimoto Yoshio Imai 《Journal of polymer science. Part A, Polymer chemistry》1988,26(11):2917-2922
Aromatic polyamides (aramids) having inherent viscosities of 0.5–1.10 dL/g were prepared by the direct polycondensation of 1,1,3-trimethyl-3-(4-carboxyphenyl)indane-5-carboxylic acid with various aromatic diamines using triphenyl phosphite and pyridine as the condensing agents. Copolyamides were also prepared by a similar procedure from a mixture of the phenylindane diacid, terephthalic acid, and p-phenylenediamine. Almost all of the aramids were soluble in a variety of solvents such as N-methyl-2-pyrrolidone, pyridine, and m-cresol, and afforded transparent and tough films by the solution casting. These aramids and copolyamides had glass transition temperatures in the range of 290–355°C, and started to lose weight at 340°C in air. 相似文献
100.
Hwa-Jin Jeong Yoshiyuki Oishi Masa-Aki Kakimoto Yoshio Imai 《Journal of polymer science. Part A, Polymer chemistry》1990,28(12):3293-3301
A new highly phenylated heterocyclic diamine, 3,4-bis(4-aminophenyl)-2,5-diphenylfuran, was synthesized in three steps from 4–-nitrodeoxybenzoin. The low temperature solution polycondensation of the diamine with various aromatic diacid chlorides afforded tetraphenylfuran-containing aromatic polyamides with inherent viscosities of 0.2–0.8 dL/g. Copolyterephthalamides were obtained from the diamine and 4,4′-oxydianiline. The polyamides were generally soluble in a wide range of solvents that included N,N-dimethylacetamide, N-methyl-2-pyrrolidone, pyridine, and m-cresol. Glass transition temperatures of the polyamides and copolyamides ranged from 302–342°C, and 10% weight loss was observed above 480°C in nitrogen. 相似文献