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201.
Stephen G. Davies Jairton Dupont Robert J.C. Easton Osamu Ichihara Jeffrey M. McKenna Andrew D. Smith José A.A. de Sousa 《Journal of organometallic chemistry》2004,689(24):4184-4209
Conjugate addition of achiral lithium dimethylamide to the chiral iron cinnamoyl complexes (S,E)- and (S,Z)-[(η5-C5H5)Fe(CO)(PPh3)(COCHCHPh)] proceeds with high diastereoselectivity, with this protocol being used to establish unambiguously the absolute configuration of Winterstein’s acid (3-N,N-dimethylamino-3-phenylpropanoic acid) as (R). The highly diastereoselective conjugate addition of lithium N-benzyl-N-trimethylsilylamide to a range of α,β-unsaturated iron acyl complexes, followed by in-situ elaboration of the derived enolate by either alkylation or aldol reactions is also demonstrated, facilitating the stereoselective synthesis of both cis- and trans-β-lactams. This methodology has been used to effect the formal asymmetric syntheses of (±)-olivanic acid and (±)-thienamycin. Addition of chiral lithium amides derived from primary and secondary amines to the iron crotonyl complex [(η5-C5H5)Fe(CO)(PPh3)(COCHCHMe)] indicates that lithium N-α-methylbenzylamide shows low levels of enantiorecognition, while lithium N-3,4-dimethoxybenzyl-N-α-methylbenzylamide and lithium N-benzyl-N-α-methylbenzylamide show high levels of enantiodiscrimination. The high level of observed enantiorecognition was used to facilitate a kinetic resolution of (RS)-[(η5-C5H5)Fe(CO)(PPh3)(COCHCHMe)] with homochiral lithium (R)-N-3,4-dimethoxybenzyl-N-α-methylbenzylamide. Further mechanistic studies show that conjugate additions of (RS)-lithium N-benzyl-N-α-methylbenzylamide to either the (RS)- or homochiral iron crotonyl complex show 2:1 stoicheiometry, while homochiral lithium N-benzyl-N-α-methylbenzylamide shows 1:1 stoicheiometry. 相似文献
202.
Yoh Sasaki Kyohei Ushimaru Katsuma Iteya Hirokazu Nakayama Shunro Yamaguchi Junko Ichihara 《Tetrahedron letters》2004,45(52):9513-9515
A new synthetic method of sulfoxides and sulfones using solvent-free oxidations of sulfides with urea–hydrogen peroxide complex (urea–H2O2) and tetrabutylammonium phosphomolybdate catalyst on fluorapatite ((Bu4N)3[PMo12O40]/FAp). In the solid-phase system the oxidations of aromatic and alkyl sulfides proceeded at 4–25 °C and the corresponding sulfoxides or sulfones were selectively obtained in good yields by controlling the amount of urea–H2O2. 相似文献
203.
Kimura N Matsumoto H Konosu Y Yamamoto R Minagawa M Tanioka A 《Journal of colloid and interface science》2005,286(1):288-293
The membrane potential across anion-exchange membranes in H2SO4 and Na2SO4 solutions was measured, and the experimental results were fitted to the theory in the 2-1 electrolyte system based on the Donnan equilibrium and the Nernst-Planck flux equations. For the Na2SO4 solution, the Donnan potential makes a significant contribution to the membrane potential, but for the H2SO4 solution, the diffusion potential significantly contributes to the membrane potential. The diffusion potential has a greater contribution to the membrane potential across AEM-2 with a high water content than that across AEM-1. These results suggest that a proton with a high mobility can move without substantial influence of electrostatic interaction in a positively charged membrane. 相似文献
204.
Akitami Ichihara Makoto Ubukata Hideaki Oikawa Kazuo Murakami Sadao Sakamura 《Tetrahedron letters》1980,21(46):4469-4472
Efficient synthesis of (±)-nanaomycin A and (±)-frenolicin from a versatile intermediate is described. 相似文献
205.
Surface morphology and biological activity of protein thin films produced by electrospray deposition
Uematsu I Matsumoto H Morota K Minagawa M Tanioka A Yamagata Y Inoue K 《Journal of colloid and interface science》2004,269(2):336-340
Protein thin films were prepared by the electrospray deposition (ESD) method from aqueous solutions of alpha-lactalbumin (alpha-LA) at different concentrations, and their surface morphologies and biological activities were characterized. The surface morphologies of the deposited films were observed using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The SEM and AFM images showed that the film surfaces had a fine porous structure, in which the pore diameters ranged from 40 to 600 nm. The biological activities of the cross-linked protein films were tested by the mechanochemical method. The response to calcium ion (Ca(2+)) demonstrated that the biological activity of the films was preserved. These results indicate that the ESD method is potentially useful for the fabrication of active protein thin films. The freestanding protein thin films prepared by ESD and postdeposition cross-linking provide novel options for protein-based biomaterials. 相似文献
206.
This work investigated the chemiluminescent reaction of free chlorine with bis(2,4,6-(trichlorophenyl)oxalate) (TCPO) in the presence of 9,10-diphenylanthracene in acetonitrile/water medium, with analytical application for free chlorine in tap water. In the absence of free chlorine, the background signal increased with the pH and the chemiluminescence emission showed strong dependence with the sample acidity. A flow injection analysis system, for free chlorine determination, was developed. The linear range for free chlorine was (0.2-3.0)×10−5 mol l−1. Chloramine 1.0×10−5 mol l−1 and chlorite 1.0×10−6 mol l−1 also enhanced the chemiluminescence intensity. 相似文献
207.
208.
Haruhisa Kato Kayori Takahashi Takeshi Saito Mie Suzuki Shinichi Kinugasa 《Chemical physics letters》2008,463(1-3):150-154
The accurate size determination of nanoparticles in solution is an important subject in nano/bio-technologies. However, interactions between particles induce a significant misinterpretation of the size determination by PFG-NMR method. In the sodium dodecyl sulfate (SDS) aqueous solution, we observed the significant change of the apparent size of PS-latex that depended on the concentration of SDS. In this Letter, accurate size determination of PS latex was carried out by extrapolation methods varying both the concentrations of the PS latex and the SDS in aqueous solution. The proposed method makes it possible to compare the determined sizes of nanoparticles in the liquid-phase by PFG-NMR to those by differential mobility analyzer (DMA) in the gas-phase. 相似文献
209.
210.
Ichihara C Kawakami N Yasuno S Hino A Fujikawa K Kobayashi A Ochi M Gotoh H Kugimiya T 《Micron (Oxford, England : 1993)》2009,40(1):66-69
High-resolution Rutherford backscattering spectrometry (HRBS) in combination with grazing angle argon sputtering was carried out to characterize the interface of aluminum-nickel (Al-Ni) alloy and amorphous-silicon films in a thin film transistor (TFT) for liquid crystal display (LCD). After thinning the top Al-Ni layer by a 1-keV Ar sputtering, the sensitivity of the interface oxygen was improved to be twice higher than that before sputtering. The results revealed that the oxygen at the interface relates to the contact characteristics. 相似文献