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101.
The catalytic intermolecular cyclotrimerization of alkynylboronates, propargyl alcohols, and terminal alkynes was accomplished by means of the ruthenium catalysis and the temporary tethering approach with the C-B-O linkage to give rise to highly substituted arylboronates with excellent selectivity. The resultant arylboronates were further converted to highly substituted biaryls via the Suzuki-Miyaura coupling with various aryl iodides using Pd2(dba)3/PCy3 as a catalyst precursor in aqueous toluene. As a consequence, the four-component coupling approach to highly substituted biaryls was successfully established by combining these two operations into a sequential one-pot process. 相似文献
102.
Twelve major anthocyanins identified in bilberry extracts were studied in vitro using capillary zone electrophoresis (CZE) for their reactions towards 2,2'-azobis(2-amidinopropane) (AAPH) radicals, hydrogen peroxides (H(2)O(2)) and tert-buthylhydroperoxides (t-BuOOH). Reactivity towards AAPH radicals was primarily determined by the aglycon structure, not by the type of sugar moiety. Delphinidins carrying three-hydroxyl groups on the B ring were most reactive followed by cyanidins, with two-hydroxyl groups. Further, methylation of the hydroxyl groups reduced reactivity towards AAPH radicals. However, reactivity of anthocyanins towards H(2)O(2) was not significantly affected by aglycon structure or by the type of sugar moiety; there being no marked difference in reaction rates among the anthocyanins. Reactivity towards t-BuOOH was essentially the same as towards H(2)O(2), although the reaction rate was several times smaller. Also, the reaction rate of anthocyanin towards peroxide was relatively high compared to that of (+)-catechin (approximately 30 times larger) measured as a reference antioxidant, whereas the reactivities of anthocyanins and (+)-catechin towards AAPH radicals were similar. 相似文献
103.
The asymetric reduction of alkyl phenyl ketones with a chiral hydride reagent derived from lithium aluminum hydride and (S)-4-anilino-3-methylamino-1-butanol, which is prepared from (S)-aspartic acid, gives (S)-alkylphenylcarbinols in high chemical and optical yields. 相似文献
104.
Surface structure, pore size distribution and pore wall thickness of a mesoporous material FSM-16 have been studied by X-ray powder diffraction (XRD), lH and 29Si MAS NMR and 1H liquid-state NMR, and by applying surface silylation as a probe. Concentrations of surface hydroxyl groups for FSM-16 are estimated from 29Si and 1H MAS NMR, which are about 3×l021 g-1, corresponding to approximately 3 nm-2. O2 molecules contribute to 29Si spin-lattice relaxation of Q2 and Q3 as well as Q4, suggesting thin wall thickness. 1H MAS NMR spectra indicate the presence of isolated and hydrogen-bonded hydroxyl groups. Both hydroxyl groups are silylated, where the silylated fraction is about 50%. The spatial distribution of surface hydroxyl groups is estimated from the line width in 1H static spectra. A rather homogeneous distribution is demonstrated in one of the samples. The sample with less homogeneous distribution has a larger affinity for moisture. Pore size and pore wall thickness were determined by 1H NMR measurements on water saturated FSM-16 samples, which are in good agreement with literature values obtained by N2 adsorption isotherms and transmission electron micrographs on a similar sample. In benzene saturated samples, a non-freezing surface layer of benzene is much thicker than that of water, which indicates a stronger interaction between benzene and the FSM-16 surface. 相似文献
105.
Dong Hwan Lee Hiroharu Suzuki Yoshihiko Moro-oka 《Journal of organometallic chemistry》1987,330(3):C20-C22
Treatment of (η5-C5Me5)RuCl2(PR3) (1) with LiAlH4 in diethyl ether gives the ruthenium(II) tetrahydroaluminate complexes, (η5-C5Me5)Ru(AlH4)(PR3) (2) (R3 = Me3, Et3, iPr3, Ph2Me, Ph3), which can be quantitatively converted to the trihydriodurthenium(IV) complexes (η5-C5Me5)RuH3(PR3) (4), via protonolysis either by reaction with ethanol or by filtration through alumina. Low-temperature 1H NMR studies suggest the fluxionality of complexes 2 in solution at ambient temperature. 相似文献
106.
Muneo Ono Yoshihiko Kashio Martin Schweiger Hamid Dehghanim Simon R. Arridge Michael Firbank Eiji Okada 《Optical Review》2000,7(5):426-431
An accurate modelling of light propagation in the head is required to develop an algorithm to reconstruct the image of brain activity. Most previous studies have calculated the light propagation in two dimensional models because of their advantage in computation time and memory requirement over three dimensional models. However, in topographic imaging, the sensitivity distribution in the cross sections parallel to the brain surface which cannot be obtained from a two dimensional model is most important to reconstruct the image. In this study, the light propagation in three dimensional adult head models is calculated by finite element method and hybrid radiosity-diffusion method. The light propagation in the adult head is strongly affected by the non-scattering cerebrospinal fluid (CSF) layer surrounding the brain. The sensitive area is shifted toward the deeper region, and is spread around the CSF layer. The intensely sensitive region on the brain surface is broadly distributed between the source and detector. However, the sensitive region does not penetrate into the deeper part of the brain. 相似文献
107.
This paper describes non-oriented electrical steel sheet for automobile motors and reactors. Electrical steel sheets for energy efficient motors show high magnetic flux density and low iron loss. They are suitable for HEV traction motors and EPS motors. A thin-gauge electrical steel sheet and a gradient Si steel sheet show low iron loss in the high-frequency range. Therefore, the efficiency of high-frequency devices can be greatly improved. Since a 6.5% Si steel sheet possesses low iron loss and zero magnetostriction, it contributes to reduce the core loss and audible noise of high-frequency reactors. 相似文献
108.
Shunsuke Katagiri Dr. Ryota Sakamoto Hiroaki Maeda Dr. Yoshihiko Nishimori Tomochika Kurita Prof. Dr. Hiroshi Nishihara 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(16):5088-5096
This article completes our comprehensive understanding of the electron transport properties of our original π‐conjugated redox‐active molecular wires comprising Fe bridged by p‐phenylene linkers (tpy=2,2′:6′,2′′‐terpyridine). The Fe(tpy)2 oligomer wires comprise three types of tpy ligands: the anchor tpy ligand ( A series) makes a junction between the wire and electrode, the bridging bis‐tpy ligand ( L series) connects the Fe(tpy)2 units, and the terminal tpy ligand ( T series) possesses a redox site as a probe for the long‐range electron transport ability. Taking advantage of the precise tunability of the composition of the Fe(tpy)2 oligomer wires, thus far we investigated how A and L impacted on the electron‐transport ability. The excellent long‐range electron transport ability with ultrasmall attenuation constants (βd, 0.002 Å?1 as the minimum) depends on L significantly [Chem. Asian J. 2009 , 4, 1361], whereas A is unrelated to the βd value, but influences the zero‐distance electron‐transfer rate constant, ket0 [J. Am. Chem. Soc. 2010 , 132, 4524]. Herein we study the influence of terminal ligand T x (x=1–3). βd is independent of T , however, T3 , with a cyclometallated Ru complex as the redox site, gives rise to a ket0 value greater than T1 and T2 with ferrocene. This series of simple but definitive conclusions indicates that we have reached the stage of being able to precisely design molecular wires to attain desirable single‐molecule electron conduction. 相似文献
109.
Nobuhiro HAYASHI Koiti TITANI 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2010,86(5):494-508
N-myristoylation, one of the co- or post-translational modifications of proteins, has so far been regarded as necessary for anchoring of proteins to membranes. Recently, we have revealed that Nα-myristoylation of several brain proteins unambiguously regulates certain protein–protein interactions that may affect signaling pathways in brain. Comparison of the amino acid sequences of myristoylated proteins including those in other organs suggests that this regulation is involved in signaling pathways not only in brain but also in other organs. Thus, it has been shown that myristoylated proteins in cells regulate the signal transduction between membranes and cytoplasmic fractions. An algorithm we have developed to identify myristoylated proteins in cells predicts the presence of hundreds of myristoylated proteins. Interestingly, a large portion of the myristoylated proteins thought to take part in signal transduction between membranes and cytoplasmic fractions are included in the predicted myristoylated proteins. If the proteins functionally regulated by myristoylation, a posttranslational protein modification, were understood as cross-talk points within the intracellular signal transduction system, known signaling pathways could thus be linked to each other, and a novel map of this intracellular network could be constructed. On the basis of our recent results, this review will highlight the multifunctional aspects of protein N-myristoylation in brain. 相似文献
110.
A series of η5‐cyclopentadienylruthenium complexes, [(η5‐C5MenH5?n)RuCl(cod)] (cod=1,5‐cyclooctadiene), are evaluated as catalysts for the cycloaddition of 1,6‐diynes with alkynes. As a result, we unexpectedly found that the complex bearing the 1,2,4‐Me3Cp ligand is the most efficient catalyst in terms of turnover number (TON) for the cycloaddition of a bulky diiododiyne with acetylene, recording the highest TON of 970 with a catalyst loading of 0.1 mol %. To obtain insight into this result, we evaluate the electron richness of all complexes by cyclic voltammetric analyses, which indicate that the electron density of the ruthenium center increases with an increase in methyl substitution on the Cp′ ligands. The initial rate (up to 10 % conversion) of the cycloaddition was then measured using 1H NMR spectroscopy. The initial rate is found to decrease as the number of methyl substituents increases. According to these results, we assumed that the optimum catalytic performance exhibited by the 1,2,4‐trimethylcyclopentadienyl complex can be attributed to its robustness under the catalytic cycloaddition conditions. The steric and electronic effects of the Cp′ ligands are also investigated in terms of the regioselectivity of the cycloaddition of an unsymmetrical diyne and in terms of the chemoselectivity in the cycloaddition of a 1,6‐heptadiyne with norbornene. 相似文献