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91.
The first, enantiocontrolled total synthesis of (+)-sundiversifolide has been accomplished using the sequential ring-closing metathesis, [3,3]-sigmatropic rearrangement, and iodolactonization for the key assembly of the cis-fused oxabicyclo[5.3.0]decene framework of the natural product. [structure: see text] 相似文献
92.
Cobalt‐Catalyzed Transformation of Molecular Dinitrogen into Silylamine under Ambient Reaction Conditions 下载免费PDF全文
Ryuji Imayoshi Dr. Hiromasa Tanaka Yuki Matsuo Dr. Masahiro Yuki Dr. Kazunari Nakajima Prof. Dr. Kazunari Yoshizawa Prof. Yoshiaki Nishibayashi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(24):8905-8909
The first successful example of cobalt‐catalyzed reduction of N2 with Me3SiCl and Na as a reductant, under ambient reaction conditions, gives N(SiMe3)3, which can be readily converted into NH3. In this reaction system, 2,2′‐bipyridine (bpy) is found to work as an effective additive to improve substantially the catalytic activity. Co?N2 complexes bearing three Me3Si groups as ancillary ligands are considered to work as key reactive species based on DFT calculations. The DFT results also allow the proposal of a detailed reaction pathway for the transformation of N2 into N(SiMe3)3. 相似文献
93.
Yi‐Bing Wu Dan Liu Pei‐Yu Liu Xue‐Mei Yang Man Liao Nan‐Nan Lu Françoise Sauriol Yu‐Cheng Gu Qing‐Wen Shi Hiromasa Kiyota Mei Dong 《Helvetica chimica acta》2015,98(5):691-698
Three novel limonoids, 2,3‐dideacetylxyloccensin S ( 1 ), 30‐deacetylxyloccensin W ( 2 ), and 7‐hydroxy‐21β‐methoxy‐3‐oxo‐24,25,26,27‐tetranortirucalla‐1,14‐diene‐23(21)‐lactone ( 3 ), were isolated from the seeds of the Chinese mangrove, Xylocarpus granatum. The structures were elucidated on the basis of 1D‐ and 2D‐NMR (including 1H‐ and 13C‐NMR, DEPT, 1H,1H‐COSY, HSQC, HMBC, and NOESY) data and confirmed by HR‐MS. 相似文献
94.
Kentaro TakaiTadaatsu Hanadate Masaki AbeYukie Ono Teiko YamadaShigefumi Kuwahara Hiromasa Kiyota 《Tetrahedron》2011,67(37):7066-7072
Macrotetrolide α (1), a designed polynactin analog composed of (+)- and (−)-bishomononactic acids, was synthesized. The monomeric acids were prepared using cis-selective iodoetherification and optical resolution of the corresponding O-acetylmandelates as the key steps. Esterification and macrolactonization of the monomers were performed by Corey-Mukaiyama-Gerlach method. Compound 1 showed no immunosuppressive activity contrary to other natural polynactin congeners. 相似文献
95.
Fujii A Hayashi H Park JW Kazama T Mikami N Tsuzuki S 《Physical chemistry chemical physics : PCCP》2011,13(31):14131-14141
The CH/π interaction energies in benzene-alkane model clusters were precisely determined by laser spectroscopy and theoretical calculations. Two-color resonant two-photon ionization spectroscopy was employed to experimentally determine the interaction energies with isomer selectivity. High precision ab initio calculations were also performed to evaluate the CCSD(T) level interaction energies of various isomers at the basis set limit. Binary clusters of benzene with ethane, propane, n-butane, iso-butane, and cyclohexane were studied. The experimental interaction energies were well reproduced by the theoretical evaluations. The magnitude of the interaction energy clearly correlates with the average polarizability of the alkane moiety, demonstrating that the CH/π interaction energy is dominated by the dispersion interaction. On the other hand, the number of C-H groups in contact with the phenyl ring has no relation to the magnitude of the interaction energy, and it indicates that the role of the hydrogen atom in the CH/π interaction is essentially different from that in hydrogen bonds. 相似文献
96.
Takeuchi A Nakafutami S Tani H Mori M Takayama Y Moriguchi H Kotani K Miwa K Lee JK Noshiro M Jimbo Y 《Lab on a chip》2011,11(13):2268-2275
Rat superior cervical ganglion (SCG) neurons and ventricular myocytes (VMs) were co-cultured separately in a minichamber placed on a microelectrode-array (MEA) substrate. The minichamber, fabricated photolithographically using polydimethylsiloxane (PDMS), had 2 compartments, 16 microcompartments and 8 microconduits. The SCG neurons were seeded into one of the compartments and all of the microcompartments using a glass pipette controlled by a micromanipulator and a microinjector. The VMs were seeded into the other compartment. Three days after seeding of the VMs, the SCG neurons were still confined to one compartment and all of the microcompartments, and the neurites of the SCG neurons had connected with the VMs via the microconduits. Constant-voltage stimulation, using a train of biphasic square pulses (1 ms at +1 V, followed by -1 ms at 1 V), was applied to the SCG neurons in the microcompartments using 16 electrodes. Evoked responses were observed in several electrodes while electrical stimulation was applied to the SCG neurons. Two-way analysis of variance (ANOVA) revealed that the frequency of the stimulation pulses had significant effects in increasing the beat rate of the VMs, and that the interaction between the frequency and the number of the pulses also had a significant effect on the ratio. No significant increases in the beat rate were observed when propranolol, a β-adrenergic receptor antagonist, was added to the culture medium. These results suggest that synaptic pathways were formed between the SCG neurons and the VMs, and that this co-culture device can be utilized for studies of network-level interactions between sympathetic neurons and cardiomyocytes. 相似文献
97.
Hiromasa?NishikioriEmail author Yosuke?Fukasawa Yuta?Yokosuka Tsuneo?Fujii 《Research on Chemical Intermediates》2011,37(8):869-881
N-doped TiO2 has been prepared by use of sol–gel systems containing titanium alkoxide, with nitric acid as the nitrogen source. The time
needed for gelation of the systems was drastically reduced by ultrasonic irradiation. The peaks assigned to the nitrate and
nitrous ions were observed by FT-IR measurement during the sol–gel reaction. The N-doping was confirmed by the observation
of N–O peaks in the XPS spectrum of the sample heated at 400 °C. The nitrate ion acted as an oxidizer of the ethanol solvent
and titanium species. The TiO2 became doped with nitrogen oxide species as a result of reduction of nitrate ion incorporated into the dried gel samples.
These results indicated that the added nitric acid was reduced during the sol–gel transition and heating process, and the
resulting NO species were situated in the titania networks. The UV and visible photocatalytic activity of the samples was
confirmed by the degradation of trichloroethylene. 相似文献
98.
Benzoic acid-doped titania electrodes were prepared from titanium alkoxide sols containing benzoic acid in order to examine the photocatalytic reaction of the fuel material concentrated on the titania surface of a photofuel cell electrode. This doping was developed in order to understand the physicochemical processes on the titania rather than to advance the practical use of the photofuel cells. The observed photocurrent and CO2 and H2O productions indicated that the oxidation of the benzoic acid enhanced the generation of electricity during the UV irradiation. Benzoic acid molecules should be oxidized by oxygen molecules and holes on the titania surface. The steam treatment of the electrodes improved the benzoic acid oxidation and the photocurrent because it promoted the titania densification and enhanced the interaction between the benzoic acid and titania. The benzoic acid-doped titania is a valid model of the fuel material concentrated in the porous titania when using benzoic acid as the fuel material. The contact between the benzoic acid and titania is important in order to obtain a high photofuel electric conversion. 相似文献
99.
Hiromasa Nishikiori Takashi Sato Satoshi Kubota Nobuaki Tanaka Yuichiro Shimizu Tsuneo Fujii 《Research on Chemical Intermediates》2012,38(2):595-613
Cu-doped TiO2 was prepared by the refluxing of a mixture of copper and titanium alkoxides. The refluxing improved the Cu2+ dispersion in the TiO2 and formed effective Ti–O–Cu bonds. The impurity states due to the highly dispersed Cu2+ were presumed to trap the electrons in the conduction band of the TiO2 and prevent charge recombination of the electrons and holes. Consequently, the prolonged charge separation duration was suggested to enhance the photocatalytic activity of the Cu-doped TiO2. This enhancement was confirmed by the hydroxyl radical generation and organic compound degradation. The Ti–O–Cu bonds and electronic interaction between Cu and Ti should effectively promote the electron trapping. The Cu-doped TiO2 exhibited a visible light-induced activity due to the transition from the TiO2 valence band to the Cu2+ impurity states. 相似文献
100.
Thin films of tungsten phosphate glasses were deposited on a Pd substrate by a pulsed laser deposition method and the flux of hydrogen passed thorough the glass film was measured with a conventional gas permeation technique in the temperature range 300–500 °C. The glass film deposited at low oxygen pressure was inappropriate for hydrogen permeation because of reduction of W ions due to oxygen deficiency. The membrane used in the hydrogen permeation experiment was a 3-layered membrane and consisted of Pd film (~ 20 nm), the glass film (≤ 300 nm) and the Pd substrate (250 µm). When the pressure difference of hydrogen and thickness of the glass layer were respectively 0.2 MPa and ~ 100 nm, the permeation rate through the membrane was 2.0 × 10? 6 mol cm? 2 s? 1 at 500 °C. It was confirmed that the protonic and electronic mixed conducting glass thin film show high hydrogen permeation rate. 相似文献