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61.
Dr. Ryohei Doi Akimasa Yabuta Prof. Dr. Yoshihiro Sato 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(23):5884-5888
Palladium-catalyzed decarboxylative alkynylation of α-acyloxyketones triggered by C(sp3)−O bond cleavage is disclosed. The decarboxylation strategy featuring a neutral reaction condition enabled an unprecedent catalytic alkynylation of a ketone enolate. The reaction was applied to a variety of substrates, giving desired products in good yields. We successfully obtained X-ray crystallography of a new palladium–enolate intermediate that was synthesized by a reaction of [Pd(cod)(CH2TMS)2] with XPhos and α-acyloxyketone at room temperature, indicating facile C(sp3)−O bond disconnection. 相似文献
62.
63.
Ryohei Yamakado Shin-ichi Matsuoka Masato Suzuki Koji Takagi Kosuke Katagiri Isao Azumaya 《Tetrahedron》2013,69(5):1516-1520
m-Calix[3]amide bearing three pyrenes (1a) was prepared by the condensation reaction of 3-nonylaminobenzoic acid derivative using Ph3PCl2. Pyrenyl groups were found to be aligned in the screw-like fashion by m-calix[3]amide as confirmed by the X-ray crystallography. Aromatic proton signals observed at the up-field region in the 1H NMR spectrum at low temperature indicated that pyrenyl groups in 1a are aligned in close proximity in THF solution. UV–vis absorption and fluorescence emission spectra did not show marked peak shift nor concentration fluorescence quenching compared with reference compounds implying no significant electronic interaction between pyrenyl groups. These results can be explained by the steric effect of the m-calix[3]amide platform. On the other hand, an excimer emission was observed for m-calix[3]amide having a flexible spacer between pyrene and m-calix[3]amide (1b). 相似文献
64.
Characteristic solution properties of lecithin were studied in 1) water+propanol/lecithin/hexadecane and 2) ethanol/lecithin/ hexadecane systems. 1) Solvent property of water changes by added alcohol and the hydrophile-lipophile property of lecithin is balanced in 13 wt% propanol aq.-hexadecane system. Three liquid phases, i.e. aqueous alcohol, lecithin and hexadecane are found. The volume fraction of the lecithin phase increases with its concentration and at 2.3 wt%/system, all solvent molecules are swelled and one microemulsion phase is obtained. 2) In ethanol/ lecithin/hexadecane system, lecithin is also insoluble in the solvent, and swells a large amount of hexadecane. 相似文献
65.
Wetting phenomena play important roles in several technological applications and in many physical and biological thin‐film phenomena, such as wetting, adhesion and friction. One of key issues of these studies is to control the surface energy (or wettability) dynamically for liquid transportation. We have developed a liquid crystal (LC) surface for use as a transport substrate since we expected that the surface energy of an LC surface can be controlled rapidly using an electric field. The rapid control of the polarisability (or wettability) of a liquid crystalline surface by an electric field has been demonstrated, together with the transportation of a liquid microdroplet. 相似文献
66.
Makoto Uchimura Ryohei Ishige Masayuki Shigeta Yuki Arakawa Yosuke Niko Junji Watanabe Gen-Ichi Konishi 《Research on Chemical Intermediates》2013,39(1):403-414
We synthesized thermotropic liquid-crystalline polyesters in which 9,10-diphenylanthracene moieties are incorporated into the main chain type of polyester forming the chiral smectic C (Sm C*). The polymers were prepared by the isopropyltitanate-catalyzed reaction of biphenyldicarboxylic acid and the corresponding diols, with different ratios of diol of 9,10-diphenylanthracene moiety to the alkane diols (1, 5, and 10 mol %) under nitrogen atmosphere. The polymers exhibited thermotropic liquid crystals despite the presence of a bulky diphenylanthracene moiety in the main chain. The circular dichroism spectra revealed that a Sm C* phase was formed in the polymer with 1 mol % of anthracene moiety, although only an Sm A phase was formed in the other polymers. This is the first example of a Sm C* polyester containing a diphenylanthracene moiety in the main chain. Furthermore, we measured the optical properties of the polymers and found that they exhibited very high fluorescent efficiency. The fluorescence spectra of the thin film differed from that of a CH2Cl2 solution. 相似文献
67.
Dr. Ryu Yamasaki Dr. Masato Ohashi Kyotaro Maeda Takuya Kitamura Minami Nakagawa Korehito Kato Tetsushi Fujita Ryohei Kamura Kazuto Kinoshita Dr. Hyuma Masu Prof. Dr. Isao Azumaya Prof. Dr. Sensuke Ogoshi Prof. Dr. Shinichi Saito 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(10):3415-3425
A detailed study of the Ni‐catalyzed [4+3+2] cycloaddition reaction between ethyl cyclopropylideneacetate and dienynes has been conducted, resulting in the development of a new method for the synthesis of compounds containing nine‐membered rings. We studied the reactivity of various dienynes, together with their substituent and conformational effects. The mechanism of the reaction was probed by examining the stoichiometric reactions of the Ni complexes and dienynes. 相似文献
68.
Prof. Dr. Masaichi Saito Tomoki Akiba Misumi Kaneko Toshiaki Kawamura Dr. Minori Abe Prof. Dr. Masahiko Hada Prof. Dr. Mao Minoura 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(50):16946-16953
Plumbacyclopentadienylidenes, in which the lead atoms have divalent states and are coordinated by THF, pyridine and N‐heterocyclic carbene, were synthesized and characterized. The THF‐ and pyridine‐stabilized compounds can be regarded as rare examples of hypervalent 10‐X‐4 species. The equilibrium between the THF adduct and the free plumbacyclopentadienylidene was evidenced by spectroscopic analysis and theoretical calculations. The THF adduct in benzene converted into a plumbylene dimer, where one of the lead centers is coordinated by THF and the other lead atom is coordinated by a divalent lead atom, the dimer gradually decomposing into spiroplumbole. The THF adduct unexpectedly reacted with trifluoroborane and trichlorogallane to afford fluoroborole and chlorogallole, which are the first examples of non‐annulated fluoroborole and gallole, respectively. 相似文献
69.
Weerasak Chomkitichai Hathaithip Ninsonti Akira Baba Sukon Phanichphant Kazunari Shinbo Keizo Kato Futao Kaneko 《Surface and interface analysis : SIA》2014,46(9):607-612
We demonstrate the multiple plasmonic effect on the photocurrent properties of photoanodes containing Ag or Au nanoparticles (NPs) loaded onto titanium dioxide film (Ag–TiO2 or Au–TiO2) on Au grating surfaces. Ag–TiO2 or Au–TiO2 nanocomposite particles are prepared by a flame spray pyrolysis route. The structures and morphologies of the prepared products are characterized by high‐resolution transmission electron microscopy. The Ag–TiO2 or Au–TiO2 composite NPs are deposited by spin coating onto the Au grating surfaces. The photoanode electrode is a layered structure of blu‐ray disc‐recordable grating substrate/Au/Ag (or Au)–TiO2/dye/electrolyte/indium‐tin oxide. The plasmonic effect is induced when Ag or Au NPs are located within the propagating surface plasmon (SP) field on the Au grating surface. The short‐circuit photocurrent is increased by exciting the grating‐coupled propagating SP on the Au gratings and is further enhanced by positioning the Ag or Au NPs within the grating‐coupled SP field. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
70.
Multiple Reaction Pathways Operating in the Mechanism of Vinylogous Mannich‐Type Reaction Activated by a Water Molecule 下载免费PDF全文
A systematic search for reaction pathways for the vinylogous Mannich‐type reaction was performed by the artificial force induced reaction method. This reaction affords δ‐amino‐γ‐butenolide in one pot by mixing 2‐trimethylsiloxyfuran, imine, and water under solvent‐free conditions. Surprisingly, the search identified as many as five working pathways. Among them, two concertedly produce anti and syn isomers of the product. Another two give an intermediate, which is a regioisomer of the main product. This intermediate can undergo a retro‐Mannich reaction to give a pair of intermediates: an imine and 2‐furanol. The remaining pathway directly generates this intermediate pair. The imine and 2‐furanol easily react with each other to afford the product. Thus, all of these stepwise pathways finally converge to give the main product. The rate‐determining step of all five (two concerted and three stepwise) pathways have a common mechanism: concerted Si? O bond formation through the nucleophilic attack of a water molecule on the silicon atom followed by proton transfer from the water molecule to the imine. Therefore, these five pathways have comparable barriers and compete with each other. 相似文献