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91.
Taishi Nakanishi Dr. Jun Kikuchi Dr. Atsushi Kaga Prof. Dr. Shunsuke Chiba Prof. Dr. Masahiro Terada 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(37):8230-8234
A catalytic enantioselective synthesis of β-amino secondary amides was achieved using vinyl azides as the enamine-type nucleophile and chiral N-Tf phosphoramide as the chiral Brønsted acid catalyst through a five-step sequential transformation in one pot. The established sequential transformation involves an enantioselective [4+2] cycloaddition reaction of vinyl azides with N-acyl imines as the key stereo-determining step that is efficiently accelerated by a chiral N-Tf phosphoramide catalyst in a highly enantioselective manner in most cases. Further generation of the iminodiazonium ion intermediate through ring opening of the cycloaddition product and subsequent skeletal rearrangement involving Schmidt-type 1,2-aryl group migration followed by recyclization of the resulting nitrilium ion were also initiated by the same acid catalyst. Final acid hydrolysis of the recyclized products in the same pot gave rise to enantioenriched β-amino amides through C−C bond formation at the α-position of the secondary amides. 相似文献
92.
Kanna Adachi Tomoshi Yamada Hayate Ishizuka Mana Oki Shunsuke Tsunogae Noriko Shimada Osamu Chiba Tatsuya Orihara Prof. Dr. Masafumi Hidaka Prof. Dr. Takatsugu Hirokawa Dr. Minami Odagi Prof. Dr. Keiichi Konoki Prof. Dr. Mari Yotsu-Yamashita Prof. Dr. Kazuo Nagasawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(9):2025-2033
A novel series of C12-keto-type saxitoxin (STX) derivatives bearing an unusual nonhydrated form of the ketone at C12 has been synthesized, and their NaV-inhibitory activity has been evaluated in a cell-based assay as well as whole-cell patch-clamp recording. Among these compounds, 11-benzylidene STX ( 3 a ) showed potent inhibitory activity against neuroblastoma Neuro 2A in both cell-based and electrophysiological analyses, with EC50 and IC50 values of 8.5 and 30.7 nm , respectively. Interestingly, the compound showed potent inhibitory activity against tetrodotoxin-resistant subtype of NaV1.5, with an IC50 value of 94.1 nm . Derivatives 3 a – d and 3 f showed low recovery rates from NaV1.2 subtype (ca 45–79 %) compared to natural dcSTX ( 2 ), strongly suggesting an irreversible mode of interaction. We propose an interaction model for the C12-keto derivatives with NaV in which the enone moiety in the STX derivatives 3 works as Michael acceptor for the carboxylate of Asp1717. 相似文献
93.
Syuuhei Komatsu Hidenari Kayano Yu Ando Taka-Aki Asoh Ryo Ishihara Akihiko Kikuchi 《Journal of polymer science. Part A, Polymer chemistry》2018,56(23):2623-2629
We herein report the preparation of thermo- and redox-responsive branched polymers by the condensation reaction of three-armed oligo(ethylene glycol) (trisOEG) and cystamine (CA). The prepared branched polymers exhibited a soluble–insoluble transition at a lower critical solution temperature (LCST) and formed coacervate droplets through a liquid–liquid phase separation process. We then demonstrated control of the LCSTs of the branched polymers by varying the feed ratio of CA and the surrounding salt concentration close to body temperature. In addition, the trisOEG-cys x polymer formed coacervate droplets above the LCST, in which hydrophobic molecules were condensed. The redox response of the branched polymers was also investigated. Interestingly, the branched polymers degraded to low-molecular-weight materials (i.e., trisOEG) in the presence of dithiothereitol as a reducing agent through cleavage of the disulfide bond of CA. This facile preparation of branched polymers is expected to be valuable in the context of functional biomedical materials and modifiers for materials surfaces, such as the bases for drug delivery carriers and separation materials. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2623–2629 相似文献
94.
Photo-induced edge-shift affect in As2S3 film has been studies for different intensities of incident light. This process depends only on the total energy E of light. A simple experimental relationship between shift of edge Δλ and E has been obtained, which coincides with a theretical prediction deduced from a model based on a first-order reaction. 相似文献
95.
Roberto M. Serikawa Masahiro Isaka Qinqquan Su Takashi Usui Tatsuya Nishimura Hirokazu Sato 《高压研究》2013,33(1-6):477-489
Abstract Electrochemical evolution of hydrogen gas, oxygen gas and chlorine at the electrodes is the usual reaction in conventional electrolysis of aqueous salt solution. However, here we demonstrate that the electrolysis governing reaction in hydrothermal solutions is different from the electrolysis performed at atmospheric pressure and temperatures up to 100°C. Experimental electrolytic reaction of aqueous salt solution carried out inside a sealed 300-mL batch autoclave showed that; accumulation of hydrogen gas, oxygen gas and chlorine is highly suppressed under hydrothermal (250°C and 7 MPa) conditions. We have also observed that, when organics are present in the aqueous salt solution being hydrothermally electrolyzed, an effective oxidation of organics is accomplished. Furthermore, for hydrothermal electrolytic oxidation (HEO) with oxygen gas added, experimentally observed TOC removal profile demonstrates apparent anodic oxidation electrical current efficiency of almost 200% for highconcentrated acetic acid solutions. 相似文献
96.
We characterize hereditary (as coalgebras) Hopf algebras by the property of ‘equivariant smoothness’, and apply the result
to generalize to the super-context, the category equivalence, due to Hochschild, between the unipotent algebraic affine groups
and the finite-dimensional nilpotent Lie algebras, in characteristic zero. The global dimension of commutative Hopf algebras,
regarded as coalgebras, is also discussed.
Presented by S. Montgomery
Mathematics Subject Classification (2000) 16W30. 相似文献
97.
We perform a Wilsonian renormalization group analysis for the nucleon–nucleon scattering in the P waves in the nuclear effective field theory including pions, in a similar way to the one done for the S-waves in our previous paper. We emphasize that the one-pion exchange interaction with large momentum transfer is of the same order as the leading contact interaction, so that there is no mismatch of the power counting. It is explicitly shown by obtaining consistent sets of renormalization group equations, that the cutoff dependence generated by the loop diagrams containing pion exchanges can be compensated by the cutoff dependence of the coupling constants of the contact interactions. 相似文献
98.
Shinji Adachi Tatsuya Watanabe 《Nonlinear Analysis: Theory, Methods & Applications》2012,75(2):819-833
We are concerned with the uniqueness result of positive solutions for a class of quasilinear elliptic equation arising from plasma physics. We convert a quasilinear elliptic equation into a semilinear one and show the unique existence of positive radial solution for original equation under the suitable conditions on the power of nonlinearity and quasilinearity. We also investigate the non-degeneracy of a positive radial solution for a converted semilinear elliptic equation. 相似文献
99.
Even at ambient temperature or less, below their 0.2% proof stresses all hexagonal close-packed metals and alloys show creep behaviour because they have dislocation arrays lying on a single slip system with no tangled dislocation inside each grain. In this case, lattice dislocations move without obstacles and pile-up in front of a grain boundary. Then these dislocations must be accommodated at the grain boundary to continue creep deformation. Atomic force microscopy revealed the occurrence of grain boundary sliding (GBS) in the ambient-temperature creep region. Lattice rotation of 5° was observed near grain boundaries by electron backscatter diffraction pattern analyses. Because of an extra low apparent activation energy of 20 kJ/mol, conventional diffusion processes are not activated. To accommodate these piled-up dislocations without diffusion processes, lattice dislocations must be absorbed by grain boundaries through a slip-induced GBS mechanism. 相似文献
100.
H. Ohta M. Kimata K. Koyama Y. Oshima M. Motokawa H. Nishikawa K. Kikuchi I. Ikemoto 《International Journal of Infrared and Millimeter Waves》2005,26(11):1525-1530
We have developed a new magneto-optical measurement system using a rotational cavity system equipped with a millimeter vector
network analyzer and a 14 T solenoid type super conducting magnet. The measurement can be performed in the transmission configuration
down to 1.6 K. The results of the precise angular dependence measurement of quasi-one-dimensional organic conductor (DMET)2I3 using the new system are shown, and its Fermi surface will be discussed in connection with the previous reports. 相似文献