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81.
82.
The electroreduction of N-methyl, N-p-anisyl, and N-unsubstituted phthalimides with aldehydes in the presence of chlorotrimethylsilane and triethylamine gave intermolecularly coupled products, 3-hydroxy-3-(1-hydroxyalkyl)isoindolin-1-ones. The coupling products were reduced with Et3SiH/BF3·Et2O to 3-(1-hydroxyalkyl)isoindolin-1-ones, which were dehydrated to alkylideneisoindolin-1-ones. From N-unsubstituted phthalimides, Z-isomers of alkylideneisoindolin-1-ones were obtained stereospecifically. 相似文献
83.
Shinsaku Fujita 《Journal of mathematical chemistry》2001,30(3):249-270
Among the four methods of the unit-subduced-cycle-index (USCI) approach, the subduced-cycle-index (SCI) method and the partial-cycle-index (PCI) method have been discussed by using adamantane of T
d
-symmetry as a probe for enumeration problems, where USCIs are derived on the basis of permutaion representations, coset representations (CRs) and marks. After the examination of the SCIs and PCIs, Pólya's theorem that is a standard method of chemical combinatorics has been derived from the USCI approach. As another approach, a new method called the characteristic-monomial (CM) method has been developed by virtue of charactereistic monomials (CMs). The CMs have been derived from Q-conjugacy representations and Q-conjugacy characters, which have been related to irreducible representations and irreducible characters of the standard repertoire of chemical group theory. The two approaches have been compared to discuss group-theoretical tools for chemical combinatorics on a common basis. 相似文献
84.
85.
Kitagawa O Yoshikawa M Tanabe H Morita T Takahashi M Dobashi Y Taguchi T 《Journal of the American Chemical Society》2006,128(39):12923-12931
In the presence of (R)-DTBM-SEGPHOS-Pd(OAc)(2) catalyst, N-arylation (aromatic amination) of various o-tert-butylanilides with p-iodonitrobenzene proceeds with high enantioselectivity (88-96% ee) to give atropisomeric N-(p-nitrophenyl)anilides having an N-C chiral axis in good yields. Atropisomeric anilide products highly prefer to exist as the E-rotamer which has trans-disposed o-tert-butylphenyl group and carbonyl oxygen. The application of the present catalytic enantioselective N-arylation to an intramolecular version gives atropisomeric lactam derivatives with high optical purity (92-98% ee). The reaction of the lithium enolate prepared from the atropisomeric anilide and lactam products with various alkyl halides gives alpha-alkylated products with high diastereoselectivity (diastereomer ratio = 13:1 to 46:1). 相似文献
86.
87.
S. C. Lin Yoshiyuki Minamisawa Kazuya Furusawa Yasuyuki Maki Hiroyuki Takeno Takao Yamamoto Toshiaki Dobashi 《Colloid and polymer science》2010,288(6):695-701
Anisotropic gelation of carboxymethylcellulose (CMC) in aqueous NaOH sandwiched between two circular cover glasses by immersing
it in aqueous CaCl2 has been studied. In the course of dialysis, gelation and phase separation occurred simultaneously to make turbid stripes
arranged radially. The time course of the gel layer width was well expressed in scaled linear plots predicted by a theory
based on “moving boundary picture” at low CMC concentrations. On the other hand, at high CMC concentrations, the time course
was expressed by a two-stage dynamics. The time course did not depend on the initial thickness of the CMC solution and the
diameter of the cover glasses, whereas the rate of gelation decreased with increasing CMC concentration. It was attributed
to the change in the calcium cation concentration required for forming the gel in the process. The universality and the individuality
of the present system in the gelation dynamics are discussed. 相似文献
88.
Shinsaku Amano Dimitri Bogdanovski Prof. Dr. Hisanori Yamane Prof. Dr. Masami Terauchi Prof. Dr. Richard Dronskowski 《Angewandte Chemie (International ed. in English)》2016,55(5):1652-1657
For the Ti/O system, three titanium monoxide (TiO) phases (α, β, and γ) with defective NaCl‐type structures and a high‐temperature hexagonal phase (H) have been known for decades. In this work, single crystals of a novel polymorph, ?‐TiO, were synthesized by using a bismuth flux. X‐ray diffraction (XRD) revealed a hexagonal crystal structure (a=4.9936(3) Å, c=2.8773(2) Å, P 2m) that is isotypic with ?‐TaN. While the Ti atoms are surrounded by trigonal prismatic (sixfold coordination) and trigonal planar (threefold coordination) arrangements of O atoms, the O atoms are found in a pseudo‐square‐pyramidal arrangement of Ti atoms. First‐principles calculations of the formation enthalpy and the electron and phonon density of states and crystal orbital Hamilton population (COHP) analysis revealed that ?‐TiO is more stable than α‐TiO, which had previously been regarded as the most stable phase at low temperatures. 相似文献
89.
Kazunori Kuwana Satoshi Morishita Ritsu Dobashi Keng H. Chuah Kozo Saito 《Proceedings of the Combustion Institute》2011,33(2):2425-2432
This paper discusses why the visibly-determined flame length of a weak fire whirl increases as compared with the corresponding pool fire without spin. Here, a fire whirl is called weak when the pure aerodynamic effect of flow circulation has a negligible influence on the flame length. Split cylinders were used to apply a flow circulation to a 3-cm-diameter methane burner flame and a 3-cm-diameter ethanol pool fire. After applying the flow circulation, the flame length of the ethanol pool fire increased about three times, while little change was observed in the flame length of the methane burner flame. The difference is explained by the fact that the burning rate of the methane burner flame was fixed constant, whereas that of the ethanol pool fire increased due to the increased heat input to the fuel surface caused by a change in flame shape pushed toward the fuel surface. The experimental observations thus demonstrate that the burning-rate effect can significantly increase the flame length even under a weak circulation condition. Computational fluid dynamics (CFD) simulations were conducted to understand the detailed flow structure of a fire whirl. An analytical model was then developed based on the experimental observations and CFD calculations; the predicted relationship between the flame height and the burning rate agreed with experimental data. 相似文献
90.
Fukuda M Aoki T Dobashi K Hirose T Iimura T Kurihara Y Okugi T Omori T Sakai I Urakawa J Washio M 《Physical review letters》2003,91(16):164801
We have developed a polarimetry of ultrashort pulse gamma rays based on the fact that gamma rays penetrating in the forward direction through a magnetized iron carry information on the helicity of the original gamma rays. Polarized, short-pulse gamma rays of (1.1+/-0.2)x10(6)/bunch with a time duration of 31 ps and a maximum energy of 55.9 MeV were produced via Compton scattering of a circularly polarized laser beam of 532 nm off an electron beam of 1.28 GeV. The first demonstration of asymmetry measurements of short-pulse gamma rays was conducted using longitudinally magnetized iron of 15 cm length. It is found that the gamma-ray intensity is in good agreement with the simulated value of 1.0x10(6). Varying the degree of laser polarization, the asymmetry for 100% laser polarization was derived to be (1.29+/-0.12)%, which is also consistent with the expected value of 1.3%. 相似文献