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101.
Itoh T Nagata K Yokoya M Miyazaki M Kameoka K Nakamura S Ohsawa A 《Chemical & pharmaceutical bulletin》2003,51(8):951-955
Chiral 1-substituted isoquinoline derivatives, which were obtained by the reaction using alanine derivatives as chiral auxiliaries, were transformed to (S)-2,3,9,10,11-pentamethoxyhomoprotoberberine (7) and a synthetic intermediate for O-methylkreysigine (9) in good yields and high stereoselectivity. The corresponding chiral allyl derivative of isoquinoline was transformed to a pyrrolidinoisoquinoline (16) in a highly enantioselective manner. 相似文献
102.
We developed a novel measurement method of the Donnan potential difference at a charged membrane/salt solution interface. The method can measure the potential under the condition that the membrane charge density is much lower than the KCl concentration of the salt bridge. This method is very useful for obtaining the effective charge density of each layer of a bipolar membrane. The present experiments in a system of a negatively charged poly(vinyl alcohol) membrane and a single salt solution of KCl, NaCl, LiCl, CaCl2 and LaC3 revealed that the membrane effective charged density has the same value for all the ions. The experiments in mixed KCl and CaCl2 solution revealed that the potential in the system is governed mainly by the concentration of the counterion having the highest valence in the system. 相似文献
103.
Shuntaro Mataka Akira Hosoki Kazufumi Takahashi Masashi Tashiro 《Journal of heterocyclic chemistry》1980,17(8):1681-1685
The reaction of tetrasulfur tetranitride ( 1 ) with various aryl and alkyl benzyl ketones ( 2a-o ), oxindole ( 11 ), benzyl α-pyridyl ketone ( 12 ) and α-phenacylpyridine ( 13 ) afforded the corresponding 1,2,5-thiadiazoles ( 3a-n, 11 and 14 ). The scope and limitations of the above reaction were investigated and the evidences suggesting the radical anion mechanism are presented. 相似文献
104.
Synthesis of diphenyl cucurbit[6]uril (CB[6]) has been achieved via co-oligomerization of diphenyl glycoluril and unsubstituted glycoluril. The unsymmetrically substituted CB[6], Ph(2)CB[6], was further converted to a rotaxane incorporating bis(dinitrophenyl)spermine. [reaction: see text] 相似文献
105.
The basic primary and scatter dose-spread kernels used for convolution methods are usually produced by Monte Carlo simulations with the interaction point forced to the center of a large water phantom. However, it is still not clear whether such Monte Carlo based kernels allow accurate dose calculations with a wide range of field sizes and depths, especially in thorax phantoms. Using the differential primary and scatter concept, this paper proposes another type of basic kernel, with which perfectly accurate primary and scatter absorbed dose calculations can be performed under conditions that the beam is parallel, the incident beam intensity is uniform within and zero outside the field, and the primary beam attenuation coefficient along raylines is not a function of depth and off-axis distance. 相似文献
106.
Yoshimasa Fukazawa Satoshi Harada Akira Inai Toshiya Okajima 《Tetrahedron letters》1993,34(52):8493-8496
The title compound (2) has been synthesized, the structure and the physical properties of which are investigated by X-ray, spectroscopic analyses, and MO calculations. There exists charge transfer (CT) interaction between the tropylium ion and the facing phenyl ring. From the pKR+ value of 2, it can be clear that the cation 2 is stabilized by the CT interaction. In spite of the presence of bond weakening σ-π orbital mixing, the cation 2 withstands retro[4+4]type bond cleavage, which is quite interesting when compared to a facile cleavage for the congener with anthracene photodimer type structure. 相似文献
107.
Akira Matsumoto Hisako Mano Masayoshi Oiwa George B. Butler 《Journal of polymer science. Part A, Polymer chemistry》1989,27(6):1811-1816
The radical polymerization of tetraallyl ammonium chloride (TAAC) was carried out in water using azo-initiator as compared to that of diallyl dimethyl ammonium chloride (DADMAC); the rate of polymerization was quite low for TAAC, around one-third of DADMAC. Kinetic discussion revealed the importance of degradative chain transfer in the polymerization of TAAC. The cyclopolymerizability of TAAC was estimated kinetically as the ability of 5-membered monocyclic radical to form a bicyclic ring, giving the cyclization constant of 21 mol/L at [M] = 2 mol/L. Gelation occurred at around 20% conversion. 相似文献
108.
Nakamura Y O-kawa K Nishimura T Yashima E Nishimura J 《The Journal of organic chemistry》2003,68(8):3251-3257
The optical resolution of trans-2 and trans-3 [60]fullerene bisadducts with an inherent chiral addition pattern, modified by Bingel reaction, cycloaddition by benzyne, Prato reaction, and cycloaddition by o-quinodimethane, was systematically investigated by using chiral HPLC columns (Chiralcel OD and Chiralpak AD). The chiroptical properties of enantiomers separated were also examined. 相似文献
109.
Yasuo Saegusa Takahiro Kato Hirotaka Oshiumi Shigeo Nakamura 《Journal of polymer science. Part A, Polymer chemistry》1992,30(7):1401-1406
Novel polyaryloxydiphenylsilanes with reduced viscosities of 0.31–0.65 dL/g were obtained by the melt polycondensation of dianilinodiphenylsilane with three bisphenols, 2,2-bis (4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane, 3 (4-hydroxyphenyl)-1,1,3-trimethyl-5-indanol, and 9,9-bis (4-hydroxyphenyl) fluorene, at 200–320°C in vacuo. These polymers are all amorphous and readily soluble in a wide variety of organic solvents such as chlorinated and aromatic hydrocarbons, cyclic ethers, and polar aprotic solvents. Because of their bulky and/or rigid ring structures, polyaryloxydiphenylsilanes containing diphenylhexafluoropropane, phenylindane, and diphenylfluorene units in the main chain have high glass transition temperatures of 106, 112, and 172°C, respectively. They are thermally stable showing almost no weight loss up to 350°C in air. Colorless, transparent, but brittle films are obtained from these polymers by solution casting. Ultraviolet transmission is sharply cut off by these polyaryloxydiphenylsilane films at ca. 300 nm, and the cut-off wavelength depends on the bisphenols used. 相似文献
110.
Tetsuji Ohata Etsuro Fukumori Akira Matsumoto Masayoshi Oiwa 《Journal of polymer science. Part A, Polymer chemistry》1980,18(3):1011-1019
The radical copolymerization of diallyl tartrate (DATa) (M1) with diallyl succinate (DASu), diallyl phthalate (DAP), allyl benzoate (ABz), vinyl acetate (VAc), or styrene (St) was investigated in order to disclose in more detail the characteristic hydroxyl group's effect observed in the homopolymerization of DATa. In the copolymerization with DASu or DAP as a typical diallyldicarboxylate, the dependence of the rate of copolymerization on monomer composition was different for different copolymerization systems and unusual values larger than unity for the product of monomer reactivity ratios, r1r2, were obtained. In the copolymerization with ABz or VAc (M2), the r1 and r2 values were estimated to be 1.50 and 0.64 for the DATa/ABz system and 0.76 and 2.34 for the DATa/VAc system, respectively; the product r1r2 for the latter copolymerization system was found again to be larger than unity. In the copolymerization with St, the largest effect due to DATa monomer of high polarity was observed. Solvent effects were tentatively examined to improve the copolymerizability of DATa. These results are discussed in terms of hydrogen-bonding ability of DATa. 相似文献