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101.
Toshifumi Tsuda 《Tetrahedron》2005,61(45):10719-10733
A direct and practical method for the construction of β-mannosidic linkages is described. While β-selectivities in the TMSOTf-promoted glycosidation of 2,3,4,6-tetra-O-benzyl-d-mannosyl diethyl phosphite are found to be highly dependent on the reactivity of acceptor alcohols, 2,3-di-O-benzyl-4,6-O-benzylidene-d-mannosyl diethyl phosphite reacts with a wide range of acceptor alcohols in the presence of TMSOTf in CH2Cl2 at −45 °C to give β-mannosides in high yields with good to high β-selectivities. 相似文献
102.
Treatment of 1-chloro-2-methylalkenyl p-tolyl sulfoxides with N-lithio 2-piperidone in THF at room temperature resulted in the formation of 1-chloro-2-(hydroxymethyl)alkenyl p-tolyl sulfides in good yields. This reaction is the first example of the Mislow-Braverman-Evans rearrangement retaining the sulfur atom on the original carbon. 相似文献
103.
Takahisa Iida Toshio Sugizaki Toshifumi Kageyama Osamu Moriya 《Journal of polymer science. Part A, Polymer chemistry》1998,36(4):655-663
Tributylstannylated silicic acid (TBSA), which was regarded as a protected polymeric silanol against self-condensation to give silica gel, was newly prepared from the reaction of water glass (WG) and bis(tributyltin) oxide (TBO). The ratios of Si/Sn contained in TBSA were determined by gravimetric analysis to be in the range of 2–3. The gelation of TBSA in usual organic solvents such as hexane, benzene, and dichloromethane was not observed over 3 weeks. In addition, TBSA was shown to be a convenient precursor for the preparations of silica gel modified with organofunctional groups. From the reaction of TBSA with trimethoxysilanes and aromatic alcohols, the silica gels havingorganofunctional groups were obtained with the elimination of a tributyltin group. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 655–663, 1998 相似文献
104.
Manabu Tsumura Takahisa Iwahara Toshifumi Hirose 《Journal of polymer science. Part A, Polymer chemistry》1996,34(15):3155-3161
The polycarbosilanes (PCS) with meta-linkage bending unit ((SINGLE BOND)Me2Si(SINGLE BOND)m(SINGLE BOND)C6H4(SINGLE BOND)Me2Si(SINGLE BOND)CH2CH2(SINGLE BOND)) were successfully synthesized in mild conditions by hydrosilylation in the presence of [Pt{(CH2(DOUBLE BOND)CHSiMe2)2O}2]. The PCS obtained were soluble in various solvents owing to the lowering of the crystallinity. These properties are well compared with those of the PCS [(SINGLE BOND)Me2Si(SINGLE BOND)p(SINGLE BOND)C6H4(SINGLE BOND)Me2Si(SINGLE BOND)CH2CH2(SINGLE BOND)]n. © 1996 John Wiley & Sons, Inc. 相似文献
105.
Toshifumi Tsujino Mitsuhiro Kawazu Koichi Maeda 《Journal of Sol-Gel Science and Technology》2000,19(1-3):825-828
We have developed tinted glasses with thin films doped with Au particles by the sol-gel method for automotive windows. Pink-colored glasses are mass-produced. The observed color is from absorption due to surface plasma resonance of Au particles. The squeeze-out of fine Au particles out of gel films was restrained by an organic additive. The index of the matrix was adjusted by the mixing ratio of TiO2 (refractive index n = 2.20) to SiO2 (n = 1.46). The absorption of Au particles is more intense with the higher index of the matrix, and its peak varies from 530 nm for n = 1.46 to 630 nm for n = 2.20, which yields a transmission color from pink to blue. The combination of the color of the glass substrate and the absorption by the Au particles in the thin films with various indices yields a variety of tinted glasses such as pink, orange, blue, blue-green and gray. 相似文献
106.
Kazuaki Yokota Toyoji Kakuchi Toshifumi Satoh Stoshi Umeda Masatoshi Kamada 《Macromolecular Symposia》2000,157(1):13-20
The selective cyclopolymerization of 1,2:5,6‐dianhydrohexitols corresponding to diepoxides was a new synthetic strategy for polycarbohydrates, though the polymer is a lack of the anomeric linkage which is found in the naturally occurring polysaccharides. 1,2:5,6‐Dianhydro‐3,4‐di‐O‐methyl‐D‐mannitol, L‐iditol, and D‐glucitol were polymerized using t‐BuOK and BF3·Oet2 to produce the polymers consisting of five‐membered rings. On the other hand, the polymers consisting of six‐membered rings were obtained by the cationic and anionic polymerizations of meso allitol and galactitol monomers, respectively. 相似文献
107.
Atsushi Narumi Yutaka Miura Issei Otsuka Shin Yamane Yoshikazu Kitajyo Toshifumi Satoh Akira Hirao Noriaki Kaneko Harumi Kaga Toyoji Kakuchi 《Journal of polymer science. Part A, Polymer chemistry》2006,44(16):4864-4879
This article describes that glucose, maltose, maltotriose, maltotetraose, maltopentaose, and maltohexaose ( a , b , c , d , e , and f , respectively) were introduced into the initiating chain‐end of polystyrene (PSt) through the 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO)‐mediated radical polymerization. A series of glycoconjuaged TEMPO‐adducts, 1a–f , was synthesized and used as the initiators for the polymerization of styrene (St) for 6 h at 120 °C to afford the end‐functionalized PSt's with the acetyl saccharides, 2a–f , in the yields of 37–43%. For 2a–f obtained by the polymerizations using the [St]/[ 1 ] of 125, 250, and 500, the number‐average molecular weights determined by size exclusion chromatography (SEC), Mn,SEC's, were 4800–6300, 8800–10,600, and 18,400–25,200, respectively, which fairly agreed with the predicted values. The end‐functionalized PSt's with saccharides, 3a–f , which were obtained from the deacetylation of 2a–f using sodium methoxide in dry THF, formed the polymeric reverse micelles consisting of a saccharide‐core and a PSt‐shell in chloroform and toluene. The static laser light scattering (SLS) measurements provided the average molar mass of the aggregates in toluene, Mw,SLS's, which ranged from 7.50 × 104 to 1.77 × 105 for 3a , from 1.90 × 105 to 4.93 × 105 for 3b , from 4.41 × 105 to 7.21 × 105 for 3c , from 5.85 × 105 to 8.51 × 105 for 3d , from 7.55 × 105 to 8.53 × 105 for 3e , and from 8.54 × 105 to 9.26 × 105 for 3f . The aggregation numbers, Nagg's, which were calculated from the Mw,SLS's, were from 7 to 24 for 3a , from 20 to 37 for 3b , from 34 to 89 for 3c , from 39 to 116 for 3d , from 41 to 145 for 3e , and from 31 to 146 for 3f . It was confirmed that the aggregation property, such as the Mw,SLS or Nagg values, was strongly related to the polymerization degrees of St (DP's) or the number of the glucose residues (n's) for 3a–f . © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4864–4879, 2006 相似文献
108.
Osamu Nishizawa Hideki Misaka Ryosuke Sakai Toyoji Kakuchi Toshifumi Satoh 《Journal of polymer science. Part A, Polymer chemistry》2008,46(22):7411-7418
The copolymerization of ethylene (E) and norbornene (NB) was investigated using the commercially available and inexpensive catalyst system, cyclopentadienylzirconium trichloride (CpZrCl3)/isobutyl‐modified methylaluminoxane (MMAO), at a moderate polymerization temperature in toluene. For the CpZrCl3 catalyst system activated by aluminoxane with a 40 mol % methyl group and a 60 mol % isobutyl group (MMAO), the quantities of the charged NB and the polymerization temperature significantly affected the molecular weights, polydispersities, and NB contents of the obtained copolymers and the copolymerization activities in all the experiments. As the charged NB increased and thereby the NB/E molar ratio increased, the NB content in the copolymer increased and reached a maximum value of 71 mol %. The CpZrCl3/MMAO ([Al]/[Zr] = 1000) catalyst system with the [NB] of 2.77 mol L?1 and ethylene of 0.70 MPa at 50 °C showed the highest activity of 1690 kg molZr?1 h?1 and molecular weight of 21,100 g mol?1. The 13C NMR analysis showed that the CpZrCl3/MMAO catalyst system produced the E‐NB random copolymer with a number of NB homosequences such as the NN dyad and NNN triad. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7411–7418, 2008 相似文献
109.
The addition reaction of the sodium α-sulfinyl carbanion of a racemic aryl dichloromethyl sulfoxide to (?)-menthone in the presence of boron trifluoride diethyl etherate gave an adduct as a mixture of two easily separable diastereomers. After separation of the diastereomers, they were each treated with sodium hydride to afford enantiomerically pure aryl dichloromethyl sulfoxides and (?)-menthone both in high yields. This procedure provides a simple and efficient method for the resolution of racemic aryl dichloromethyl sulfoxides. 相似文献
110.