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121.
Aoyagi Y Saitoh Y Ueno T Horiguchi M Takeya K Williams RM 《The Journal of organic chemistry》2003,68(18):6899-6904
Lipase TL-mediated kinetic resolution of (+/-)-5-benzyloxy-1-tert-butyldimethylsilyloxy-2-pentanol (5) at low temperature proceeded to give the corresponding (S)-alcohol 5 and (R)-acetate 6 in quantitative yields with high enantiomeric purity. The addition of bases such as pyridine, DMAP, 2,4- and 2,6-lutidines, or triethylamine considerably enhanced the rate of kinetic resolution. The alcohol (S)-5 and the acetate (R)-6 were converted to piperazic acid derivatives (R)- and (S)-3, respectively, via the intramolecular Mitsunobu reaction as a key step. 相似文献
122.
Amii H Ichihara Y Nakagawa T Kobayashi T Uneyama K 《Chemical communications (Cambridge, England)》2003,(23):2902-2903
N-Allylic difluoroenamines exhibited unusual behaviors under thermal conditions; N-allyl difluoroenamines in refluxing xylene afforded not only aza-Claisen rearrangement products, but also 2-azabicyclo[2.1.1]hexanes, whose formation could be explained via intramolecular [2+2]-cycloaddition, whilst N-prenyl difluoroenamine underwent an ene reaction to give the pyrrolidine as a sole product. 相似文献
123.
Koike R Motoyoshiya J Takaguchi Y Aoyama H 《Chemical communications (Cambridge, England)》2003,(6):794-795
A kinetic study of peroxyoxalate chemiluminescence reactions employing 2,4,6-trichlorophenyl N-aryl-N-tosyloxamates supports the 1,2-dioxetanones still bearing the eliminating group as the key intermediates that interact with the fluorophores rather than 1,2-dioxetanedione. 相似文献
124.
Yokoyama Y Shiraishi H Tani Y Yokoyama Y Yamaguchi Y 《Journal of the American Chemical Society》2003,125(24):7194-7195
Introduction of an asymmetric center to C-2 of one of the benzothiophene rings of bisbenzothienylperfluorocyclopentene results in a highly diastereoselective photochromic system. The stereogenic center bears a hydrogen atom, a methyl group, and a methoxymethoxy group. The steric as well as the electronic repulsions gave an 87-88% diastereomer excess in various solvents at room temperature with 80-85% conversion to the colored form. The enantioselective synthesis was also carried out. Upon photoirradiation in hexane, a change in optical rotation at 820 nm, where neither the open form nor the colored form absorbs light, was observed repeatedly. 相似文献
125.
Kanai M Yasumoto M Kuriyama Y Inomiya K Katsuhara Y Higashiyama K Ishii A 《Organic letters》2003,5(7):1007-1010
[reaction: see text] The highly regioselective hydrogenolysis of bis(alpha-methylbenzyl)amine derivatives proceeded with influence not from the electronic effect but from the steric effect of the trifluoromethyl substituent on the aromatic ring to provide a practical asymmetric synthesis of trifluoromethyl-substituted alpha-phenylethylamines. 相似文献
126.
Ikushima Y Hatakeda K Sato O Yokoyama T Arai M 《Angewandte Chemie (International ed. in English)》2001,40(1):210-213
127.
Yasutaka Takahashi Ayako Ohsugi Takeshi Arafuka Tomokazu Ohya Takayuki Ban Yutaka Ohya 《Journal of Sol-Gel Science and Technology》2000,17(3):227-238
The effects of several hydroxyketones such as acetol, actoin, -ketobutanol themselves and their combinations with monoethanolamine (MEA) or ethylenediamine (ED) on the stabilization of titanium tetraisopropoxide (TTIP) in isopropanol solution are examined. Acetoin itself and the imine derivatives of acetol and acetoin were found to show extraordinarily strong stabilizing effect for the alkoxide. The properties including the crystal modifications and refractive index of TiO2 films that were dip-coated using each stabilized solution are examined and discussed in comparison with those of the films obtained from the diethanolamine (DEA) systems. The effect of UV-light irradiation to the gel films on the crystallization of TiO2 is also examined and discussed. 相似文献
128.
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130.
A facile method for the construction of an immunoconjugate which displays targeting ligands, such as antibody fragments, with a high density is reported. For this purpose, we synthesized a novel trifunctional crosslinking reagent. By the use of this reagent, ligands targeting the specific cell can be displayed on the surface of the drug carrier with a high density. In this study, we display HER2 (human epidermal growth‐factor receptor‐2) binding ligands on branched polyethylenimine (PEI), which can form polyplexes with plasmid DNA. Kinetic analysis of the binding to the extracellular domain of HER2 show the PEI displaying a high density of ligands binds to the target more strongly compared to the PEI displaying ligands at a low density. The increased density of HER2 ligands displayed on the gene carrier contributes to the improved transfection efficiency. This approach can be applied to other drug delivery systems, including liposome, micelle, and so on. 相似文献