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排序方式: 共有144条查询结果,搜索用时 15 毫秒
1.
Two trans stereoisomers of 3‐methylcyclopentadecanol (=muscol), (1R,3R)‐ 2 and (1S,3S)‐ 2 , were efficiently synthesized from (3RS)‐3‐methylcyclopentadecanone (=muscone; (3RS)‐ 1 ) by a highly stereoselective reduction (Scheme). L‐Selectride® (=lithium tri(sec‐butyl)borohydride) was used, followed by the enantiomer resolution by lipase QLG (Alcaligenes sp.). The cis stereoisomers of muscol, (1S,3R)‐ 2 and (1R,3S)‐ 2 , were obtained by the Mitsunobu inversion of (1R,3R)‐ 2 and (1S,3S)‐ 2 , respectively (Scheme). The absolute configuration of (1R,3R)‐ 2 was determined by X‐ray crystal‐structure analysis of its 3‐nitrophthalic acid monoester, 2‐[(1R,3R)‐3‐methylcyclopentadecyl hydrogen benzene‐1,2‐dicarboxylate ((1R,3R)‐ 3b ), and by oxidation of (1R,3R)‐ 2 to (3R)‐muscone. 相似文献
2.
The Fraunhofer diffraction pattern of an aperture formed between a knife edge and a smooth surface of a turned metal cylinder or half cylinder is different from the diffraction pattern of an ideal slit aperture. The diffraction pattern is simulated by adding the light reflected by the cylinder surface to the pattern formed by a slit, and is measured using a cylinder that has been partly cut away so that it can represent either a full or half cylinder. The theoretical and measured patterns agree well with each other. 相似文献
3.
Isao Takahashi Fumika Morita Shunsuke Kusagaya Haruhiko Fukaya Osamu Kitagawa 《Tetrahedron: Asymmetry》2012,23(24):1657-1662
In the presence of an (R)-MOP-Pd2(dba)3 catalyst, the reaction of ortho-tert-butylaniline with 2-bromophenyl arylethynyl ketone proceeded via a tandem amination (1,4-addition of aniline to an ynone and subsequent intramolecular Buchwald–Hartwig amination) to afford axially chiral N-(2-tert-butylphenyl)-2-aryl-4-quinolinone derivatives with moderate enantioselectivity (up to 72% ee). 相似文献
4.
Yutaka Aoyagi Kei Ozawa Tatsuya Kobayashi Tomoyo Hasuda Ming-Yu Gui Yong-Ri Jin Xu-Wen Li Haruhiko Fukaya Reiko Yano Yukio Hitotsuyanagi Koichi Takeya 《Tetrahedron》2014
Transformation of plant-origin 7,14-dihydroxy-ent-kaurenes to ent-abietanes having a cis-fused α-methylene γ-lactones was accomplished efficiently under the Mitsunobu reaction conditions. The yields of the desired products were apparently influenced by the steric hindrance at C-1. The cytotoxic activity on P388 murine leukemia cells of the ent-abietanes having cis-fused α-methylene γ-lactones produced were assayed. 相似文献
5.
Sekiguchi A Ishida Y Fukaya N Ichinohe M Takagi N Nagase S 《Journal of the American Chemical Society》2002,124(7):1158-1159
Dark red crystals of the halogen-substituted cyclotrigermenes [(tBu3Si)3Ge3X; X = Cl, Br, I] were obtained in good yields by the reaction of [(tBu3Si)3Ge3]+.TTFPB- (TTFPB- = tetrakis(2,3,5,6-tetrafluorophenyl)borate) with potassium halides (KCl, KBr, or KI) in diethyl ether. The crystal structures of the halogen-substituted cyclotrigermenes reveal a cis-bent Ge=Ge double bond, caused by the introduction of the electronegative halogen atom on the sp3 germanium atom of cyclotrigermene. In solution, an intramolecular halogen migration over the three-membered ring skeleton was observed. Facial stereoselectivity in the Diels-Alder reaction of new cyclotrigermenes with 2,3-dimethyl-1,3-butadiene is also reported. 相似文献
6.
Yoshio Hayakawa Eiji Hayashi Haruhiko Fukaya Naohiro Terasawa Takashi Abe Kota Omori Koichi Murai 《Liquid crystals》1996,20(3):367-371
Novel liquid crystals which have the perfluoropyrrolidino group, a heterocyclic perfluoroalkyl group, and which show smectic phases have been synthesized with perfluoro-(2-pyrrolidinopropionyl fluoride) as one of the starting materials. Analogues with a polymerizable functional group also have been prepared and polymerized to give side chain liquid crystal polymers. 相似文献
7.
Savici AT Fukaya A Gat-Malureanu IM Ito T Russo PL Uemura YJ Wiebe CR Kyriakou PP MacDougall GJ Rovers MT Luke GM Kojima KM Goto M Uchida S Kadono R Yamada K Tajima S Masui T Eisaki H Kaneko N Greven M Gu GD 《Physical review letters》2005,95(15):157001
Muon spin relaxation measurements in high transverse magnetic fields [FORMULA: SEE TEXT] revealed strong field-induced quasistatic magnetism in the underdoped and Eu-doped (La,Sr)2CuO4 and La1.875Ba0.125CuO4, existing well above Tc and TN. The susceptibility counterpart of Cu spin polarization, derived from the muon spin relaxation rate, exhibits a divergent behavior towards T approximately 25 K. No field-induced magnetism was detected in overdoped La1.81Sr0.19CuO4, optimally doped Bi2212, and Zn-doped YBa2Cu3O7. 相似文献
8.
The Au adsorption induced √21 × √21 super-lattice structure on the Si(1 1 1)-√3 × √3-Ag structure has been investigated using reflection high-energy positron diffraction. The height of the Au adatom was determined to be 0.59 Å from the underlying Ag layer from the rocking curve analysis with the dynamical diffraction theory. The adatoms were preferentially situated at the center of the large Ag triangle of the inequivalent triangle structure of the Si(1 1 1)-√3 × √3-Ag substrate. From the intensity distribution in the fractional-order Laue zone, the in-plane coordinate of the Au adatoms was obtained. 相似文献
9.
We have investigated a quasi-one-dimensional structure of In/Si(1 1 1) surface using reflection high-energy positron diffraction (RHEPD), which is sensitive to the topmost surface structure under the total reflection condition. From the rocking curves, we found that In atoms are located at two different vertical positions, i.e., 0.99 Å and 0.55 Å from the Si zigzag chain in both 4 × 1 (210 K) and 8 × 2 (60 K) phases. 相似文献
10.
Y. Fukaya I. Matsuda M. Hashimoto K. Kubo T. Hirahara S. Yamazaki W.H. Choi H.W. Yeom S. Hasegawa A. Kawasuso A. Ichimiya 《Surface science》2012,606(11-12):919-923
The atomic structures of Au and Ag co-adsorption-induced √21 × √21 superstructure on a Si(111) surface, i.e., (Si(111)-√21 × √21-(Au, Ag)), where the Si(111)-5 × 2-Au surface is used as a substrate, have been investigated using reflection high-energy positron diffraction (RHEPD) and photoemission spectroscopy. From core-level spectra, we determined the chemical environments of Ag and Au atoms present in the Si(111)-√21 × √21-(Au, Ag) surface. From the rocking curve and pattern analyses of RHEPD, we found that the atomic coordinates of the Au and Ag atoms were approximately the same as those of the Au and Ag atoms in other Si(111)-√21 × √21 surfaces with different stoichiometries. On the basis of the core-level and RHEPD results, we revealed the atomic structure of the Si(111)-√21 × √21-(Au, Ag) surface. 相似文献