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1.
Simultaneous Induction of Axial and Planar Chirality in Arene–Chromium Complexes by Molybdenum‐Catalyzed Enantioselective Ring‐Closing Metathesis 下载免费PDF全文
Prof.Dr. Ken Kamikawa Dr. Sachie Arae Dr. Wei‐Yi Wu Chihiro Nakamura Prof.Dr. Tamotsu Takahashi Prof.Dr. Masamichi Ogasawara 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(13):4954-4957
The molybdenum‐catalyzed asymmetric ring‐closing metathesis of the various Cs‐symmetric (π‐arene)chromium substrates provides the corresponding bridged planar‐chiral (π‐arene)chromium complexes in excellent yields with up to >99 % ee. With a bulky and unsymmetrical substituent, such as N‐indolyl or 1‐naphthyl, at the 2‐positions of the η6‐1,3‐diisopropenylbenzene ligands, both biaryl‐based axial chirality and π‐arene‐based planar chirality are simultaneously induced in the products. The axial chirality is retained even after the removal of the dicarbonylchromium fragment, and the chiral biaryl/heterobiaryl compounds are obtained with complete retention of the enantiopurity. 相似文献
2.
3.
Ryohei Yoshisaki Dr. Shinya Kimura Dr. Masashi Yokoya Prof. Dr. Masamichi Yamanaka 《化学:亚洲杂志》2021,16(14):1937-1941
Maltose is a ubiquitous disaccharide produced by the hydrolysis of starch. Amphiphilic ureas bearing hydrophilic maltose moiety were synthesized via the following three steps: I) construction of urea derivatives by the condensation of 4-nitrophenyl isocyanate and alkylamines, II) reduction of the nitro group by hydrogenation, and III) an aminoglycosylation reaction of the amino group and the unprotected maltose. These amphiphilic ureas functioned as low molecular weight hydrogelators, and the mixtures of the amphipathic ureas and water formed supramolecular hydrogels. The gelation ability largely depended on the chain length of the alkyl group of the amphiphilic urea; amphipathic urea having a decyl group had the highest gelation ability (minimum gelation concentration=0.4 mM). The physical properties of the supramolecular hydrogels were evaluated by measuring their thermal stability and dynamic viscoelasticity. These supramolecular hydrogels underwent gel-to-sol phase transition upon the addition of α-glucosidase as a result of the α-glucosidase-catalyzed hydrolysis of the maltose moiety of the amphipathic urea. 相似文献
4.
The European Physical Journal A - High-K isomers are well known in the rare-earth region and provide unique access to the high spin structures of the nuclei. With the current interest in the study... 相似文献
5.
Masamichi Takase 《Mathematische Zeitschrift》2012,272(1-2):101-108
We give a formula to detect the oriented bordism class of a codimension one immersion of an oriented 7-manifold in terms of singularities of its singular Seifert surface, that is, a generic map from a compact 8-manifold which extends the given immersion. Our argument involves a study of a relative version of the Thom polynomials for certain singularities of generic maps from manifolds with non-empty boundaries. 相似文献
6.
Atsunori Ono Yohei Takahashi Sumio Kato Masataka Ogasawara Takashi Wakabayashi Yuunosuke Nakahara Shinichi Nakata 《Research on Chemical Intermediates》2011,37(9):1225-1230
A10(PO4)6(OH)2 (A = Ca and Sr)-supported Pt catalysts were prepared and their catalytic activity in NO reduction were investigated. The Sr10(PO4)6(OH)2-supported catalyst had high catalytic activity in the C3H6?CNO?CO2 reaction; the activity was higher than that of the ??-Al2O3-supported catalyst at 300 °C. The basicity of the apatite supports would affect the chemical state of Pt on catalyst, resulting in promotion of NO reduction. 相似文献
7.
The (132R)-methoxycarbonyl group of methyl pheophorbide a, one of the chlorophyll-a derivatives, was converted to a methyl group through methylation at the C132 position followed by removal of the methoxycarbonyl group. The methylation of the C132 carboanion gave a 4:1 mixture of methyl 132-methyl-pheophorbide a and its 132-epimer. The successive pyrolysis of the major methylated product afforded methyl (132R)-methyl-pyropheophorbide a with a small amount of its (132S)-epimer. The substitution effects at the C132 position including stereochemistry were discussed on the basis of 1D/2D NMR, UV–vis absorption, and circular dichroism spectroscopic analyses as well as molecular modeling simulation. 相似文献
8.
Norio Shibata Banibrata Das Masamichi Hayashi Shuichi Nakamura Takeshi Toru 《Journal of fluorine chemistry》2009,130(12):1164-1170
Synthesis of 1,3-butadiyne-bridged perfluoroisopropyl binuclear phthalocyanine 2 has been successfully achieved from unsymmetrical A3B-type iodo-perfluoroisopropyl phthalocyanine by palladium-catalyzed cross-coupling with trimethylsilylacetylene and copper-catalyzed Glaser homo-coupling as key reactions. The dyad 2 essentially remains non-aggregated irrespective of solvent and concentration. Electrochemical analysis suggests oxidation is not possible whereas the molecule is more easily reduced. All the results are advantages for photodynamic therapy (PDT). 相似文献
9.
Haruhiko Ogasawara 《Annals of the Institute of Statistical Mathematics》2009,61(4):995-1017
Asymptotic cumulants of the distributions of the sample singular vectors and values of cross covariance and correlation matrices
are obtained under nonnormality. The asymptotic cumulants are used to have the approximations of the distributions of the
estimators by the Edgeworth expansions up to order O(1/n) and Hall’s method with variable transformation. The cases of Studentized estimators are also considered. As an application
of the method, the distributions of the parameter estimators in the model of inter-battery factor analysis are expanded. Interpreting
the singular vectors and values in the context of the factor model with distributional conditions, the asymptotic robustness
of some lower-order normal-theory cumulants of the distributions of the sample singular vectors and values under nonnormality
is shown. 相似文献
10.
Hydrothermal formation of tobermorite studied by in situ X‐ray diffraction under autoclave condition
Jun Kikuma Masamichi Tsunashima Tetsuji Ishikawa Shin‐ya Matsuno Akihiro Ogawa Kunio Matsui Masugu Sato 《Journal of synchrotron radiation》2009,16(5):683-686
Hydrothermal formation of tobermorite from a pre‐cured cake has been investigated by transmission X‐ray diffraction (XRD) using high‐energy X‐rays from a synchrotron radiation source in combination with a newly designed autoclave cell. The autoclave cell has a large and thin beryllium window for wide‐angle X‐ray diffraction; nevertheless, it withstands a steam pressure of more than 1.2 MPa, which enables in situ XRD measurements in a temperature range of 373 to 463 K under a saturated steam pressure. Formation and/or decomposition of several components has been successfully observed during 7.5 h of reaction time. From the intensity changes of the intermediate materials, namely non‐crystalline C–S–H and hydroxylellestadite, two pathways for tobermorite formation have been confirmed. Thus, the newly developed autoclave cell can be used for the analyses of reaction mechanisms under specific atmospheres and temperatures. 相似文献