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61.
Grosch B Orlebar CN Herdtweck E Kaneda M Wada T Inoue Y Bach T 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(9):2179-2189
1,2,3,4-Tetrahydro-2-oxoquinoline-5-aldehyde (2) was prepared from m-aminobenzoic acid and 3-ethoxyacryloyl chloride (4) in 19 % overall yield. Compound 2 underwent a photochemically induced [4+2]-cycloaddition reaction with various dienophiles upon irradiation in toluene solution. The exo product 10 a was obtained with acrylonitrile (9 a) as the dienophile, whereas methyl acrylate (9 b) and dimethyl fumarate (9 c) furnished the endo products 11 b and 11 c (69-77 % yield). The reactions proceeded at -60 degrees C in the presence of the chiral complexing agent 1 (1.2 equiv) with excellent enantioselectivity (91-94 % ee). The enantiomeric excess increases in the course of the photocycloaddition as a result of the lower product association to 1. The intermediate (E)-dienol 8 was spectroscopically detected at -196 degrees C in an EPA (diethyl ether/isopentane/ethanol) glass matrix. The association of the substrate 2 to the complexing agent 1 was studied by circular dichroism (CD) titration. The measured association constant (K(A)) was 589 M(-1) at room temperature (25 degrees C) and normal pressure (0.1 MPa). An increase in pressure led to an increased association. At 400 MPa the measured value of K(A) was 703 M(-1). Despite the stronger association the enantioselectivity of the reaction decreased with increasing pressure. At 25 degrees C the enantiomeric excess for the enantioselective reaction 2 + 9 a-->10 a decreased from 68 % ee at 0.1 MPa to 58 % ee at 350 MPa. This surprising behavior is explained by different activation volumes for the diastereomeric transition states leading to 10 a and ent-10 a. 相似文献
62.
[reaction: see text] N-Tosyl 3-substituted indoles were hydrogenated with high enantioselectivities (95-98% ee) by use of a trans-chelating chiral bisphosphine, (S,S)-(R,R)-PhTRAP ligand. The chiral catalyst, which was generated in situ from [Rh(nbd)(2)]SbF(6), PhTRAP, and Cs(2)CO(3), is useful for enantioselectively synthesizing a range of diverse optically active indolines possessing a chiral carbon at the 3-position. 相似文献
63.
Kohki Ebitani Masaki Kato Ken Motokura Tomoo Mizugaki Kiyotomi Kaneda 《Research on Chemical Intermediates》2006,32(3):305-315
Montmorillonite-enwrapped titanium hydroxide species (Ti4+-mont) acted as a highly efficient heterogeneous acid catalyst for the acylation of aromatic compounds with acid anhydrides
or carboxylic acids. The catalytic activity of the Ti4+-mont was higher than those of other acid catalysts such as zeolites, SO
4
2−
/ZrO2 and p-toluenesulfonic acid. For example, the reaction of anisole with dodecanoic acid in the presence of the Ti4+-mont catalyst gave 1-(4-methoxyphenyl)-1-dodecanone in 97% yield. Furthermore, the Ti4+-mont catalyst was easily separated from the reaction mixture and was recyclable. 相似文献
64.
Aqueous dispersions of cross-linked poly(methylmethacrylate)-g-poly(ethylene oxide) [PMMA-g-PEO] microgel particles have been prepared from mixtures of methylmethacrylate [MMA] and MMA-PEO macromonomer, with ethylene glycol dimethacrylate [EGDM] as the cross-linking monomer (0.2-0.5% wt%). The hydrodynamic radius of these (unswollen) microgel particles ranged from 73 to 85 nm, and the particles were essentially monodisperse with regard to their size distribution. Their swelling behavior has been investigated in the presence of both water-miscible and water-immiscible organic solvents. In general, with the addition of a water-miscible solvent, deswelling behavior was observed. However, the microgel particles were swollen on addition of 1,4-dioxan, which is a good solvent for PMMA. With water-immiscible organic solvents, the extent of swelling depended on the solvency properties of the organic liquid for PMMA. In the presence of benzene, the somewhat large increases in particle size have been attributed to weak flocculation. This has been assumed from an estimate of the van der Waals attraction energy between the swollen microgel particles. 相似文献
65.
Masayoshi Kaneda 《Journal of Functional Analysis》2007,251(1):346-359
Let X be an operator space, let φ be a product on X, and let (X,φ) denote the algebra that one obtains. We give necessary and sufficient conditions on the bilinear mapping φ for the algebra (X,φ) to have a completely isometric representation as an algebra of operators on some Hilbert space. In particular, we give an elegant geometrical characterization of such products by using the Haagerup tensor product. Our result makes no assumptions about identities or approximate identities. Our proof is independent of the earlier result of Blecher, Ruan and Sinclair [D.P. Blecher, Z.-J. Ruan, A.M. Sinclair, A characterization of operator algebras, J. Funct. Anal. 89 (1) (1990) 188-201] which solved the case when the bilinear mapping has an identity of norm one, and our result is used to give a simple direct proof of this earlier result. We also develop further the connections between quasi-multipliers of operator spaces and their representations on a Hilbert space or their embeddings in the second dual, and show that the quasi-multipliers of operator spaces defined in [M. Kaneda, V.I. Paulsen, Quasi-multipliers of operator spaces, J. Funct. Anal. 217 (2) (2004) 347-365] coincide with their C∗-algebraic counterparts. 相似文献
66.
Kuramoto T Kameyama Y Kaneda M Shiro M Hoshita T Une M 《Chemical & pharmaceutical bulletin》2000,48(1):53-55
The structure and stereochemistry of the higher bile acid, tetrahydroxyisosterocholanic acid (TISA), which was previously isolated from the bile of Amyda japonica (turtle) and proposed as a tetrahydroxyisosterocholanic acid, have been established as (22S,25R)-3 alpha,12 alpha,15 alpha,22-tetrahydroxy-5 beta-cholestan-26-oic acid by X-ray crystallographic analysis of its ethyl ester. 相似文献
67.
68.
Based on isotopic frequency shifts and model calculations, bands observed near the region of 155 cm-1 in Raman spectra of sodium beta-alumina containing ammonium ions have been assigned to translational modes of NH4+. The spectra of a crystal containing 61% NH4+ ions show a pair of bands at 165 and 145 cm-1 (11 K). Possible origins of these bands are discussed. 相似文献
69.
70.
J.B. Bates T. Kaneda W.E. Brundage J.C. Wang Herbert Engstrom 《Solid State Communications》1979,32(3):261-265
Raman scattering from vibrations of mobile cations in single crystal Na, K, and Agβ”-aluminas has been measured. The frequency of a band near 33 cm-1 is believed to correspond to the attempt frequency for sodium conduction. The frequencies calculated from a defect model are in good agreement with the observed spectra. 相似文献