Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 78 , Issue 5
Showing 1-28 articles out of 28 articles from the selected issue
Award Accounts
The Chemical Society of Japan Award for Young Chemists for 2003
  • Takeaki Ozawa
    2005 Volume 78 Issue 5 Pages 739-751
    Published: 2005
    Released: May 06, 2005
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    Protein–protein interactions and protein localization have key roles in many essential biological processes in living cells. We have developed novel reporter proteins with general applicability for detecting the biological processes in living cells and animals. The principle is based on reconstitution of split reporter proteins by protein splicing, which involves a self-catalyzed excision of a protein splicing element, intein, from flanking polypeptide sequences, exteins, leading to ligation of the flanking exteins by a peptide bond. As the exteins, N- and C-terminal halves of rationally-split green fluorescent protein (GFP) or split bioluminescent proteins were used. The N- and C-terminal reporters connected respectively with a pair of interacting proteins worked as indicators for protein–protein interactions in bacteria and mammalian cells. The split GFP reporter provided a genetic method for identifying mitochondrial proteins from large-scale complementary DNA libraries. The split bioluminescent reporter enabled high-throughput sensing and noninvasive imaging of nuclear transport of target proteins in living animals. This basic concept of split reporter reconstitution by protein splicing provides a wide variety of applications not only for fundamental biological studies, but also for assay and screening methods for chemicals that inhibit or facilitate the biological processes in living cells.
The Chemical Society of Japan Award for Technical Development for 2003
  • Masahiro Sugiura, Masakuni Ozawa, Akihiko Suda, Tadashi Suzuki, Takaak ...
    2005 Volume 78 Issue 5 Pages 752-767
    Published: 2005
    Released: May 06, 2005
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    Innovative three-way catalysts containing ceria–zirconia solid solutions (CZ) with a ZrO2 content ranging from 5 to 75 mol% were developed. Such catalysts have very high oxygen storage/release capacity (OSC). The OSC of catalysts containing first-generation CZ was found to increase linearly with the amount of zirconia dissolved in the solid solution in the 0–20 mol% ZrO2 range. The thermal stability of the catalyst containing first-generation CZ was higher than that containing ceria. Second-generation CZ with greater OSC than first-generation CZ was developed by a homogeneous coprecipitation process, followed by heat-treatment below 1000 °C, enabling dissolution of zirconia into ceria up to 75 mol% zirconia as estimated by XRD. Third-generation CZ, CZ-doped alumina (ACZ), was developed by homogeneous coprecipitation based on the “diffusion barrier concept”. The OSC of ACZ was 23 times larger than that of pure ceria. The NOx emission over the catalyst containing ACZ was reduced by about a factor of five compared with that containing pure ceria. Toyota Motor Corp. has put three-way catalysts containing first-, second-, and third-generation CZ into practical use globally.
BCSJ Award Article
Articles
  • Kshatrapati Shivaji Sharma, Animesh Kumar Rakshit
    2005 Volume 78 Issue 5 Pages 771-780
    Published: 2005
    Released: May 06, 2005
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    The effect of the concentration and the nature of different n-alcohols (C2–C5) on the growth of C12E10 [CH3(CH2)11(OCH2CH2)10OH] micelles has been studied by tensiometric, viscometric, and proton NMR techniques. Critical micelle concentrations (CMC) were determined by surface-tension measurements in the presence of different concentrations of n-alcohols (C2–C4) and at different temperatures. The Gibbs free energy, enthalpy, and entropy of micellization ( , , ) and adsorption at an air/water interface ( , , ) were computed and discussed. An enthalpy–entropy compensation effect was observed at an isostructural temperature of about 300 K for both micellization and interfacial adsorption. The transfer enthalpies and heat capacities of the micelle from water to aqueous n-alcohol solutions were also computed. The intrinsic viscosity gave the hydrated micellar volume (Vh), volume of the hydrocarbon core (Vc), and the volume of the palisade layer of the OE unit (VOE). The spin–lattice proton relaxation time (T1) in the aqueous micellar region and 1H NMR were also used to study the behavior of OE micelles in both the absence and presence of alcohols. There was a slight rise in the cloud point (CP) when using lower alcohols. However a decrease was seen for n-BuOH and n-PenOH.
  • AbdelRahman A. Dahy, Nobuaki Koga
    2005 Volume 78 Issue 5 Pages 781-791
    Published: 2005
    Released: May 06, 2005
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    The transformation of bis(acetylene)cobalt complex to cobaltacyclopentadiene complex was studied using a hybrid density functional theory method. B3LYP calculations showed that the reaction of an unsubstituted system, bis(η2-acetylene)cobalt complex, on a singlet potential energy surface is an easy reaction with a small activation energy of 11.2 kcal/mol and an exothermicity of −19.2 kcal/mol. The low activation barrier was as expected for a symmetry-allowed reaction. Because the product of cobaltacyclopentadiene has a low-lying unoccupied orbital, the two Co–Cα bonds are different in distance due to the second-order Jahn–Teller effect, and the triplet cobaltacyclopentadiene is more stable than the singlet cobaltacyclopentadiene, different from the reactant and transition state. In addition, we performed calculations for the reactions of acetylenes substituted by methyl and/or methoxycarbonyl groups, in order to investigate the factors that control the regioselectivity observed in this type of reaction. The calculations for the mono- and disubstituted reactions showed that these substituents prefer α-carbon to β-carbon. We analyzed the origin of this regioselectivity based on the relative stability of the products, to find that it is closely related to the site preference in the substituted butadienes. This suggests that the site preference of substituents is an important factor of regioselectivity.
  • AbdelRahman A. Dahy, Cherumuttathu H. Suresh, Nobuaki Koga
    2005 Volume 78 Issue 5 Pages 792-803
    Published: 2005
    Released: May 06, 2005
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    With the B3LYP theoretical method, the reaction of cobaltacyclopentadiene complex with acetylene in singlet and triplet states leading to benzene cobalt complex was studied in detail. In the most favorable path in the singlet state, an acetylene molecule attacks cobaltacyclopentadiene from the side, where the vacant d orbital extends over, so that [4 + 2] cycloaddition gives a η4-benzene complex without any activation energy, called the collapse mechanism. The reaction in the triplet state passes through a single transition state with an activation barrier of 14.1 kcal/mol, leading to the η6-benzene complex. The reactant of cobaltacyclopentadiene and the product of the benzene complex in the triplet state are more stable than those in the singlet state, whereas a substantial activation energy is required in the triplet state, suggesting that the spin may change during the reaction. Calculations of the crossing points between the singlet and triplet states showed that in the most favorable reaction path, the spin changes to the singlet state before passing through the triplet transition state, and that the collapse mechanism in the singlet state is followed. The energy required to lead to the crossing point for this spin change was calculated to be 7.0 kcal/mol, which is lower than the activation barrier.
  • Yutaka Mouri, Yoshihisa Fujiwara, Takeshi Aoki, Hiroshi Yoshida, Kazun ...
    2005 Volume 78 Issue 5 Pages 804-813
    Published: 2005
    Released: May 06, 2005
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    The g and hyperfine tensors of radicals were theoretically estimated by quantum chemical calculations, and compared with experimentally obtained ones. From the comparison, it was found that the theoretically calculated tensors can reproduce the experimental ones with accuracy. By using those tensors, therefore, high magnetic field dependences of the lifetimes of biradicals, which were generated by a photo-induced electron transfer in α-cyclodextrin inclusion complexes of chain-linked molecules of phenothiazine–(CH2)n–viologen (PhnV2+, n = 12, 10, and 8) and carbazole–(CH2)12–viologen (Cz12V2+), were quantitatively analyzed on the basis of the relaxation mechanism of the generated bi-cationic biradicals (Ph•+nV•+ and Cz•+12V•+). The analysis conclusively showed that two extremely small correlation times of each radical motion were still necessary for reversals characteristic of the high magnetic field dependences, and also that the order of the obtained correlation time was Cz•+ > V•+ > Ph•+. The order in the correlation time was discussed while referring to the rigidity of the radical frameworks.
  • Yukiko Hayashi, Kimiko Kobayashi, Daisuke Hashizume, Masahisa Osawa, Y ...
    2005 Volume 78 Issue 5 Pages 814-817
    Published: 2005
    Released: May 06, 2005
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    The irradiation of (η5-C5H4R)2Ti(C≡CRc)2 (R = Me, SiMe3 (= TMS); Rc = ruthenocenyl) at the band assignable to CT from Rc to Ti in the presence of equimolar amounts of RcC≡CH and MeO2CC≡CCO2Me smoothly gave titanacyclic complexes (η5-C5H4R)2Ti{–C(Rc)=C(C≡CRc)–CH=C(Rc)–} and (η5-C5H4TMS)2Ti{–C(C≡CRc)=C(Rc)–C(OMe)(C≡CCO2Me)–O–}, respectively, two of which were structurally characterized. The formation of these complexes has been explained by the extremely easy reductive coupling in (η5-C5H4R)2Ti(C≡CRc)2, brought about by photo-excitation at the Rc group, followed by metallacycle formation that involves the resulting diyne unit and the externally added alkynes.
  • Jahan Bakhsh Raoof, Reza Ojani, Mansoure Kolbadinezhad
    2005 Volume 78 Issue 5 Pages 818-826
    Published: 2005
    Released: May 06, 2005
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    The preparation of ferrocene-modified carbon paste electrode by incorporation of a mediator into a graphite powder–paraffin oil matrix is described. The suitability of this chemically modified electrode for electrocatalytic oxidation of L-cysteine was studied in buffered solution by cyclic voltammetry and double potential step chronoamperometry. It has been found that, under optimum conditions (pH = 7.00), the oxidation of L-cysteine at the surface of such an electrode occurs at a potential about 500 mV less positive than on an unmodified carbon paste electrode. The kinetic parameters such as electron transfer coefficient α and catalytic reaction rate constant Kh were determined using various electrochemical approaches. The electrocatalytic oxidation peak current of L-cysteine at the surface of this modified electrode was used for determination of L-cysteine by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Linear analytical curves were obtained in the ranges of 10−5 M (= mol dm−3) – 10−3 M and 8.9 × 10−6 M – 2 × 10−4 M of L-cysteine concentration with CV and DPV methods, respectively. The detection limits were determined as 6.5 × 10−6 M and 4.7 × 10−6 M by CV and DPV methods. This method was also examined for determination of L-cysteine in samples, such as Soya protein powder, serum and plasma of human blood, using recovery and standard addition methods.
  • Ryo Horikoshi, Masahiro Mikuriya
    2005 Volume 78 Issue 5 Pages 827-834
    Published: 2005
    Released: May 06, 2005
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    A twisted ligand, 4,4′-dithiobis(pyridine), 4pds, was reacted with copper(II) carboxylates to synthesize one-dimensional coordination polymers: [Cu4(CH3COO)63-OH)2(4pds)2]n (1), [Cu(CH3COO)2(4pds)·6H2O]n (2), [{Cu2(C6H5COO)4}2(4pds)2]n (3), and [{Cu2[CH3(CH2)4COO]4}2(4pds)2]n (4). The crystal structure of 1 reveals a repeated rhomboid structure in which the Cu4(CH3COO)6(OH)2 core is linked by two 4pds ligands. The 4 : 2 (Cu : 4pds) stoichiometry of 1 transforms into the 1 : 1 (Cu : 4pds) one of 2 in aqueous solution. Compound 2 has a porous honeycomb-like structure, which is occupied by carboxylate ions and water molecules. Compounds 3 and 4 are zigzag chains consisting of alternate linking of the Cu2(RCOO)4 unit and 4pds ligand. The variable-temperature magnetic susceptibility data of 1 and 3 are consistent with the net antiferromagnetic interaction within the tetranuclear or dinuclear core.
  • Palanisamy Uma Maheswari, Venugopal Rajendiran, Mallayan Palaniandavar ...
    2005 Volume 78 Issue 5 Pages 835-844
    Published: 2005
    Released: May 07, 2005
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    The dinuclear ruthenium(II) complex [{(5,6-dmp)2Ru}2(μ-bpm)]4+ (5,6-dmp = 5,6-dimethyl-1,10-phenanthroline; bpm = 2,2′-bipyrimidine) was synthesized and the meso (ΔΛ) and rac (ΔΔ, ΛΛ) diastereoisomers separated using cation-exchange chromatography, and characterized using CHN analysis as well as UV–visible and 1H NMR spectra. The rac form was interacted with calf thymus DNA (CT DNA) and certain selected dodecanucleotides, like poly d(GC)12 and poly d(AT)12 and the hexanucleotide d(GTCGAC)2. Absorption, emission and circular dichroic spectral techniques, DNA melting studies and viscometry were used to monitor the interactions. Induced biphasic CD signals due to exciton coupling between dinuclear complexes bound on the DNA nanotemplate and the complexes free in solution were observed in the UV region. In contrast, the mononuclear analogue rac-[Ru(5,6-dmp)2(bipy)]2+ did not show any biphasic CD signal upon an interaction with DNA under identical conditions. An increase in the ionic strength of the buffer and a decrease in the length of the DNA lowered the extent of exciton coupling. Also, the complex preferentially bound to GC, rather than the AT sequence, as revealed from the higher intensity of the biphasic CD signal for the former. An equilibrium dialysis experiment unambiquously revealed the preferential binding of ΔΔ-enantiomer to CT DNA, and also its potential, interestingly, to induce a B-to-Z conformational change on DNA. The latter was confirmed by the 31P NMR spectra of poly d(GC)12 bound to the dinuclear complex. A DNA binding model involving the partial insertion of one of the 5,6-dmp ligands of the large dinuclear complex (ΔΔ-enantiomer) between the DNA base pairs in the minor groove was suggested using molecular modeling; this model is preferred over one involving simple, electrostatic groove binding. This is supported by viscometry studies, which indicate an enhancement in the relative viscosity of CT DNA upon an interaction with the dinuclear complex.
  • V. Uma, V. G. Vaidyanathan, Balachandran Unni Nair
    2005 Volume 78 Issue 5 Pages 845-850
    Published: 2005
    Released: May 06, 2005
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    Two copper(II) complexes, Cu(ttpy)22+ 1 and Cu(Brphtpy)22+ 2, were synthesized and characterized for their DNA binding and cleaving ability. The crystal structure of complex 1 reveals an axially compressed six-coordinate geometry around Cu(II). In spite of having an axially compressed geometry, the polycrystalline EPR spectrum of complex 1 at 298 K shows g|| > g, indicating a dx2y2 ground state for the Cu(II) complex. Both complexes 1 and 2 bind to CT DNA intercalatively with moderate binding strength (Kb = (8.4 ± 0.2) × 103 and (10.9 ± 0.2) × 104 M−1 (1 M = mol dm−3) respectively). Both of these complexes cleave plasmid DNA efficiently in the presence of peroxide.
  • Kanako Matsufuji, Hitomi Shiraishi, Yuji Miyasato, Takuya Shiga, Masaa ...
    2005 Volume 78 Issue 5 Pages 851-858
    Published: 2005
    Released: May 06, 2005
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    Some dinucleating compartmental ligands of “end-off” type, 2,6-bis{N-[(2-dimethylamino)ethyl]iminomethyl}-4-methylphenol (HL1), 2,6-bis{N-(2-pyridylethyl)iminomethyl}-4-methylphenol (HL2), and 2,6-bis{N,N-di(2-pyridylmethyl)aminomethyl}-4-methylphenol (HL3), have afforded the following dinuclear Zn(II) and Ni(II) complexes: [Zn2(L1)(OH)(py)2](ClO4)2 (1), [Zn2(L2)(OH)(py)3](ClO4)2 (2), [Zn2(L3)(OH)](ClO4)2 (3), [Ni2(L1)(OH)(py)2](ClO4)2 (4), and [Ni2(L2)(OH)(py)4](ClO4)2 (5). X-ray crystallographic studies for 1·Pr2OH, 2·0.5Pr2OH, 3·MeCN, 4·py, and 5 indicate that they have a dinuclear core doubly bridged by the endogenous phenolic oxygen of each compartmental ligand and by exogenous hydroxide oxygen. Physicochemical properties of 15 are studied.
  • Hisashi Shimakoshi, Yasunori Maeyama, Takeshi Kaieda, Takashi Matsuo, ...
    2005 Volume 78 Issue 5 Pages 859-863
    Published: 2005
    Released: May 06, 2005
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    Heptamethyl cobyrinate, hydrophobic vitamin B12, was reduced to its Co(I) species by a reaction with sodium tetrahydroborate, which reacted with various organic halides, such as CH2Cl2, CHCl3, CCl4, CHBrCl2, CHBr3, CCl3CH3, CFCl3, and BrCH2CH2CH3, to form the corresponding alkylated complexes with dehalogenation. The alkylated complexes were characterized by elemental analyses and ESI-MS, and the photo-lability of the alkylated complexes was confirmed by the UV–vis absorption spectral change. The fashion for cleavage of the cobalt–carbon bond under irradiation with visible light was investigated by an ESR spin-trapping technique. The redox behavior of a series of alkylated complexes was investigated by cyclic voltammetry. The alkylated complexes showed an irreversible reduction peak at −1.21 to −1.29 V vs Ag–AgCl, which showed cleavage of the cobalt–carbon bond by electrolysis.
  • Ying Shih, Jyh-Myng Zen, Annamalai Senthil Kumar, Yu-Neng Huang
    2005 Volume 78 Issue 5 Pages 864-866
    Published: 2005
    Released: May 06, 2005
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    A copper-metal enriched printed-circuit board waste modified screen-printed electrode has been demonstrated for the sensitive electroanalysis of a tyrosinase biosynthesis-inhibiting cosmetic agent, arbutin by flow-injection analysis.
  • Katsuhiko Ono, Takeshi Iwao, Hideki Uchiumi, Takahisa Suzuki, Masaaki ...
    2005 Volume 78 Issue 5 Pages 867-872
    Published: 2005
    Released: May 06, 2005
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    1,1′,3,3′-Tetramethyl-2,2′-bi-1H-imidazolium bis(tetraphenylborate), an ion-association compound, afforded inclusion crystals with a variety of guest molecules, such as ketone, aldehyde, and nitrile. X-ray crystallographic analyses revealed intermolecular interactions between the biimidazolium dication and the guest molecules in the inclusion crystals. Their contact modes depended on the molecular structures of the guest molecules, resulting in various molecular arrangements.
  • Takayuki Suyama, Noriyuki Suzuki, Masami Nishimura, Yuka Saitoh, Hiroy ...
    2005 Volume 78 Issue 5 Pages 873-876
    Published: 2005
    Released: May 06, 2005
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    Regioselective preparation of 3,5-diamino-1,2,4-oxadiazoles which have a substituent on one or the other amino group has been developed. When 1-substituted 3-cyano-2-ethylisourea (2) was allowed to react with hydroxylamine under basic conditions, 5-amino-3-(substituted amino)-1,2,4-oxadiazole (3) was obtained in good yield. On the other hand, 3-amino-5-(substituted amino)-1,2,4-oxadiazoles (4), a regioisomer of 3, could be synthesized by the reaction of N,O-bis(trimethylsilyl)hydroxylamine (9) with 2 or 1-substituted 3-cyano-2-methylisothiourea (1) and subsequent alcoholysis.
  • Jui-Hsin Su, Ho-Cheng Huang, Chih-Hua Chao, Liang-Yu Yan, Yang-Chang W ...
    2005 Volume 78 Issue 5 Pages 877-879
    Published: 2005
    Released: May 06, 2005
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    A new eunicellin-type diterpenoid, vigulariol (1), has been isolated from the sea pen Vigularia juncea. Metabolite 1 has been obtained previously as a side product from a chemical reaction; however, it was isolated for the first time from natural resources. Also, this study established the full structure of 1 and afforded the detailed assignments of 1H and 13C NMR spectral data.
  • Zhaohui Wang, Takuji Hirose, Hiroaki Shitara, Midori Goto, Hiroyuki No ...
    2005 Volume 78 Issue 5 Pages 880-885
    Published: 2005
    Released: May 06, 2005
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    The absolute configuration of endo-3-benzamidonorborn-5-ene-2-carboxylic acid was determined by X-ray single crystal analysis of the diastereomeric salt with cis-2-(benzylamino)cyclohexylmethanol. It was demonstrated that the CH–π interaction between the vinylic hydrogen atom of the acid and the aromatic ring of the amine worked as an additional interaction for the stabilization of the structure formed by the hydrogen bond network. The chiral recognition ability was studied using a 1H NMR titration technique and the intermolecular interactions were discussed based on the results of its saturated counterpart, endo-3-benzamidonorbornane-2-carboxylic acid.
  • Kazuhiro Kobayashi, Kazuna Miyamoto, Osamu Morikawa, Hisatoshi Konishi
    2005 Volume 78 Issue 5 Pages 886-889
    Published: 2005
    Released: May 06, 2005
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    The iodoamination of o-(acylamino)styrene derivatives using iodine and sodium hydrogencarbonate, producing 7-acyl-8-iodomethylbicyclo[4.2.0]-7-azaoct-1,3,5-triene [1-acyl-2-(iodomethyl)benzazetine] derivatives, is described. Replacement of the iodo moiety by hydrogen or phenylthio group is also reported.
  • Lawrence M. Pratt
    2005 Volume 78 Issue 5 Pages 890-898
    Published: 2005
    Released: May 06, 2005
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    Lithium dialkylamides form several mixed aggregates with lithium chloride in ethereal solvents. The relative amounts of mixed dimer, trimer, and tetramer are dependent on the steric strain of the lithium dialkylamide homodimer and on solvent effects. Microsolvation with coordinating THF ligands generated results in qualitative agreement with available experimental data.
  • Kazuaki Shimada, Seiji Oikawa, Hidenori Nakamura, Akiko Moro-oka, Miho ...
    2005 Volume 78 Issue 5 Pages 899-905
    Published: 2005
    Released: May 06, 2005
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    Alkyl or alkenyl N,N-dimethylchalcogenocarbamates were easily prepared by a stepwise treatment of bis(N,N-dimethylcarbamoyl) dichalcogenides with NaH or NaBH4, followed by various alkylating agents or acetylenes bearing electron-withdrawing substituents. The one-step conversion of alkyl or alkenyl N,N-dimethylselenocarbamates or N,N-dimethyltellurocarbamates into the corresponding symmetrical dialkyl or dialkenyl dichalcogenides was also achieved efficiently by treating with SnCl4.
  • Gregory S. Coumbarides, Jason Eames, J. Erik W. Scheuermann, Kevin F. ...
    2005 Volume 78 Issue 5 Pages 906-909
    Published: 2005
    Released: May 06, 2005
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    The synthesis of enantiomerically enriched (R)-2-methyl-1-tetralone (1) with 77% e.e. was achieved through protonation of its lithium enolate (3) using a C2-symmetric tris-sulfonamide (6) as an internal chiral proton source. Access to the complementary (S)-enantiomer 1 with 33% e.e. was achieved using a related C2-symmetric bis-sulfonamide (9) as the chiral proton source.
  • Yohei Kobashi, Teruaki Mukaiyama
    2005 Volume 78 Issue 5 Pages 910-916
    Published: 2005
    Released: May 06, 2005
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    Highly α-selective glycosylations of several glycosyl acceptors with 2,3,4,6-tetra-O-benzyl-D-glucopyranosyl bromide (4) proceeded smoothly in the presence of tri(1-pyrrolidino)phosphine oxide in CH2Cl2 at room temperature or in refluxing CHCl3 via glycosyl phosphonium bromide intermediates and the corresponding disaccharides were afforded in good yields with high selectivities. Further, the one-pot glycosylation starting from glycosyl acetate using iodotrimethylsilane and phosphine oxide also proceeded efficiently in CH2Cl2 at room temperature to give the corresponding disaccharides, although this one-pot synthesis of α-glycoside via in situ anomerization procedure is considered difficult because glycosyl halide reacts with trimethylsilyl acetate easily to regenerate glycosyl acetate, a starting glycosyl donor.
  • Toshiaki Makino, Shinji Toyota
    2005 Volume 78 Issue 5 Pages 917-928
    Published: 2005
    Released: May 06, 2005
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    Some sterically congested di(9-anthryl)ethynes with substituted phenyl groups (4-Me, 4-iPr, 4-tBu, 3-iPr, 3,5-iPr2) at the 1-positions were synthesized by the Stille coupling of the corresponding triflate and bis(tributylstannyl)ethyne to realize the restricted rotation of the acetylenic axis in diarylethyne derivatives. In the X-ray structure of the 4-Me compound, the two 9-anthryl groups were staggered about the acetylenic axis by ca. 60°. The dynamic NMR study of the iPr substituted compounds afforded the kinetic data of the two independent processes: the faster and slower processes were assigned to the rotation about the acetylenic axis (ΔG 45–51 kJ mol−1) and the rotation of the phenyl groups (ΔG ca. 75 kJ mol−1), respectively, from the details of the lineshape changes. The observed barriers to the rotation about the acetylenic axis are rather high for acyclic diarylethynes, being attributed to the severe steric interactions between the 1-phenyl groups and the rigid di(9-anthryl)ethyne framework in the transition state. The mechanism of the dynamic stereochemistry and the substituent effect on the rotational barrier are discussed on the basis of the kinetic data and the molecular structures.
  • Masaru Kimura, Mitsuru Tsunenaga, Shizuka Takami, Yukiko Ohbayashi
    2005 Volume 78 Issue 5 Pages 929-931
    Published: 2005
    Released: May 15, 2005
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    A potential functional chemiluminescent (CL) bidentate chemosensor, 2-[4-(N-salicylidene)aminophenyl]-4,5-diphenylimidazole (1a), was prepared. The chemiluminescence (CL) efficiency of the corresponding bidentate peroxide 2a was independent of bridge length between the CL and acceptor centers. The peroxide was 10 times as efficient as the monodentate peroxide 2b. Ionic ZnII worked as a CL enhancer of 2a, whereas transition metals CoII, FeIII, and CuII worked as quenchers.
  • Yasutomo Goto, Kentaro Okamoto, Shinji Inagaki
    2005 Volume 78 Issue 5 Pages 932-936
    Published: 2005
    Released: May 06, 2005
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    The molecular scale periodicity within the pore walls of amorphous mesoporous phenylene-silicas, derived using triblock copolymers under acidic conditions, was generated by the post-synthesis treatment with alkaline solution. Usually, acid conditions are not favorable for the formation of periodic arrangement of phenylene-silica moieties. The treatment with alkaline solution at 363–373 K facilitated the restructuring of phenylene-silica moieties and resulted in the formation of periodic structure within the pore walls. The treatment also enlarged the pore size of mesoporous phenylene-silica from 5.4 to 12.4 nm. Such a material with large pore size and molecular periodicity should have several advantages in potential applications, particularly in the catalysis for relatively large molecules.
  • Hiroshi Shimada, Tomokazu Ogoshi
    2005 Volume 78 Issue 5 Pages 937-939
    Published: 2005
    Released: May 06, 2005
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    Amorphous oxides formed upon the calcination of Zn2Al layered double hydroxide chloride or carbonate intercalates showed high catalytic efficiency in the benzylation of benzene with benzyl chloride. The IR spectra of pyridine adsorbed on amorphous oxides suggest that the benzylation activity is due to the formation of zinc chloride on the surface.
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