Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 80 , Issue 3
Showing 1-25 articles out of 25 articles from the selected issue
Vol. 80 Commemorative Accounts
  • Hirohmi Watanabe, Richard Vendamme, Toyoki Kunitake
    2007 Volume 80 Issue 3 Pages 433-440
    Published: March 15, 2007
    Released: March 13, 2007
    JOURNALS FREE ACCESS
    Large nanomembranes, which are characterized by aspect ratios (size/thickness) of greater than one million, are described. The combination of nanometer thickness and macroscopic size facilitates important applications in materials separation, selective transport and electrochemical devices. In the past, only small pieces of nanomembranes have been fabricated, in spite of intensive research. We describe here the first examples of a general fabrication procedure. Spin coating of the precursor solutions on appropriate underlayer was effectively used to prepare 10–30 nm thick nanomembranes of metal oxides, interpenetrating network of cross-linked acrylate with metal oxide, and highly cross-linked organic polymers (epoxy resin, etc.). The underlayer is composed of an affinity (e.g., poly(vinyl alcohol)) layer and/or sacrificial layer, and the role of these layers is discussed. Some of the mechanical properties of nanomembranes were measured by using a bulge test and a compression method. The nanomembranes of the organic and inorganic hybrids and the purely organic resins were surprisingly robust and defect-free.
    Giant membranes that are characterized with nanometer thickness and macroscopic size are reviewed for the first time. They are fabricated from only metal oxides, from hybrids of metal oxides and cross-linked acrylate, and from totally organic thermosetting resins. Fullsize Image
Award Accounts
The Chemical Society of Japan Award for 2005
  • Yoshio Umezawa
    2007 Volume 80 Issue 3 Pages 441-448
    Published: March 15, 2007
    Released: March 13, 2007
    JOURNALS FREE ACCESS
    For imaging molecular processes in living cells, we developed novel intracellular fluorescent and bioluminescent indicators for second messengers, protein phosphorylation, protein/protein interactions, and protein localizations that work in single living cells. Key molecules and steps of cellular signaling pathways were visualized in target live cells under fluorescent microscopy using developed fluorescent indicators. A second new approach to molecular imaging is also described. Chemically modified STM tips (molecular tips) were developed for molecular imaging at the interfaces. The molecule-specific imaging is based on an increase in a tunneling current due to the overlap of electronic wave functions induced by the chemical interactions between tip and sample molecules. Chemically selective imaging using STM molecular tips can be described as intermolecular tunneling microscopy.
    We have developed methods for imaging and detecting ions and molecules. We have tried to implement “seeing what was unseen” in single live cells and interfacial molecular recognition chemistry. Fullsize Image
The Chemical Society of Japan Award for Creative Work for 2005
  • Seiji Motojima, Xiuqin Chen
    2007 Volume 80 Issue 3 Pages 449-455
    Published: March 15, 2007
    Released: March 13, 2007
    JOURNALS FREE ACCESS
    Carbon micro-coils (CMCs) with 3D-helical/spiral structures and coil diameters on the order of micrometer were obtained by metal-catalyzed pyrolysis of acetylene at 700–800 °C. The preparation conditions, morphology, growth mechanism, microstructure, and some properties of the CMCs were examined in detail. Two pieces of vapor grown carbon fibers grown from a metal catalyst grain curl and entwine each other due to the anisotropic catalytic activity between different crystal faces of the catalyst grain and thus form double-helix CMCs. CMCs have an almost amorphous structure but could be graphitized by high-temperature heat treatment with full preservation of the coiling morphology. The CMCs could effectively generate inductive electromotive force, inductive current and thus Joul’s heat under microwave irradiation. The CMCs/elastic polymer composite elements showed high tactile sensing properties which are comparable to that of human skin. The CMCs are a possible candidate for electromagnetic wave absorbers, remote heating materials, visualization elements of microwaves, tactile sensor elements, micro-antennae, chiral catalysts, bio-activators or bio-deactivators, energy converters, etc.
    Carbon microcoils (CMCs) with 3D-helical/spiral structures were obtained by the metal-activated pyrolysis of acetylene. The preparation conditions, morphologies, growth mechanism, microstructure, and some properties of the CMCs are examined, and their potential applications are discussed. Fullsize Image
Accounts
  • Hajime Katô, Masaaki Baba, Shunji Kasahara
    2007 Volume 80 Issue 3 Pages 456-463
    Published: March 15, 2007
    Released: March 13, 2007
    JOURNALS FREE ACCESS
    We measured Zeeman effects for rotationally resolved spectra of several low-lying vibrational bands of the S1 ← S0 transition of benzene and naphthalene. We demonstrated that for both benzene and naphthalene (i) Zeeman splittings of the rotational lines were caused by a magnetic moment of the S1 state, and (ii) the magnetic moment lies perpendicular to the molecular plane and originates from an electronic angular momentum induced by JL coupling between the S1 and S2 states. We found from the Zeeman spectra that the rotational levels of the S1 state are not mixed with a triplet state, and all the perturbing levels were found to be a singlet state. Coupling to a triplet state was shown not to be responsible for nonradiative relaxation. Accordingly, intersystem crossing is not the dominant nonradiative process at low-lying vibrational states, and the main nonradiative process is presumed to be internal conversion.
    Coupling to a triplet state was shown not to be responsible for nonradiative relaxation. Accordingly, intersystem crossing is not the dominant nonradiative process at low-lying vibrational states, and the main nonradiative process is presumed to be internal conversion. Fullsize Image
BCSJ Award Article
  • Tsuyoshi Watabe, Kenji Kobayashi, Ichiro Hisaki, Norimitsu Tohnai, Mik ...
    2007 Volume 80 Issue 3 Pages 464-475
    Published: March 15, 2007
    Released: March 13, 2007
    JOURNALS FREE ACCESS
    Cocrystallization of brucine with a series of aliphatic alcohols was systematically investigated to understand molecular recognition through supramolecular isomerism and chirality. Guest-induced supramolecular isomers of brucine were obtained by cocrystallization and were categorized into three structural types based on the common 21 helical tape-like assemblies. These supramolecular isomers were elucidated from the molecular structures on the basis of qualitative hierarchical structural analysis through supramolecular chirality. Moreover, it was found that the supramolecular isomerization occurred depending on the size of the guest molecules. This dependence was clearly evaluated on the relationship between the volume of the guest molecules and the packing coefficient of the void spaces in the host cavities.
    Guest-induced supramolecular isomers of brucine inclusion crystals with aliphatic alcohols consist of the common 21 helical tape-like assemblies. Supramolecular isomerization occurred mainly depending on the size of the guest molecules. Fullsize Image
 
  • Kazuhiko Shiono, Toshio Naito, Tamotsu Inabe
    2007 Volume 80 Issue 3 Pages 476-483
    Published: March 15, 2007
    Released: March 13, 2007
    JOURNALS RESTRICTED ACCESS
    Pyromellitate is known to form hydrogen-bonding anionic networks when the number of deprotonation from pyromellitic acid is one or two. This unique anion has been utilized for the construction of the π-radical cationic salts of the tetrathiafulvalene (TTF) derivatives. In the crystals of three kinds of the TTF salts and the tetramethyltetraselenafulvalene salt, pyromellitate was found to form two-dimensional sheets. The anions in the two TTF salts were connected by rhombic-type inter-anionic connection, which is a typical inter-anionic connection pattern for pyromellitate. The TTF derivatives were all in a π-radical mono-cationic state and dimerized in a space dictated by the anionic networks. The extra space in the crystals was filled with crystal solvents. On the other hand, in the crystals of the ethylenedithia-tetrathiafulvalene salts, pyromellitate formed only intra-molecular hydrogen bonds. The anion was thus isolated in these crystals.
  • Kokkuvayil Vasu Radhakrishnan, Saithalavi Anas, Eringathodi Suresh, No ...
    2007 Volume 80 Issue 3 Pages 484-490
    Published: March 15, 2007
    Released: March 13, 2007
    JOURNALS RESTRICTED ACCESS
    The synthesis, crystal structure analysis, theoretical modeling at DFT and semiempirical PM3 levels, and molecular electrostatic potential analysis of an organic host–guest system containing an azapolycyclic system 3 and ethyl acetate are presented. The structure of 3 was charaterized by the presence of seven-connected five-membered rings. Though 3 contained six-saturated nitrogen atoms capable of CH···N interactions, its crystal structure and the host–guest complexation were completely governed by CH···O and CH···π interactions. Further, an aromatic pocket consisting of four phenyl rings from four molecules of 3 existed located in the crystal structure. The guest molecule ethyl acetate trapped inside this aromatic pocket was found to interact with it via three CH···π and two CH···O interactions. A model structure for this host–guest complex was also optimized at DFT level, which showed good agreement with the experimental structure.
  • Yoshifumi Tanimoto, Kazutaka Sueda, Masahiro Irie
    2007 Volume 80 Issue 3 Pages 491-494
    Published: March 15, 2007
    Released: March 13, 2007
    JOURNALS RESTRICTED ACCESS
    The effects of vertical magnetic fields on laser-induced convection of water were studied using a photochromic reaction of a water-soluble 1,2-diarylethene (WSD). A thin blue disk of its photoisomer (PI) solution was formed on the bottom surface; it moved upward when the WSD aqueous solution was irradiated using a 355 nm laser from the bottom of the vessel. The lift speeds of the PI solution were about 2.5 (11 T, +1200 T2 m−1), 1.2 (11 T, −1500 T2 m−1), and 1.6 mm min−1 (15 T, −100 T2 m−1). All results are described in terms of the magnetic force acting on the PI solution.
  • Masahiro Nishizawa, Kosei Shioji, Yoshimitsu Kurauchi, Kentaro Okuma, ...
    2007 Volume 80 Issue 3 Pages 495-497
    Published: March 15, 2007
    Released: March 13, 2007
    JOURNALS RESTRICTED ACCESS
    Spin-trapping properties of a novel spin-trapping reagent, 5-(diphenylphosphinoyl)-5-methyl-4,5-dihydro-3H-pyrrole N-oxide (DPPMDPO), were investigated by ESR spectroscopy. DPPMDPO had larger rate constants than DMPO and DEPMPO. DPPMDPO should be better than DEPMPO as a spin-trapping reagent for superoxide detection.
  • Takuya Hasegawa, Jotaro Ishise, Yasuharu Fukumoto, Hirotaka Matsuura, ...
    2007 Volume 80 Issue 3 Pages 498-502
    Published: March 15, 2007
    Released: March 13, 2007
    JOURNALS RESTRICTED ACCESS
    Chemical speciation of arsenic species in human blood serum was performed by high-performance liquid chromatography/inductively coupled plasma mass spectrometry (HPLC/ICP-MS) with direct sample injection, where an octadecylsilyl silica (ODS) column coated with phosphatidylcholine (PC) (hereafter known as “PC-coated ODS column”) was used as the separation column. In arsenic species analysis, a citrate buffer solution (pH 4.0) was used as the mobile phase, in which the following reagents were added: sodium 1-dodecanesulfonate (SDS), tetramethylammonium hydroxide (TMAH), which are ion-pair reagents to separate inorganic and organic arsenic species, and 3-[(3-cholamidopropyl)dimethylammonio]-1-propane sulfonate (CHAPS), which is a protein-solubilizing agent to prevent adsorption of proteins on the column. As a result of optimization, five representative arsenic species spiked in human blood serum reference material could be separated from each other within 5 min on the PC-coated ODS column by elution with a 5 mM citrate buffer (pH 4.0) containing 5 mM SDS, 5 mM THAH, and 0.2 mM CHAPS. The detection limits obtained by ICP-MS were 3.1, 2.7, 4.5, 2.5, and 2.5 ng of As g−1 for arsenate (iAsV), arsenite (iAsIII), monomethylarsonic acid (MMA), dimethylarsenic acid (DMA), and arsenobetaine (AB), respectively, when the injection volume was 20 μL. The present separation system was also applied to speciation analysis of arsenic species in human blood serum collected from a leukemia patient after therapeutic treatment with arsenic.
  • Takuya Hasegawa, Yoshinori Wakita, Yanbei Zhu, Hirotaka Matsuura, Hiro ...
    2007 Volume 80 Issue 3 Pages 503-506
    Published: March 15, 2007
    Released: March 13, 2007
    JOURNALS RESTRICTED ACCESS
    A multiply hyphenated HPLC/UV/ICP-MS system equipped with a fraction collection valve for subsequent MALDI-TOF-MS analysis was constructed, and its applicability to the speciation of metalloproteins in human serum was evaluated. A weak anion-exchange CIM® monolithic disk column was employed for protein separation, in which gradient elution of proteins with volatile salts was carried out while taking into account the compatibility with ICP-MS instrument. As a result of optimization, representative serum proteins, such as γ-globulin (γGb), albumin (Ab), ceruloplasmin (Cp), transferrin (Tf), and α2-macroglobulin (α2Mgb), were separated on the disk column with a linear concentration gradient of CH3COONH4 in 20 mM Tris-HCl buffer (pH 7.4). These proteins, which were primarily assigned by UV absorption at 280 nm, were clearly identified with on-line multielement detection using ICP-MS as well as with off-line MALDI-TOF-MS analysis of each successive fraction collected. It was concluded that the present multiply hyphenated system will be useful for identifying proteins in biological samples.
  • Takeshi Okumura, Yuji Morishima, Hiroyoshi Shiozaki, Takeyoshi Yagyu, ...
    2007 Volume 80 Issue 3 Pages 507-517
    Published: March 15, 2007
    Released: March 13, 2007
    JOURNALS RESTRICTED ACCESS
    Ruthenium(II) complexes, [Ru(babp)(dmso)L], consisting of tetradentate square-planar ligand (babp = 6,6′-bis(benzoylamino)-2,2′-bipyridinato) and two monodentate axial ones, DMSO and L (L = dmso or heterocycles), were synthesized and structurally characterized using UV–vis, NMR, ESI-MS, and IR spectroscopies and X-ray crystallography. These complexes showed catalytic activity toward the oxygen-atom-transfer reactions, such as epoxidation, allylic oxidation, cleavage reaction of olefins, and sulfoxidation of thioethers, in the presence of oxidant, PhIO. The relationship between the coordination structure and the catalytic activities of [Ru(babp)(dmso)L] was investigated. The active species for the reaction was assigned to be a high valent RuV=O or RuVI=O species. The oxo ligand was generated from the ligand-exchange reaction involving the dmso attached to [Ru(babp)(dmso)L]. Some complexes having a labile ligand at an axial position gave a RuVI=O species as an active intermediate, and others having moderate coordinating one gave a RuV=O one. The oxidation activities of these complexes were affected by the axial ligand, L, through the trans-influence.
  • Hossein Dehghani, Ali Reza Ansari Sardrood
    2007 Volume 80 Issue 3 Pages 518-522
    Published: March 15, 2007
    Released: March 13, 2007
    JOURNALS RESTRICTED ACCESS
    Reaction of bismuth(III) chloride (BiCl3) with free base meso-tetraarylporphyrins (H2t(X)pp, X = 4-Me, 4-OMe, 3-Me, 3-OMe, and H) in CHCl3 under mild conditions gives exclusively 1:1 molecular complexes with the general formula [(BiCl3{H2t(X)pp})2]. The remarkable agreement between 1H and 13C NMR and UV–vis spectra of the porphyrin macrocycle in these complexes and those of meso-tetraarylporphyrin molecular complexes with DDQ, TCNE, SiR3Cl, and BF3 indicates that they all have a similar porphyrin core. The molecular complexes have a dimer structure containing a Bi2Cl6 moiety. In the proposed structures for the complexes, four pyrroles are tilted alternatively up and down with respect the porphyrin mean plane, which leads to the appropriate orientation of the nitrogen lone pairs towards the central bismuth atoms. Therefore, octahedral geometry for the bismuth center is proposed.
  • Takefumi Hamamatsu, Kazuya Yabe, Masaaki Towatari, Naohide Matsumoto, ...
    2007 Volume 80 Issue 3 Pages 523-529
    Published: March 15, 2007
    Released: March 13, 2007
    JOURNALS RESTRICTED ACCESS
    Three tetranuclear copper(II)–lanthanide(III) complexes, [{CuIILLnIII(o-van)(CH3COO)(MeOH)}2]·2H2O (LnIII = GdIII, TbIII, and DyIII), were synthesized and characterized, where H3L is 1-(2-hydroxybenzamido)-2-(2-hydroxy-3-methoxybenzylideneamino)ethane and o-van is 3-methoxysalicylaldehydato. These compounds are isomorphous to each other and consist of a cyclic tetranuclear CuII2LnIII2 structure, in which the CuII and LnIII ions are alternately arrayed and the CuII component complex. [CuIIL] unit functions as a “bridging ligand-complex” between two adjacent LnIII ions through the phenolato and methoxy oxygen atoms at one side and the amido oxygen atom at the another side. The temperature-dependent magnetic susceptibilities from 2.0 to 300.0 K and the field-dependent magnetizations at 2.0 K from 0 to 5 T showed that the magnetic interaction between CuII and each of the lanthanide ions is ferromagnetic. The magnetic susceptibilities of [{CuIILGdIII(o-van)(CH3COO)(MeOH)}2]·2H2O were analyzed by using a spin-only Hamiltonian H = −2J1(SCu1SGd1 + SCu2SGd2) − 2J2(SCu1SGd2 + SCu2SGd1) based on a cyclic tetranuclear structure and gave the best-fit parameters of g = 1.97, J1 = +3.8 cm−1, J2 = +0.7 cm−1, and zJ′ = −0.01 cm−1. The magnetization data at 2.0 K of [{CuIILGdIII(o-van)(CH3COO)(MeOH)}2]·2H2O were well reproduced by using a Brillouin function with an S = 8 spin ground state due to the ferromagnetic interactions between CuII and GdIII ions and g = 1.97. The ac magnetic susceptibilities of [{CuIILLnIII(o-van)(CH3COO)(MeOH)}2]·2H2O (LnIII = TbIII and DyIII) in the temperature range 1.8–10.0 K with a 3 G ac field oscillating in the range 1–1000 Hz showed a frequency dependence characteristic of SMMs.
  • Yutaka Yoshikawa, Mika Morishita, Midori Nishide, Eriko U. Yoshikawa, ...
    2007 Volume 80 Issue 3 Pages 530-532
    Published: March 15, 2007
    Released: March 13, 2007
    JOURNALS RESTRICTED ACCESS
    We prepared zinc(II) complexes with a series of mono-methyl-substituted pyridine-2-sulfonic acid derivatives to clarify the relationship between the structure and insulinomimetic activity. Towards in vitro insulinomimetic activity, bis(3-methylpyridine-2-sulfonato)zinc(II) gave the best result among the zinc(II) complexes with methylpyridine-2-sulfonates.
  • Ken Saito, Toshiaki Tsukuda, Kenji Matsumoto, Taro Tsubomura
    2007 Volume 80 Issue 3 Pages 533-535
    Published: March 15, 2007
    Released: March 13, 2007
    JOURNALS RESTRICTED ACCESS
    A tetrahedral four-coordinate bis-diphosphine gold(I) complex, [Au(biphep)2]PF6 (biphep = 2,2′-bis(diphenylphosphino)-1,1′-biphenyl), was prepared, and the structure was determined by X-ray structure analysis. The complex showed photoluminescence at room temperature in the solid state and in CH2Cl2.
  • Xiaoyong Zhang, Ken Sasaki, Yasuhisa Kuroda
    2007 Volume 80 Issue 3 Pages 536-542
    Published: March 15, 2007
    Released: March 13, 2007
    JOURNALS RESTRICTED ACCESS
    Magnesium tetrakis(4-sulfonatophenyl)porphyrin complex was synthesized and purified. MgTPPS (tetrasodium salt) and MgTPPSC8 (tetraoctylammonium salt) showed unique spectroscopic behaviors in an aqueous buffer and CH3OH respectively, indicating solvent ligation on the Mg ion. In pure CH2Cl2, the MgTPPSC8 formed unique J-type oligomers, in which the sulfonato groups mutually coordinate to the vicinal Mg ion. In binary solvent systems of CH2Cl2 and CH3OH, MgTPPSC8 formed H-aggregates as well as other TPPS derivatives, and aggregation was controlled by changing the ratio of the solvents. The geometrical structure of J-type oligomers was estimated by using the exciton point-dipole coupling theory.
  • Keiko Okimura, Kazuhiro Ohki, Yuki Sato, Kuniharu Ohnishi, Yoshiki Uch ...
    2007 Volume 80 Issue 3 Pages 543-552
    Published: March 15, 2007
    Released: March 13, 2007
    JOURNALS RESTRICTED ACCESS
    The chemical conversions of natural polymyxin B and colistin, which are fatty-acylated cyclic decapeptides, to polymyxin (2–10) and colistin (2–10) derivatives were examined. The Nα-free and side chain Nγ-protected nonapeptides, i.e., tetrakis(Nγ-trifluoroacetyl)–polymyxin B (2–10) and tetrakis(Nγ-trifluoroacetyl)–colistin (2–10), were prepared by trifluoroacetylation of polymyxin B and colistin, followed by chemical cleavage with 50% methanesulfonic acid to remove Nα-alkanoyl–Nγ-trifluoroacetyl–Dab–OH. The Nγ-protected nonapeptides were useful starting materials for the semi-synthesis of N-terminal derivatives by selective Nα-acylation at Thr2, followed by the removal of the Nγ-trifluoroacetyl protecting group with aqueous piperidine. Further, myristoyl–polymyxin B (2–10) and myristoyl–colistin (2–10) retained their antimicrobial activity with an MIC of 2–4 nmol mL−1 against Escherichia coli, Salmonella Typhimurium, and Pseudomonas aeruginosa. They also retained their high lipopolysaccahride (LPS) binding activity. Acetyl–polymyxin B (2–10) and acetyl–colistin (2–10) exhibited very low biological activities, except for a high bactericidal activity specifically against Pseudomonas aeruginosa with an MIC of 2 nmol mL−1. The distinct sensitivity of three Gram-negative bacteria tested toward acetyl-nonapeptides suggested that the N-terminal hydrophobic character of the fatty-acylated polymyxin peptides was necessary for the bactericidal activity against Escherichia coli and Salmonella Typhimurium, but not against Pseudomonas aeruginosa.
  • Saithalavi Anas, Valiyaveetil Sanjayan Sajisha, Rani Rajan, Rajasekara ...
    2007 Volume 80 Issue 3 Pages 553-560
    Published: March 15, 2007
    Released: March 13, 2007
    JOURNALS RESTRICTED ACCESS
    A facile synthesis of the 1,2-orthoesters of carbohydrates in the ionic liquid [bmim]PF6 without a quaternary ammonium salt like tetrabutylammonium iodide, is described. The glycosidation reactions of 4-pentenyl orthoesters (NPOEs) with different alcohols are also discussed. The work described in this paper showed that [bmim]PF6 is an efficient and recyclable solvent for the synthesis and glycosidation reaction of orthoesters.
  • Asuka Ohshima, Masashi Ikegami, Yoshihiro Shinohara, Atsuya Momotake, ...
    2007 Volume 80 Issue 3 Pages 561-566
    Published: March 15, 2007
    Released: March 13, 2007
    JOURNALS RESTRICTED ACCESS
    The photochemistry of 2-(2-hydroxy-3-methoxyphenyl)benzoxazole (3-MHBO) and 2-(2-hydroxy-4-methoxyphenyl)benzoxazole (4-MHBO) have been investigated. The excited-state properties of 4-MHBO were similar to those for the parent compound 2-(2-hydroxyphenyl)benzoxazole (HBO), whereas different properties were observed for 3-MHBO. 4-MHBO in benzene exhibited large Stokes-shifted fluorescence from the keto-form in the excited singlet state (KE*) after excited-state intramolecular proton transfer (ESIPT), whereas 3-MHBO emitted dual fluorescence from E* and KE* species. Fluorescence due to KE* for 3-MHBOmax = 525 nm) occurred at a considerably longer wavelength than that of 4-MHBOmax = 480 nm). The fluorescence efficiency of 3-MHBOf = 0.002) was much smaller than those of 4-MHBO and HBOf = 0.018 and 0.02, respectively). These results are consistent with suppression of ESIPT, stabilization of KE* species, and acceleration of non-radiative decay, probably because of the formation of a hydrogen bond between phenol oxygen and methoxy hydrogen at 3-position in 3-MHBO. Thus, 3-MHBO displayed a meta-substituent effect involving the relaxation pathway of excited state HBO derivatives.
  • Kazuaki Shimada, Akiko Moro-oka, Akiko Maruyama, Hiroyuki Fujisawa, To ...
    2007 Volume 80 Issue 3 Pages 567-577
    Published: March 15, 2007
    Released: March 13, 2007
    JOURNALS RESTRICTED ACCESS
    β-(N,N-Dimethylcarbamoylselenenyl)- and β-(N,N-dimethylcarbamoyltellurenyl)alkenyl ketones were converted into isoselenazoles and isotellurazole Te-oxides, respectively, simply by treating with hydroxylamine-O-sulfonic acid, and deoxygenation of the latter products was successfully carried out by treating with PPh3. Alternative treatment of ynone oxime tosylates with hydrochalcogenide ions or N,N-dimethylchalcogenocarbamate ions also gave the same isochalcogenazole rings. These reactions were assumed to proceed through intramolecular nucleophilic substitution on the nitrogen atom of oxime sulfonates by the attack of in situ generated chalcogen nucleophiles.
  • Tadashi Yokoyama, Noriki Kutsumura, Tadaaki Ohgiya, Shigeru Nishiyama
    2007 Volume 80 Issue 3 Pages 578-582
    Published: March 15, 2007
    Released: March 13, 2007
    JOURNALS RESTRICTED ACCESS
    Conversion of dibromides carrying O-functional groups at adjacent positions to the corresponding propargylic ethers was successfully carried out under the DBU conditions through 2-bromo-1-alkenes as intermediates. The optically active γ-lactone-class natural products, such as (−)-muricatacin (4) and (R,R)-sapinofuranone B (5) were synthesized using the propargylic ether intermediate produced by the elimination reaction mentioned above.
  • Hidetoshi Yamada, Kotaro Okajima, Hiroshi Imagawa, Tatsuya Mukae, Yosh ...
    2007 Volume 80 Issue 3 Pages 583-585
    Published: March 15, 2007
    Released: March 13, 2007
    JOURNALS RESTRICTED ACCESS
    The rings of the (±)-trans-1,2-bis(tert-butyldiphenylsiloxy)-, (triisopropylsiloxy)-, and (tert-butyldimethylsiloxy)cyclohexanes prefer a diaxial chair conformation in the crystal state. The ring of the tert-butyldimethylsiloxy derivative switched its chair conformation between the diaxial and a diequatorial conformations in the crystal and in solution, respectively.
  • Shinko Watanabe, Masashi Ikegami, Ritsuko Nagahata, Tatsuo Arai
    2007 Volume 80 Issue 3 Pages 586-588
    Published: March 15, 2007
    Released: March 13, 2007
    JOURNALS RESTRICTED ACCESS
    Stilbene dendrimers were prepared by coupling 4,4′-dihydroxystilbene with first, second, third, or fouth generation benzyl ether-type dendrons. Despite a short lifetime of the core structure (< 1 ns), all the generations of stilbene dendrimers underwent photoisomerization with the same efficiency as that of 4,4′-dimethoxystilbene.
  • Hiroaki Shitara, Marie Aruga, Emi Odagiri, Kayoko Taniguchi, Mikio Yas ...
    2007 Volume 80 Issue 3 Pages 589-593
    Published: March 15, 2007
    Released: March 13, 2007
    JOURNALS RESTRICTED ACCESS
    Dehydroabietic acid esters were prepared as new chiral dopants for the nematic liquid crystals. The magnitude of the helical twisting power (HTP) was good due to simple but rigid three-ring structure and two axial methyl groups. The relationship between the HTP or MHTP (molar helical twisting power) values and the terminal structures was studied. Considering the synthetic accessibility and their miscibility with liquid crystals, the acid was shown to be a good candidate as the scaffold of chiral dopants for the nematic liquid crystals.
feedback
Top