Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
80 巻 , 9 号
選択された号の論文の25件中1~25を表示しています
Vol. 80 Commemorative Accounts
  • Shinji Fujimori, Thomas F. Knöpfel, Pablo Zarotti, Takashi Ichika ...
    2007 年 80 巻 9 号 p. 1635-1657
    発行日: 2007/09/15
    公開日: 2007/09/13
    ジャーナル フリー
    In this account, new methods for the catalytic and stereoselective conjugate addition of terminal alkynes are described. Our laboratories have disclosed asymmetric addition reactions to aldehydes and imines using a combination of a zinc or copper salt and a terminal alkyne. Under these conditions, terminal alkyne is transformed in situ into an alkynyl metal species. Recently, it was found that these in situ generated alkynyl metal species can undergo conjugate additions to alkylidene malonate-type acceptors. In the zinc(II) triflate-catalyzed system, a highly diastereoselective conjugate addition has been realized using a chiral oxazepene acceptor. Subsequently, alternative conjugate addition protocols have been developed which employ a terminal alkyne, substoichiometric amounts of copper and a highly eletrophilic Meldrum’s acid derived acceptor. This reaction can be made enantioselective using a novel atropisomeric P,N-ligand (PINAP). With this ligand, excellent enantioselectivities can be achieved for the conjugate addition of aromatic alkynes to various Meldrum’s acid derived acceptors.
    In this account, new methods for stereoselective conjugate additions of terminal alkynes catalyzed by copper or zinc are described. We have also developed a novel class of atropisomeric P,N-ligand (PINAP) which exhibited excellent performance in these reactions. Fullsize Image
  • Didier Astruc
    2007 年 80 巻 9 号 p. 1658-1671
    発行日: 2007/09/15
    公開日: 2007/09/13
    ジャーナル フリー
    The 19-electron complexes [FeI5-C5R5)(η6-arene)] (R=H, arene = C6Me6, 1,3,5-tBu3C6H3; R=Me, arene = C6Me6, C6Et5H) are thermally stable and serve as strong single-electron reductant in a variety of stoichiometric and catalytic electron-transfer processes that are detailed in this review (prototype: [FeI5-C5H5)(η6-C6Me6)]). They are electron-reservoirs because their redox potential is very negative and they form a redox system for which both redox forms are stable. In this sense, they are Green redox reagents, since the oxidized form is recovered after use and is even frequently catalytically used. Symmetrically, the 17-electron complex [FeIII5-C5R5)(η6-C6Me6)][SbCl6]2, the strongest organometallic single-electron oxidant with a redox potential 1 V more positive than that of its isoelectronic ferrocenium analog, is a reservoir of electron hole.
    Electron-reservoir systems are defined by redox systems having at least two stable redox forms and a very negative redox potential. They are Green redox systems, because this stability allows to efficiently carrying out stoichiometric and catalytic electron-transfer reactions. Fullsize Image
Award Accounts
The Chemical Society of Japan Award for Young Chemists for 2005
  • Mitsuru Shoji
    2007 年 80 巻 9 号 p. 1672-1690
    発行日: 2007/09/15
    公開日: 2007/09/13
    ジャーナル フリー
    Asymmetric total synthesis of epoxyquinonoid natural products, such as epoxyquinols A, B, and C, epoxytwinol A, and EI-1941-1, -2, and -3, are described. In the first-generation synthesis of epoxyquinols, the HfCl4-mediated diastereoselective Diels–Alder reaction of furan with a chiral acrylate ester was developed. In the second-generation synthesis, a chromatography-free preparation of an iodolactone by using acryloyl chloride as the dienophile in the Diels–Alder reaction of furan, and the lipase-mediated kinetic resolution of a cyclohexenol derivative were developed. This second-generation synthesis is suitable for large-scale preparation. A biomimetic cascade reaction involving oxidation, 6π-electrocyclization, then Diels–Alder dimerization, is the key reaction in the formation of epoxyquinols A–C. Epoxytwinol A was synthesized by the cascade reaction composed of oxidation, 6π-electrocyclization, and formal [4+4] cycloaddition. A 2H-pyran, generated by oxidation/6π-electrocyclization, acts as a good diene, reacting with several dienophiles to afford polycyclic compounds in one step. The asymmetric total synthesis of EI-1941s was accomplished, starting from a chiral epoxy iodoquinone, a key intermediate in the total synthesis of epoxyquinols. They were diastereoselectively synthesized via an intramolecular carboxypalladation in a 6-endo cyclization mode, followed by β-hydride elimination, as the key steps.
    The asymmetric total syntheses of epoxyquinols A, B, and C, epoxytwinol A, and EI-1941-1, -2, and -3, are described. The key reactions are biomimetic oxidative dimerization of the cyclohexenol for epoxyquinols, and carboxypalladation for EI-1941s, respectively. Fullsize Image
Accounts
  • Tamás Kiss, Akira Odani
    2007 年 80 巻 9 号 p. 1691-1702
    発行日: 2007/09/15
    公開日: 2007/09/13
    ジャーナル フリー
    This paper gives insight into chemical speciation. After a brief introduction, the methods available to study solution state of metal ions and the importance of speciation in biology are discussed through different examples. Speciation of toxic AlIII, beneficial CuII and CaII and potentially medicinal PdII and VOIV in various biofluids and tissues is discussed in order to describe the solution state of these metal ions in an organism. The relevance of ternary complex formation with endogenous biomolecules is emphasised. The importance of the biospeciation of AlIII ion in its transport and involvement in neurological disorders, of the actual chemical form of the insulin-mimetic VOIV complexes in its biological occurrence and CaII in mineralization/demineralization processes is discussed. The role of time, i.e., the kinetic aspects of biospeciation, is discussed in the case of the transport of AlIII and CuII and some PdII complexes (models of the anticancer PtII complexes) in blood serum.
    Examples from different fields of bioinorganic chemistry are given to demonstrate the importance of the solution state and solution speciation of metal ions or metal complexes in biology. Fullsize Image
BCSJ Award Article
  • Fiorella Brustolin, Mathieu Surin, Vincent Lemaur, Giuseppe Romanazzi, ...
    2007 年 80 巻 9 号 p. 1703-1715
    発行日: 2007/09/15
    公開日: 2007/09/13
    ジャーナル フリー
    The self-organization behavior of an amphiphilic sexithiophene bearing amide functionalities is studied and compared to that of a derivative bearing an ester group at the same position. The introduction of hydrogen-bond interactions in assemblies of these π-conjugated oligomers is found to affect the molecular organization both in protic media and in thin deposits on mica. The amphiphilic 2,2′;5′,2'';5'',2''';5''',2'''';5'''',2'''''-sexithiophene-5,5'''''-dicarboxylic acid bis[(4,7,10,13,16-pentaoxaheptadecyl)amide] forms assemblies in n-butanol and water and partially aggregates in toluene. Spectroscopy reveals that the presence of a hydrogen-bonding moiety increases the thermal stability of the assemblies in n-butanol and even more in water solution. On mica surfaces, the formation of rod-like one-dimensional nanostructures is observed after deposition from toluene solutions. In addition, transmission electron microscopy in combination with selected area electron diffraction shows that in water plate-like structures are formed built from parallel oriented stacks, with a π–π distance of 3.5 Å. Comparison of these data to molecular modeling and quantum chemistry calculations is used to better understand the influence of the amide group on the stacking of these compounds. The introduction of these H-bonding interactions leads to denser and more stable stacks. Furthermore, we show that a derivative of the amide compound, bearing terminal ammonium groups, forms a complex with chiral polyanions in aqueous media such that the sexithiophene segments are stacked in a meta-stable helical fashion with preferred handedness. We observed that poly(glutamate) and DNA generate a chiral sexithiophene assembly. In time the induced chirality disappears, which is explained by the meta-stability of the kinetically formed adduct. This constitutes one step forward towards the controlled formation of functional multi-component systems in aqueous solution.
    The self-organization of amphiphilic sexithiophenes bearing amide functionalities is studied and compared to that of the ester group counterparts. A derivative of the amide compound, bearing terminal ammonium groups, forms a complex with chiral polyanions in aqueous media such that the sexithiophene segments stack in a meta-stable helical fashion. Polyglutamate and DNA are able to generate these chiral assemblies. Fullsize Image
 
  • Koji Yamada, Hiromitsu Terao, Kazuko Sumimura, Masao Hashimoto, Hirosh ...
    2007 年 80 巻 9 号 p. 1716-1722
    発行日: 2007/09/15
    公開日: 2007/09/13
    ジャーナル 認証あり
    The temperature dependence of 2H NMR spectra and 81Br and 127I NQR frequencies was investigated for the deuterated compounds of [C(NH2)3]HgBr3 and [C(NH2)3]HgI3 between 77 and ca. 400 K. Due to deuteration, the phase-transition temperatures of the iodine compound were increased by 2 and 6 K for the second-order (251 K) and the first-order (210 K) phase transitions, respectively. Distinctive 127I NQR frequency-shifts of more than 200 kHz were observed in the intermediate phase of the iodine compound on deuteration. The temperature dependences of the 2H NMR spectra for [C(ND2)3]HgBr3 and [C(ND2)3]HgI3 could be explained by invoking C3 reorientation of the guanidinium cation. The activation energies for the reorientation evaluated from 2H NMR were consistent with the former 1H NMR T1 results with the exception of the low-temperature phase of the iodine compound. The quite low activation energy from 2H NMR spectrum for this phase may indicate that the quenching of the orientation disordering of the cations is responsible for the fade-out phenomenon in the 127I NQR resonance lines below ca. 100 K.
  • Osamu Tsukamoto, Masumi Villeneuve, Akira Sakamoto, Hiroo Nakahara
    2007 年 80 巻 9 号 p. 1723-1730
    発行日: 2007/09/15
    公開日: 2007/09/13
    ジャーナル 認証あり
    Differrent adsorption behaviors and the orientation of pyranine molecules were investigated for the cationic Langmuir monolayers by using Brewster angle microscopy (BAM), two-dimensional (2D) phase behavior with elasticitic property of the monolayers and in situ visible spectroscopy. The structural change in the cationic Langmuir–Blodgett (LB) films before and after adsorbing pyranine molecules was found by using small angle and in-plane XRD. The excited-state proton-transfer (ESPT) between octadecylamine (ODA) and pyranine adsorbed in the films was investigated using time-resolved fluorescence spectroscopy together with consideration of the film structures.
  • Mika Ito, Hiroaki Tokiwa
    2007 年 80 巻 9 号 p. 1731-1739
    発行日: 2007/09/15
    公開日: 2007/09/13
    ジャーナル 認証あり
    The stability and reactivity of the 1-aminocyclopropane-1-carboxylic acid (ACC) amine radical cation, which is a key intermediate of ethylene biosynthesis in plants, were examined by quantum chemical calculations. The local interactions to stabilize radical species were treated with a hydrated cluster. Potential energy curves were obtained for two types of reactions from ACC amine radical cation: (1) direct ring opening of ACC amine radical cation, followed by proton abstraction from the amino group, and (2) proton abstraction from the amino group, followed by ring opening of ACC aminyl radical. A remarkable difference was found in the ring-opening processes of reactions (1) and (2). Rate constants (k) of 6.10×1012 and 8.89×109 s−1 at 298.15 K were estimated for the ring openings of ACC amine radical cation and ACC aminyl radical, respectively, at the B3LYP/6-31+G(d,p) level, and were in agreement with experimental results. The ring opening of ACC amine radical cation was 103-fold faster than that of ACC aminyl radical with almost no barrier height. It was thus quantitatively demonstrated that reaction (1) was more favorable than reaction (2) for ethylene synthesis.
  • Qiqige Wulan, Fusao Kitamura
    2007 年 80 巻 9 号 p. 1740-1745
    発行日: 2007/09/15
    公開日: 2007/09/13
    ジャーナル 認証あり
    The reaction between CO2 and electrochemically reduced bis(phthalocyaninato)neodymate(III) complex in a dimethylformamide solution was investigated by cyclic voltammetry and in situ visible spectroscopy. The introduction of gaseous CO2 into the phthalocyanine solution caused a considerable increase in the first reduction peak current of the complex and a shift in the second reduction peak to more positive potentials. In addition, new anodic current peaks appeared in the reverse sweep at potentials different from those of the complex. These observations were explained in terms of the formation of a CO2-adduct. The formation and decomposition of the CO2-adducts occurred reversibly with the applied potential, which was confirmed by in situ visible spectroscopy.
  • Yasuo Kameda, Motoya Sasaki, Yuko Amo, Takeshi Usuki
    2007 年 80 巻 9 号 p. 1746-1749
    発行日: 2007/09/15
    公開日: 2007/09/13
    ジャーナル 認証あり
    Neutron diffraction measurements were carried out on 14N/15N isotopically substituted aqueous 5 mol % sodium L-hydrogenglutamate solutions in D2O in order to obtain direct information concerning the structure of the first hydration shell around the amino-group of the L-hydrogenglutamate ion. Hydration parameters were determined through the least-squares fitting analysis of the observed intermolecular difference function, ΔNinter(Q). It was shown that, on average, 3.1(1) D2O molecules were hydrogen-bonded to the amino-hydrogen atoms of the hydrogenglutamate ion with interatomic distances of rNOW=2.92(2) and rNDW=3.47(1) Å, respectively.
  • Masashi Hatanaka, Ryuichi Shiba
    2007 年 80 巻 9 号 p. 1750-1757
    発行日: 2007/09/15
    公開日: 2007/09/13
    ジャーナル 認証あり
    Through-space interactions in non-Kekulé biradicals were analyzed. We defined PNBMOi,j as a product of i-th and j-th NBMO of non-Kekulé biradicals. Whereas through-space interactions between non-nearest-neighbor carbon atomic sites in PNBMOi,j were negligible in so-called disjoint-type biradicals, antibonding-through-space interactions between second-nearest-neighbor carbon atomic sites in PNBMOi,j destabilized the singlet states in so-called nondisjoint-type biradicals. The instabilities in the singlet states contributed to the triplet state preference for nondisjoint-type biradicals.
  • Keisuke Watanabe, Masaharu Oguni
    2007 年 80 巻 9 号 p. 1758-1763
    発行日: 2007/09/15
    公開日: 2007/09/13
    ジャーナル 認証あり
    The behavior of the water accommodated between the silicate layers of a clay Na8[Si32O64(OH)8]·32H2O was investigated by using adiabatic calorimetry. A phase transition was observed showing a heat-capacity peak at 194 K and its entropy was roughly estimated to be 5.2 J K−1 (H2O-mol)−1. The transition was interpreted to be essentially due to an order–disorder process involving two orientations of the water molecule which can form hydrogen bonds with siloxane-oxygen atoms. It is thought that the water molecules move with a large amplitude of vibration as well as disorder between the two permissible orientations at room temperature and become gradually ordered to take a more stable orientation of the two below 194 K. A glass transition was found at a temperature Tg=106 K, due to freezing of the water molecule in the orientations, which causes a little disorder to remain. The potential barrier (Δεa) of the reorientation was assessed from the Tg to be about 34 kJ mol−1, which corresponds to the energy to break two hydrogen-bonds. There remains a possibility that the silanol-hydrogen atom takes a tunneling state involving two accessible sites between two silanol-oxygen atoms; however, it was not confirmed in this work.
  • Yoshiro Yasaka, Masahito Kubo, Nobuyuki Matubayasi, Masaru Nakahara
    2007 年 80 巻 9 号 p. 1764-1769
    発行日: 2007/09/15
    公開日: 2007/09/13
    ジャーナル 認証あり
    High-sensitivity Raman vibrational spectroscopic equipment was developed to study the hydrogen-bonding structure in supercritical fluids over a wide density range. Supercritical water was investigated to the very dilute region of 0.1 MPa (3×10−4 g cm−3) at 400 °C, and the spectroscopic profile at the isolated state was observed. For comparison, supercritical methanol was also investigated, and the effect of the alkyl group on the hydrogen bonding is elucidated. For both water and methanol, the OH stretching peak shifted toward a lower frequency with an increase in the density as a result of hydrogen-bond formation. The red shift relative to the isolated value was not always proportional to the density. In the case of water at 400 °C, the shift was nonlinear over a wide density range; it was almost linearly dependent on the density between 0.6 and 0.2 g cm−3, whereas at lower densities, the dependence became steeper. For methanol, a nonlinear density dependence was similarly observed at a corresponding reduced temperature. The density dependence then became more linear at higher temperatures. The density dependence of the spectroscopic profile is interpreted in terms of the matrix of force constants affected by the formation of hydrogen bonding.
  • José R. B. Gomes, Mónica A. A. Vieira, Dawn M. Stovall, ...
    2007 年 80 巻 9 号 p. 1770-1775
    発行日: 2007/09/15
    公開日: 2007/09/13
    ジャーナル 認証あり
    The standard molar enthalpy of formation at T=298.15 K of 6-chloro-2,3-dimethylquinoxaline 1,4-dioxide in the gas-phase was derived using the values of the enthalpies of combustion for the crystalline solid, measured by using rotating-bomb combustion calorimetry, and of the enthalpies of sublimation, measured by using Calvet microcalorimetry. This value was used for calibrating the computational procedure employed to estimate the gas-phase enthalpies of formation for the deoxygenated quinoxaline derivatives and also to compute the first, second, and mean (N–O) bond dissociation enthalpies in the gas-phase. The B3LYP/6-311+G(2d,2p) calculations were also extended to the fluorine, bromine, and iodine derivatives and to the isomers with a halogen substituted at position 5. When the halogen atom enters the same position in the quinoxaline ring, it was found that the substituent had almost no influence on the computed (N–O) bond dissociation enthalpies, except for 5-fluoro-2,3-dimethylquinoxaline 1,4-dioxide.
  • Satoshi Takara, Andrei S. Batsanov, Douglas J. Schaffer, Michael Takas ...
    2007 年 80 巻 9 号 p. 1776-1779
    発行日: 2007/09/15
    公開日: 2007/09/13
    ジャーナル 認証あり
    Solid-state structures of trans-[RuCl2{Cl2PN(Me)N(Me)PCl2}2] (1), cis-[PdCl2{Cl2PN(Me)N(Me)PCl2}] (2), and cis-[PtCl2{Cl2PN(Me)N(Me)PCl2}] (3) were studied by using 13C CPMAS NMR spectroscopy and X-ray crystallography. The ruthenium atom in 1 was on a crystallographic inversion center and had a slightly distorted octahedral coordination. 2 and 3 contained palladium and platinum atoms in a square-planar geometry, respectively. In 2, axial sites of the Pd atom were filled by intermolecular Pd···Cl contacts to form an infinite chain. Molecules of 3 pack in an edge-to-face manner and no obvious “axial” contacts at the Pt atom were observed. Different geometries of hydrazide nitrogens in 1, 2, and 3 were observed: in 1 and 2, one of the nitrogen atoms was trigonal planar and the other one was pyramidal; the two hydrazine nitrogen atoms in 3 had trigonal planar geometry. 13C CPMAS NMR spectra are consistent with X-ray data. The P–N distances are shorter than normally accepted P–N single bond lengths, suggesting a degree of P–N π bonding.
  • Kazuhiro Kobayashi, Daizo Nakamura, Kazuna Miyamoto, Osamu Morikawa, H ...
    2007 年 80 巻 9 号 p. 1780-1784
    発行日: 2007/09/15
    公開日: 2007/09/13
    ジャーナル 認証あり
    A new and convenient method for the preparation of 3-substituted benzo[b]thiophenes was developed. α-Substituted 2-(1-phenylethylthio)styrenes, which could easily be prepared from 2-mercaptophenyl ketones or benzenethiols in two or three steps, respectively, underwent 5-endo cyclization on treatment with iodine in the presence of sodium hydrogencarbonate in acetonitrile at room temperature to give 3-substituted benzo[b]thiophenes in fair to good yields.
  • Kentaro Okuma, Koichiro Yoshitake, Toshiharu Izaki, Keiko Yoshida, Kos ...
    2007 年 80 巻 9 号 p. 1785-1790
    発行日: 2007/09/15
    公開日: 2007/09/13
    ジャーナル 認証あり
    1-Arylethyltriphenylphosphonium bromides thermally rearranged to 2-arylethyltriphenylphosphonium bromides. Direct formation of 2-arylethylphosphonium bromides was achieved by reacting styrene, HBr, and triphenylphosphine. On the other hand, thermolysis of 1-indanyltriphenylphosphonium bromide gave indene and triphenylphosphonium bromide. From deuterium and 13C-labeled experiments, the interconversion of primary and secondary cation intermediates was suggested. No neighboring phenyl group (phenonium cation intermediate) interaction was observed.
  • Shigeru Sasaki, Kiyotoshi Kato, Masaaki Yoshifuji
    2007 年 80 巻 9 号 p. 1791-1798
    発行日: 2007/09/15
    公開日: 2007/09/13
    ジャーナル 認証あり
    電子付録
    Crowded triarylphosphines carrying a nitroxide radical were synthesized to investigate intramolecular interaction between the crowded triarylphosphine redox centers and a neutral radical. A crowded triarylphosphine carrying a bromoaryl group was developed as a key synthetic intermediate. Lithiation of the (bromoaryl)phosphine, followed by reaction with 2-methyl-2-nitrosopropane, afforded a crowded triarylphosphine carrying a nitroxide after aerobic oxidation. Similar procedure using isoamyl nitrite (isoamyl = 3-methylbutyl) gave nitroxide and azobenzene derivatives with two crowded triarylphosphine moieties. The azobenzene derivative was alternatively prepared by photolysis of the corresponding (azidoaryl)phosphine. EPR spectra of the nitroxide radicals showed hyperfine couplings with 31P nuclei, which were larger than previously reported phosphinoaryl nitroxide radicals. Cyclic voltammograms of the newly synthesized triarylphosphines showed reversible redox waves corresponding to the phosphorus redox centers. The two triarylphosphine moieties connected by a nitroxide linkage showed a reversible two-step oxidation reflecting considerable interaction between the phosphorus redox sites across the nitroxide linkage. Oxidation of the crowded triarylphosphines carrying a nitroxide and photolysis of the chemically oxidized (azidoaryl)phosphine was studied by EPR spectroscopy.
  • Tomoyuki Kurata, Takashi Mohri, Kazuo Takimiya, Tetsuo Otsubo
    2007 年 80 巻 9 号 p. 1799-1807
    発行日: 2007/09/15
    公開日: 2007/09/13
    ジャーナル 認証あり
    Conductive, magnetic, and optical properties of sterically hindered dodecithiophenes bearing bulky 2,2-bis(butoxymethyl)-1,3-propanediyl groups were examined. At high doping with FeCl3, a completely hindered dodecithiophene had only a poor conductivity of 5×10−4 S cm−1, but two partially hindered dodecithiophenes had relatively high conductivities of 1.9 and 0.6 S cm−1, which are one or two orders lower than the conductivity (38 S cm−1) of the unhindered dodecithiophene. Despite having different structures and conductivities, all of the doped solids of these dodecithiophenes were magnetically inactive and demonstrated similar optical absorption spectra in the near infrared region, as generally observed for polythiophenes. On the other hand, their optical spectra in dichloromethane were quite different from one another. A solution spectrum of the unhindered dodecithiophene under high doping was characterized by two absorption transitions assignable to a π-dimer. On the other hand, a solution spectrum of the completely hindered dodecithiophene was characterized by an absorption transition due to a bipolaron. Furthermore, the solution spectra of two partially hindered dodecithiophenes could be explained as an overlap of both π-dimeric and bipolaronic bands. From these results, both π-dimer and bipolaron species appear to serve as active charge carriers in conductive poly(oligo)thiophenes.
  • Ryosuke Kamitani, Kenichi Niikura, Tomohiro Onodera, Norimasa Iwasaki, ...
    2007 年 80 巻 9 号 p. 1808-1813
    発行日: 2007/09/15
    公開日: 2007/09/13
    ジャーナル 認証あり
    電子付録
    We describe a graft-type modification of a solid surface to be able to immobilize unprotected carbohydrates with a desired pattern. Water soluble carbohydrate-trapping polymers were grown from a solid surface through surface-initiated polymerization. The polymerization of an N-tert-butonyloxycarbonyl (N-Boc)-protected aminooxy monomer 3 was carried out from the immobilized initiator on silicon or glass surfaces. The N-Boc protecting group was then removed in an acidic solution to generate an aminooxy group, which reacts with free carbohydrates through oxime bonds on immersion of the plate in a carbohydrate solution. Sugar attachment on the surface polymer was confirmed by using infrared reflection absorption spectroscopy (IR-RAS) and fluorescent images after sugar-specific binding of fluorescein-labeled lectin proteins. The polymer was also grafted in a desired pattern by partial UV-irradiation over a photomask, giving a new material to create carbohydrates arrays.
  • Takamitsu Shimamoto, Motoharu Chimori, Hiroaki Sogawa, Yuki Harada, Ma ...
    2007 年 80 巻 9 号 p. 1814-1823
    発行日: 2007/09/15
    公開日: 2007/09/13
    ジャーナル 認証あり
    電子付録
    A new hydrosilylative cross-coupling reaction of a variety of alkynes with several alkenes, which is catalyzed by a cationic palladium complex A (1 mol %) without or with added PPh3 ligand, was studied systematically. The reaction using HSiCl3 as an addend afforded more or less two types of products consisting of four possible derivatives, R1CH=CR2–CHR3–CHR4–SiCl3, which always contained 4-trichlorosilyl-1-butene frameworks, in acceptable combined yields. The coupling pattern was dependent both on the precatalyst A in the absence or presence of PPh3 [also P(C6F5)3] and on the combination of the alkyne and alkene counterpart employed. A possible catalytic cycle that involves an initial hydropalladation of an alkyne, followed by a facile and specific carbopalladation of an alkene, is proposed. At the same time, the lack of regioselectivity in the latter step is noted. The effect of the added phosphine ligand on the coupling pattern is briefly discussed.
  • Kentaro Okuma, Takumi Yasuda, Kosei Shioji, Yoshinobu Yokomori
    2007 年 80 巻 9 号 p. 1824-1827
    発行日: 2007/09/15
    公開日: 2007/09/13
    ジャーナル 認証あり
    2-Arylquinolines 1 were obtained in good yields by reacting iodine or NIS with 2-aminochalcones 2, which were easily synthesized by the Claisen–Schmidt reaction from 2-nitrobenzaldehyde and acetophenones. The reaction of iodine with 2-isopropenylacetanilide (3a), followed by the addition of aq. NaHCO3, afforded 4-iodomethyl-2,4-dimethyl-4H-3,1-benzoxazine (6a), of which the structure has previously been reported to be 1-acetyl-2-iodomethyl-2-methyl-1,2-dihydrobenzazete (4a) or 1-acetyl-3-iodo-3-methylindoline (5a). The reaction mechanism is discussed.
  • Pengyu Wang, Hiroyuki Kojima, Kazuya Kobiro, Koichi Nakahara, Toshihik ...
    2007 年 80 巻 9 号 p. 1828-1832
    発行日: 2007/09/15
    公開日: 2007/09/13
    ジャーナル 認証あり
    Benzhydrol and benzoin, which have two benzene subunits, a secondary hydroxy group, and no hydrogen atom on the β-position of the hydroxy group, were treated in supercritical water in the absence of an oxidizing agent or a catalyst. Water played a key role in the product distributions in these reactions. Each reaction proceeded smoothly to give larger amounts of oxidation products, benzophenone (3) and benzil (6), as well as smaller amounts of reduction products, diphenylmethane (4) and benzyl phenyl ketone (7), respectively, in the presence of water, while the ratios of 3:4 and 6:7 were almost 1:1 in both cases in the absence of water. The best yield of benzophenone (63%) was achieved by the reaction of benzhydrol at 460 °C for 180 min in 0.35 g mL−1 water density in the SUS 316 reactor. Hydrogen gas evolution was observed in the reaction of benzhydrol in a quartz tubular reactor.
  • Masashi Ikegami, Masato Nagao, Hiroyuki Katayama, Fumiyuki Ozawa, Tats ...
    2007 年 80 巻 9 号 p. 1833-1835
    発行日: 2007/09/15
    公開日: 2007/09/13
    ジャーナル 認証あり
    電子付録
    Photoisomerization mechanism of para-substituted oligo(phenylenevinylene)s (OPVs) was dependent on the number of olefin units. While mono-olefin OPV1 underwent two-way photoisomerization, other OPVs (OPV2, OPV3, and OPV4) underwent photochemical one-way Z-to-E isomerization. As the number of olefin units increased, contribution of the triplet excited state to the Z-to-E isomerization becomes larger.
  • Masafumi Yoshio, Takahiro Ichikawa, Harutoki Shimura, Takayoshi Kagata ...
    2007 年 80 巻 9 号 p. 1836-1841
    発行日: 2007/09/15
    公開日: 2007/09/13
    ジャーナル フリー
    電子付録
    Two series of 1-methyl-3-[3,4,5-tris(alkyloxy)benzyl]imidazolium salts (1(n/X); n=8, 12, 16, and 18) and 1,2-dimethyl-3-[3,4,5-tris(dodecyloxy)benzyl]imidazolium salts (2(12/X)) containing anions (X), such as tetrafluoroborate, hexafluorophosphate, trifluoromethylsulfonate, and bis(trifluoromethylsulfonyl)imide, have been synthesized. The thermal properties of these salts were characterized by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction. The salts form hexagonal columnar liquid-crystalline phases except for 1(8/X) and 1(12/X) containing CF3SO3 and (CF3SO2)2N, and 2(12/(CF3SO2)2N) which melt directly to isotropic ionic liquids. The clearing points show a decreasing trend with an increase in the size of anions. The ionic conductivities of 1(16/X) forming columnar phases have been measured by using an alternating current impedance method. The conductivities depend on the nature of anions, suggesting that the predominant conduction mechanism is hopping and/or diffusion of anions in the columnar structures.
feedback
Top