Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 71 , Issue 7
Showing 1-30 articles out of 30 articles from the selected issue
  • Fumio Hirata
    1998 Volume 71 Issue 7 Pages 1483-1499
    Published: 1998
    Released: June 05, 2006
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    A variety of chemical processes in solution is explored theoretically by means of the extended RISM equation, an integral equation theory of molecular liquids. The chemical processes include the classical problem of ion hydration, solvent induced electronic structure change and chemical reactivity in solution, protein folding, and dynamics of solvent as well as solvated ions. A special emphasis is laid on the ability of the theory to account for chemical specificities of molecules, which is crucial for any chemical processes in solution.
  • Hideo Tomioka
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 7 Pages 1501-1524
    Published: 1998
    Released: June 05, 2006
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    A series of phenyldiazomethanes and phenyl azides bearing proximate substituents matrix-isolated in Ar at cryogenic temperatures have been photolyzed. Products are characterized mainly by IR spectroscopy in combination with ab initio theoretical calculations. In most cases, several intermediates are produced as a result of interaction between the divalent centers and the proximate functional group; they are photo-interconvertible under these conditions.
    Phenylcarbenes and phenylnitrenes having hydrogen donors such as CH3, OH, and NH2 groups at the ortho position have been shown to abstract hydrogen to form o-quinonoid compounds. Both the carbene and nitrene undergo oxygen transfer from the nitro group at the ortho position to form the corresponding nitroso compounds. While phenylcarbene interacts with o-CO2Me group to generate the corresponding carbonyl ylide, phenylnitrene undergoes 1,4-MeO shift in its excited states to produce 5-carbonyl-6-methoxyimino-1,3-cyclohexadiene. Interesting differences in the reactivity between carbenes and nitrenes are noted; these are discussed in terms of the electronic configuration, singlet-triplet energy gap and tunneling.
    1,3-Bis(diazo) ketones incorporated in five- and seven-membered rings are prepared and photolyzed under matrix conditions. While the seven-membered ring bis(diazo)ketone affords phenanthryne by way of 9,10-cyclopropa-phenanthren-3′-one, the five-membered analogue generates 1,2-cyclopropabenzocyclobutadien-3′-one, which does not undergo photodecarbonylation to form benzocyclobutenyne.
    Finally, a series of bis(divalent) species conjugatively connected through aromatic rings are generated and characterized. In both p- and o-phenylene systems, there is a significant interaction between the benzene nucleus and the divalent substituents. The species are best regarded as p- and o-quinonoidal biradical structures, respectively, having a singlet ground state with a low-lying excited triplet state.
  • Take-aki Mitsudo
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 7 Pages 1525-1538
    Published: 1998
    Released: June 05, 2006
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    The chemistry of η3-vinylcarbene transition-metal complexes is reviewed. The η3-vinylcarbene complexes are prepared by 1) the alkylation of (η3-acryloyl)tricarbonylferrate, 2) the treatment of cyclopropenes with [Fe2(CO)9], 3) the insertion of acetylenes into a carbene–metal double bond, 4) the reaction of acetylene with [ReCl3(Me5C5)]2, 5) the reaction of carbyne complexes with allyl bromides, and 6) the thermal decarbonylation of (η1-vinylcarbene)pentacarbonylchromium. The structures of the complexes, which were determined by X-ray analyses, are represented by the hybrid of the resonance structures (A) and (B). The contribution of the two structures was very sensitive to the respective MLn fragments. The vinylcarbene complex, [Fe(η3-vinylcarbene)(CO)3] (1), is a parent complex of a series of various complexes. The carbene carbons of the reported Fischer-type η3-vinylcarbene complexes are electrophilic. Carbonylation of the η3-vinylcarbene complexes gives η4-vinylketene complexes. Treatment of the η3-vinylcarbene(carbonyl)irons with an excess of tertiary phosphines or bidentate amines gives ferracyclopentenones. Reaction of 1 with isocyanides gives the first example of the η4-vinylketenimine complex. Treatment of 1 with diazomethane gives (η4-1,3-butadiene)tricarbonyliron. The complex 1 with a methoxycarbonyl group on the 3-position reacts with carbon monoxide to give a η4-pyrone complex, which thermally rearranges to its isomer. The rearrangement was deduced to proceed via a η4-methoxyfuran complex. The complex 1 reacts with hydride to give a η3-allyl complex. Reaction of (η3-2-trifluoromethylvinylcarbene)tricarbonyliron with K[BH(s-Bu)3] or phenyllithium gives (η4-difluorotrimethylenemethane)tricarbonyliron, leaving a fluoride ion. η3-Vinylcarbene complexes react with acetylenes to give η4-cyclopentadiene metal complexes. The reaction proceeds via a metallacyclohexadiene. The complex 1 reacts with an unsaturated metal complex M2Ln to give a binuclear vinylcarbene complex or (η3 : η1-allyl)(FeM2). Reaction of 1 with Ru(CO)3(COD) provides a method for selective preparation of (η3 : η1-allyl)(FeRu), which reacts with acetylenes to give [Fe(η4-ruthenacyclohexadiene)(CO)3]. Formation of a η3-vinylcarbene complex by the reaction of a carbene complex with acetylene, and subsequent carbonylation of this complex, is the essential pathway of the Dötz reaction.
  • Mandeep Singh Bakshi, Pooja Kohli, Gurinder Kaur
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 7 Pages 1539-1542
    Published: 1998
    Released: June 05, 2006
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    The conductances of sodium decyl sulfate (SDeS), sodium dodecyl sulfate (SDS), dodecyltrimethylammonium bromide (DTAB), and trimethyltetradecylammonium bromide (TTAB) have been determined in 18-crown-6 ether + water (CR + W), β-cyclodextrin + W (CYC + W), and in CR + CYC + W mixtures with fixed 0.0151 mol dm−3 of CR and varying the amount of CYC with the overall change in the mole–fraction range of CYC from 0.0 to 0.5 in a CR + CYC + W mixture at 30 °C. From the conductivity data, the critical micellar concentration (cmc), degree of counter ion dissociation (β), free energy of transfer of the surfactant hydrocarbon chain from medium to the micelle (), and free energy of transfer of surface contributions () of SDS, SDeS, DTAB, and TTAB have been computed. It has been found that the micelles of anionic surfactants are stabilized in a CR + W mixture in comparison to that in pure water, whereas micelles of cationic surfactants remain more or less unaffected. Micelles of all of the above surfactants are denatured as the amount of CYC is increased in the CR + CYC + W mixture. The effect of denaturisation is stronger on the micelles of SDS and TTAB in comparison to that of SDeS and DTAB, respectively.
  • Shafiqul D.-M. Islam, Yuko Yoshikawa, Mamoru Fujitsuka, Akira Watanabe ...
    1998 Volume 71 Issue 7 Pages 1543-1548
    Published: 1998
    Released: June 05, 2006
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    The rate constants for quenching of the triplet states of eosin and erythrosin (3D*) with various substrates have been evaluated using nanosecond laser flash photolysis while observing the transient absorption bands in the visible/near-IR regions. Intense transient absorption bands due to 3D* were observed at about 1040 nm. An energy-transfer reaction from 3D* to anthracene-9-carboxylic acid was confirmed by the appearance of the absorption band of the triplet state of the acid at 425 nm. The ion radicals of electron donors and electron acceptors were also observed with the decay of 3D*, indicating the occurrence of an electron-transfer reaction. High hydrogen-abstraction abilities of 3D* were also confirmed for substituted phenols and benzenethiols. The negative slopes of the Hammett plots indicate that the reaction center of 3D* has a highly electrophilic nature.
  • Sanyo Hamai
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 7 Pages 1549-1554
    Published: 1998
    Released: June 05, 2006
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    In aqueous solutions, 6-deoxy-6-iodo-β-cyclodextrin (β-CDI) forms a 1 : 1 inclusion complex with naphthalene. The naphthalene fluorescence is quenched upon the formation of the inclusion complex with β-CDI. The room-temperature phosphorescence of naphthalene has been observed from aqueous naphthalene solutions containing both D-glucose and β-CDI. Although the room-temperature phosphorescence has also been observed from aqueous naphthalene solutions containing both D-glucose (5.0 g/5.0 mL) and β-cyclodextrin (1.0 × 10−2 mol dm−3), its intensity amounts to at most 9% of that containing D-glucose (5.0 g/5.0 mL) and β-CDI (1.0 × 10−3mol dm−3). In addition to the high viscosities of D-glucose solutions, the external heavy atom effects of β-CDI cause the appearance of the room-temperature phosphorescence. The room-temperature phosphorescence quantum yield of naphthalene in D-glucose (5.0 g/5.0 mL) solution containing β-CDI (1.0 × 10−3 mol dm−3) has been estimated to be 2.2 × 10−3, which is around 1.8% of the intrinsic phosphorescence quantum yield of naphthalene in ethanol at 77 K.
  • Yuichi Masuda, Junko Tobita, Akiko Muramoto
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 7 Pages 1555-1563
    Published: 1998
    Released: June 05, 2006
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    The 13C NMR spin-lattice and spin–spin relaxation times (T1 and T2), and the nuclear Overhauser effect (NOE) were measured for tetraalkylammonium ions (R4N+, R = C2H5 (Et), n-C3H7 (n-Pr), n-C4H9 (n-Bu), and n-C5H11 (n-Pen)) in the concentrated aqueous solutions of their bromides or chlorides. A minimum was observed in the temperature dependence of T1 for the α-carbon in each solution. The value was 1.2—1.4 times higher than that predicted assuming only the isotropic overall rotation of the R4N+ ion. This increase in the T1 minimum values was ascribed to the rotations around the N–α-C bonds with an restriction in the azimuthal angle for each bond. The ranges where the N–α-C bonds could rotate with the time scales much less than those for the overall rotations were determined by the values of the T1 minima for the corresponding R4N+ ions as ±20°, ±17°, ±20°, and ±20° centering the gauche conformations, respectively, for Et4N+, n-Pr4N+, n-Bu4N+, and n-Pen4N+. These values well reproduced the T2 and NOE values observed at various temperatures in the concentrated aqueous solutions of the R4N+ halides. By using the thus obtained ranges of the azimuthal angles, the overall rotational correlation times in the dilute aqueous solutions (0.01 mol kg−1) were also determined. The obtained rotational correlation times were compared with those calculated using the Stokes–Einstein–Debye equation and the effect of the hydrophobic hydration was discussed.
  • Yoshihiro Yokoyama, Yuji Ohashi
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 7 Pages 1565-1571
    Published: 1998
    Released: June 05, 2006
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    The crystal structures of 1-methoxy-2-(methylthio)ethane (MMTE) and 1,2-bis(methylthio)ethane (BMTE), which are liquid materials at room temperature, have been analyzed by X-rays at 143 and 243 K, respectively. The crystal of MMTE belongs to the monoclinic system and the space group is P21/n. The cell dimensions are; a = 8.416(1), b = 7.817(2), c = 10.181(2) Å, β = 113.79(1)°, and V = 612.8(2) Å3. The MMTE molecule has a TTG conformer, which is different from the most stable one derived from the ab initio molecular orbital calculation on the MP2/6-31G* basis set. The crystal of BMTE belongs to the monoclinic system and the space group is P21/c. The cell dimensions are; a = 6.549(1), b = 5.835(1), c = 8.728(1) Å, β = 97.330(9)°, and V = 330.7(1) Å3. The BMTE molecule lies on an inversion center and has a GTG′ conformer, which is consistent with the most stable one derived from the ab initio calculation. The relative stability of these crystal structures and the possibility of crystal structures with the other conformers were examined by the molecular mechanics calculation. Trials to make a mixed crystal with MMTE and BMTE were in vain.
  • Toshio Oguchi, Sontaya Limmatvapirat, Chikako Takahashi, Srisagul Sung ...
    1998 Volume 71 Issue 7 Pages 1573-1579
    Published: 1998
    Released: June 05, 2006
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    Deoxycholic acid (DCA) was ground with a guest compound by using a vibrational mill. Powder X-ray diffraction, differential scanning calorimetry, and fluorescence spectroscopic data indicated the formation of the inclusion complex in the ground mixture of DCA–phenanthrene and DCA–naphthalene systems. The DCA–naphthalene ground mixture was found to have higher crystallinity than the DCA–phenanthrene ground mixture, and this was assumed to relate to the difference in the crystallization temperature of the inclusion complex. When low-temperature grinding was performed for DCA and other aromatic hydrocarbons along with naphthalene and phenanthrene, all the ground mixtures were obtained in amorphous state. Crystallization of inclusion compounds from the amorphous ground mixtures was observed to occur at a higher temperature as the stoichiometric ratio (DCA/guest) of the compound increased. With regard to the formation of crystalline complex between DCA and a guest, such as naphthalene, by grinding at room temperature, a two-step mechanism was proposed: i.e., (i) amorphization of both DCA and guest crystals, and (ii) crystallization of the inclusion complex induced above a certain temperature.
  • Shinji Tsuboi, Toshihiro Sawai, Hiroshi Ohoyama, Toshio Kasai
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 7 Pages 1581-1585
    Published: 1998
    Released: June 05, 2006
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    The chemiluminescence spectrum of product OH(A2Σ) in a crossed beam reaction of the hot H atom with N2O was observed for the first time. The nascent internal-state distribution of OH(A2Σ) was identified by spectral simulation. The rotational distribution was found to be characterized by a Boltzmann temperature of 750 ± 100 K, and the vibrational distribution is non-Boltzmann with the populations of v = 0, 1, and 2 being 1 : 0.75 : 0.15, respectively. These results indicate that the product rotation is poorly excited while vibration is highly excited to the contrary.
  • Shinsaku Fujita
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 7 Pages 1587-1596
    Published: 1998
    Released: June 05, 2006
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    Q-Conjugacy character tables for cyclic groups are obtained by starting from character tables. Thus, irreducible representations for a cyclic group are classified into primitive and non-primitive ones. They are collected to form a matrix corresponding to each subgroup. Such a matrix is shown to be a representation (called Q-conjugacy representation) for characterizing Q-conjugacy and dominant classes. The traces of the Q-conjugacy representation are collected to form a Q-conjugacy character table, which is shown to be a square matrix. The elements of such a Q-conjugacy character table for a cyclic group are shown to be integers, which are related to the values of the corresponding character tables. They are also correlated to the markaracter tables for the cyclic group. Characteristic monomial tables for cyclic groups are obtained by starting from the Q-conjugacy character tables and dominant unit-subduced-cycle-index tables. They are applied to combinatorial enumeration of isomers derived from a skeleton belonging to a cyclic group.
  • Nobuhiko Iki, Naoya Morohashi, Fumitaka Narumi, Sotaro Miyano
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 7 Pages 1597-1603
    Published: 1998
    Released: June 05, 2006
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    The ability of tetra(p-t-butyl)tetrathiacalix[4]arenetetrol (TCA, H4L), a cyclic tetramer of p-(t-butyl)phenol bridged with four epithio groups, to bind metal ions was investigated via a solvent extraction study. Although tetra(p-t-butyl)calix[4]arenetetrol (CA) has very poor affinity for transition metal ions (M2+), TCA is an excellent extractant of these metal ions. The chemical formulae of the extracted TCA metal complexes were found by slope analysis to be neutral 1 : 1 complexes [MH2L]. The origin of the high affinity of TCA for transition metal ions is discussed, in which it is suggested that ligation of the epithio group is important as evidenced by an NMR study of the [ZnH2L] complex.
  • Dušan J. Radanovic, Vesna D. Miletic, Tomoharu Ama, Hiroshi Kaw ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 7 Pages 1605-1614
    Published: 1998
    Released: June 05, 2006
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    The preparation and resolution of the two hexadentate Co(III) complexes containing unsymmetrical edta-type ligands, [Co(ed3ap)] (A) and [Co(u-eddadp)] (B) (ed3ap = ethylenediamine-N,N,N′-triacetate-N′-3-propionate ion; u-eddadp = ethylenediamine-N-diacetate-N′-di-3-propionate ion) have been reexamined. The X-ray data are reported for the Λ-(−)546-trans(O)5-Li[Co(ed3ap)]·H2O for which the same (Λ) absolute configuration was predicted from the CD sign pattern of the lowest energy band. The complex crystallizes in the space group P21 (#4) of the monoclinic crystal system with a = 6.523(4), b = 15.025(7), c = 7.464(3) Å, β = 105.40(4)°, and Z = 2. The conformations of the chelate rings are found to be envelope for the glycinates and skew-boat (half-chair) for the β-alaninate ring. Structural parameters and strain analysis of [Co(edta-type)] chelates are discussed in relation to the structure of the ligand and octahedral distortion of complexes. The CD and IR (carboxylate region) spectra of complexes A and B are also discussed.
  • Ji-Shi Wu, Kei Toda, Akira Tanaka, Isao Sanemasa
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 7 Pages 1615-1618
    Published: 1998
    Released: June 05, 2006
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    The association constants of ferrocene with cyclodextrins (CyD’s) in an aqueous medium at 25 °C have been determined by solubility measurements of ferrocene in both the absence and presence of CyD. The solubility of ferrocene in pure water was found to be (4.25 ± 0.02) × 10−5 mol dm−3 at 25.0 ± 0.1 °C. The β- and γ-CyD’s form only 1 : 1 complexes with ferrocene. The 1 : 1 association constants were determined to be (1.39 ± 0.21) × 102 (α), (1.65 ± 0.04) × 104 (β), and (9.04 ± 0.11) × 102 dm3 mol−1 (γ). The 2 : 1 (CyD : ferrocene) association constant was (2.36 ± 0.06) × 103 dm3 mol−1 (α). Ferrocene-included CyD precipitates were also prepared in water, and their stability upon drying in air was studied. The sublimation enthalpy of ferrocene in the temperature range of 290.65 to 298.15 K was estimated to be 74.2 ± 1.5 kJ mol−1.
  • Masashi Hojo, Hiroshi Hasegawa, Hitoshi Tsurui, Kazushi Kawamura, Sei- ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 7 Pages 1619-1627
    Published: 1998
    Released: June 05, 2006
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    In an acetonitrile solution, the extents of ionization of trityl halides (Ph3CX: X = Cl, Br) in the presence of various concentrations of alkali metal (M+ = Li+, Na+) and alkaline-earth metal (M2+ = Mg2+, Ca2+, Sr2+, Ba2+) perchlorates were examined by spectrophotometry. The promoted formation of the trityl ion (Ph3C+) in the presence of metal ions was attributed to “chemical” interactions, such as coordination or covalent bonding between the halide ions and M+ or M2+ ions, and not merely the electrostatic interaction. The salt effects increased with methoxy-substituents on trityl chloride as non-substituted < 4-methoxy < 4,4′-dimethoxy < 4,4′,4″-trimethoxytrityl. At higher RX (or X) concentrations, not only “coordination”, but also precipitation reactions between X and M+ or M2+ (except for Li+ and Mg2+) seemed to promote the ionization of RX. In the co-presence of a small amount of CH3SO3H, trityl benzoate gave the Ph3C+ ion upon the addition of LiClO4 or Mg(ClO4)2. A red color with strong fluorescence due to the zwitterion (R+–COO) of Rhodamine (Rhodamine B base) was observed upon the addition of M+ and M2+, which should have been caused by an interaction between the metal ions and the intramolecule carboxylate (from the γ-lactone) of Rhodamine in the solution. The γ-lactone ring of Crystal Violet lactone in acetonitrile was cleaved by the addition of Mg(ClO4)2 to give a strong violet color, whereas, LiClO4, NaClO4, or Ba(ClO4)2 had no (or very small) effects in the solution. It was found that the interactions between X or RCOO and M+ or M2+ in acetonitrile were strong enough to promote the ionization of partly ionized covalent bonds.
  • Toshiaki Yoshimura, Masanori Ohkubo, Takayoshi Fujii, Hiroshi Kita, Yo ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 7 Pages 1629-1637
    Published: 1998
    Released: June 05, 2006
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    S-Alkoxy-S,S-diarylthiazynes were prepared by two methods: the alkaline hydrolysis of S,S-diaryl-N-halosulfilimines in aqueous alcohols and the reaction of S,S-diaryl-S-fluorothiazynes with sodium alkoxides. The structure of S,S-diphenyl-S-propoxythiazyne was determined by an X-ray crystallographic analysis, which showed a short SN bond length of 1.441(3) Å. The thermolysis of S-alkoxythiazynes gave elimination products, which were identified as the corresponding carbonyl compounds and N-unsubstituted S,S-diarylsulfilimines. Kinetic experiments for the thermolysis of the S-alkoxy-S,S-diarylthiazynes were carried out. The first-order kinetic behavior, a large kinetic isotope effect (kH/kD = 6.1) using S,S-diphenyl-S-[1,1-2H2]propoxythiazyne, a negative activation entropy (ΔS = −30 J K−1mol−1), and a negative Hammett ρ-value (ρ = −0.35) on the phenyl group were obtained, suggesting that the reaction proceeds via a concerted five-membered cyclic transition state. A deviation from the ideal concerted transition state is discussed in comparison with that for sulfoxides.
  • Chiaki Kuroda, Atsushi Murase, Hideyuki Suzuki, Toru Endo, Shuzo Anzai
    1998 Volume 71 Issue 7 Pages 1639-1647
    Published: 1998
    Released: June 05, 2006
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    Treatment of cis- and trans-4-[3-(trimethylsilyl)prop-1-en-1-yl]cyclohexanecarbaldehyde (2a and 2b) with tetrabutylammonium fluoride in dilute tetrahydrofuran afforded 7-vinylbicyclo[2.2.1]heptan-1-ol (3), the same product obtained from 4-[3-(trimethylsilyl)prop-1-en-1-yl]cyclohexanone (1). It was found that oxidative deformylation of 2a, b to 1 takes place under basic conditions before the cyclization to 3. It was also shown that cyclization of allylsilane with carbonyl does not proceed via an eclipsed conformation.
  • Iraj Mohammadpoor-Baltork, Abdol Reza Hajipour, Hasan Mohammadi
    1998 Volume 71 Issue 7 Pages 1649-1653
    Published: 1998
    Released: June 05, 2006
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    Benzyltriphenylphosphonium peroxodisulfate is an easily prepared and stable reagent. It could be used as an oxidant under aprotic and nonaqueous conditions in organic solvents. This reagent oxidizes different classes of alcohols to carbonyl compounds, thiols to disulfides, sulfides to sulfoxides, oximes to carbonyl compounds and aromatic amines to azo compounds efficiently. α-Hydroxy carboxylic acids and phenylacetic acids undergo oxidative decarboxylation to produce carbonyl compounds.
  • Masahide Yasuda, Ryuji Kojima, Ryujiro Ohira, Tsutomu Shiragami, Kensu ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 7 Pages 1655-1660
    Published: 1998
    Released: June 05, 2006
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    The photoamination of 1-(2-methyl-1-propenyl)naphthalene (1a) with ammonia in the presence of p-dicyanobenzene (p-DCB) occurred selectively at the alkenyl group but not at the naphthyl group to give 1-(2-amino-2-methylpropyl)naphthalene (2a). Similarly, the photoamination of several kinds of alkenylnaphthalenes (1) proceeded selectively at the alkenyl group. The photoamination proceeded via the nucleophilic addition of ammonia to the cation radical of 1 generated by the photoinduced electron transfer to p-DCB to give the aminated radical after deprotonation. Distribution of the positive charge in 1+• and the stabilities of the aminated radicals were calculated by the PM3-UHF method. The stabilities of the aminated radicals agreed with the regioselectivity.
  • Takeru Nose, Yusuke Satoh, Tsugumi Fujita, Motonori Ohno, Masahide Nak ...
    1998 Volume 71 Issue 7 Pages 1661-1665
    Published: 1998
    Released: June 05, 2006
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    Synthetic heptapeptide of the human thrombin receptor tethered-ligand peptide, H–Ser–Phe–Leu–Leu–Arg–Asn–Pro–NH2 (SFLLRNP), activates fully the thrombin receptor without thrombin. The functional role of Arg-5 was examined using a series of analogs having amino acid substitutions at position 5 in this assays was to assess the abilities to hydrolyze phosphoinositide in human neuroblastoma SH-EP cells and to aggregate the human platelet. The replacement of Arg-5 by Ala reduced the activity (9% activity of the parent peptide) in the PI-turnover assay, and abolished completely the platelet aggregation activity. SFLL/Lys/NP was also active, but moderately: 36% in PI-turnover and 12% in platelet aggregation. These results indicated that the electrostatic interaction of the Arg-guanidino group is important for a peptide to interact with the receptor. When citrulline or glutamine was placed at position 5 instead of arginine, the resulting SFLL/citrulline/NP and SFLL/Gln/NP were found to be potent in both assays. Since citrulline and glutamine possess a side chain which can serve as hydrogen donor and/or acceptor, the receptor activation of these peptides appears to be due to hydrogen bonding at this position. The molecular mechanisms to explain both electrostatic and hydrogen-bonding interactions were postulated based on the structural modeling of seven-transmembrane domain thrombin receptor.
  • Masanori Wada, Hideki Konishi, Takanori Kai, Hiroshi Takeuchi, Satoko ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 7 Pages 1667-1672
    Published: 1998
    Released: June 05, 2006
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    The title compound, Φ2CHOH [Φ = 2,6-(MeO)2C6H3] (1), reacted in acetone under mild conditions in the presence of acid to give a new ketone, Φ2CHCH2COMe. Analogous reactions were observed in some other alkyl ketones and aldehydes, such as diethyl ketone, methyl phenyl ketone, 2,4-pentanedione, propanal, and butanal. In ethyl methyl ketone, an 80 : 20 mixture of Φ2CHCHMeCOMe and Φ2CHCH2COEt was obtained in agreement with the pKE values of two enols derived from ethyl methyl ketone. Compound 1 reacted in primary and secondary alcohols to give the reduced compound, Φ2CH2 (6), and the corresponding aldehyde and ketone derived from the alcohols, respectively. The reactivity of the alcohols was in the order, 1-propanol ≈ 1-butanol < ethanol < 2-butanol < 2-propanol. Compound 1 also reacted in ethers, such as tetrahydrofuran and diethyl ether, to give 6. It was either recovered unreacted from 2-methyl-2-propanol and from dimethyl sulfoxide, or it reacted under more forcing conditions to give products derived by Φ–C bond cleavage, followed by reactions of 1 with ΦH.
  • Takanori Yamazaki, Hirokazu Urabe, Fumie Sato
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 7 Pages 1673-1681
    Published: 1998
    Released: June 05, 2006
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    Malonates and methanetricarboxylates having an unsaturated side chain such as 2, 12, 20, 22, 24, 31, or 37 underwent a new ester rearrangement reaction promoted by (η2-propene)Ti(O-i-Pr)2 to afford the succinate derivative 4 or α,β-unsaturated ester 17, 21, 23, 25, 34, or 38 via the migration of the ester group from its original bis- or tris-ester position to the acetylene- or olefin-titanium complex. It has been found that the side reactions competing with the desired migration are dealkylation of the side chain of the ester and a simple cyclization. The substrates and conditions which allow the ester migration a preferential path were determined as well as the scope and limitation of this reaction.
  • Jun Li, Jun Uzawa, Yoshiharu Doi
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 7 Pages 1683-1689
    Published: 1998
    Released: June 05, 2006
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    Oligomers of (R)-3-hydroxybutanoic acid (3-HB) with different end groups and chain lengths have been prepared as model compounds of bacterial poly[(R)-3-hydroxybutanoate] [P(3-HB)]. They were studied in terms of their conformational behavior generated by rotation about CH2–CH bond of 3-HB units in solutions. The conformational behaviors of 3-HB oligomers were investigated in various solvents by analysis of vicinal coupling in the 500-MHz 1H NMR spectra. For all 3-HB oligomers studied in this work, 3-HB units without hydroxy group were found, in every solvent, to adopt similar conformational distributions to those of P(3-HB) polymer backbone in solutions, in which trans and gauche conformers are preferable, while the other gauche conformer is strongly disfavored. On the other hand, 3-HB units adjacent to hydroxy terminal group in 3-HB oligomers show different conformational behaviors relative to those of other 3-HB units. In non-polar organic solvents, only gauche conformer is predominant, due to the formation of an intramolecular hydrogen bond between hydroxy and carbonyl groups, while in polar organic solvents, the conformer distributions are similar to those of 3-HB units without hydroxy groups. In aqueous solution, for 3-HB units adjacent to hydroxy terminal group, the fractions of gauche conformer are still higher than those of trans conformer due to the formation of an intramolecular hydrogen bond.
  • Kazuhiro Kobayashi, Tomokazu Uneda, Koujirou Tanaka, Masako Mori, Hide ...
    1998 Volume 71 Issue 7 Pages 1691-1697
    Published: 1998
    Released: June 05, 2006
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    The 3+2-type cycloaddition reaction of 2-hydroxy-1,4-naphthoquinones with various alkenes or phenylacetylene was mediated by ammonium cerium(IV) nitrate (CAN) to give the corresponding naphtho[2,3-b]furan-4,9-dione and naphtho[1,2-b]furan-4,5-dione derivatives. The reaction of 2-hydroxy-1,4-benzoquinones with alkenes in the presence of CAN similarly proceeded to give benzofuran-4,7-dione and benzofuran-4,5-dione derivatives. 3-Hydroxy-1H-phenalen-1-one also underwent the CAN-mediated cycloaddition with alkenes or phenylacetylene to give the corresponding 7H-phenaleno[1,2-b]furan-7-one derivatives.
  • Naoki Kawazoe, Yoshihiro Ito, Masahiro Shirakawa, Yukio Imanishi
    1998 Volume 71 Issue 7 Pages 1699-1703
    Published: 1998
    Released: June 05, 2006
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    A DNA aptamer that selectively binds to a hormone, thyroxine, was isolated using the in vitro selection method. A pool of single-stranded DNAs consisting of random sequences was incubated with the thyroxine-immobilized agarose gel; bound DNAs were then collected and amplified by the polymerase chain reaction. This selection process was repeated nine times. The selected DNAs were cloned and sequenced. Some of the cloned DNA contained a consensus sequence. Several DNAs containing the sequence were chemically synthesized and the binding ratios to the thyroxine-immobilized gel were determined. Among them a DNA containing 14 nucleotides was found to bind selectively to thyroxine.
  • Tsukasa Matsuo, Akira Sekiguchi, Masaaki Ichinohe, Keisuke Ebata, Hide ...
    1998 Volume 71 Issue 7 Pages 1705-1711
    Published: 1998
    Released: June 05, 2006
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    The intramolecular reaction of 3,3,5,5,8,8,10,10,13,13,15,15,18,18,20,20-hexadecamethyl-3,5,8,10,13,15,18,20-octasilacycloicosa-1,6,11,16-tetrayne (1) with three molar amounts of [Mn(CO)3(Me-Cp)] in THF under photochemical and refluxing conditions produced octasilyl[4]radialene derivative (2). The reaction of 2 with alkali metals (Li, Na, and K) in THF gave dialkali metal salts of the corresponding dianion (4) with an eight-center ten-electron π-system. The molecular structure of dilithium salt of octasilyl[4]radialene dianion (4a) has been established by X-ray crystallography. The two lithium atoms are located above and below and are bonded to the atoms of the radialene framework to give a bis-CIP structure. The structural parameters of 4a are discussed in comparison to those of 2. The structure of 4a in solution has also been discussed on the basis of NMR spectroscopic data. The two Li+ ions of 4a are not fixed to the π-skeleton in toluene-d8, but are fluxional, giving a symmetric structure (bis-CIP) on the NMR time scale. In a solvating medium such as THF-d8, one of the Li+ ions dissociates to yield an ion pair (CIP and SSIP). Some evidence for the Li+ ion walk on the π-skeleton is demonstrated.
  • Masaki Okazaki, Nobuhiko Uchino, Makoto Ishihara, Hiroo Fukunaga
    1998 Volume 71 Issue 7 Pages 1713-1718
    Published: 1998
    Released: June 05, 2006
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    From the viewpoint of noncentrosymmetric molecular arrangement design in crystalline state, which is indispensable to second order nonlinear optical materials, intermolecular hydrogen bond formation of eight 5-benzylidene-2,4-thiazolidinedione derivatives and related compounds were investigated by X-ray crystallography. 5-Benzylidene-2,4-thiazolidinedione (1) itself forms centrosymmetric head-to-head (or tail-to-tail) intermolecular hydrogen bonds and takes a centrosymmetric molecular arrangement in crystalline state. Introduction of 4-methoxy group into the phenyl moiety of 1 was the only useful means for head-to-tail type intermolecular hydrogen bond formation. 5-(4-Methoxybenzylidene)-2,4-thiazolidinedione shows head-to-tail type intermolecular hydrogen bonds and noncentrosymmetric molecular arrangement in crystalline state. Similarities in both hydrogen bond formation and molecular arrangement in crystalline state are obtained by conversion of 2,4-thiazolidinedione to 2-thioxo-4-oxazolidinone, but in the case of conversion to 2,4-oxazolidinedione only hydrogen bond formation is shown in a similar manner. In the case of conversion to rhodanine, no similarity in either hydrogen bond formation or molecular arrangement in crystalline state was shown. Such behaviors were considered from viewpoints of pKa and hydrogen bond energy.
  • Hiroki Iwanaga, Katsuyuki Naito, Kazuyuki Sunohara, Masaki Okajima
    1998 Volume 71 Issue 7 Pages 1719-1723
    Published: 1998
    Released: June 05, 2006
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    To realize bright and pure colors in Guest–Host type Liquid Crystal Displays (GH-LCDs), the solubilities and/or absorption coefficients of dichroic dyes which are dissolved in liquid crystals are the most important properties. We have found that a mixture of coumarin and anthraquinone dyes was very useful because it had a large absorption coefficient and little fluorescence. On the other hand, substitution of a sulfur atom for an oxygen atom of the coumarin dye contributes to increase its solubility to liquid crystals, particularly at low temperatures.
  • Guo-Qing Tang, Naoki Tanaka, Shigeru Kunugi
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 7 Pages 1725-1730
    Published: 1998
    Released: June 05, 2006
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    We investigated the pressure perturbations of DNA minor groove binding of the antibiotic drug Hoechst 33258 (2′-(4-hydroxyphenyl-5-(4-methyl-1-piperazinyl)-2,5′-bi-1H-benzimidazole trihydrochlolride) on fluorescent titrations and on restriction endonuclease protection assays. Significantly, pressure elevations were found to disturb the binding of Hoechst 33258 with poly(dA)·poly(dT) and poly[d(A–T)]·poly[d(A–T)] in opposite directions, which suggested different volume changes (sign and size) in their complexation reactions. The ability of Hoechst 33258 to provide the restriction endonuclease protection for plasmid DNA was notably enhanced by the application of pressure, implying that there is a large volume contraction following the EcoRI site-drug interaction. These data were explained by DNA hydration and its effects on the ligand complexation that is sequence dependent.
  • Satoko Nishiyama, Shinjiro Machida, Takashi Yamashita, Kazuyuki Horie
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 7 Pages 1731-1737
    Published: 1998
    Released: June 05, 2006
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    The photochemical behavior at cryogenic temperatures of phenoxazine and phenothiazine dyes in poly(vinyl alcohol) was investigated by using persistent spectral hole burning. The importance of hydrogen-bondings has been confirmed by measuring the effects of the addition of N,N,N′,N′-tetramethyl-p-phenylenediamine on the holewidth and the hole area of various cationic dyes at 20 K. The hydrogen bonds around the ring-N atom affect the total dephasing time, while the hydrogen bonds around the amino groups as the substituents and around the ring-N atom control the efficiency of hole formation.
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