Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 71 , Issue 6
Showing 1-29 articles out of 29 articles from the selected issue
  • Akito Sasaki, Loïc Mahé, Akira Izuoka, Tadashi Sugawara
    1998 Volume 71 Issue 6 Pages 1259-1275
    Published: 1998
    Released: February 01, 2006
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    UV photolysis of powdered crystals of several aryl azides at cryogenic temperatures afforded azo compounds predominantly. In the cases of p-(N-methylacetamido)phenyl azide and 2-azidobiphenyl, a CH insertion product or a carbazole was formed, competing with azo formation. These products can be considered to be formed through topotactic processes when the crystal structures are taken into account. The arylnitrenes generated in the azide crystals were monitored by ESR spectroscopy; they turned out to have extremely long half life-times, compared with those in the gas phase or in solution. Such high kinetic stabilities are ascribed to the inert environment around the generated nitrenes. The decay process of arylnitrenes in the initial stage obeyed a pseudo-first order kinetics; activation parameters were evaluated by Arrhenius plots. The activation enthalpies and entropies indicate that the diffusional processes of arylnitrenes may be the vital factors determining the kinetic stability and the product distribution in the crystalline environment.
  • Tsuyoshi Asahi, Akihiro Furube, Hiroshi Masuhara
    1998 Volume 71 Issue 6 Pages 1277-1283
    Published: 1998
    Released: February 01, 2006
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    The electronic structure of the excited states and triplet formation dynamics in the acridine microcrystal have been studied by femtosecond diffuse reflectance absorption spectroscopy and picosecond fluorescence spectroscopy. It was confirmed that an excimer was formed in the microcrystal within a few picoseconds after excitation. The time constant of triplet formation from the lowest excited singlet (S1) state was obtained to be about 900 ps at room temperature, which is about ten times slower than that in an aprotic solvent. Also, triplet formation was not observed up to 6 ns at 77 K. Slow intersystem crossing in the crystal was explained in terms of a selective stabilization of the 1ππ* electronic configuration due to excimer formation. An important role of intermolecular interactions on the intersystem crossing process of the crystal is discussed.
  • Wei Hua Tan, Noriaki Niino, Takahiro Ishikura, Aya Maruta, Tatsuyuki Y ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 6 Pages 1285-1292
    Published: 1998
    Released: February 01, 2006
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    Complexation of cyclodextrins (CD’s) with some regioisomers of naphthalenedicarboxylic acid (NDC) was examined in 0.1 mol dm−3 NaHCO3 at 25 °C by means of 1H NMR spectroscopy, together with the measurement of induced circular dichroism spectra of NDC’s with the addition of CD’s. The 1H NMR spectra of 2,6- and 2,7-NDC’s showed characteristic AB-type patterns, which changed continuously with increasing CD concentration in accord with the Pople theory. The binding constants (Ka) for β-CD complexes with NDC’s increased in the order of: 1,4-NDC ≈ 1,5-NDC < 1,3-NDC < 1,6-NDC < 2,3-NDC < 2,7-NDC ≤ 2,6-NDC, indicating that β-CD is able to recognize the molecular structures of NDC’s. On the other hand, interactions of α- and γ-CD’s with NDC’s were very weak and nonspecific to NDC’s. The molecular structures of β-CD complexes with some NDC’s were estimated based on the ROESY spectra of the systems. Column chromatography of NDC’s using a β-CD-(2-chloromethyloxirane) polymer column showed that the retention volumes for NDC’s increased in the order of: 1,4-NDC < 1,6-NDC < 2,3-NDC < 2,7-NDC < 2,6-NDC, which agreed with the order the Ka values.
  • Ramalingam Rajan, Venkatesan Subramanian, Balachandran Unni Nair, Thir ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 6 Pages 1293-1298
    Published: 1998
    Released: February 01, 2006
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    The force field for Ti(IV) Schiff-base complexes having the general formula Ti(Schiff-base) Cl2 (where Schiff-base = OC6H4–CH=N–(CH2)n–N=CH–C6H4O and n = 2, 3, 4, 5, and 6) has been generated. Using the generated force-field minimum energy conformers have been predicted for the corresponding Ti(IV) complexes. It has been shown that when n = 2 and 3, the compound prefers a trans-configuration. In the case where n = 4, 5 and 6, the total energy difference between the cis- and trans-conformers are not large enough for one to make any definite predictions about the preferred conformation. However the total energy of the trans-conformer is also lower than that of the cis-conformer in these cases.
  • Norihiro Kato, Fujio Takahashi
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 6 Pages 1299-1304
    Published: 1998
    Released: February 01, 2006
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    The deswelling kinetics of a macroporous poly(N-isopropylacrylamide) gel in a NaCl solution was investigated. NaCl was used as the probe in order to trace out any hydration from the hydrated polymer chains. In the case of macroporous gel immersed in a NaCl solution, the minimum of the initial deswelling rate (v = 0.06 s−1) appeared at around 0.2—0.3 M (1 M = 1 mol dm−3) when the equilibrated gels (at 22 °C) were heated to 40 °C. The maxima of the apparent activation energy (Ea = 110 kJ mol−1) and the change in the activation entropy (ΔS313 = 80 J K−1 mol−1) were at 0.2—0.3 M NaCl. These results indicate that deswelling of the gel in a NaCl solution advanced on the condition of the following two factors. One is an electrostatic repulsion between Cl ions below 0.2—0.3 M. Another is a salting-out effect due to NaCl above 0.2—0.3 M. The deswelling kinetics and the lower critical solution temperatures of the gels in other alkalimetal halide solutions were also measured in order to clarify the effect of the species of the cations and the anions on the interaction between the water and polymer chains.
  • Yasuo Kameda, Takeshi Usuki, Osamu Uemura
    1998 Volume 71 Issue 6 Pages 1305-1313
    Published: 1998
    Released: February 01, 2006
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    The neutron diffraction measurement with the H/D isotopic substitution technique has been carried out on the aqueous 21 mol% hydrochloric acid solutions, in order to investigate the short-range structure in the concentrated aqueous acid solution, in comparison with the structural information available on liquid pure water. Observed partial structure factors : aHH(Q), aXH(Q), and aXX(Q) (X: O, Cl), determined by the least-squares fitting analysis, have exhibited that the nearest-neighbor intermolecular hydrogen-bond distances, r(H···H) and r(O···H), between oxonium ion and water molecule in the 21 mol% hydrochloric acid solution were 2.02 ± 0.05 and 1.69 ± 0.02 Å, respectively; such values are much smaller than those in liquid pure water. Consequently, a strong intermolecular hydrogen bond between oxonium ion and its nearest-neighbor water molecules is concluded to be present in the concentrated aqueous hydrochloric acid solution.
  • Masayoshi Nakano, Kizashi Yamaguchi
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 6 Pages 1315-1320
    Published: 1998
    Released: February 01, 2006
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    In our previous paper (Int. J. Quant. Chem., in press1)) we discussed a novel numerical calculation scheme for the dynamics of a quantum network for linear molecular aggregates under time-dependent electric fields. The population and polarizability spectra for dimer models were found to exhibit a change, like a phase-transition behavior, for applied field intensities. In the present work we apply this method to a calculation of nonperturbative second hyperpolarizability γ of a dimer model and investigate the dependence of γ on the field intensity.
  • Takehiko Mori, Tadashi Kawamoto, Yohji Misaki, Kazuyoshi Tanaka
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 6 Pages 1321-1326
    Published: 1998
    Released: February 01, 2006
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    A novel selenium-containing bis-fused tetrathiafulvalene donor, TSM-TTP (2,5-bis[4,5-bis(methylseleno)-1,3-dithiol-2-ylidene]-1,3,4,6-tetrathiapentalene) forms a 3 : 5 triiodide salt, (TSM-TTP)(I3)5/3. This salt has uniform one-dimensional columns of the donors, and is isostructural to the corresponding complex of the sulfur analog. This compound shows a high electrical conductivity, 200 S cm−1 at room temperature, and undergoes a metal-insulator transition around 20 K. Another insulating (σrt = 0.03 S cm−1) phase with trimerized columns is also obtained.
  • Yuko Takao, Tokuji Takeda, Keiko Miyashita, Jun-ichiro Setsune
    1998 Volume 71 Issue 6 Pages 1327-1335
    Published: 1998
    Released: February 01, 2006
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    Palladium complexes of N(21),N(22)-(etheno)-bridged porphyrins were synthesized by the reaction of palladium(II) chloride and N(21),N(22)-(etheno)-tetraphenylporphyrins or N(21),N(22)-(etheno)-octaethyl-5,22-dihydroporphyrins. The metallation proceeded via an initially produced monoprotonated porphyrin with a palladate anion. Dinuclear complexes including two PdCl2 units were preferentially produced and were converted into mononuclear complexes by a treatment with a saturated aqueous NaCl solution. Single-crystal X-ray diffraction shows the di-μ-chlorodipalladium(II) structure of the dinuclear complex, N(21),N(22)-(EtC=CEt)(TPP)(PdCl2)2·CH2Cl2·H2O (TPP = 5,10,15,20-tetraphenylporphyrin dianion). Pd(1) is coordinated by two adjacent imine nitrogens of the porphyrin as the terminal ligands and placed out of the porphyrin 4N mean plane by 1.32 Å. The distal Pd(2) is placed at a distance of 3.78 Å from the porphyrin 4N mean plane and comes close to the porphyrin ring with a dihedral angle of 139.8° between the two square planes of the Pd coordination. The NMR spectrum in solution indicated the influence of the distal Pd(2) on the porphyrin ring. The etheno bridge keeps the geometry of the 4N core of the porphyrin relatively undeformed in comparison with the previously reported methano bridge, which accounts for the enhanced stability of Pd(II) complexes.
  • Isoroku Nagasawa, Tatsuya Kawamoto, Hiro Kuma, Yoshihiko Kushi
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 6 Pages 1337-1342
    Published: 1998
    Released: February 01, 2006
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    The reaction of bis(hexafluoroacetylacetonato)platinum(II) with 2-(ferrocenyl)benzothiazoline affords trans and cis isomers of platinum(II) Schiff base complex, trans-[Pt(fabt)2] (1) and cis-[Pt(fabt)2] (2) (fabt = 2-(ferrocenylmethyleneamino)benzenethiolato). The structures of 1 and 2 have been determined by the single crystal X-ray diffraction method. Crystal data for complex 1 are triclinic with space group ; a = 15.283(15), b = 13.180(8), c = 9.847(12) Å; α = 72.91(6), β = 98.02(9), γ = 94.95(6)°; V = 1875.2(30) Å3; Z = 2. Crystal data for complex 2 are orthorhombic with space group P212121; a = 20.593(7), b = 12.300(5), c = 11.754(4) Å; V = 2977.0(18) Å3; Z = 4. The complex 1 has a trans-planar N2S2 configuration and two fabt groups take an unique umbrella conformation. On the other hand, the complex 2 has a cis-planar N2S2 configuration and two fabt groups take a helical geometry with a stepped conformation. The space group P212121, Z = 4 for 2 indicates that 2 is spontaneously resolved.
  • Tatsuya Murakami, Kazuya Yamaguchi, Yoshihito Watanabe, Isao Morishima
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 6 Pages 1343-1353
    Published: 1998
    Released: February 01, 2006
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    A new type of high-valent oxoiron porphyrin (3b) has been prepared by the reaction of FeIII(tdcpp) (1b) [tdcpp: 5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin] with an oxidant such as p-nitroperbenzoic acid and pentafluoroiodosylbenzene at −90 °C in CH2Cl2 in the presence of a small amount of methanol. The UV-vis spectrum of 3b (λmax at 418 and around 550 nm) is similar to that of O=FeIV(tdcpp) (4b, λmax 419, 543 nm). However, titration of 3b by iodide ion indicates that the oxidation state of 3b is two-electron oxidized from the iron(III) state. Further, 3b catalyzes oxygenation of olefins such as styrene even at −90 °C. Possible formulation of 3b as a π-cation radical is readily ruled out by deuterium NMR observation. The solution magnetic susceptibility (μeff = 4.0 ± 0.2 μB) of 3b indicates that 3b has three unpaired electrons. These results indicate the formal description of 3b as being a high spin complex of either an O=Fe(V) porphyrin or ·O–Fe(IV) porphyrin. The same oxidation of 1b in the absence of methanol gave O=FeIV(tdcpp) π-cation radical (2b). We think the ligation of methanol causes the destabilization of iron d orbitals and eventually turns upside down the energy levels between the iron dxz, dyz orbitals and the porphyrin HOMO orbital (a2u) since the a2u orbital is stabilized by the introduction of electron-withdrawing groups on the porphyrin ring.
  • Mala Nath, Rakesh Yadav
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 6 Pages 1355-1362
    Published: 1998
    Released: February 01, 2006
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    New organotin(IV) complexes of the general formula R3SnL [where R = Me, Bu, and Ph], Ph2SnL2 and Bu2SnL2 [where L = monoanion of DL-methionine (HL-1) and L-asparagine (HL-2)] were synthesized and characterized by elemental analyses as well as molar conductance, electronic, infrared, far-infrared, 1H and 13C NMR, and 119Sn Mössbauer spectral studies. Probable structures are suggested for the complexes. Thermal studies of a few complexes have been carried out in the temperature range 25—1000 °C using the TG, DTG, and DTA techniques, indicating the formation of SnO as a residue. The complexes were tested in vitro against a wide spectrum of bacteria and fungi and found to be active. Only two complexes, Ph3SnL-1 and Ph3SnL-2, have been found to be slightly active in vivo against a multiinfection fungal model in mice.
  • Ken-ichi Okamoto, Yukie Yoshinari, Yasunori Yamada, Narumi Sakagami, T ...
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 6 Pages 1363-1371
    Published: 1998
    Released: February 01, 2006
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    The reactions of [Ni(aet)2] with [PtCl2(L)] gave a new type of S-bridged dinuclear complexes [Pt(L){Ni(aet)2(H2O)2}]2+ (aet = aminoethanethiolate; L = bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline (5), dmbpy = 4,4′-dimethyl-2,2′-bipyridine). These complexes readily react with L′ to form [M(L){Ni(aet)2(L′)}]2+ (L = bpy, L′ = bpy (3), phen; L = phen, L′ = phen, bpy; L = L′ = dmbpy). A similar reaction of [Ni(aet)2] with [PtCl2(phen)] and phen gave only [Pt(phen){Ni(aet)2(phen)}]2+. The crystal structures of 3 and 5 were determined by X-ray crystallography. The Ni atoms are surrounded by two aet and a bpy or two water molecules to have an approximately octahedral geometry, forming the C2-cis(S)-[Ni(aet)2{bpy or (H2O)2}] unit. The Pt atoms have a square-planar geometry, in which two Cl atoms of the starting [PtCl2(L)] (L = bpy or phen) have been substituted by the two S atoms from the Ni(II) unit. The Pt(II) plane and the Ni(II) equatorial plane are almost coplanar, and the Pt–Ni distance is 3.4987(8) Å (3) and 3.476(4) Å (5). All of the complexes were characterized on the basis of the electronic absorption and infrared spectra and the cyclic voltammetry. The conversion of a square-planar [Ni(aet)2] to an octahedral [Ni(aet)2{(H2O)2 or (L′)}] units was also considered. In the solid state, the water molecule in [Pt(L){Ni(aet)2(H2O)2}]2+ could be readily exchanged by nitrate.
  • Toshio Takayanagi, Tadashi Iwachido, Shoji Motomizu
    1998 Volume 71 Issue 6 Pages 1373-1379
    Published: 1998
    Released: February 01, 2006
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    Reaction equilibria in liquid–liquid distributions of alkali metals as crown ether complexes were clarified. The reactions and their equilibria of interest are the complex formation, the ion association of the complexes with the pairing anions in an aqueous solution, and the distribution of the formed ion associates to the organic phase. A capillary-electrophoretic method was proposed for the analysis of the equilibria in an aqueous solution. By using this method, complex formation and ion association in an aqueous solution were studied by electrophoretic mobility measurement, which was done in reactant systems consisted of alkali metal ion, dibenzo-18-crown-6, and picrate or perchlorate ion by capillary zone electrophoresis. Complex formation constants obtained agreed with the reported values obtained by the solubility measurement, and the ion association equilibria between the metal complexes and pairing anions were for the first time analyzed in this study. The reactivity of complex formation in the aqueous solution was in the order of K+ > Na+ > Rb+ > Cs+ > Li+, and the ion associability with picrate ion was in the order of Na+ > K+. By using the ion association constants and the extraction constants, distribution coefficients of the ion associates between an aqueous and a benzene phase were calculated.
  • Yugen Zhang, Zhaomin Hou, Yasuo Wakatsuki
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 6 Pages 1381-1384
    Published: 1998
    Released: February 01, 2006
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    Reaction of [{Sm(C5Me5)(μ-OAr)}2] (Ar = 2,6-(t-Bu)2-4-MeC6H2) or [Sm(C5Me5)2(thf)2] with 1 equiv of [{Ir(C5Me5)Cl(μ-Cl)}2] in THF gave the “ate” complex [Ir(C5Me5)2][Sm(C5Me5)2Cl2] (1) as orange-red crystals in 60—74% yields (based on Sm). Complex 1 represents the first example of a structurally characterized metallocenium lanthanocene dihalide complex. Crystal data for 1: monoclinic, space group P21/m (No. 11), a = 9.781(4), b = 14.956(4), c = 13.842(5) Å, β = 93.38(3)°, V = 2021(1) Å3, Z = 2, Dc = 1.57 g cm−3, R = 7.75%, RW = 9.23%, GOF = 1.12.
  • Tomohiro Narukawa, Wataru Yoshimura, Atsushi Uzawa
    1998 Volume 71 Issue 6 Pages 1385-1390
    Published: 1998
    Released: February 01, 2006
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    The behavior and effect of cobalt as a chemical modifier for lead were studied by electrothermal atomic absorption spectrometry using a tungsten furnace. The characterization of materials formed on the tungsten surface at the charring stage was performed using of a scanning electron microscope and X-ray photoelectron spectrometer. The experimental results indicate that the effect of a cobalt modifier is related to the formation of granular cobalt crystals during a pre-heating stage. Under the coexistence of lead, however, the cobalt crystals became irregularly shaped, probably forming an intermetallic compound between cobalt and lead. By an examination using sample materials containing chloride, nitrate, and sulfate salts, it was found that a cobalt modifier is effective for suppressing the interference of chloride and nitrate. All of the sulfate salts gave negative interference; the cobalt crystal, which acted as a chemical modifier, was included inside a large crystal which originated from the sulfate at the charring stage. The thermal stability of lead is difficult to maintain with increasing sulfate salts. The cobalt modifier was applied to the determination of lead in several water samples.
  • Kazuyuki Umemura, Hirofumi Noda, Juji Yoshimura, Akihito Konn, Yasuchi ...
    1998 Volume 71 Issue 6 Pages 1391-1396
    Published: 1998
    Released: February 01, 2006
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    Two 4-ethoxycarbonyl thiazolyl groups were introduced into 2- and 5-positions of 3-hydroxypyridine in 8 steps using 5-cyano-3-hydroxypyridine (2) as the starting material. The pyridine derivative obtained in the last step was converted to a fragment A derivative (21) by stepwise introduction of the 2-substituted 4-thiazolyl group into the 6-position. The total yield for the formation of 21 via 14 steps was 7.6%.
  • Ian R. Dunkin, Adam McCluskey
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 6 Pages 1397-1400
    Published: 1998
    Released: February 01, 2006
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    Photolysis of tetrachlorodiazocyclopentadiene (1) in oxygen-saturated hydrocarbon solvents results in the transient formation of tetrachlorocyclopentadienone O-oxide (3). This rapidly decomposes, giving rise to products derived from oxidation of the hydrocarbons. Cyclopentane, cyclopentene, cycloheptane, cycloheptene, cycloheptatriene, and indene have been studied. Cycloheptatriene and indene gave only low yields of tractable products, but the others gave the corresponding ketones and secondary alcohols as the major products. Although yields varied considerably, the ketone and alcohol products were always obtained, within experimental error, in a 1 : 1 molar ratio. This observed product ratio supports the disproportionation of cycloalkyldioxyl radicals as a crucial step.
  • Mustanir, Masaaki Mishima, Mizue Fujio, Yuho Tsuno
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 6 Pages 1401-1407
    Published: 1998
    Released: February 01, 2006
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    The thermodynamic stabilities of the phenonium (ethylenebenzenium) ion and ring-substituted derivatives were determined based on the bromide-transfer equilibria in the gas phase. It has been shown that the phenonium ion is 2.4 kcal mol−1 more stable than the t-butyl cation, and that the substituent effect on its stability can be correlated with the Yukawa–Tsuno equation with a ρ value of −12.6 and an r+ of 0.62. An r+ value smaller than unity of the α-cumyl(1-methyl-1-phenylethyl) cation suggested that π-delocalization in the phenonium ion is essentially less effective than through a benzylic π-interaction. On the other hand, the ρ value of −12.6 is distinctly larger than that for the ordinary benzylic carbocation systems, but is comparable to that of the benzenium ion. In addition, it has been found that the r+ value of the phenonium ions in the gas phase is in complete agreement with that for the aryl-assisted process in the acetolysis of 2-arylethyl toluenesulfonates. This suggests that the degree of π-delocalization of the positive charge is the same in the transition state and the intermediate cation. It is concluded that an r+ value of 0.6, which is ranked at a unique position in the continuous spectrum of the resonance demand, is characteristic of the bridged structure of the phenonium ion intermediate and the transition state.
  • Atsushi Fukuoka, Takeyuki Nagano, Shuichi Furuta, Michito Yoshizawa, M ...
    1998 Volume 71 Issue 6 Pages 1409-1415
    Published: 1998
    Released: February 01, 2006
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    Zero-valent ruthenium complexes, [Ru(cod)(cot)] and [Ru(cod)(benzene)], are effective catalyst precursors for the tail-to-tail dimerization of acrylonitrile. Hydrogen pressure is necessary for the catalytic reaction, and the turnover number for dimers is greatly improved in neat acrylonitrile. Under the conditions of 150 °C and 25 atm of H2 (initial pressure at room temperature), the conversion of acrylonitrile is 61% and the yield of tail-to-tail dimers is 42% (selectivity 69%) in 3 h. The turnover number for the dimers is 2060, which is much higher than those reported so far. From the results of a catalytic reaction under D2 pressure, a reaction mechanism is proposed, in which two successive insertions of acrylonitrile into dihydridoruthenium complex are involved. A fast and reversible insertion of the third acrylonitrile is responsible for the H–D exchange of acrylonitrile in the deuterium labeling experiment.
  • Minoru Yasuda, Mitsuaki Ide, Yuka Matsumoto, Masaya Nakata
    1998 Volume 71 Issue 6 Pages 1417-1429
    Published: 1998
    Released: February 01, 2006
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    An asymmetric total synthesis of the 14-membered diene unit, (1S,2S,4E,6E,10S,11Z,14R)-10,14-epoxy-4-isopropenyl-1,7,11-trimethyl-4,6,11-cyclotetradecatriene-1,2-diol (3), of methyl sarcophytoate (1) has been achieved. Methyl ketone, (3S,4S)-3,4-(isopropylidenedioxy)-3,7-dimethyl-6-octen-2-one (6), was enantioselectively prepared from geraniol via Sharpless asymmetric epoxidation and a regioselective epoxide-opening reaction. The aldol coupling between the lithium enolate of 6 and aldehyde, (2E,6E)-2,6-dimethyl-8-(2,2-dimethylpropanoyloxy)-2,6-octadienal (7), which was also prepared from geraniol, gave a 1 : 1 separable mixture of the adducts (17 and 18). Reduction of the carbonyl group in 17 and 18, followed by regioselective oxidation of the allylic hydroxy group, afforded α,β-unsaturated ketone, (2E,6E,10R,11R,12S)-1-(2,2-dimethylpropanoyloxy)-10-hydroxy-11,12-(isopropylidenedioxy)-3,7,11,15-tetramethyl-2,6,14-hexadecatrien-8-one (5). The intramolecular oxy-Michael addition of 5 followed by regioselective enol triflation and deoxygenation gave dihydropyran, (2E,6S,7Z,10R,11R,12S)-1-(2,2-dimethylpropanoyloxy)-6,10-epoxy-11,12-(isopropylidenedioxy)-3,7,11,15-tetramethyl-2,7,14-hexadecatriene (31). The regioselective epoxidation of 31 and a subsequent functional-group transformation gave (2E,6S,7Z,10R,11R,12S,14RS)-6,10 : 14,15-diepoxy-11,12-(isopropylidenedioxy)-3,7,11,15-tetramethyl-1-(phenylthio)-2,7-hexadecadiene (4). The 14-membered ring formation was achieved by the treatment of 4 with the n-BuLi–Bu2Mg complex to give (1Z,3S,6E,8RS,9RS,11S,12R,13R)-3,13-epoxy-9-(1-hydroxy-1-methylethyl)-11,12-(isopropylidenedioxy)-2,6,12-trimethyl-8-(phenylthio)-1,6-cyclotetradecadiene (33), which was transformed to 3 through triene construction and deacetonidation.
  • Kazuo Takimiya, Tetsuya Yanagimoto, Takashi Yamashiro, Fumio Ogura, Te ...
    1998 Volume 71 Issue 6 Pages 1431-1435
    Published: 1998
    Released: February 01, 2006
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    The title compound (TANT) and its 9,10-dichloro derivative (TANT-Cl) have been prepared as higher homologues in an extended electron-acceptor series of TCNQ and TNAP. On the basis of cyclic voltammetry, the accepting ability of TANT is nearly comparable to those of TCNQ and TNAP, and that of TANT-Cl is further enhanced by the chloro substitutuent groups. In addition, TANT and TANT-Cl show an effective reduction of on-site coulombic repulsion, due to their extensive anthraquinone quinonoid system. They thus behave as superior electron acceptors for forming electrically conductive charge-transfer complexes with various electron donors, mostly of the TTT type.
  • Masanori Miura, Noriyoshi Arai, Koichi Narasaka
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 6 Pages 1437-1441
    Published: 1998
    Released: February 01, 2006
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    Oxidation of cyclohexane-1,2-dione with ammonium hexanitratocerate(IV) (CAN) generates 2,3-dioxocyclohexyl radical, which reacts with electron-rich olefins to afford the corresponding addition products. The adducts thus generated are converted to 4,5-dihydro-7(6H)-benzofuranone by acid treatment. In addition to cyclohexane-1,2-dione, radical species are also generated from cyclopentane-1,2-dione and cycloheptane-1,2-dione.
  • Tomoshige Kobayashi, Kiyomi Miki
    1998 Volume 71 Issue 6 Pages 1443-1449
    Published: 1998
    Released: February 01, 2006
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    A norbornadiene-fused pyrazine was prepared by the condensation reaction of bicyclo[2.2.1]hept-5-ene-2,3-dione with ethylenediamine followed by oxidation. Treatments of the norbornadiene-fused pyrazine and its benzo derivative with bromine in carbon tetrachloride or in dioxane afforded trans-adducts as major products, accompanied by the formations of cis-adducts and dibromo derivatives derived from Wagner–Meerwein type skeletal rearrangement, while bromination of a fused dicyanopyrazine in carbon tetrachloride gave only a trans-adduct. In contrast, a fused pyrazine with an electron-donating N-oxide group gave a 7,9-dibromo derivative as the main component. The possibility of the intervention of a 2H-pyrazinium ion for the formation of the skeletally rearranged products is discussed together with the results of ab-initio (3-21G*) calculations.
  • Nobuhiro Iwasa, Noriaki Ogawa, Satoshi Masuda, Nobutsune Takezawa
    1998 Volume 71 Issue 6 Pages 1451-1455
    Published: 1998
    Released: February 01, 2006
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    Temperature programmed reduction (TPR) experiments were carried out over Pd/ZnO with different Pd loadings. Combined results with an X-ray diffraction method and X-ray photoelectron spectroscopy showed that a Pd–Zn alloy with a structure of PdZn was selectively produced in the course of TPR of Pd/ZnO. It was suggested that hydrogen retained in Pd spilled over to ZnO. The ZnO was reduced to metallic Zn, being converted to PdZn. The molar amounts of the ZnO reduced were practically the same as the those of Pd loaded. Hence, all the Pd loaded was completely transformed to the PdZn alloys upon reduction.
  • Mineo Watase, Hideyuki Itagaki
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 6 Pages 1457-1466
    Published: 1998
    Released: February 01, 2006
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    The thermal and rheological properties of gels formed from 2,4-(mono)-O-benzylidene-D-sorbitol (MBS), 1,3 : 2,4-di-O-benzylidene-D-sorbitol (DBS), and 1,3 : 2,4 : 5,6-tri-O-benzylidene-D-sorbitol (TBS) in ethylene glycol (EG) and from DBS in glycerol (GL) were investigated. In all the gels studied, the values of the enthalpy of melting for the gel obtained from the Eldridge–Ferry plot agreed well with those obtained from the peak area of the DSC curves. This agreement has not been demonstrated clearly for biopolymeric systems thus far but can now be successfully shown by first using small molecule systems. In conclusion, the transitions of the gel formation and gel melting proceed via a second order or higher order process. The experimental results show that the ease by which formation and stabilization of gels takes place for the sorbitol derivatives in EG is in the following order: DBS > TBS > MBS. Accordingly, the main reason for the stabilization of sorbitol gels in alcoholic solvents is concluded to be not simply due to hydrogen bonding or hydrophobic interactions among benzylidene groups but rather it is due to a delicate balance of chemical structure that facilitates the formation of crystals. In particular, the symmetric structure of a DBS molecule, which has a rigid and chiral ten-member ring symmetrically connected with two benzylidene groups in equatorial positions, is considered to be the most crucial reason to form most stable gels studied in this work.
  • Masashi Takahashi, Koichi Kobayashi, Kyo Takaoka, Kazuo Tajima
    1998 Volume 71 Issue 6 Pages 1467-1470
    Published: 1998
    Released: February 01, 2006
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    The monolayer properties of octadecylamine (ODA) on both distilled water and aqueous Methyl Orange (MO) solution were studied from the measurements of surface pressure–area (πA) isotherms. From the πA isotherms at various pHs, hydroxide ions, and MO anions in the subphase were confirmed to interact competitively with the ODA monolayer. Furthermore, Langmuir–Blodgett (LB) film of ODA was fabricated from the surface of an alkaline subphase, and the adsorption characteristics of the ODA LB film were investigated by using MO as an adsorbate. As a result, the ODA LB film exhibited specific adsorbability for the MO anion, similar to that of the LB film of long-chain quaternary alkylammonium salt, but the adsorption rate of the MO on the ODA LB film was slower than that on the LB film of long-chain quaternary alkylammonium salt. In addition, adsorbability of the ODA LB film showed pH dependence.
  • Shinji Takeoka, Tomitaro Hara, Kazuaki Fukushima, Kimihisa Yamamoto, E ...
    1998 Volume 71 Issue 6 Pages 1471-1476
    Published: 1998
    Released: February 01, 2006
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    In order to improve the thermal stability of the electric conductivity of polypyrrole (PPy), a series of aromatic sulfonate derivatives having acid-type substitute groups, such as –COOH, –OH, and –SO3H, were used as dopants. The PPy doped with these dopants showed excellent thermal stability of their electric conductivity, even at 150 °C in air. Especially, 2-hydroxy-5-sulfobenzoic acid, having one –COOH and one –OH, provided the highest thermal stability; the doped PPy maintained 95% of its initial conductivity, even after heating for 8 h at 150 °C in air. Furthermore, the PPy showed 20-times higher stability against long-term heating at 125 °C for 1000 h in comparison with PPy doped with p-methylbenzenesulfonic acid, which is conventionally used to provide high thermal stability. The thermal-stabilization mechanism has suggested that dopants having acidic substituents should suppress proton dissociation from the N-position of the PPy main chain and keep the π-conjugation structure by supplying a proton from the acidic groups. Such a proton supplement was confirmed by the IR spectroscopy of deuterized PPy.
  • Kohtaro Osakada, Yasumasa Takenaka, Isao Yamaguchi, Takakazu Yamamoto
    Type: Accounts
    Subject area: AI
    1998 Volume 71 Issue 6 Pages 1477-1482
    Published: 1998
    Released: February 01, 2006
    JOURNALS RESTRICTED ACCESS
    NaH promoted coupling reaction of HO(CH2)12O–TBDMS (1, TBDMS=SiMe2(t-Bu)) and Br(CH2)12O–TBDMS (2) followed by deprotection of the organosilyl groups affords HO(CH2)12O(CH2)12OH (5). 1,12-Dodecanediol reacts with an excess amount of 2 in the presence of NaH to give TBDMS–O(CH2)12O(CH2)12O(CH2)12O–TBDMS (6) which is turned into HO(CH2)12O(CH2)12O(CH2)12OH (7) by removal of the protecting groups. Similar 1 : 2 condensation of hydroquinone with 2 and with Br(CH2)6O–TBDMS (3) leads to formation of the corresponding α,ω-diols, HO(CH2)12OC6H4O(CH2)12OH (9) and HO(CH2)6OC6H4O(CH2)6OH (11), respectively. The four new long α,ω-diols are isolated and characterized by means of IR and NMR spectroscopy as well as elemental analyses. Polyaddition reactions of 5, 7, 9, and 11 to 1,3-bis(isocyanatomethyl)benzene and 1,1′-methylenebis[4-isocyanatobenzene] give the corresponding poly(urethane)s in high yields. The obtained polymers, which were characterized by IR and NMR spectroscopy, have molecular weights over 20000 as determined from gel permeation chromatography using polystyrene standards.
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