Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 70 , Issue 2
Showing 1-27 articles out of 27 articles from the selected issue
  • Shashidhar N. Rao, Ming Fai Chan, Vitukudi N. Balaji
    1997 Volume 70 Issue 2 Pages 293-299
    Published: 1997
    Released: June 11, 2006
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    Peptides with conformationally restricted 1-aminocyclopropane-1-carboxylic acid (Acc3) moieties were previously shown to exhibit preference for γ-turn structures in the solution phase and solid phase. We present conformational energy calculations on model compounds containing 1-aminocycloalkane carboxylic acid with 4, 5, and 6-membered rings using molecular mechanics methods. The low-energy models adopt conformations characteristic of a variety of regular structures, such as the α-helix, γ-turn, and polyproline-II-type three- and four-fold helices. The energetically most favored models adopt the γ-turn (2.27 helix) conformation in the model peptide of 1-aminocyclobutane-1-carboxylic acid (Acc4), similar to Acc3 peptides, while they adopt the α-/310-helical conformation (of either handedness) in the corresponding compounds with cyclopentane (Acc5) and cyclohexane (Acc6). The salient features of our investigations are qualitatively consistent with the crystal structures of peptide analogs containing Acc4, Acc5, and Acc6 and the previously reported solution phase and conformational studies on peptides containing Acc5. Our results have implications for the design of γ-turn and α-/310-helical peptidomimetics.
  • Kana M. Mukherjee, T. N. Misra
    1997 Volume 70 Issue 2 Pages 301-305
    Published: 1997
    Released: June 11, 2006
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    Surface enhanced Raman spectra (SERS) of 2- and 3-bromothiophene molecules in silver sol are compared with those of molecules in acetonitrile solution. The experimental results suggest that the 2-isomer is adsorbed on the metal surface through both the sulfur and the bromine atoms, with the thiophene molecular plane almost normal to the surface, whereas the 3-isomer is adsorbed principally through the sulfur atom. The Raman excitation profile of the molecules in the surface adsorbed state follows surface plasmon resonance frequency, reflecting the contribution of classical electromagnetic effect to SERS in silver sol. The observed “first layer effect”, i.e. maximum enhancement on a monomolecular layer formation on the metal surface, suggests charge transfer contribution to SERS of these molecules. Further, appearance of Ag–Br and Ag–S stretching modes in the SER spectra of 2-isomer indicates chemisorption of the adsorbate molecules on the metal surface.
  • Somes Kumar Das, Ashish Bansal, Sneh Kumar Dogra
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 2 Pages 307-313
    Published: 1997
    Released: June 11, 2006
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    Spectral characteristics of 2-(2-hydroxyphenyl)benzimidazole (HPBI) have been studied in solutions containing different compositions of dioxane–water mixtures, aqueous sodium dodecyl sulfate (SDS), hexadecyltrimethylammonium bromide (HTAB), and Triton X-100 (TX-100). The correlation curve between the fluorescence band maxima () and the dielectric constant of dioxane–water solutions provides a better rule than the pure solvents to find the polarity at the binding site of the fluorophore in micelles. The effective dielectric constant at the binding sites of SDS, HTAB, and TX-100 are found to be 40, 20, and 20, respectively. The values of the binding constants of HPBI to these micelles conform to the above results. pKa values for various proton transfer reactions were determined at different concentrations of SDS, HTAB, and TX-100, both in the ground and singlet states, and these are discussed.
  • Minoru Handa, Mayumi Kataoka, Makoto Wakaumi, Yukio Sasaki
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 2 Pages 315-320
    Published: 1997
    Released: June 11, 2006
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    The physical properties of 3-propyl-4-ethylsydnone at various temperatures were investigated by dielectric constant (ε), refractive index (nD), density (ρ), and viscosity (η) measurements. The dielectric constant of 3-propyl-4-ethylsydnone was very high compared with those of many organic solvents. For example, it was found to be 64.6 at 25 °C, close to that of propylene carbonate (64.9), a typical nonaqueous polar solvent with a high dielectric constant. The refractive index and density for 3-propyl-4-ethylsydnone decreased linearly with increasing temperature. The viscosity of 3-propyl-4-ethylsydnone at 25 °C was 11.2 cP (1 cP = 10−3 N s m−2). This was larger than those of many organic solvents and close to that of phenol (11.6 cP at 20 °C). From a line for log η vs. 1/T, the activation energy (Eη) for the viscosity of 3-propyl-4-ethylsydnone was found to be 29.7 kJ mol−1. The estimation of donor (DN) and acceptor (AN) numbers for 3-propyl-4-ethylsydnone were also done from 29Si and 13C NMR spectroscopies, respectively. Donor number of 3-propyl-4-ethylsydnone was about 25, and its acceptor number was approximately about 20. Both numbers were large in many organic solvents. Both physical and donor–acceptor properties were influenced by alkyl substituent groups in the 3-, 4-positions of the sydnone ring.
  • Michio Kobayashi, Xinghai Yuan, Norio Shinbo, Masashi Watanabe, Masuno ...
    1997 Volume 70 Issue 2 Pages 321-327
    Published: 1997
    Released: June 11, 2006
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    A unified theory of uniaxially- and biaxially-stretched film methods has been proposed. This theory allows the decomposition of the electronic absorption spectrum into three-dimensional reduced spectra polarized along the molecular orientation axes. A transformation theory has also been proposed to transform these reduced spectra to the three-dimensional reduced spectra polarized along the molecular axes, assuming that there exist a pure band and an overlapping band in the spectrum. These theories were applied to get the three-dimensional reduced spectra of perylene.
  • Masashi Tanaka, Hisahiro Hayashi, Shingo Matsumoto, Setsuo Kashino, Ko ...
    1997 Volume 70 Issue 2 Pages 329-337
    Published: 1997
    Released: June 11, 2006
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    The crystals of 2,3-bis(phenylthio)-1,4-naphthoquinone have the dimorphs of red and violet forms. The crystal structures of a monoclinic form (violet form) and an orthorhombic form (red form) have been determined by the X-ray diffraction method. In the orthorhombic form, two phenylthio groups are located on the same side of the naphthoquinone plane, while in the monoclinic form one phenylthio group is located on the naphthoquinone plane and the other phenylthio group is located under the plane. The violet form changes to the red form upon heating. The thermochromism of these crystals was studied, based on the crystal structures of the dimorphs and the solid state CP-NMR and IR and visible absorption spectra and the differential scanning calorimetry together with the theoretical analysis of the data of IR and visible absorption spectra.
  • Mojtaba Shamsipur, Morteza Akhond
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 2 Pages 339-343
    Published: 1997
    Released: June 11, 2006
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    A given mixture of aza-18-crown-6 and plamitic acid was found to be an excellent cooperative carrier for the efficient transport of Ag+ ions through a bulk liquid membrane. In the presence S2O32− ion, as a suitable metal ion acceptor in the receiving phase, the amount of silver transported across the liquid membrane after 90 min was 93.6 ± 1.5%. The selectivity and efficiency of silver transport from aqueous solutions containing other cations such as Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Pb2+, and Fe2+ ions were investigated. In the presence of diphosphate as a suitable masking agent in the source phase, the interfering effect of Cd2+ ion was eliminated.
  • Kazuyuki Maeda, Yoshie Hashiguchi, Yoshimichi Kiyozumi, Fujio Mizukami
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 2 Pages 345-349
    Published: 1997
    Released: June 11, 2006
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    The first aluminum methylphosphonate with a layered structure, designated AlMepO-ζ, giving an ideal composition of Al(OH)(O3PCH3)·H2O was synthesized with a hydrothermal procedure. AlMepO-ζ is monoclinic, space group P21/c, with a = 7.8676(7), b = 7.0744(13), c = 9.4789(7), β = 106.599(6)°. The framework in a sheet containing unidimensional [–Al–(OH)–Al–] chain is topologically the same as VO(O3PC6H5)·H2O. Methyl groups protrude into the interlamellar space. TG-DTA and MAS-NMR results revealed the decomposition mechanism.
  • Yoriko Saitoh, Hitoshi Watarai
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 2 Pages 351-358
    Published: 1997
    Released: June 11, 2006
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    Interfacial ion-association adsorption of 5,10,15,20-tetrakis(4-sulfonatophenyl)-21H,23H-porphine (H2tpps4−) with hexadecyltrimethylammonium ion and 5,10,15,20-tetrakis(1-methyl-4-pyridinio)-21H,23H-porphine (H2tmpyp4+) with 1-hexadecanesulfonate was measured by means of a total internal reflection fluorometry at toluene/water systems. The adsorptivity of the porphyrins was negligibly small in the absence of the ionic surfactants, but it was increased by the addition of the surfactants in the 10−8—10−7 M concentration. The adsorptivity was governed by the positive or negative charge of the surface-active counter ion and its concentration, which determined the electrostatic potential of the interface. Further, it was found that zinc(II)-1,10-phenanthroline, a hydrophobic complex cation, remarkably enhanced the interfacial adsorption of [Zntpps]4− ion, but showed no positive effect on the adsorption of [Zntmpyp]4+ ion.
  • Toshiaki Hattori, Kazuhito Katai, Sadao Hattori, Masanao Kato
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 2 Pages 359-364
    Published: 1997
    Released: June 11, 2006
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    Ion association constants of two types of poly(vinylamine) and poly(ethylenimine) were determined from pH measurements of the polyamine/counter ion mixtures at an aqueous solution of the polymers (5 × 10−4 equiv mol dm−3). The results are discussed in terms of chemical structure (distance between reacting groups, and straight or branched chain), molecular weight, and ionic strength. The ion association at very low concentration protonated polyamines was promoted by the close location of amino groups. When the bound counter ions became close to each other, further ion association was inhibited by counter ions which had already bounded. From the colloidal titration of these polyamines, the stoichiometry could be discussed, especially under the conditions where all amino groups on the polymer are converted into ammonium ions. The results of the colloidal titration indicated that the stability constant for the ion association was drastically increasing near the equivalence point of the colloidal titration.
  • Isao Sanemasa, Ji-Shi Wu, Kei Toda
    1997 Volume 70 Issue 2 Pages 365-369
    Published: 1997
    Released: June 11, 2006
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    Cyclodextrins (CyD’s) have been precipitated as inclusion complexes with guest hydrocarbons from an aqueous medium, in which the guest hydrocarbon of interest was present in various concentrations. The solubility product constant of the CyD precipitate at 25 °C was determined by measuring the CyD concentration in the supernatant aqueous solution. Five model hydrocarbons were used as guests: hexane, cyclohexane, benzene, naphthalene, and biphenyl. The solubility products and the solubility in water of α-, β-, and γ-CyD inclusion complex precipitates with 36 varieties of guests were calculated based on the solubility of the guest hydrocarbon in water and the concentration of free CyD in the supernatant aqueous medium.
  • Isao Sanemasa, Ji-Shi Wu, Kei Toda
    1997 Volume 70 Issue 2 Pages 371-375
    Published: 1997
    Released: June 11, 2006
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    Cyclodextrin (CyD) precipitates with normal alcohols (guests, 1-butanol to 1-decanol) were prepared at 25 °C by introducing an alcohol vapor into an aqueous CyD solution and circulating it in a closed system. The guest/CyD molar ratio of the precipitates was measured immediately after preparation and after having been allowed to stand in air at room temperature for 30 or 40 d. Precipitates were obtained with alcohols higher than 1-pentanol for α-CyD, 1-hexanol for β-CyD, and 1-butanol for γ-CyD. The reason that CyD does not precipitate with lower alcohols could be explained in terms of the solubility product. There was a linear relationship between the apparent solubility (derived from the solubility product) of the CyD precipitates in water and the guest–CyD association constant. Upon drying in air, the guest/CyD molar ratio in the precipitates gradually decreased with days allowed to stand. In the cases of α- and γ-CyDs, the ratio remained constant after one week.
  • Shuji Emori, Toshiaki Hara
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 2 Pages 377-379
    Published: 1997
    Released: June 11, 2006
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    Dinuclear nickel(II) alkanoates, [Ni2(RCOO)4(quin)2] (R = C2H5CH(CH3)–, C2H5C(CH3)2–, and (C3H7)2CH–; quin = quinoline), were prepared, and then characterized by means of magnetic-susceptibility and IR spectroscopy. The equilibria between the mono- and dinuclear species in mixed acetone–benzene, mixed ethanol–benzene, and mixed tetrahydrofuran–benzene solution are discussed in terms of the donor number of acetone, ethanol, and tetrahydrofuran and in terms of the Ni–O bond strength. By comparing the Ni–O and Cu–O bond strengths, the exchange-coupling strength through the carboxylate bridges between the nickel(II) ions was estimated from that between copper(II) ions.
  • Atsushi Shibayama, Tetsuya Nakamura, Takahiro Asada, Takehiko Shintani ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 2 Pages 381-396
    Published: 1997
    Released: June 11, 2006
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    It was found that the desulfonylation reaction of α,α-dialkylated (E)-allylic sulfones with a base preferentially affords the sterically unfavorable (Z)-alkadienes. The relative degree of the “syn-effect”, which is herein defined as an effect which stabilizes the syn-conformation, leading to (Z)-products, in the transition state against the steric hindrance, was revealed for various substituents at the δ-position of the (E)-allylic sulfones to be as follows: RO– >> CH3– > RS– > –CH2– > (CH3)2CH– >> (CH3)3C– > C6H5–. This finding is in accord with a previously found tendency in the conversion of (E)-vinylic sulfones to the corresponding allylic sulfones under basic conditions.
  • Yoshimi Sueishi, Yuzo Miyake
    1997 Volume 70 Issue 2 Pages 397-403
    Published: 1997
    Released: June 11, 2006
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    The reactions of dibenzoyl peroxide (BPO) with organophosphorus compounds have been studied by means of an ESR technique combined with spin trapping. The intermediate phosphorus-centered radicals were trapped by N-benzylidene-t-butylamine N-oxide (PBN) and 5,5-dimethyl-1-pyrroline N-oxide (DMPO). The spin adducts with a characteristic hyperfine coupling constant (hfcc) due to a phosphorus atom were observed. From identification of trapped radicals, possible mechanisms of the reactions have been proposed. The hfccs due to β-hydrogen and phosphorus atoms exhibited a large temperature dependence for phosphoranyl–PBN spin adducts, while for phosphinyl–PBN spin adduct the dependence was small. Based on the P and H hfccs, the conformational positions of the adducts trapped by PBN and DMPO are discussed.
  • Hiroyuki Noda, Hiroaki Ohya-Nishiguchi, Hitoshi Kamada
    1997 Volume 70 Issue 2 Pages 405-412
    Published: 1997
    Released: June 11, 2006
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    The electronic states of hematoporphyrin (HP) adsorbed on the cell wall of yeast [biological heterogeneous (BH) system] have been characterized based on its fluorescence spectra, in comparison with those of the HP monomer and oligomer in a homogeneous system. The formation of some adsorption structures of HP on a BH system was confirmed from the fluorescence excitation spectra. An ESR method has also been applied to clarify the mechanism for the production and reaction of active-oxygen species from photoexcited HP on a BH system. The hydroxyl radical derived through a three-electron reduction of oxygen was the major product. The mechanism for producing the hydroxyl radical from photoexcited HP on a BH system is discussed as a characteristic feature for the formation of a heterogeneous system containing monomeric HP.
  • Tatsuo Yamamura, Kyouichi Suzuki, Tatsuya Yamaguchi, Tomihiro Nishiyam ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 2 Pages 413-419
    Published: 1997
    Released: June 11, 2006
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    The antioxidant activities of phenothiazines, carbazoles, and related diphenylamines were evaluated in the oxidation of tetralin at 60 °C and linoleic acid micelles in aqueous dispersion at 37 °C induced by an azo initiator. Phenothiazines were highly antioxidant in both systems. Although diphenylamine and carbazole were not good antioxidants, those having a hydroxy group as a substituent at the ortho or para position to the amino group were potently antioxidant. The antioxidant activity of o-hydroxydiphenylamine was much greater than that of other compounds in both systems due to a stabilization of the phenoxyl radical by delocalization of the unpaired electron to the p-type lone pair of the amino group. A semiempirical MNDO-AM1 calculation was applied to study hydrogen abstractions of antioxidants in the chain process of autoxidation. These results indicated that the rates of oxidation during the induction period correlated with the dissociation energies of the O–H or N–H bonds.
  • C. Akira Horiuchi, Shinji Kiji
    1997 Volume 70 Issue 2 Pages 421-426
    Published: 1997
    Released: June 11, 2006
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    The direct α-iodination of various ketones using iodine-ammonium cerium(IV) nitrate in acetic acid or alcohol gave the corresponding α-iodo ketones in high yields. The effect of cerium salt on the iodination of ketones, and the iodination of 5α-cholestan-3-one using several methods are also discussed. In the reaction of 3,3,5-trimethylcyclohexanone and unsymmetrical ketones, such as 2-hexanone and 2-heptanone, using methanol, ethanol, 1-propanol, and 2-propanol, the regioselective iodination product was obtained. In the case of bromination, the reaction of ketones with bromine and ammonium cerium(IV) nitrate also yielded the corresponding α-bromo ketones.
  • Kuniaki Tatsuta, Shozo Miura, Hiroki Gunji
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 2 Pages 427-436
    Published: 1997
    Released: June 11, 2006
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    A glycosidase inhibitor, nagstatin, has been synthesized from protected L-ribofuranose through the inter- and intra-molecular nucleophilic reactions of the imidazole moieties and the regioselective introduction of a carboxymethyl group.
  • Hayao Matsuhashi, Satoshi Asai, Kazunori Hirabayashi, Yasuo Hatanaka, ...
    1997 Volume 70 Issue 2 Pages 437-444
    Published: 1997
    Released: June 11, 2006
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    A cross-coupling reaction of alkyltrifluorosilanes with aryl halides was achieved using a catalytic amount of tetrakis(triphenylphosphine)palladium(0) and excess of tetrabutylammonium fluoride (TBAF) at 100 °C with high chemoselectitvity. Functional groups like nitro, ketone carbonyl, and formyl tolerated the coupling conditions. Because potassium(18-crown-6) alkyltetrafluorosilicates also underwent a cross-coupling reaction in the presence of an additional molar amount of TBAF, the active species of the coupling reaction was assumed to be pentacoordinate silicates. TBAF in excess was considered to be required for trapping the tetrafluorosilane produced in the catalytic cycle of the cross-coupling reaction.
  • Hiroto Harayama, Takayuki Nagahama, Toyohiro Kozera, Masanari Kimura, ...
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 2 Pages 445-456
    Published: 1997
    Released: June 11, 2006
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    A wide structural variety of S-allylic thiocarbamates 2 can be prepared in good yields by the rearrangement of O-allylic thiocarbamates 1 under three different conditions: thermal activation (neat, 120—150 °C), palladium(0) (25—65 °C), and palladium(II) catalysis (25—65 °C). Of the two possible regioisomers of unsymmetrical S-allylic thiocarbamates 2, those of higher thermodynamic stability can be prepared in high purity under either thermal activation or palladium(0) catalysis. Although the thermodynamically less stable regioisomers of 2 are, in general, hard to be prepared in high purity, some of them (e.g., 2d and 2h′) can be obtained with an exclusive or high selectivity by the catalysis of palladium(II). The stereoisomeric pair of 2j and 2j′ can be prepared selectively by the palladium(0)-catalyzed rearrangement of 1j and 1k, respectively. These reactions proceed with retention of configuration at the allylic stereocenters. S-Allylic (2) and S-alkyl thiocarbamates (7) undergo fragmentation to generate thiolates in the presence of inorganic bases (e.g., K2CO3, K2CO3·Et4N+I) by heating in an aprotic solvent; the thus-formed thiolates react with aromatic iodides and vinyl bromides in the presence of palladium(0) complexes to furnish aryl and vinyl sulfides, respectively. A wide variety of aryl sulfides can be prepared in good yields irrespective of the kind of substituents and their substitution positions (o-, m-, p-) under conditions B [Pd(OAc)2, PPh3, K2CO3·Et4N+I, dioxane, 100 °C]. Under conditions E [Pd(OAc)2, PPh3, Cs2CO3, dioxane, 100 °C], better yields result specifically for the sulfenylation of aromatic iodides bearing substituents having large Hammett σ constants.
  • Michinori Oki, Ichiro Fujino, Daisuke Kawaguchi, Kazumasa Chuda, Yoko ...
    1997 Volume 70 Issue 2 Pages 457-469
    Published: 1997
    Released: June 11, 2006
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    The ap and sc rotamers of the title compound, where substituents are 1,4-dimethyl, 1,4-dimethoxy, 1,2,3,4-tetrafluoro, and 1,2,3,4-tetrachloro, were thermolyzed in toluene solutions to examine the effects of interactions between the radical center and the substituent. The rates of thermolyses were affected neither by the substituent nor by the rotameric positions, but the product distributions showed dependence on the substituent. In the ap-forms, the effectively bulkier the substituent at the 1-position, the higher the yields of the 5-membered ring compound. This was attributed to the degree of the tilting of the 9-substituent, which forces the radical center to be pushed into the triptycene skeleton. For the sc-forms, the chloro and the methyl substituents exhibited special effects, the former affording a colligation product between benzyl and 2-(1,2,3,4-tetrachloro-9-triptycyl)-2-methylpropyl radicals and the latter showing a tendency of radical migration to the benzylic position. Comparison of the results of thermolyses of the 1,4-dimethyl peroxyester with those of 2(1H)-thioxo-1-pyridyl 3-(1,4-dimethyl-9-triptycyl)-3-methylbutanoate indicates that, although it is believed that these precursors afford the same 2-(1,4-dimethyl-9-triptycyl)-2-methylpropyl radicals, the product distributions were significantly different from each other. These results were attributed to the stabilizing effects of the sulfur compound on the radical in the solvent cage in the latter.
  • Keiichi Akimoto, Kazuto Masaki, Juzo Nakayama
    1997 Volume 70 Issue 2 Pages 471-476
    Published: 1997
    Released: June 11, 2006
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    The nucleophilic addition of 1,1-dipiperidinoethene to carbon disulfide gives an inner salt, 3,3-dipiperidino-3-propylium-1-dithioate (8), in good yield. The inner salt 8 exists as an equilibrium mixture with its tautomer 3,3-dipiperidinodithioacrylic acid in the ratio of 9 : 1 in CDCl3 at 22 °C. The air-oxidation of 8 leads to bis(3,3-dipiperidinothioacryloyl) disulfide. The inner salt 8, prepared in situ, reacts with a wide variety of alkyl halides to provide a convenient synthesis of alkyl 3,3-dipiperidinodithioacrylates in one-pot.
  • Tadao Uyehara, Miyuki Ishikawa, Fumi Iikura, Noriko Yoneta, Masako Uen ...
    1997 Volume 70 Issue 2 Pages 477-482
    Published: 1997
    Released: June 11, 2006
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    Both enantiomers of 1-methoxybicyclo[2.2.2]oct-5-en-2-ones were prepared in more than 80%ee on the basis of a chemoenzymatic reaction sequence. The optical resolution was achieved by the enantioselective hydrolysis of chloroacetyl esters 1-methoxybicyclo[2.2.2]oct-5-en-endo-2-ols using commercially available lipases.
  • Yoshikazu Ohtsuka, Osamu Katoh, Takeshi Sugai, Hiromichi Ohta
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 2 Pages 483-491
    Published: 1997
    Released: June 11, 2006
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    A Pichia farinosa IAM 4682 mediated reduction of sulfur containing ketones afforded secondary alcohols with (R)-absolute configuration. For example, 4-(phenylthio)-2-butanone and 4-(phenylsulfonyl)-2-butanone afforded (R)-4-(phenylthio)-2-butanol (91%ee) in 90% yield and (R)-4-(phenylsulfonyl)-2-butanol (97%ee) in 94% yield, respectively. In the case that the ee of the product was not satisfactory, any contaminating (S)-enantiomer was selectively oxidized by Rhodococcus rhodochrous IFO 15564 to leave pure (R)-enantiomer. The substrate specificity of Pichia farinosa-mediated reduction and Rhodococcus rhodochrous-mediated oxidation was further examined.
  • Katsutaka Yasue, Akira Yanagisawa, Hisashi Yamamoto
    1997 Volume 70 Issue 2 Pages 493-497
    Published: 1997
    Released: June 11, 2006
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    The regioselective coupling reaction of epoxides with allylic barium reagents was achieved. All reactions resulted in high yields with remarkable α-selectivities. 2-Propynylbarium reagent afforded exclusively the corresponding acetylenic alcohol.
  • Masaaki Haneda, Yoshiaki Kintaichi, Megumu Inaba, Hideaki Hamada
    Type: Accounts
    Subject area: AI
    1997 Volume 70 Issue 2 Pages 499-508
    Published: 1997
    Released: June 11, 2006
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    The catalytic performance of metal-impregnated TiO2–ZrO2 binary metal oxide for the selective reduction of NO was investigated. The addition of silver to TiO2–ZrO2 catalyst caused a drastic enhancement of NO reduction activity with propene. This silver additive effect was accounted for by the assumption that silver promotes the reaction of NO2 with propene to form a partially oxidized hydrocarbon, which is the rate-determining step. However, the catalytic activity of silver-supported TiO2–ZrO2 was depressed by the presence of water vapor because of its inhibiting effect on the formation of the oxygenated intermediate. Oxygen-containing compounds such as 2-propanol and acetone were also found to be good reductants on silver-supported TiO2–ZrO2 in the absence of water vapor. Moreover, the presence of water vapor significantly enhanced NO reduction activity of silver-supported TiO2–ZrO2 with these reductants. It was presumed that water vapor accelerates the selective reduction of NO by suppressing the undesirable oxidation of the reductants by O2.
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