Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 68 , Issue 1
Showing 1-50 articles out of 53 articles from the selected issue
  • Eizi Hirota
    1995 Volume 68 Issue 1 Pages 1-16
    Published: 1995
    Released: June 30, 2006
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    The microwave and/or infrared spectra of alkali monoxides and NO3 were observed in order to characterize these molecules in detail, which play significant roles in atmospheric chemistry. Similar studies were carried out on a few inorganic molecules, including SinHm neutrals and ions with n = 1, 2 and m = 1, 2, 3, in view of their important roles in electronic-device processing. Recent innovations in high-resolution spectroscopic methods are briefly discussed.
  • Teruaki Mukaiyama, Tohru Yamada
    1995 Volume 68 Issue 1 Pages 17-35
    Published: 1995
    Released: June 30, 2006
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    Recent advances in the aerobic oxygenations of olefins using transition-metal complex catalysts are reviewed. The main topics focused on are the cobalt(II)-complex-catalyzed oxygenation of olefins, nickel(II)-complex-catalyzed aerobic epoxidation, enantioselective, aerobic epoxidation using chiral manganese(III) complex catalysts, aerobic Baeyer–Villiger oxidation and direct oxygenation of aromatic compounds.
  • Ryoji Noyori, Makoto Tokunaga, Masato Kitamura
    1995 Volume 68 Issue 1 Pages 36-55
    Published: 1995
    Released: June 30, 2006
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    Asymmetric catalysts, either chemical or biological, effect the reactions of enantiomeric substrates at unequal rates, allowing for the kinetic resolution of racemates. The asymmetric reaction of chirally labile compounds capable of undergoing in situ racemization can, in principle, afford a single stereoisomer in 100% ee and in 100% yield. The second-order reaction provides a powerful tool for the stereoselective synthesis of chiral compounds, as exemplified by, among others, the biochemical hydrolysis of hydantoins or oxazolinones and microbial reductions or BINAP–Ru(II) catalyzed hydrogenation of certain α-substituted β-keto esters. Such transformations are characterized by the presence of parallel reactions interrelated by the stereoinversion of the enantiomeric substrates. The efficiency is decisively affected by the kinetic parameters, particularly the relative rates of the stereoinversion and reaction as well as the intrinsic stereochemical parameters of the catalyst and substrate. Such stereoselective reactions via dynamic kinetic resolution are expressed mathematically and the stereochemical profiles are displayed graphically. The validity of this basic approach has been verified by the correlation to the experimental results.
  • Hiroshi Uyama, Kazuhiro Takeya, Shiro Kobayashi
    1995 Volume 68 Issue 1 Pages 56-61
    Published: 1995
    Released: June 30, 2006
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    Enzymatic ring-opening polymerization of macrolides was carried out by using various lipases as catalysts. The monomers used in this study were 11-undecanolide (12-membered, UDL) and 15-pentadecanolide (16-membered, PDL). Among the enzymes examined, lipases derived from Pseudomonas fluorescens (lipase P) and from Candida cylindracea (lipase B) gave polyUDL with high molecular weight in a high yield. From 1H and 13C NMR analysis, the polymer was found to possess the terminal structure of a carboxylic acid group at one end and a hydroxyl group at the other. The rate of the UDL polymerization using lipase P was larger than that using lipase B, whereas the polymerization of UDL using lipase B produced the polymer of higher molecular weight in comparison with that obtained by using lipase P. Lipases from Pseudomonas sp. and porcine pancreas showed a catalytic activity for the polymerization of UDL. PDL was also polymerized by lipase catalyst to give the corresponding polyester. The enzymatic polymerizations of UDL and PDL have been compared with that of 6-hexanolide (ε-caprolactone, ε-CL). The polymerization of the macrolides using lipase P proceeded much faster than that of ε-CL. This is probably due to the strong recognition of the macrolides by the lipase catalyst.
  • Fumitoshi Kakiuchi, Shinya Sekine, Yasuo Tanaka, Asayuki Kamatani, Mot ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 62-83
    Published: 1995
    Released: June 30, 2006
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    Ruthenium complexes, e.g., Ru(H)2(CO)(PPh3)3, have been found to catalyze the addition of ortho C–H bonds of aromatic ketones to olefins with a high degree of efficiency and selectivity. 2′-Methylacetophenone reacts with various types of terminal olefins to give 1 : 1 coupling products in good to excellent yields. The C–C bond formation takes place exclusively at the terminal carbon atom of olefins except for styrene which affords a mixture of two regioisomers. Acetylnaphthalenes, cyclic aromatic ketones, and heteroaromatic ketones also react with triethoxyvinylsilane to give 1 : 1 addition products in virtually quantitative yields. From 2′-acetonaphthone or 3-acetylthiophene, in which two different reaction sites are available, only one out of four possible regioisomers is obtained. The importance of the coordination of the oxygen atom of the ketone to ruthenium and the intervention of a cyclometallation intermediate are suggested. A deuterium labeling experiment using acetophenone-d5 and triethoxyvinylsilane shows that an H/D exchange between the aromatic and olefinic positions takes place to some extent, even prior to the formation of the product. This implies that the rate-determining step is not the C–H bond cleavage step, but the product forming step.
  • Janakiamma Jayasree, Cadavallore S. Narayanan
    1995 Volume 68 Issue 1 Pages 84-88
    Published: 1995
    Released: June 30, 2006
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    Binary oxides of alumina with rare earths like europium, samarium, praseodymium, neodymium, and yttrium were prepared by coprecipitation from corresponding nitrates. The composition, thermal stability, and surface properties of the catalysts were determined using XRD, TGA, XPS, and MAS 27Al NMR. Surface area and pore size of the catalysts were determined by BET and mercury porosimetry. The catalysts were found to be amorphous and aluminium atom showed tetrahedral and octahedral coordination in its lattice. Catalysts showed weak to moderate acidity and basicity.
  • Janakiamma Jayasree, Cadavallore S. Narayanan
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 89-94
    Published: 1995
    Released: June 30, 2006
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    The catalytic activity of binary oxides of Al2O3–Eu2O3, Al2O3–Sm2O3, Al2O3–Nd2O3, Al2O3–Pr6O11, and Al2O3–Y2O3 were checked in the transformations of α and β-pinene oxides. Al2O3–Eu2O3 and Al2O3–Nd2O3 are found to be best catalysts for α-pinene oxide isomeriztion. Among the oxiranes, α-pinene oxide showed more activity mainly yielding 2,2,3-trimethyl cyclopentene-1-acetaldehyde. β-pinene oxide produced trans-myrtanal and myrtanol.
  • Kazuyoshi Ueda, Hiroshi Ochiai, Akira Imamura, Setsuko Nakagawa
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 95-106
    Published: 1995
    Released: June 30, 2006
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    Carrageenan is known to change its conformation from coil to helix and to form a gel. However, the accurate conformation and the transition mechanism have not yet been detailed. In this work, the conformational behavior of β-carrageenan (a copolymer with a carrabiose repeating unit, 1,4-linked 3,6-anhydro-α-D-galactose (A) and 1,3-linked β-D-galactose (B)), was studied by using molecular mechanics and molecular dynamics simulation methods with the program CHARMM22. The energy maps of the carrabiose as a function of the dihedral angles of the glycosidic linkages between the AB (1–3 linkage) and BA (1–4 linkage) carrabiose units were calculated. Both carrabiose units were found to have five deep potential energy minima. Based on these carrabiose conformations, 25 conformers of the single helical chain carradodecaose were constructed and their minimum energy conformations were investigated by molecular mechanics and molecular dynamics simulations. From the results of these analyses, a possible single helical structure of β-carrageenan was elucidated. The stability of this helical conformation is discussed by comparing it with a double helical conformation, which was found from X-ray diffraction analyses of oriented fiber samples of κ-and ι-carrageenans, which are well-studied members of the carrageenan family.
  • Mohamed Karroua, Haris Matralis, Edgardo Sham, Paul Grange, Bernard De ...
    1995 Volume 68 Issue 1 Pages 107-119
    Published: 1995
    Released: June 30, 2006
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    Unsupported Co9S8, MoS2, and CoMoS sulfides (prepared by the HSP method) as well as supported MoS2/Al2O3 and CoSx/C (prepared by impregnation) were used to prepare a series of binary mechanical mixtures of various compositions. A variety of physicochemical techniques (temperature programmed decomposition and sulfidation, both followed by subsequent TPO, XRD, TPR, microelectrophoresis, XPS and AEM) were used to study the samples, verify the formation of the “CoMoS phase” in the mixed CoMo sulfide and investigate the existence of interactions between the sulfides forming the mechanical mixtures. The catalytic activity of the supported and unsupported HSP sulfides as well as that of the mechanical mixtures was tested in the hydrodesulfurization of thiophene (HDS) and the hydrogenation of cyclohexene (HYD) at 573 K and 3 MPa. The mechanical mixtures exhibit a synergy in HDS and HYD. This shows that cobalt sulfide (supported or unsupported HSP) can promote the activity not only of molybdenum sulfide, but also of the unsupported HSP “CoMoS phase”. In addition, XRD and AEM (performed before and after catalytic tests) were used to study the evolution of the unsupported “CoMoS phase” during the catalytic reaction. It was found that this phase is unstable; cobalt segregates from the CoMoS association to form Co9S8, even after a relatively short period in the reactor. These results provide more evidence that the remote control mechanism plays a major role in the synergetic behavior of the CoMo hydrotreating catalysts.
  • Terutake Koizumi, Osamu Kikuchi
    1995 Volume 68 Issue 1 Pages 120-122
    Published: 1995
    Released: June 30, 2006
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    Ab initio calculations of the molecular structure and NMR C–Li coupling constant for trichloromethyllithium have indicated that the classical C3v form is favorable for trichloromethyllithium observed by NMR spectroscopy.
  • Seiji Yamasaki, Hisao Tsutsumi
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 123-127
    Published: 1995
    Released: June 30, 2006
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    1,3 : 2,4-Di-O-benzylidene-D-sorbitol (D-DBS) is known as a chiral oil gelator for a wide variety of organic solvents. The relationship between texture, structure of the gel, and the aggregated structure formed by D-DBS was investigated in various solvents. In the low polar solvents, the gel held a mesh type network structure in which the fiber appeared to be a rope-like helical structure. In the moderately polar solvents, the gel held an isotropic mesophase, but in the polar solvents, a spherulite texture was observed. From the experiments for the critical gel concentration of D-DBS in various solvents, it is assumed that there are three regions that differ in the form of hydrogen bonding, depending upon the polarity of solvents. By IR spectroscopic measurements, we found that, with the increase of solvent polarity, the hydrogen bonding between D-DBS and the solvent became more predominant than the intramolecular hydrogen bonding, and the hydrogen bonding between D-DBS became weaker at the same time. In addition, the intensities of CD spectra in the D-DBS gel decreased according to the increase of the solvent polarity. Here it is considered that textures and structurs observed in the gel are related to the aggregated structure that is mainly formed through hydrogen bonding among D-DBS.
  • Hajime Torii, Mitsuo Tasumi
    1995 Volume 68 Issue 1 Pages 128-134
    Published: 1995
    Released: June 30, 2006
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    Model calculations are performed on the Raman noncoincidence effect (frequency difference between the isotropic and anisotropic components) observed in the region of the S=O stretching band of liquid dimethyl sulfoxide (DMSO). Liquid structures are obtained by Monte Carlo simulations, by using potential functions without specific interactions involving the hydrogen atoms of the methyl groups. Intermolecular coupling between the S=O stretches is evaluated by the transition dipole coupling mechanism. The magnitude and the direction of the transition dipole are calculated by ab initio molecular orbital calculations at the second-order Møller–Plesset perturbation level with a basis set extended from 6-31G(2d,p). The calculated sign and magnitude of the Raman noncoincidence are in reasonable agreement with the observed, indicating that the observed large Raman noncoincidence can be mostly explained by the liquid structures obtained without specific interactions involving the hydrogen atoms of the methyl groups. The pair distribution function of liquid DMSO is also calculated to the second order in the orientation correlation of molecules. The origin of the Raman noncoincidence effect is discussed by comparing the cases of liquid DMSO, acetone, and methanol.
  • Shigeyoshi Miyagishi, Hirotaka Kurimoto, Tsuyoshi Asakawa
    1995 Volume 68 Issue 1 Pages 135-139
    Published: 1995
    Released: June 30, 2006
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    The dependence of microviscosity on salt and surfactant concentrations was determined in micellar solutions of alkyltrimethylammonium bromides by using two fluorescent probes, auramine and 1,3-dipyrenylpropane (P3P). The microviscosity increased with the growth of the micelles, it changed at the sphere to rodlike micelles transition point, and it became constant above the overlap threshold point of rod micelles, that is, the overlapping of micelles did not influence the microviscosity. The transition points of the micellar solutions (the critical micelle concentrations, the sphere-rod transition point, and the micelle overlapping point) determined by the present method were in good agreement with those in the literature. Phase diagrams of the micellar solutions were determined from the above data.
  • Souichi Kubota, Michio Matsushita, Tadamasa Shida, Atieh Abu-Raqabah, ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 140-145
    Published: 1995
    Released: June 30, 2006
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    The ESR spectrum of the t-butyl radical in a rigid matrix is observed at temperatures between 6.6 and 70 K. At temperatures below about 50 K equally spaced nineteen lines are observed which is associated with the tunneling rotation of the three methyl groups. By the analysis of the spectral pattern at a low temperature of 6.6 K the pairwise interaction potential of the internal rotation, if any, is deduced to be proportional to cos θi cos θj where θi and θj are the internal rotation angles of two methyl groups. By the simulation of the spectral change with temperature the thermal activation energy for the internal rotation is estimated to be 6 ± 2 kJ mol−1.
  • Seiji Yamasaki, Yukihiro Ohashi, Hisao Tsutsumi, Kaoru Tsujii
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 146-151
    Published: 1995
    Released: June 30, 2006
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    1,3 : 2,4-Di-O-benzylidene-D-sorbitol (D-DBS) can cause gelation of organic solvents of a wide range of polarity into a gel state. The aggregated structures of D-DBS/organic solvent systems were studied, mainly by using IR, UV, and circular dichroism (CD) spectroscopy. In the case of the racemate DL-DBS, no gel state was formed. In IR spectra of D-DBS and DL-DBS in the solid state, the intensities of νOH and νCO absorption in D-DBS were found to be larger than those in DL-DBS. It is assumed that the hydrogen bonding formed between an acetal oxygen and a hydroxyl group in the aggregation of D-DBS. From the changes in the IR spectra from solution into a gel state, we can conclude that the chirality and the hydrogen bonding of DBS molecules are essential for the formation of the gel. Comparing the gel-forming ability of D-DBS with its derivatives, 5- or 6-hydroxyl-group-blocked compounds by methyl group, the 6-hydroxyl group seems to be important in the formation of D-DBS aggregates. The results of UV spectra suggest that the benzene rings are ordered in a side by side arrangement. The molar ellipticities in CD spectra increased about 500 times during the change from the solution to the gel state. From these results, it is concluded that D-DBS forms a helical structure of thin fibrous crystals in the gel state.
  • Yosuke Kataoka, Minoru Fujita
    1995 Volume 68 Issue 1 Pages 152-159
    Published: 1995
    Released: June 30, 2006
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    The self-diffusion coefficient in Lennard–Jones fluid was studied by molecular dynamics simulation. Simulations were done at 414 states in the temperature–volume plane. An equation of state for the self-diffusion coefficient was derived by the least-square fitting. The calculated equation of state was in agreement with the experimental results on CO2. Its pressure dependence was also consistent with that in liquid hexane. The liquid structure was analyzed by the excess coordination number, the distributions of the cluster size and the hole volume. The volume dependence of the self-diffusion coefficient in the two-phase region was discussed in terms of the coordination number in the first shell.
  • Fumio Shimizu, Yoshinori Nibu, Tomoe Osaki, Hiroko Shimada, Ryoichi Sh ...
    1995 Volume 68 Issue 1 Pages 160-164
    Published: 1995
    Released: June 30, 2006
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    The values of the Raman polarizability of some totally symmetric normal vibrations of naphthalene and maleic anhydride were estimated from the analysis of the polarized Raman spectra observed in single crystal. For the totally symmetric ring vibrations of naphthalene the principal elements of the Raman polarizability in the molecular plane are about isotropic and the principal element perpendicular to the molecular plane has the value almost one-half of the values of the in-plane elements. For the totally symmetric C=O and C=C stretching vibrations of maleic anhydride the Raman polarizability shows quite anisotropic character.
  • Toshiyuki Suzawa, Yoshihito Ikariyama, Masuo Aizawa
    1995 Volume 68 Issue 1 Pages 165-171
    Published: 1995
    Released: June 30, 2006
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    A novel homogeneous electrochemical immunoassay using ferrocene- (Fec-), digoxin- (Dig-) doubleconjugated protein, has been developed. The system is based on the principle that electrochemical activity of the conjugate is suppressed in the presence of an antibody, and restored in the presence of free digoxin. Hence, a new homogeneous immunoassay can be carried out when the electroactivity of the conjugate is determined. Here, we synthesize the conjugate by controlling the numbers of ferrocene and digoxin on individual carrier proteins simultaneously. Bovine serum albumin (BSA) is selected as a carrier protein to which the electrochemical labels and the several hapten molecule are bound by Schiff’s base formation. Since the conjugate synthesized here behaves as a multivalent antigen, and is capable of binding to antidigoxin antibody, therefore the antigen having electrochemical activity loses its activity depending on antibody concentration. When the conjugate, in which 39 molecules of ferrocene and 8 molecules of digoxin are bound, is used for the inhibition experiment of electrochemical reaction before and after the immunoreaction, peak height currents, responsible for the redox reactions of the bound ferrocene, decreased depending on the added antibody in a dose-dependent fashion. This system is feasible as a homogeneous electrochemical immunoassay, since the method may provide a simple and a rapid approach toward a homogeneous assay of bioactive substances.
  • Hisao Kokusen, Yoshiki Sohrin, Hiroshi Hasegawa, Sorin Kihara, Masakaz ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 172-177
    Published: 1995
    Released: June 30, 2006
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    Mixed-ligand chelate extraction of trivalent lanthanoid ions (M3+) into benzene with poly(pyrazol-1-yl)borate (HnB(pz)4−n; n = 0, 1) and β-diketone was studied. The β-diketones used were dibenzoylmethane (dbm) and dipivaloylmethane (dpm). Lanthanoid ions were extracted as [M{HnB(pz)4−n}2(β-diketone)]. The logarithmic extraction constants (log Kex) of the [HB(pz)3] systems were 5—6 higher than those of the [B(pz)4] systems. The highest separability for lanthanide ions was achieved with the [B(pz)4]– dbm system. These features of log Kex were principally governed by intra- and interligand steric contact.
  • Nobuyoshi Shinohara, Hirohiko Shibukawa, Kazuteru Shinozaki, Mika Yosh ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 178-182
    Published: 1995
    Released: June 30, 2006
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    Photolyses of μ-amido-μ-hyperoxo-dicobalt(III) complexes, [LCo(NH2,O2)CoL]4+ (L = 4NH3 (1), en + 2NH3 (2), 2en (3), tren (4)), (tren: 2,2′,2″-triaminotriethylamine, en: ethylenediamine) were investigated. The photolysis of complex 4 in a neutral aqueous solution produced a μ-hydroxo-μ-peroxo-dicobalt(III) complex, [(tren)Co(OH,O22−)Co(tren)]3+, together with a mononuclear cobalt(III) complex, [Co(NH3)(tren)(H2O)]3+. A mononuclear complex and Co2+ were produced in the photolyses of μ-hyperoxo complexes 1 and 2 containing NH3 ligand in neutral aqueous solutions. In acidic media, only mononuclear complex and Co2+ were produced in the photolysis of all μ-hyperoxo complexes examined. Quantum yields of the complexes with NH3 increased with increasing the number of coordinated NH3 (φ = 0.25, 0.11, 0.023, and 0.028 for complexes 1, 2, 3, and 4, respectively, at 365 nm irradiation in neutral region). The quantum yields obtained in acidic solutions were similar in magnitude to those obtained in neutral solutions.
  • Nobuyuki Shinkawa, Aya Sato, Junko Shinya, Yukio Nakamura, Seichi Okey ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 183-190
    Published: 1995
    Released: June 30, 2006
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    Oxidative-addition reactions of excess 2-(chloromethyl) and 2,6-bis(chloromethyl)pyridines with [RhCl(PPh3)3] in toluene at room temperature afforded (2-pyridylmethyl)- and {2-(6-chloromethyl)pyridylmethyl}rhodium(III) complexes, cis(PP)-[RhCl2{C5H3(6-R)N-2-CH2}(PPh3)2] (R = H, 1-cis; R = CH2Cl, 2-cis), respectively, which isomerized to the corresponding trans(PP) complexes at elevated temperature. In refluxing toluene, the reactions thus resulted in the trans(PP) complexes (R = H, 1-trans; R = CH2Cl, 2-trans) exclusively. A novel dinuclear rhodium(III) complex [Rh2Cl4{C5H3N-2,6-(CH2)2}(PPh3)2], in which the 2,6-dimethylpyridine-α,α′-diyl ligand is C,N-chelated to one rhodium atom and bound to the second one in an η3-pseudo-1-azaallylic fashion, was obtained by reactions of 2,6-bis(chloromethyl)pyridine with [RhCl(PPh3)3] (1 : 2 in mole) and of the 2-cis with [RhCl(PPh3)3] (1 : 1 in mole), both in refluxing toluene. These were characterized by 1H, 13C, and 31P NMR spectroscopy and mass spectrometry as well as an elemental analysis and a molecular-weight determination.
  • Yasushi Inoue, Hiromichi Yamazaki, Fuminori Kasuga
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 191-196
    Published: 1995
    Released: June 30, 2006
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    The isotopic exchange rate of Na+ between hydrous titanium(IV) oxides, precipitated at pH 6 and 13, in the Na+ form and aqueous solution of sodium salt was determined radiochemically. The rate in the exchanger precipitated at pH 6 is controlled by the diffusion of Na+ in the exchanger particles (particle diffusion). The diffusion coefficient and its activation energy are 1.9 × 10−11 m2 s−1 (pH 12, 5.0 °C) and 29 kJ mol−1 (pH 12), respectively. The rate in the exchanger precipitated at pH 13 is also controlled by the particle diffusion. The rate is much slower than that in the other; this can be explained by assuming the existence of two kinds of independently diffusing ions (fast and slow species) in the exchanger. The diffusion coefficients are of the order of 10−12 and 10−13 m2 s−1 for the fast and the slow species, respectively. Their activation energies are 48—60 kJ mol−1 at pH 12. The marked difference in kinetics between two exchanges was interpreted in terms of the difference in the acid-base property and in the microstructure of the matrix.
  • Mikio Nakamura
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 197-203
    Published: 1995
    Released: June 30, 2006
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    Dissociation rates of the imidazoles in [Co(tpp)(L)2]+ and [Co(tmp)(L)2]+, where L is an unhindered imidazole such as 1-methylimidazole or a hindered imidazole such as 2-alkylimidazole, have been determined in chloroform-d solution by the 1H NMR saturation transfer method. The rate constants in the tmp complexes were smaller than those of the corresponding tpp complexes in every imidazole ligand examined. The largest difference between these two systems was observed in bis(1,2-dimethylimidazole) complexes and the ratio of the rate constants, k(tpp)/k(tmp), reached as much as 2500 at 90 °C. While the rate constants greatly increased in the tpp system on going from the unhindered imidazole to the hindered one, the increase was rather small in the tmp system. These results were interpreted in tems of the deformation of the porphyrinatocobalt core: Since the two hidered ligands in the tmp complexes are fixed perpendicularly in the cavities created by the deformed porphyrin ring, the distance between the 2-alkyl and the deformed porphyrinatocobalt core would increase, which results in weakening the steric repulsion and slowing down the dissociation rate. The attractive interaction between the ortho-methyls and the imidazole π system would also contribute to the stability of the tmp complexes.
  • Yoshio Kamiya, Takashi Hama, Ichiro Kijima
    1995 Volume 68 Issue 1 Pages 204-210
    Published: 1995
    Released: June 30, 2006
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    In order to elucidate the reaction mechanism and the optimum reaction conditions for the formation of 2,6-naphthalenedicarboxylic acid (NDCA), the Co(OAc)2–Mn(OAc)2–NaBr-catalyzed oxidation of 2,6-diethylnaphthalene by molecular oxygen was carried out in acetic acid. The oxidation of the ethyl groups to carboxyl groups proceeded mainly via acetyl groups and partly via 1-hydroxyethyl and 1-acetoxyethyl groups. A synergistic catalytic effect due to Co and Mn acetates was observed not only on the rate of oxidation but also on the selective formation of NDCA. The rate of oxidation was strongly retarded at higher concentrations of the substrate, showing that the naphthalene nucleus terminates the chain reaction step of the oxidation. A high concentration of metal catalyst resulted in an increase of acetoxyethylnaphthoic acid. At the optimum reaction conditions, a nearly 90% yield of NDCA was obtained along with small amounts of substituted naphthoic and trimellitic acids. The differences in the yield of NDCA from 2,6-dimethyl, 2,6-diethyl, and 2,6-diisopropylnaphthalenes were compared under similar reaction conditions and are discussed.
  • Toshiaki Yoshimura, Kazuhiro Hamada, Satoru Yamazaki, Choichiro Shimas ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 211-218
    Published: 1995
    Released: June 30, 2006
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    Reaction of 2-methyl-2-propanesulfenic acid (1) with methyl arenesulfenates (2) gave S-aryl 2-methyl-2-propanethiosulfinates quantitatively, and kinetic investigation was carried out. Second-order rate dependence (first-order in methyl benzenesulfenate (2a) and first-order in the sulfenic acid (1)) was observed, and a small activation enthalpy (ΔH = 28 kJ mol−1) and a large negative activation entropy (ΔS = −130 J K−1 mol−1) were obtained. Kinetics for the reaction of trans-decalin-9-sulfenic acid (3) with the sulfenates 2 under acidic conditions in methanol–water gave the observation of the second-order dependence, a small activation enthalpy (ΔH = 30.5 kJ mol−1), a large negative activation entropy (ΔS = −140 J K−1 mol−1), a large negative Hammett ρ-value (ρ = −1.39) and no solvent isotope effect (kMeOH/kMeOD = 1.10—1.14 in the range of 15.64—29.98 °C). Kinetics for acidic hydrolysis of the sulfenate 2 under the same conditions afforded the similar activation parameters (ΔH = 40.7 kJ mol−1, ΔS = −200 J K−1 mol−1 at [H2O] = 0.80 × 10−3mol dm−3) and a larger negative Hammett ρ-value (ρ = −2.22) than that for the reaction of the sulfenic acid 3 with the sulfenate 2. From these results, structures of the transition state for both the self-condensation of sulfenic acid and the hydrolysis of the sulfenate ester 2 were discussed. The reaction of sulfenate esters 2 with stable sulfenic acids is a good model for studying the self-condensation of sulfenic acids.
  • Bunsho Makino, Masao Kawai, Yasushi Iwata, Hatsuo Yamamura, Yasuo Buts ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 219-226
    Published: 1995
    Released: June 30, 2006
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    Physalin K was isolated from Physalis alkekengi var. francheti. Spectroscopic studies and chemical correlations, however, revealed that the reported structure of physalin K at the AB ring moiety, namely, 4α,5α-epoxy-6α-hydroxy-2-en-1-one, should be revised to 2α,5α-epidioxy-6β-hydroxy-3-en-1-one. A new physalin, named physalin Q, was also isolated and identified as the 2β,5β-epidioxy diastereomer of physalin K.
  • Tatsuya Nabeshima, Naoko Tsukada, Tsutomu Haruyama, Yumihiko Yano
    1995 Volume 68 Issue 1 Pages 227-229
    Published: 1995
    Released: June 30, 2006
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    Cyclization reaction of S-substituted thioglycerol and oligoethylene glycol ditosylate gave thiolariat ethers in moderate yields. Mercaptomethyl crown ethers were obtained easily from benzylthiomethyl crown ethers by Na in liq. NH3–BuOH.
  • Michihiro Ohnishi, Coe Ishimoto, Jun’etsu Seto
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 230-236
    Published: 1995
    Released: June 30, 2006
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    The adsorption of two kinds of chromoproteins, cytochrome c and glucose oxidase, was observed at an air/water interface by reflection spectroscopy using optical fibers. The relation between the adsorption of cytochrome c onto an amphiphilic monolayer and the deposition of the monolayer with cytochrome c by the Langmuir–Blodgett (LB) technique was clarified. It was found out that a good Y-type LB film, with a transfer ratio of 0.9—1.0, was obtained when the adsorbed area of cytochrome c was less than about 84% of the maximum average coverage. The reflection spectrum of glucose oxidase, not as such, but stained with coomassie brilliant blue (CBB), could be successfully observed. Since CBB is applicable to almost any protein, the reflection spectroscopy of almost any protein, not only chromoproteins, is possible.
  • Ryoji Yanagihara, Jun Egashira, Sadao Yoshikawa, Shuichi Osanai
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 237-242
    Published: 1995
    Released: June 30, 2006
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    A simple one-stage reaction system which yields 2-C hydroxymethylated aldopentose has been investigated. Four different 2-C branched aldopentoses (2-C hydroxymethylated D-arabinose, D-ribose (Hamamelose), L-lyxose, and D-xylose) were prepared from the corresponding ketoses (D-psicose, D-fructose, L-sorbose, and D-tagatose, respectively). These branched sugars were synthesized by a similar mechanism to the 2-C epimerization of aldose using a nickel complex. It was confirmed that the isomerization of ketose to the side-branched sugar proceeded in the ternary nickel complex through a sequence of stereospecific rearrangements in the sugar. The yields were dependent upon the structure of the substrate ketose and the nickel-ethylenediamine complex. N,N′-Dialkylated cyclohexanediamines were the most suitable ligands for preparing the 2-C hydroxymethylated branched chain sugar.
  • Masanori Wada, Hisashi Mishima, Tetsuya Watanabe, Satoko Natsume, Hide ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 243-249
    Published: 1995
    Released: June 30, 2006
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    A series of triarylmethanols bearing o-methoxyl groups (1a: [2,6-(MeO)2C6H3]3COH, 1b: (2-MeOC6H4)[2,6-(MeO)2C6H3]2COH, 1c: Ph[2,6-(MeO)2C6H3]2COH, 1d: [2,5-(MeO)2C6H3]3COH, 1e: Ph2[2,6-(MeO)2C6H3]COH) were prepared. Corresponding carbenium salts, [Ar3C]X 2ac, were isolated by short-period treatments of Ar3COH 1ac with a slight excess of acid in some bulky alcohols, such as 2-propanol or 2-methyl-1-propanol. The high basicity of 1ac was explained by through-space interactions of a pair of 2p electrons of an o-methoxyl oxygen with an empty 2p orbital of the resulting carbenium carbon. In ethanol, 1-butanol or 3-methyl-1-butanol, 1c, as well as 2c, was reduced under very mild conditions to triarylmethane, Ar3C–H 3c, and in other bulkier alcohols it was reduced under more forcing conditions. The formations of aldehyde or ketone, the by-product, were confirmed in some cases. Compounds 1a,b,d,e, as well as 2a,b, reacted in analogous manners under more forcing conditions. The reaction rates in several alcohols increased in the order 2a < 2b < 2c, and the reaction rates of alcohol for 2c decreased in the order ethanol > 3-methyl-1-butanol > 1-butanol > 2-propanol > methanol > 2-butanol > 2-methyl-1-propanol. Compounds 2b,c were also reduced in tetrahydrofuran, and formed xanthene derivatives in dimethyl sulfoxide or in water.
  • Kozo Matsumoto, Yoshihiro Takeyama, Katsukiyo Miura, Koichiro Oshima, ...
    1995 Volume 68 Issue 1 Pages 250-261
    Published: 1995
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    Two methods for ring enlargement of silacyclobutane into silacyclopentane have been described. (1) Treatment of 1-(1-iodoalkyl)silacyclobutane with t-BuOK or AgOAc provided 2-alkyl-1-silacyclopentanes which were easily converted into 1,4-diols by oxidative cleavage of carbon–silicon bond. (2) An addition of i-PrOLi to 1-[(Z)-1,2-epoxyhexyl]-1-methylsilacyclobutane gave erythro-2-(1-hydroxypentyl)-1-isopropoxy-1-methylsilacyclopentane, which was converted into (Z)-4-nonen-1-ol, (E)-4-nonen-1-ol, or 1,4,5-nonanetriol.
  • Atsuhiro Osuka, Shinji Marumo, Kazuhiro Maruyama, Noboru Mataga, Yoshi ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 262-276
    Published: 1995
    Released: June 30, 2006
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    The synthesis and excited-state dynamics are described for fixed-distance porphyrin–oxochlorin–pyromellitdimide triads (P–C–Im) and related reference compounds. In zinc-oxochlorin–pyromellitdimide (ZnP–Im), the 1(ZnC)* is quenched by the attached Im through intramolecular charge separation (CS) in benzene, THF, and DMF, while the 1(H2C)* in the corresponding free base is not significantly quenched by the Im even in polar DMF. In the steady-state fluorescence emission spectra, only the emission from the 1(C)* is commonly observed, indicating an efficient intramolecular singlet–singlet excitation energy transfer from P to C. Of these, the fluorescence intensities of the 1(H2C)* in ZnP–H2C and ZnP–H2C–Im are significantly reduced in polar DMF solution and this is attributed to the intramolecular CS that gives (ZnP)+–(H2C)–Im and (ZnP)+–(H2C), respectively. The (ZnP)+–(H2C)–Im ion pair is clearly shown, by picosecond absorption spectroscopy, to be converted into a secondary, longer-lived charge separated state (ZnP)+–H2C–(Im) via charge-shift reaction in competition with wasteful charge recombination to the ground state. The (ZnP)+–H2C–(Im) state is formed in 0.09 quantum yield from ZnP–1(H2C)*–Im and has a lifetime of 0.24 μs in DMF.
  • Toshiki Komatsu, Masahiro Tsuchiya, Gen-ichi Furusawa, Yasunao Kuriyam ...
    1995 Volume 68 Issue 1 Pages 277-281
    Published: 1995
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    Pulsed laser excitation of contact charge transfer pairs of hexamethylbenzene (HMB) and oxygen in methanol-acetonitrile gave no evidence for intermediacy of reactive species such as HMB radical cations and pentamethylbenzyl cations (ArCH2+), though stationary irradiation of the pair in hydroxylic solvents afforded distinct products arising from the cationic species. The mechanism of reactions was discussed in comparison with 9,10-dicyanoanthracene-sensitized oxygenation of HMB.
  • B. Radha Rani, Makoto Ubukata, Hiroyuki Osada
    1995 Volume 68 Issue 1 Pages 282-284
    Published: 1995
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    Zinc dust in acetic acid has been found to be a versatile and chemoselective reagent for the reduction of various arylcarbonyls to the corresponding alcohols or their acetates in fair yields.
  • Yasushi Kawai, Kousuke Takanobe, Atsuyoshi Ohno
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 285-288
    Published: 1995
    Released: June 30, 2006
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    Stereoselectivity of microbe-catalyzed reduction of ethyl 2-methyl-3-oxobutanoate to optically active 3-hydroxy-2-methylbutanoate can be controlled by the addition of methyl vinyl ketone to the reaction system. The reduction by Geotrichum candidum, Endmyces magnusii, and Mucor javanicus with an appropriate additive affords the corresponding anti-(2S,3S)-hydroxy ester selectively, whereas the reduction by bakers’ yeast and Candidatropicalis with an additive gives the corresponding syn-(2R,3S)-hydroxy ester selectively.
  • Jun Fujiwara, Jin Tokuyasu, Tadashi Sato
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 289-296
    Published: 1995
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    α-Ethylidenecycloalkanones underwent a ring enlargement to β-alkylidenecycloalkanones upon a treatment with trimethylstannyllithium/aldehyde equivalents/Lewis acids with high stereoselectivity.
  • Yoo Tanabe, Hitomi Yamamoto, Yoshihiro Yoshida, Takashi Miyawaki, Naok ...
    1995 Volume 68 Issue 1 Pages 297-300
    Published: 1995
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    Several 2-alkynyl and 2-alkenyl alcohols were effectively sulfonylated with methanesulfonyl chloride or p-toluenesulfonyl chloride using the combined bases of a catalytic amount of tertiary amine and potassium carbonate. The reaction was conducted with reliable safety and while avoiding the disposal of wasted amines. The mesylation of 2-propyn-1-ol proceeded on a large scale (more than 20 kg) without a substantial production of explosive 3-chloro-1-propyne. The choice of the catalysts was important, and sterically unhindered tertiary amines, such as trimethylamine, N,N-dimethylbenzylamine, and triethylamine, were effective. Without these catalysts the reactions were significantly retarded. The reaction was so mild that it could be applied to complex and optically active 4-hydroxy-3-methyl-2-(2-propynyl)-2-cyclopenten-1-one, which is an important alcohol moiety of synthetic pyrethroids.
  • Takashi Kumagai, Mayumi Ohno, Kooji Mitani, Ken-ichi Yamamoto, Masaji ...
    1995 Volume 68 Issue 1 Pages 301-304
    Published: 1995
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    Thermolyses of isomeric mixtures of dicyclopentadienylmethyl alcohols were obtained by reactions of the corresponding isomeric mixture of metallodicyclopentadiene with aldehydes and ketones at 300 °C by a flow method. These thermolyses give by cycloreversion the corresponding isomeric mixtures of cyclopentadienylmethyl alcohols. These mixtures in turn furnish the corresponding fulvenes upon treatment with bases. At higher temperatures, the thermolyses regenerate starting ketones, probably by retro-ene reaction of the cycloreversed alcohols.
  • Seiji Yamaguchi, Noriaki Shouji, Kazuyoshi Kuroda
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 305-308
    Published: 1995
    Released: June 30, 2006
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    Natural dl-cannabichromene was synthesized in 6 steps from methyl 5-methoxy-2-methyl-7-pentyl-2H-chromen-2-acetate prepared by the cyclization of 2-hydroxy-6-methoxy-4-pentylbenzaldehyde with dimethyl isopropylidenemalonate.
  • Katsunori Teranishi, Atsuko Komoda, Makoto Hisamatsu, Tetsuya Yamada
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 309-314
    Published: 1995
    Released: June 30, 2006
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    A synthesis of new “alkoxymethyl carbonate” is presented starting with alcohol. In the presence of potassium carbonate, primary alcohols react with chloromethyl alkyl ethers in N,N-dimethylformamide under mild conditions to give the corresponding alkoxymethyl carbonates in good yields without giving the alkoxymethyl ethers. The yield of alkoxymethyl carbonate is seriously effected by reaction solvent and the present method is not applicable for tertiary alcohol. Methoxymethyl carbonate can be removed readily under mild basic or acidic conditions, and undergoes selective alkoxide interchange of methoxymethoxide group under basic conditions.
  • Kazuo Yamaguchi, Hitoshi Kuboniwa, Satoru Nagami, Toru Bando, Akira Hi ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 315-321
    Published: 1995
    Released: June 30, 2006
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    2-[[2-[2-[2-[2-[2-[2-[2-(2-Hydroxyethoxy)phenoxy]ethoxy]phenoxy]ethoxy]phenoxy]ethoxy]phenoxy]methyl]benzoic acid (1) was employed as a carrier to transport alkali metal ions. The transport selectivity sequence through 1,2-dichloroethane membrane was K+ ≥ Rb+ > Cs+ > Na+ ≥ Li+. The high preference of K+ to Na+ in competitive transport through 1,2-dichloroethane–toluene was consistent with the difference of solubility between the potassium and sodium salts of 1. However, the separate transport rates of K+ and Na+ through 1,2-dichloroethane were comparable. The amount of water incorporated from aqueous to organic layer by the sodium salt was much more than by the potassium salt, and the amounts were dependent on the stirring rates of the two layers. The sodium salt lowered the interfacial tension between the aqueous and organic layers, while the potassium salt did not change it. Emulsion-like aggregates of the sodium salt in the organic layer were observed by dynamic light scattering. The above experiments showed that K+ was transported as the potassium salt of 1, while Na+ was incorporated into the organic layer and transported as an aggregate of the sodium salt containing water.
  • Yasushi Kohno, Koichi Narasaka
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 322-329
    Published: 1995
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    The oxidation of α-tributylstannyl alkanoates with tetrabutylammonium hexanitratocerate(IV) generates α-radicals of the alkanoates by eliminating the stannylium ion. The thus-formed radicals react with various electron-rich olefinic compounds, such as silyl enol ethers, giving addition products in good yield. This method formally achieves selective cross coupling between alkanoates and ketones.
  • Hironobu Hojo, Shoko Yoshimura, Mitiko Go, Saburo Aimoto
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 330-336
    Published: 1995
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    The Barnase-like Domain in DNA-Directed RNA Polymerase II of Saccharomyces cerevisiae containing three cysteine residues was synthesized by a thioester method. A partially-protected cysteine-containing peptide thioester was prepared via a peptide obtained by a solid-phase method using 3-nitro-2-pyridinesulfenyl amino acid derivatives. Four peptide segments covering 112 amino acid residues of the barnase-like domain were condensed from the C-terminal to the N-terminal one by one in the presence of silver ions and N-hydroxysuccinimide to give a full sequence peptide. RNase activity of the synthetic domain could not be detected because of its extreme low solubility in the neutral buffer.
  • Ikuo Aoki, Yoshiaki Nishibayashi, Sakae Uemura
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 337-340
    Published: 1995
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    Metal hydride reduction of a variety of α-[phenyl(or methyl)seleno]alkyl aryl ketones gives a mixture of threo- and erythro-β-aryl-β-hydroxyalkyl phenyl(or methyl)selenides by carbonyl reduction and 1-aryl-1-alkanol by the substitution of a phenyl(or methyl)seleno group with hydrogen. With all metal hydrides examined the formation of the threo-isomer always predominated. The addition of various metal chlorides in the reduction system did not affect the diastereoselectivity much, in a sharp contrast to the so-far known reduction of various α-heteroatom (N, P, O, S)-substituted ketones.
  • Shinzo Kagabu, Hideaki Tsuji, Itsumi Kawai, Hitomi Ozeki
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 341-349
    Published: 1995
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    The thermolysis of N-t-alkyl-, and N-aryl-(2,2-dichlorocyclopropyl)methyleneamines yielded directly 1-t-alkyl, and 1-aryl-3-chloropyrroles as the major products along with a slight amount of the 2-chloro isomers. The transformation to the 3-chloropyrroles was enhanced in polar solvents. But basic additives directed the thermal rearrangement into the 1,2-bond cleavage of the cyclopropane ring, leading to the 2-chloropyrroles. On the other hand, (difluorocyclopropyl)methyleneamines were pyrolyzed exclusively to 3-fluoropyrroles under 1,3-bond cleavage. The ionic mechanism involving a heterolytic dissociation of chlorine atom under 1,3-bond scission of the cyclopropane ring is proposed for the rearrangement to 3-chloropyrroles, while a homolytic cleavage pathway is proposed for 3-fluoropyrroles. The present thermolysis supplies a unique preparative tool for 2-, and 3-halo-4-phenylpyrrole derivatives.
  • Tamejiro Hiyama, Guntoori Bhaskar Reddy, Tatsuya Minami, Takeshi Hanam ...
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 350-363
    Published: 1995
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    Condensation of N-methoxy-N-methyl amides with the dianions of acetoacetates gives in good yields β,δ-diketo esters, which are reduced with Et2BOMe–NaBH4 in tetrahydrofuran–methanol highly selectively to give syn-β,δ-dihydroxy esters in one step. Similarly, the β,δ-diketo esters of the Taber’s chiral alcohol or its enantiomer respectively are reduced to give syn-β,δ-dihydroxy esters of moderate enantiomeric excess. Higher diastereo- and enantioselectivity were achieved by reduction of the β,δ-diketo esters of the Taber’s chiral alcohol or its enantiomer successively with diisobutylalane and with Et2BOMe–NaBH4. The resulting syn-diol esters were hydrolyzed and lactonized to give various types of β-hydroxy-δ-lactones commonly found in artificial HMG-CoA reductase inhibitors.
  • Tamejiro Hiyama, Tatsuya Minami, Kyoko Takahashi
    Type: Accounts
    Subject area: AI
    1995 Volume 68 Issue 1 Pages 364-372
    Published: 1995
    Released: June 30, 2006
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    Synthetic methods were studied for optically active 6-oxo-3,5-isopropylidenedioxyhexanoate esters (4), which could be used as a key precursor of various kinds of artificial analogs of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors. An enantiomer (+)-4 was prepared by asymmetric reduction of β,δ-diketo esters derived from the Taber’s alcohol or L-tartrate followed by a series of chemical transformations, and the desired enantiomer (−)-4 was prepared by the same asymmetric reduction starting from D-tartrate. The key intermediate (−)-4 was finally converted into a highly potent HMG-CoA reductase inhibitor, NK-104.
  • Hiroyuki Kusama, Yuko Yamashita, Koichi Narasaka
    1995 Volume 68 Issue 1 Pages 373-377
    Published: 1995
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    The Beckmann rearrangement of oximes is catalyzed by a combined use of tetrabutylammonium perrhenate (Bu4NReO4) and trifluoromethanesulfonic acid in nitromethane under azeotropic conditions, giving amides in high yield. By employing this catalytic system, amides can be prepared directly from ketones and hydroxylamine hydrochloride.
  • Po-Chung Cheng, Tsutomu Nonaka
    1995 Volume 68 Issue 1 Pages 378-384
    Published: 1995
    Released: June 30, 2006
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    This work demonstrates the procedures needed to extract kinetic parameters from experimental data and to establish a reasonable model for the electroreduction of benzoic acid in a citrate buffer solution, a reaction typical of consecutive electrochemical reactions with solvent decomposition. Influences of operating conditions (current density, flow rate, etc.) on the formation ratio of benzaldehyde to benzyl alcohol were examined in a flow cell system with a lead cathode. Three reaction mechanism models taking into account dehydration and mass transfer of a hydrated benzaldehyde intermediate were discussed. Numerical calculations showed that the electrolyte in the vicinity of the cathode during an electrolysis was weakly alkaline. Factors controlling the product-selectivity of benzaldehyde are also discussed on the basis of simulation.
  • Yoshio Uemichi, Kiyoshi Shouji, Masatoshi Sugioka, Takaji Kanazuka
    1995 Volume 68 Issue 1 Pages 385-387
    Published: 1995
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    The dehydrogenation of cyclohexanol to cyclohexanone has been studied over activated carbon-supported transition metals as catalysts. The Co/carbon catalyst was found to be highly effective for the reaction. Its catalytic behaviors strongly depended on the temperature of hydrogen reduction. Highly dispersed and well-reduced cobalt catalyst showed pronounced activity and stability.
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