bluuebunny/crossref_metadata_2025_split huggingface dataset:
Syntheses of Several Muramyl Peptides in Relation to Chemical Structures of Less Immunoadjuvant Bacterial Cell Walls
Authors: Kusumoto Shoichi , Ikenaka Kazuhiro , Shiba Tetsuo 
Published: July 2006

Abstract
Various structural analogs of N-acetylmuramyl-l-alanyl-d-isoglutamine, which had been shown to be the minimum structure required for the immunoadjuvant activity of bacterial cell walls, were synthesized in order to investigate in more detail the relationship between the activity and chemical structures. Particularly, the compounds of the structures corresponding to the cell walls of special bacteria without immunoadjuvant activity were prepared in this study. Several novel procedures including the preparation of a branched glutamyl peptide were newly exploited to accomplish the syntheses of muramyl peptides with complicated structures. As a result of this synthetic study, new informations were obtained on the structural requirement for the immunoadjucant activity.
Restricted Rotation Involving the Tetrahedral Carbon. XXVI. Certainties and Uncertainties Involved in the Rates of Exchange among Three Sites as Obtained by Total Line Shape Analyses of 1H NMR Spectra: The Case of Methylene Signals
Authors: \={O}ki Michinori , Kono Motomichi , Kihara Hiroshi , Nakamura Nobuo 
Published: July 2006

Abstract
Benzyl methylene signals, which split into an AB quartet and a singlet and show temperature dependence, are obtained at various temperatures and are simulated with the use of two independent rates of rotation. Certain limitations of accuracy are found in this method. The uncertainty becomes less if additional data are provided from other sources, but never becomes negligible. Contribution of the slower process is found difficult to detect especially when the population involved in the process are the less.
Syntheses of Cecropia Juvenile Hormones by Selective Side-chain Methylation of (E,E)-Farnesol
Authors: Yasuda Arata , Tanaka Shin , Yamamoto Hisashi , Nozaki Hitosi 
Published: July 2006

Abstract
The stereoselective route to the title insect hormones (JH-1 & JH-2) depends crucially on the epoxidation of allylic alcohols with t-butyl hydroperoxide in the presence of oxobis(2,4-pentanedionato-O,O′)vanadium(IV). The oxidation of 2-methyl-1-hepten-3-ol exclusively produces the (2R*,3S*) isomerofthe diastereomeric epoxy alcohols. This is converted into (Z)-6-methyl-5-undecene by the sequence involving oxirane reaction with lithium dibutylcuprate(I) and the removal of both hydroxyl groups of the resulting 1,2-diol. Extension of the series of reactions to the mono- and bisoxirane derived from (E,E)-farnesol gives JH-2 and JH-1, respectively.
Synthesis of D:A-Friedo-18β-lupane Derivatives
Authors: Yokoyama Yasushi , Tsuyuki Takahiko , Moriyama Yoshihiko , Murae Tatsushi , Toyoshima Hirokazu , Takahashi Takeyoshi 
Published: July 2006

Abstract
D:A-Friedo-18β-lup-19-ene and D:A-friedo-18β-lup-19-en-3-one with a new migrated lupane framework were synthesized and the former compound was converted into known methyl trinorshionanoate.
The Ullmann Condensation Reaction of Haloanthraquinone Derivatives with Amines in Aprotic Solvents. IV. Kinetic Studies of the Condensation with Ethylenediamine
Authors: Arai Sadao , Tanaka Akira , Hida Mitsuhiko , Yamagishi Takamichi 
Published: July 2006

Abstract
In the Ullmann condensation of bromoanthraquinones (AQBr) with ethylenediamine using copper(I) bromide as a catalyst, the reaction rate decreased with time which has been interpreted in terms of the formation of the ineffective copper(II) species. The kinetic investigation showed the reaction rate to be first order both for the copper(I) species and AQBr. After prolonged reaction the copper(I) species was quantitatively converted to the copper(II) species, the copper(II) species appearing to have little catalytic activity due to strong coordination with ethylenediamine. The reactivities of the haloanthraquinones were dependent on the ease of coordination with Cu(I) and the rate of Cu(II) formation. The mechanism, including the reaction between CuI(AQBr) and ethylenediamine, has been proposed and discussed.
Photochemical and Thermal Reactions of Cyclohexadienone Oximes
Authors: Okazaki Renji , Watanabe Masako , Inamoto Naoki 
Published: July 2006

Abstract
Photolysis of (E)-1-hydroxyimino-2,4,5-tri-t-butyl-6-methyl-2,4-cyclohexadiene (1) and the corresponding (Z)-isomer in methanol, benzene, or pentane afford 1,3,5-tri-t-butyl-5-cyano-1,3-cyclohexadiene (3), 5-t-butyl-7-cyano-2,2,3,8,8-pentamethyl-3,4,6-nonatriene (4), 5-t-butyl-3-cyano-2,2,7,8,8-pentamethyl-3,4,6-nonatriene (5), 5-t-butyl-7-cyano-2,3,3,8,8-pentamethyl-1,4,6-nonatriene (6), 5-t-butyl-3-cyano-7-methoxy-2,2,7,8,8-pentamethyl-3,5-nonadiene (7), 5-t-butyl-7-cyano-7-methoxy-2,2,3,8,8-pentamethyl-3,5-nonadiene, and 2,4-di-t-butyl-6-cyano-7,7-dimethyl-1,3,5-octatriene (9). The presence of an oxaziridine in the reaction mixture has been confirmed by iodometry. The photoreaction in the presence of 1,3-pentadiene or oxygen gives essentially the same results, suggesting the involvement of the singlet excited state in these photoreactions. Thermal Beckmann rearrangement of 1 has been conducted for comparison to give only 6, 7, and 9. The photochemical formation of 3–9 has been rationalized in terms of the “free” cyclopentadienyl cation formed by ionic α-cleavage of the oxime. Photoreaction of 1-hydroxyimino-2,4,6-tri-t-butyl-2,4-cyclohexadiene with one alkyl group at 6-position gives 5-t-butyl-7-cyano-2,3,8,8-tetramethyl-1,4,6-nonatriene, 5-t-butyl-3-cyano-8-methoxy-2,2,7,8-tetramethyl-4,6-nonadiene, 5-t-butyl-7-cyano-2-methoxy-2,3,8,8-tetramethyl-3,5-nonadiene, and 1,3-di-t-butyl-5-cyano-3-methoxy-6,6-dimethyl-1,4-heptadiene.
A Stereoselective 1,3-Transposition Reaction of Allylic Alcohols
Authors: Yasuda Arata , Yamamoto Hisashi , Nozaki Hitosi 
Published: July 2006

Abstract
Reduction of glycidyl mesylate with dissolving metal produces allylic alcohol in fair to excellent yield. Combined with the highly stereoselective epoxidation of allylic alcohols with t-butyl hydroperoxide and oxobis(2,4-pentanedionato-O,O′)vanadium(IV) as a catalyst, the sequence provides a new and efficient means for 1,3-trans-position of allylic alcohols, by which geraniol is transformed into linalool, farnesol into nerolidol, and furthermore, (−)-cis-carveol into the (+) antipode and vice versa in a stereospecific way.
A Theoretical Approach to the Possible Hydrogen Migration in Butadiene under Electron Impact
Authors: Takagi Tsutomu , Oiwa Masayoshi 
Published: July 2006

Abstract
The hydrogen migration in butadiene under electron impact was studied by means of the calculated potential energy surfaces. The all-valence electron semi-empirical SCF-MO(MINDO/2-Unrestricted Hartree Fock) theory was employed. The possibility of the migration of hydrogen has been discussed. Moreover, the mechanisms (I–IV) including the hydrogen migration for the formation of the C3H3 ion have been discussed. The hydrogen-migration models are presented based on the variations in the total and the partitioned energies. It is very probable that the hydrogen on C1 in the M\underset.+ ion migrates to the other carbon, C4, via Models 1 and 2 in Mechanism IV. It was predicted that the formation of the C3H3 ion occurs by means of the fragmentation of the migrated M\underset.+ ion, although the other mechanisms can not always be ignored. Finally, for the hydrogen-migration models, the theoretical predictions were found to be in good agreement with the available experimental results.
A Study of the Reduction Mechanism of p-Dimethylaminobenzaldehyde to 1,2-Bis(p-dimethylaminophenyl)-1,2-ethanediol by Rotating Disk Electrode Voltammetry
Authors: Taniguchi Isao , Yasukouchi Kazuo , Yoshiyama Akiko , Sekine Taro 
Published: July 2006

Abstract
Rotating disk electrode voltammetry was applied to study the reduction mechanism of p-dimethylaminobenzaldehyde (1) in water–ethanol alkaline solutions by using a mercury-plated platinum rotating disk electrode. In the logarithmic analysis of the wave, the plots of log [i2⁄3/(id–i)] vs. E showed good linearity, and the shifts of the half-wave potential with an increase in the rotation speed of the electrode (ω) and in the initial concentration of 1 (C) were ∂E1⁄2⁄∂logω=−22±2 mV and ∂E1⁄2⁄∂logC=19±2 mV, respectively. On the other hand, no appreciable change in E1⁄2 was observed with varying alkalinities of the solutions. These results and the large shift of E1⁄2 with an increase in the concentration of water (∂E1⁄2⁄∂log[H2O]=ca. 50 mV) are explained in terms of the following reactions:
R+e\ightleftarrowsR\ewdot (solvated by water), (1)
2R\ewdot\oversetk→D2− (r.d.s.), (2)
D2−+2H2O→DH2+2OH−, (3)
where R and R\ewdot are the molecule and the radical of 1, respectively, D2− is the dimer of R\ewdot and DH2 is the hydro-dimer (2) of R. The rate of the dimerization reaction (k in Eq. 2) was estimated to be 2.5×104 M−1 s−1 from the shift of E1⁄2 with logω for the 50% water-ethanol solution containing 1 M NaOH, and this rate constant decreased with decreasing water concentration.
Studies of the Dissolved State of Sodium Tetradecyl Sulfate in Ethanol–Water Mixtures by Measurements of the Activity
Authors: Koshinuma Masakatsu 
Published: July 2006

Abstract
The details of electromotive-force measurement by means of a concentration cell consisting of sodium tetradecyl sulfate (NaTS) in ethanol–water mixtures and of anionic and cationic ion-exchange membranes as septams were described. The membranes used proved to be permeable exclusively to the surfactant (TS−) and Na+ ions respectively. The activities of the TS− and Na+ ions were measured separately, and then the mean activity was computed as a function of the ethanol content in the solvent. Below the CMC, the activities for TS− and Na+ ions and the mean activity increased with an increase in the NaTS concentration, but decreased with an increase in the ethanol concentration. Above the CMC, the activity of the TS− ion decreased, whereas that of the Na+ ion increased; the mean activity also slightly increased with an increase in the NaTS concentration. The values of CMC obtained were 1.5×10−3, 1.7×10−3, and 2.2×10−3 mol/dm3 for 5, 10, and 15 vol % ethanol concentrations respectively. The mechanism of mixed micelle formation was also expressed by a charged phase-separation model in an ethanol–water mixture much as in the case of a simple aqueous solution. The degrees of counterion attachment were found to be 0.73, 0.68, and 0.62 for 5, 10, and 15 vol % ethanol respectively. The intermicellar concentrations of TS−, (CTS), and Na+ ions, (CNa), were calculated. With an increase in the NaTS concentration, CNa monotonously increased, but CNa decreased. At a given NaTS concentration, CNa increased with an increase in the ethanol concentration, while CNa was approximately constant.
The Similarity between the π,π* Absorption Spectra of 1-Indenone and 1,2-Naphthoquinone
Authors: Kuboyama Akira , Matsumoto Hitoshi 
Published: July 2006

Abstract
The π,π* absorption spectrum and its solvent effect of 2-methyl-1-indenone have been found to be similar to those of 1,2-naphthoquinone. This fact is discussed on the basis of the results calculated using the P-P-P method. The similarity of the calculated π-electronic structures in the low-energy π,π* singlet states between 1-indenone and 1,2-naphthoquinone is not so good as that between fluorenone and 9,10-phenanthrenequinone.
Allylic Oxidation of Methyl 2-Alkenoates
Authors: Nakayama Mitsuru , Shinke Shuzo , Matsushita Yoichi , Ohira Susumu , Hayashi Shuichi 
Published: July 2006

Abstract
Allylic oxidation of methyl 2-alkenoates with chromium trioxide in a mixture of acetic anhydride and acetic acid afforded methyl 4-oxo-2-alkenoates.
Conformational Effect on the Bridgehead Reaction of Bicyclo[3.3.1]nonan-2-ones. A Facile Bridgehead Deuteration of a Bicyclo[3.3.1]nonan-2-one Derivative with the Cyclohexanone Ring Locked in the Boat Conformation
Authors: Yamada Kiyoyuki , Manabe Shunichi , Kyotani Yoshinori , Suzuki Masaaki , Hirata Yoshimasa 
Published: July 2006

Abstract
Five bicyclo[3.3.1]nonan-2-ones, two known (1, 3) and three new ones (2, 4, 5) were prepared. The hydrogen-deuterium exchange reaction at the bridgehead position of the bicyclo[3.3.1]nonan-2-one system was examined under mild basic conditions (2 M NaOMe-MeOD, 33 °C, 22 h) using these five bicyclo[3.3.1]nonan-2-ones. Virtually no deuteration took place at the bridgehead in each case of the bicyclic ketones (1, 2, 3, 4), whereas one deuterium was incorporated into the bridgehead of the ketone (5). 13C NMR spectroscopy was employed for the unambiguous determination of the site(s) of deuteration in all cases studied. The enhanced bridgehead acidity of (5) could be explained in terms of the locked boat conformation of the cyclohexanone ring contained in (5).
Nitration of Hexamethylbenzene and Hexamethylbenzene-d18 in Acetic Acid. Deuterium Isotope Effect on the Product Distribution. Mechanism of Side-chain Substitution of Arenes
Authors: Suzuki Hitomi , Mishina Tadashi , Hanafusa Terukiyo 
Published: July 2006

Abstract
The reaction in acetic acid of hexamethylbenzene and hexamethylbenzene-d18 with nitric acid in the dark has been investigated under various conditions using a high-pressure liquid chromatographic method. Pentamethylbenzyl nitrate, pentamethylphenylnitromethane, pentamethylbenzyl acetate, and pentamethylbenzyl alcohol were formed immediately after the mixing of reactants; their relative amounts remained almost unchanged up to nearly 50% conversion. The addition of sodium nitrite gave little influence on the composition of the product mixture, while urea was found to depress somewhat the formation of nitromethane. In the presence of lithium nitrate, the reaction was modestly accelerated and the nitrate formation seems to be slightly favored over the nitromethane formation. Hexamethylbenzene-d18 reacted with nitric acid at the same rate as the non-labeled hydrocarbon did, but the benzyl nitrate/phenylnitromethane ratio in the product mixture was considerably higher in the former. Based on the quantitative data obtained, the mechanism for the side-chain substitution has been discussed in terms of the SN1′ pathway: nitronium ion makes an ipso attack on the substrate to form the arenium ion, which releases a proton from the activated methyl group para to the site of attack to give the 3-methylene-6-nitro-1, 4-cyclohexadiene intermediate (7). Heterolytic fission of the C–N bond in 7 will form a benzyl cation-nitrite anion pair, which recombines at the benzylic carbon atom via a C–N bond or via a C–O bond, giving benzyl nitrite or phenylnitromethane, respectively. Benzyl nitrite will be further converted into benzyl nitrate and benzyl alcohol, while benzyl acetate will arise from the incorporation of solvent molecules into the ion-pair.
Improved Synthesis of Antimycin A3
Authors: Aburaki Shimpei , Kinoshita Mitsuhiro 
Published: July 2006

Abstract
An improved synthesis of antimycin A3 was accomplished by a suitable lactonization of 3-O-benzyl or 3-O-isovaleryl derivative (10a or 10b) of (2R, 3R, 4S)-4-(N-benzyloxycarbonyl-l-threonyloxy)-2-butyl-3-hydroxypentanoic acid, which was synthesized by starting from the corresponding 3-O-benzyl or 3-O-isovaleryl derivative (4a or 4b) of methyl 2-C-butyl-2, 5-dideoxy-β-l-arabinofuranoside, respectively. Acid hydrolysis of 4a or 4b followed by reduction with sodium borohydride afforded 3-O-benzyl or 3-O-isovaleryl-1, 3,4-pentanetriol (5a or 5b), respectively. Tritylation of 5a or 5b followed by succesive 4-O-acylation with N-benzyloxycarbonyl-O-t-butyl-l-threonine, detritylation, oxidation with chromium trioxide-acetic acid-pyridine, and de-t-butylation gave the hydroxy ester acid 10a or 10b, respectively. Lactonization of 10a or 10b through its 2-pyridinethiol ester 11a or 11b activated with silver perchlorate afforded the corresponding nine-membered dilactone derivative 12a or 12b in 33 or 13% yield, respectively. Removal of N,O-protecting groups of 12a by hydrogenolysis, followed by successive N- and O-acylation gave the antimycin A3 precursor, (3S, 4R, 1R, 8R, 9S)-3-(2-benzyloxy-3-nitrobenzoylamino) -4, 9-dimethyl-7-butyl-8-isovaleryloxy-1, 5-dioxonane-2, 6-dione derived from 12b.
Methylation of Pyrimidine 2′-Deoxynucleosides with Trimethyl Phosphate
Authors: Tanabe Toshizumi , Yamauchi Kiyoshi , Kinoshita Masayoshi 
Published: July 2006

Abstract
The reactions of thymidine, deoxyuridine, and deoxycytidine with trimethyl phosphate (TMP) were studied in a homogeneous water solution at 37–60 °C and pH 7–10. Three pyrimidine deoxynucleosides were methylated mainly at the N-3 position to afford their 3-methyl derivatives. The methylation rate at the N-3 position was found to be dependent on the pH of reaction medium. At pH 10, thymidine and deoxyuridine were methylated much faster than deoxycytidine, the tendency being reversed at pH 7.
Kinetic Studies of Spin Trapping Reactions. II. Radiolysis of Cyclohexane
Authors: Doba Takahisa , Noda Shoji , Yoshida Hiroshi 
Published: July 2006

Abstract
In order to extend kinetic utilization of the spin-trapping techniques in radiation chemistry, γ-radiolysis of cyclohexane has been studied at room temperature using pentamethylnitrosobenzene as a spin trap. With increasing radiation dose, the cyclohexyl radical spin adduct has been found by ESR to form and then decay. Consumption of the spin trap has also been monitored by observing the optical absorption. The observed kinetic aspects indicate that the radiation-generated cyclohexyl radicals are completely trapped by 1.3×10−4–6.6×10−4 mol dm−3 of the spin trap, and their G-value is 3.0. The spin-trapping rate constant has been determined to be 1.6×107 mol−1 dm3 s−1 at 299 K based on the reported rate constant for the reaction between the cyclohexyl radical and tributylstannane. From the optical absorption study, dimeric pentamethylnitrosobenzene has been found to dissociate into the monomer, effective in the spin-trapping, with an equilibrium constant of 8×10−4 mol dm−3 in cyclohexane at 299 K. The monomer has an absorption coefficient of 48 mol−1 dm3 cm−1 at its absorption peak of 790 nm.
Effect of Gelatin on the Reduction of Cobalt(II) in Thiocyanate Solutions at Mercury Electrodes
Authors: Itabashi Eiki , Takaya Kumiko 
Published: July 2006

Abstract
Reduction of cobalt(II) in thiocyanate solutions at mercury electrodes has been greatly accelerated in the presence of small amounts of gelatin. This accelerating effect results in an inhibition of the amalgamation of electrodeposited Co(0)SCN−, which reacts chemically to yield CoS and CN−. Both CoS and CN− further stimulate the reduction of cobalt(II).
Absorption and Circular Dichroism Spectra of Bis(ethylenediamine)(1,3-diamine)cobalt(III) Complexes
Authors: Kashiwabara Kazuo , Kojima Masaaki , Arakawa Sumio , Fujita Junnosuke 
Published: July 2006

Abstract
New bis(ethylenediamine)cobalt(III) complexes containing various 1,3-diamines have been prepared and resolved (or separated) into optical isomers. The preferred conformations of six-membered 1,3-diamine chelate rings in these complexes seem to be reflected on the absorption and circular dichroism spectra.
Topological Ligand Design. I. Definition and Derivation of Simple Ligand Graph
Authors: Takamoto Susumu 
Published: July 2006

Abstract
A simple ligand graph and a pattern graph are defined topologically in order to design the patterns of the chelating ligands. This ligand graph, which comprises m donor atoms and n carbon chains capable of forming medium-sized chelate rings, is an irregular graph containing neither multiple lines nor self-loops. All the ligand graphs with m≤8 can be systematically obtained from fifty pattern graphs. These are derived from fifteen basic pattern graphs, which are cubic general graphs containing some multiple lines and self-loops. A pattern code and a set of series indices are tabulated for each ligand graph with m≤8. For the ligand graphs with m≤6, all the geometric isomers of their octahedral chelates are also illustrated.
A Note on the Nature of Ionic Hydrations and Hydrophobic Interactions in Aqueous Solutions
Authors: Arakawa Kiyoshi , Tokiwano Kazuo , Ohtomo Norio , Uedaira Hisashi 
Published: July 2006

Abstract
A theoretical consideration on the nature of solute-water and solute-solute interactions in aqueous solutions has been performed. Thermodynamic functions for the creation of cavities accommodating solute molecules were calculated by the use of the scaled particle theory, and the “negative hydration” effect of univalent ions such as Rb+, Cs+, Cl−, I− etc., which was proposed first by Samoilov, Krestov and others, was interpreted and discussed. The nature of solute-water and solute-solute interactions in aqueous solutions of inert gases and hydrocarbons was elucidated in comparison with the interactions in nonaqueous solutions of those solutes.
Electrical Properties and Constitution of Several Low-resistivity Iodine Complexes
Authors: Doi Susumu , Fujita Akiyoshi , Ikeura Shigeo , Inabe Tamotsu , Matsunaga Yoshio 
Published: July 2006

Abstract
The electrical resistivity and Seebeck coefficient of the iodine complexes with eight aromatic compounds were examined as functions of the composition and the temperature. The formation of complexes is indicated by maxima or shoulders in the resistivity-composition isotherms at the following compositions: (anthanthrene)2I9, (6,12-dioxoanthanthrene)I2, (6,12-dioxoanthanthrene)I3, (pyranthrene)I3, (violanthrene)2I7, (phthalocyanine)I2, (phthalocyanine)I5, (phenoxazine)2I3, (pyridazine)5I9, and (N,N′-diphenyl-p-phenylenediamine5I13. Furthermore, some sharp resistivity minima are considered as evidence of the complex formation: e.g., (6,12)-dioxoanthanthrene)2I3 and (phthalocyanine)2I3. On the basis of these compositions, a nonintegral formal oxidation state for the organic molecules and the presence of iodine as triiodide or higher polyiodide ions are established for most of the complexes.
Proton NMR Spectra of Selectively Deuterated p,p′-Azoxyanisoles in the Solid State
Authors: Hayamizu Kikuko , Yamamoto Osamu 
Published: July 2006

Abstract
Selectively deuterated PAA’s, PAA-d8, and PAA-d6 have been studied by proton NMR from 77 K to the melting point (390 K). The temperature dependences of T1 the line width, and the second moment for these compounds are presented. It has been demonstrated that PAA is in the rigid state at 77 K on an NMR time scale, and as the temperature increases the two methyl groups begin to rotate about the C3 axis, followed by libration about the C–O axis. There is no evidence for motions of the ring protons except self-diffusion and/or slow reorientation of the molecular axis in the higher temperature range from 286 K to the melting point.
Friedel-Crafts Reaction of Benzene with 2-Phenylpentanedioic Anhydride
Authors: Hashimoto Iwao 
Published: July 2006

Abstract
The reaction of benzene with 2-phenylpentanedioic anhydride in the presence of AlCl3 afforded a mixture of 1,2,3,4-tetrahydro-4-oxo-1-naphthalenecarboxylic acid, 4-benzoyl-2-phenylbutanoic acid and the isomeric 4-benzoyl-4-phenylbutanoic acid. The relative yields among the products were markedly affected by a change in the polarity of the solvent.
Preparation and Spectra of 9-(p-Vinylphenyl)anthracene
Authors: Mukoh Akio , Nozaki Sukekatsu , Hagitani Akira , Morishita Hirosada 
Published: July 2006

Abstract
A novel vinyl monomer containing the polyaromatic ring, 9-(p-vinylphenyl)anthracene, was prepared by the Grignard reaction of anthrone and p-vinylphenylmagnesium halides which could be obtained either from p-bromostyrene or p-chlorostyrene. The results and the spectra of products are discussed.