bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diene-Transmissive Diels–Alder Reaction of α,β: α′,β′-Unsaturated Thioketones
Authors: Motoki Shinichi , Matsuo Yoshihisa , Terauchi Yasuhiro 
Published: July 2006

Abstract
Diene-transmissive Diels–Alder reaction of l,3-bis(p-tolylmethylene)-2-propanethione has been investigated. The cycloadducts obtained by the reaction of the thione with dimethyl acetylenedicarboxylate and diethyl azodicarboxylate underwent Diels–Alder reaction further with various dienophiles to give sulfur-containing polycyclic compounds.
The Reaction of (Arylthio)trimethylgermanes with Various Haloalkanes —Steric Effect on the Reaction Mechanism—
Authors: Kozuka Seizi , Nitta Takemi 
Published: July 2006

Abstract
A kinetic study has been conducted on the reactions of (arylthio)trimethylgermanes with various haloalkanes. Bimolecular nucleophilic attack of the sulfur atom has been found as the mechanisms for the reactions with normal haloalkanes while the mechanism was found to deviate from bimolecular attack to unimolecular ionization of the haloalkane, dependent on the structure of the alkyl groups with increasing of the steric hindrance. Reaction of a secondary haloalkane also proceeded by unimolecular ionization.
Intramolecular Cycloaddition of the Azomethine Ylides Derived from α-Amino Acids or Esters and 5-Oxo-6-heptenals or 4-Oxo-5-hexenals
Authors: Kanemasa Shuji , Doi Kenji , Wada Eiji 
Published: July 2006

Abstract
Intramolecular cycloadditions of the azomethine ylides bearing a carbonyl-activated olefinic moiety, generated from α-amino acids or esters and 5-oxo-6-heptenals or 4-oxo-5-hexenals, produce the stereoselective internal cycloadducts either to olefin or carbonyl dipolarophilic function with normal or inverse regioselectivity, depending upon the types of ylides as well as the intervening chain length. Exclusively high diastereofacial selectivity has been achieved when 2-phenyl-4-thiazolidinecarboxylic acid and its methyl ester are utilized.
Acyliminium Cyclization of Several Chiral N-Alkenylsuccinimide Derivatives
Authors: Ohwada Jun , Inouye Yoshinobu , Kimura Motoko , Kakisawa Hiroshi 
Published: July 2006

Abstract
The acyliminium intermediate derived from (3R,4R)-N-(3-butenyl)-3,4-bis(benzyloxy)succinimide cyclized to give (8aS)- and (8aR)-hexahydro-3(2H)-indolidinone derivatives. On the other hand, those derived from N-3-hexenyl derivatives afforded (8aS)-hexahydro-3(2H)-indolidinone(s) exclusively. The geometry of the double bond reflected the stereochemistry of the products.
Photoinduced Hydrogen Evolution with Viologen-Linked Zinc Porphyrins
Authors: Okura Ichiro , Kinumi Yuichi 
Published: July 2006

Abstract
Viologen-linked water-soluble zinc porphyrins with different methylene chain lengths between porphyrin and viologen, Zn-PC3(CnV) (n=2–6), were both synthesized and characterized. The lifetimes of the photoexcited triplet states of these compounds were almost the same as those of zinc porphyrins without linked viologen. The fluorescence decay profiles, however, comprised two components with first-order decay (shorter and longer lifetimes) indicating the existence of two conformations: complexed and extended conformers. In the complexed conformer, photoexcited singlet state is quenched by linked viologen. These compounds were applied to photoinduced hydrogen evolution in a system containing NADPH, Zn-PC3(CnV), and hydrogenase under steady state irradiation. Upon irradiation of the sample solution hydrogen was generated, indicating that all of the compounds, Zn-PC3(CnV) (n=2–6), can be substrates of the enzyme hydrogenase, and that every compound participates as both a photosensitizer and an electron carrier in the same molecule.
Magnetic Study of N,N,N′,N′-Tetramethyl-p-phenylenediamine (Wurster’s Blue) Iodide Cation Radical
Authors: Yamauchi Jun , Fujita Hideo 
Published: July 2006

Abstract
One of the Wurster’s blue cation radicals, which is composed of the N,N,N′,N′-tetramethyl-p-phenylenediamine cation and iodine anion moieties, was prepared and its magnetic susceptibility measured from 2.6 to 300 K. The cation radical underwent no phase transition within this temperature range in striking contrast with the first-order phase transition observed in perchlorate and tetrafluoroborate salts, regardless of similar crystallographic structures. In addition, the temperature dependence of the magnetic susceptibility could be well-reproduced by a dimer model: a thermally accessible triplet state lying above a singlet ground state with an energy separation of ΔE⁄k=229 K. This behavior is controversial regarding the crystallographic determination. The unusual magnetic properties of the iodide salt were discussed, together with the crystal structure, ESR and visible absorption data, in comparison with those of the other salts.
Preparation and Reactions of 5-Aryl-1,4,2-dithiazolium Salts
Authors: Yonemoto Katsumi , Shibuya Isao , Tsuchiya Tohru , Yasumoto Masahiko , Taguchi Yoichi 
Published: July 2006

Abstract
S-Thioaroylsulfenamides (ArCSSNH2), formed by reaction of ArCSS−Na+ with hydroxylamine-O-sulfonic acid, were aroylated or acylated to give N-aroyl- or N-acyl-S-thioaroylsulfenamides, respectively, which were then cyclized with dehydration to afford 3-substituted 5-aryl-1,4,2-dithiazolium salts. The behavior of 3,5-diphenyl-1,4,2-dithiazolium perchlorate toward nucleophiles such as active methylene and amino compounds was studied systematically. The reaction can be classified into two cases depending on fission modes of initial adducts, i.e., ring opening–ring closure reaction (Path B) and fragmentation of dithiazole ring (Path C), and in some cases the initial adducts were isolated.
The Characterization and Cycloaddition Reaction of 5,6-Dihydro-1,3-dimethyl-6-methylene-5-[(substituted amino)methylene]-2,4(1H,H)-pyrimidinediones
Authors: Noguchi Michihiko , Kiriki Yasutoshi , Ushijima Takashi , Kajigaeshi Shoji 
Published: July 2006

Abstract
5,6-Dihydro-1,3-dimethyl-6-methylene-5-[(substituted amino)methylene]-2,4(1H,3H)-pyrimidinedione intermediates (E) were characterized spectroscopically and chemically. The cycloaddition reaction of E with olefinic dienophiles was carried out in highly regio- and stereoselective manners to give quinazoline derivatives.
The Behavior of Mixing in Liquid Binary Alloys. Volume of Mixing in the Systems Lead–Tin, Lead–Antimony, and Lead–Thallium
Authors: Badawi Walid A , El-Talbi Mohamed , Oun M Ahmed , Abu-Halguma A Said 
Published: July 2006

Abstract
The molar volume of mixing in the liquid systems Pb–Sn, Pb–Sb, and Pb–Tl has been studied by means of silica glass pycnometer at 1045, 907, and 773 K respectively. The volumes of mixing in the systems Pb–Sn and Pb–Tl are slight positive (0.0263×10−6–0.1767×10−6 m3mol−1), while that in the system Pb–Sb is slight negative (−0.1524×10−6 m3mol−1).
Ozonolysis of Pyrimidine Nucleosides
Authors: Matsui Masaki , Inoue Tooru , Shibata Katsuyoshi , Muramatsu Hiroshige 
Published: July 2006

Abstract
Cytidine, uridine, and thymidine are transformed into the ring-contracted 1-substituted derivatives by ozone. A plausible mechanism is proposed.
Kinetics of Dehydrogenation of 2-Propanol on La2−xSrxCuO4−y
Authors: Jeyalakshmi R , Jagannadhaswamy B , Rengaraj K , Sivasanka B 
Published: July 2006

Abstract
The catalytic properties of mixed oxides La2−xSrxCuO4−y (0.0≤x≤1.0 and y=non-stoichiometry) having K2NiF4 structure were investigated with regard to the effect of changes in the lattice parameters, the oxidation state of copper and oxygen nonstoichiometry in order to correlate the catalytic activity with physicochemical properties. The decomposition of 2-propanol was studied by pulse and flow reactor techniques. The flow reactor data was analyzed by statistical methods to deduce the mechanism on the basis of Langmuir–Hinshelwood and Hougen–Watson models. The reaction followed the first order kinetics with dual site surface reaction as the rate controlling step. The kinetic and thermodynamic parameters obtained from flow reactor data are comparable to those obtained from pulse reactor studies. The higher catalytic activity as indicated by low activation energy and higher conductivity value of La1.8Sr0.2CuO3.96 among the series have been attributed to the presence of higher concentration of Cu(III).
On the Gaussian Basis Set Extended by Their Derivatives with Respect to Scale Factor
Authors: Takahashi Atsuya , Miyazaki Tomoo 
Published: July 2006

Abstract
There has been discussion with regard to the effect of the ζ value, which is a parameter adopted in the Gaussian exponent on the molecular orbital results calculated by use of a basis set extended by their derivatives with respect to ζ. These results are compared with the effect of polarization functions on the molecular orbital results.
Solid State Multinuclear NMR Studies on M4(CO)12 (M=Co, Rh) and (NMe3Bz)2[Rh6(CO)15C]
Authors: Heaton Brian T , Sabounchei Javad , Kernaghan Stuart , Nakayama Hirokazu , Eguchi Taro , Takeda Sadamu , Nakamura Nobuo , Chihara Hideaki 
Published: July 2006

Abstract
Variable Temperature 13C MAS and 59Co NMR data on solid Co4(CO)12 show that there is a symmetry conserved reorientation of the CO4-tetrahedron which is more restricted than has been reported previously whereas the room temperature 13C MASNMR spectra of Rh4(CO)12 and (NMe3Bz)2[Rh6(CO)15C] are consistent with their solid state static structure.
Preparation and Characterization of [Co2(bidentate-N,S)3(triamine)]-Type S-Bridged Dinuclear Complexes
Authors: Konno Takumi , Okamoto Ken-ichi , Hidaka Jinsai 
Published: July 2006

Abstract
Three kinds of S-bridged dinuclear complexes, Δ- and Λ-[Co2(aet)3(dien)]3+ (aet=2-aminoethanethiolate and dien=diethylenetriamine), Δ- and Λ-[Co2(aet)3(dpt)]3+ (dpt=bis(3-aminopropyl)amine)), and ΔLLL-[Co2(l-cys-N,S)3(dien)] (l-cys=l-cysteinate), were prepared by the reactions of [Co(aet)3] or ΔLLL-[Co(l-cys-N,S)3]3− with [CoCl3(dien)] or [CoCl3(dpt)]. The isomers were characterized from their absorption, CD, and 13C NMR spectra.
A Novel Synthesis of 4B-Element-Containing Styrene Derivatives
Authors: Nagasaki Yukio , Kurosawa Koichi , Tsuruta Teiji 
Published: July 2006

Abstract
To synthesize 4B-group element-containing styrene monomers, alkylmetalation reactions of 4-methylstyrene (1) in the presence of lithium diisopropylamide (2) were investigated. Trialkylsilylation of 1 proceeded easily by the reaction with trialkylsilyl chloride in the presence of 2 to form mono- and bis-trialkylsilylated methylstyrene. This synthetic method was expanded to other 4B-element-containing styrenes such as germyl and stannyl compounds.
Kinetics and Mechanism of Anation of cis-β-Diaqua(3,6-diazaoctane-1,8-diamine) Cobalt(III) in 30% (v/v) Ethanol–Water Medium
Authors: Chatterjee Debabrata , Mallick Debnath , De G S 
Published: July 2006

Abstract
The kinetics of the aqua-ligand substitution of the title complex [CoIII(trien)(H2O)23+] (trien=3,6-diazaoctane-1,8-diamine) with various substituting amino acid ligands L=glycine, Dl-alanine, l-proline, Dl-valine, and l-serine was studied spectrophotometrically as a function of incoming ligand concentration, pH (3.0–5.0) and temperature (45–60 °C). The results are consistent with an ion-pair dissociative mechanism.
New Optically Active Liquid Crystal Compounds: (+)-4-Alkoxyphenyl 4-[5-(2-Methylbutyl)-1,3-oxathian-2-yl]benzoates
Authors: Haramoto Yuichiro , Kamogawa Hiroyoshi 
Published: July 2006

Abstract
New liquid-crystal compounds, (+)-4-alkoxyphenyl 4-[5-(2-methylbutyl)-1,3-oxathian-2-yl]-benzoates (9), have been synthesized. The mesomorphic behaviors of these compounds were compared with those of (+)-4-(2-methylbutoxy)phenyl 4-(5-alkyl-1,3-oxathian-2-yl)-benzoates and (+)-4-(5-alkyl-1,3-oxathian–2-yl)phenyl-4-(2-methylbutoxy)benzoates; compounds 9 exhibit a cholesteric phase and their transtition temperatures to isotropic were found to be lower those of the corresponding compounds. These properties seem to originate in the wider molecular width caused by both the 2-methylbutyl group at the 5 position of the 1,3-oxathiane ring and the molecular bend in the 1,3-oxathiane ring.
The Structures of Cytotoxic Diterpenes Containing Bromine from the Marine Red Alga Laurencia obtusa (Hudson) Lamouroux
Authors: Takeda Satoshi , Kurosawa Etsuro , Komiyama Kanki , Suzuki Teruaki 
Published: July 2006

Abstract
Four new brominated diterpenes possessing parguerane or isoparguerane skeleton have been isolated from the title alga collected in the Japanese waters along with several known parguerol, isoparguerol, and deoxyparguerol congeners. The structures of three new compounds were determined by the chemical correlation with the corresponding known compounds. The structural elucidation of the remaining one was carried out on the basis of a combination of chemical and spectroscopic means including 2D NMR technique. One of the new metabolites has proved to be cytotoxic. The cytotoxic properties of the several chemically derived compounds in addition to the known diterpenes are also described.
Synthesis of a Chiral α-(Aminooxy)arylacetic Ester. I. A Route through Optical Resolution of a Racemic α-(Phthalimidooxy)arylacetic Acid
Authors: Iwagami Hisao , Nakazawa Masakazu , Yatagai Masanobu , Hijiya Toyoto , Honda Yutaka , Naora Hirokazu , Ohnuki Takashi , Yukawa Toshihide 
Published: July 2006

Abstract
A synthetic route has been developed to the synthesis of a chiral O-alkyloxime (S)-16, which can be a synthetic intermediate for a potent antipsedomonal cephalosporin antibiotic M-14659 (1). The oxime moiety in (S)-16 has a chiral center at the carbon atom adjacent to the oxygen atom. We have achieved that (S)-16 can be prepared via t-butyl 2-aminooxy-2-[3,4-(isopropylidenedioxy)phenyl]acetate [(S)-15] from an optically active α-(phthalimidooxy) acid (S)-12a which is obtained by resolution using quinine. It has been demostrated that M-14659 prepared from (S)-16 is completely free from its (R)-diastereomer.
Formation of 1,3-Oxathiole-2-thione and 1,2,4-Trithiolane Derivatives by the Catalytic Reaction of α-Diazocarbonyl Compounds with Carbon Disulfide
Authors: Ibata Toshikazu , Nakano Hirofumi 
Published: July 2006

Abstract
The rhodium(II) acetate-catalyzed decomposition of α-diazocarbonyl compounds such as substituted α-diazoacetophenones, cyclic diazoketones, cyclic diazodiketones, and α-diazo-β-ketoesters in carbon disulfide gave 1,3-oxathiole-2-thione derivatives in good yields. Diazomalonates also gave alkyl 5-alkoxy-2-thioxo-1,3-oxathiole-4-carboxylates together with 3,5-bis[bis(alkoxycarbonyl)methylene]-1,2,4-trithiolanes. The formation of 1,3-oxathiole-2-thiones can be explained by the intermediacy of zwitterionic intermediate containing rhodium(II) acetate formed by the reaction of carbon disulfide with ketocarbenoids generated in the catalytic decomposition of the diazocarbonyl compounds.
Preference of [6e/4p], [6e/5p], and [6e/6p] Conjugations in Determining Relative Stabilities of Fused Five-Membered Heteroaromatic Isomers
Authors: Inagaki Satoshi , Urushibata Masahiro 
Published: July 2006

Abstract
Ab initio molecular orbital calculations showed that fused five-membered heteroaromatics 1 (X=O, NH, S) could be slightly or almost equally stable relative to their isomers 2. The results suggest that the [6e/6p] triene conjugation is only a little in preference to (or in the balance with) the counteracting [6e/4p] and [6e/5p] conjugations. Kinetically, the isomers 2 were predicted from the qualitative orbital theory and the calculated HOMO energies to be more stable.
Synthesis and Chemiluminescence of Coelenterazine (Oplophorus Luciferin) Analogues
Authors: Teranishi Katsunori , Goto Toshio 
Published: July 2006

Abstract
In the case of chemiluminescence of coelenterazine, effects of conformation rigidity of and hydrogen bonding with the emitter, coelenteramide, on the chemiluminescence efficiency have been examined with several coelenterazine analogues synthesized. Conformational rigidity has a light enhancing effect, whereas decreasing light yield was observed by hydrogen-bond formation with the emitter.
Systematic Classification of Molecular Symmetry by Subductions of Coset Representations
Authors: Fujita Shinsaku 
Published: July 2006

Abstract
The notation based on the subduction of coset representations (the SCR notation) is presented for the systematic characterization of molecular symmetry. The positions of a parent skeleton are divided into orbits on which the corresponding coset representations (CRs) act. Each of the CRs is then subduced to the subsymmetry that characterizes a molecule derived from the skeleton. The resulting subduced representations are further reduced into CRs, which provide a basis of the SCR notation. The SCR notation is more discriminative than the point-group notation as well as than the framework-group notation. A new concept “unit subduced cycle index” is introduced in order to determine which subsymmetry is realized if we begin with a parent skeleton of a given symmetry.
Hydrogenation Pathway of Quinolines over Raney Nickel and Ru/C
Authors: Okazaki Hiroshi , Onishi Kiyotaka , Soeda Mahito , Ikefuji Yoshio , Tamura Ryuji , Mochida Isao 
Published: July 2006

Abstract
Quinoline, 2-methylquinoline, and 8-methylquinoline were hydrogenated over Raney nickel (R-Ni) under 10 atm hydrogen pressure at about 200°C and over ruthenium on carbon (Ru/C) under 100 atm hydrogen pressure at 150°C. All the substrates were commonly hydrogenated into the initial products, 1,2,3,4-tetrahydroquinolines. The initial products were competitively converted over R-Ni to the final products, decahydroquinolines, directly or via 5,6,7,8-tetrahydroquinolines which were mainly formed from the initial products by isomerization. Ru/C promoted exclusively the direct hydrogenation of 1,2,3,4-tetrahydro derivatives to the final products. The hydrogenation and isomerization of 1,2,3,4-tetrahydroquinoline was completely inhibited in the competitive hydrogenation of quinoline and isoquinoline over R-Ni. Such features of these substrates are explained by the strong basicity of 1,2,3,4-tetrahydroisoquinoline. Roles of 1,2,3,4-tetrahydroisoquinoline are much moderate on Ru/C, where the π-coordination may be important. The effects of methyl substituent and different reactivities of quinoline and isoquinoline are discussed in terms of the steric hindrance on adsorption, heats of hydrogenation, basicities, and electronic properties of the related compound, which are calculated according to the MNDO-PM3 method.
Characterization of Surface Oxide Layer of Iron Particles for Magnetic Recording II. Surface Oxide Layer of Further Oxidized Iron Particles in High Humidity
Authors: Makishima Akio , Yamamoto Yukihiro , Watanabe Kohji 
Published: July 2006

Abstract
The surface oxide layer of additionally oxidized iron particles for magnetic recording in high humidity (90%) and at 60°C was examined by Mössbauer spectrometry. The mechanism of deterioration was concluded to begin with oxidation: the deterioration of the saturation magnetization (Is) of iron particles was caused by a deterioration of the Is of the surface oxide layer; later deterioration was caused by an increase in the amount of the oxide layer. The specific gravity of the surface oxide layer became gradually reduced during the oxidation.
Cation Distribution in a Series of Mixed Ferrites MgxMn1.1−xSn0.1Fe1.8O4 by Means of Powder X-Ray Diffraction and 57Fe, 119Sn Mössbauer Spectroscopy
Authors: Yamada Koji , Ohshita Hiroyuki , Funabiki Shinya , Sakai Hiroshi , Ichiba Sumio 
Published: July 2006

Abstract
The cation distribution in a series of MgxMn1.1−xSn0.1Fe1.8O4 spinel ferrites has been studied by means of X-ray powder diffraction and 57Fe, 119Sn Mössbauer spectroscopy. All of these ferrites showed broad 119Sn Mössbauer spectra due to the hyperfine magnetic field from the ferrimagnetically ordered cations at the A and B sites. With increasing x the distribution of the hyperfine field at the Sn atom became broader and the hyperfine field decreased abruptly above x=0.825. This observation indicates that diamagnetic Mg2+ ions are excluded from the A site below x=0.55, but occupy the A site as well as the B site only above x=0.825. This result is consistent with the Rietveld analyses of the X-ray powder diffraction data. The 119Sn Mössbauer spectroscopy is shown to be a useful technique for studying the cation distribution of ternary spinels in which the site preference of cations can not be empirically predicted.
Recognition of Substrates by Immobilized Bienzyme Membranes
Authors: Higuchi Akon , Nakagawa Tsutomu 
Published: July 2006

Abstract
Glucose oxidase and/or ascorbate oxidase were immobilized (entrapped) in poly(l-leucine-co-Nε-benzyloxycarbonyl-l-lysin) using a spin casting method. Current shifts and time lags for immobilized single-enzyme and bienzyme membranes were investigated as a function of the substrate concentration at 37°C. The current shifts of l-ascorbic acid in the bienzyme membrane were found to be 2–3.5 times higher than those of a single-enzyme membrane. Both the time lags of l-ascorbic acid and d-glucose were found to depend on the concentration of the substrates for both single-enzyme and bienzyme membranes. The method was presented in order to estimate the concentration of two substrates simultaneously. The concentration of d-glucose and l-ascorbic acid in a model solution was simultaneously estimated from an analysis of the current shifts and the time lags using a nonlinear least-squares method as an example.
The Synthesis of Two 6-Acetyl-2,3-dihydro-5-benzofuranols Naturally Obtained from Baccharis conferta
Authors: Yamaguchi Seiji , Nitta Toshiyuki , Hosaka Tsutomu , Nishino Yuji , Kawase Yoshiyuki 
Published: July 2006

Abstract
6-Acetyl-2-isopropenyl-5-methoxy-2,3-dihydrobenzofuran was prepared from 2-isopropenyl-5-methoxy-2,3-dihydrobenzofuran via formylation, Grignard methylation, and oxidation. It was then converted to two racemic dihydrobenzofuran derivatives obtained from Baccharis conferta.
Vapor Liquid Equilibrium Behavior of an Ethyl Acetate–Ethanol–Toluene System at Atmospheric Pressure
Authors: Katayama Hirotake 
Published: July 2006

Abstract
The VLE data of 85 points for a system of ethyl acetate–ethanol–toluene were measured at atmospheric pressure. The results were examined by boilling-point calculations using two forms of the Wilson equation: one with constants of constituent binary systems and the other with constants from a least-squares fit minimizing the Q-function(gE⁄RT=Σxilnγi) of the ternary data. Two binary systems, ethyl acetate–ethanol and ethanol–toluene, show minimum azeotropic points. The normal boiling point of toluene is much higher than the boiling points of the other two substances by 32–3 K. Because the system had a complicated behavior, calculations using the Wilson equation had difficulty to accurately cover the entire area of compositions.