bluuebunny/crossref_metadata_2025_split huggingface dataset:
Total Synthesis of Bioactive Marine Terpenoids
Authors: Miyaoka Hiroaki , Yamada Yasuji 
Published: September 2002

Abstract
This paper presents the total synthesis of bioactive marine terpenoids as conducted at this laboratory. The syntheses of marine sesquiterpenoid upial and marine diterpenoid sanadaol were conducted from D-mannitol via sequential Michael reaction and fragmentation reaction. The marine diterpenoid fuscol, its related compound, and phomactin D were obtained by sequential Michael reaction and oxidative cleavage of carbon–carbon double bond. The marine diterpenoid claenone was produced by sequential Michael reaction and retro-aldol reaction. Synthesis of the marine diterpenoid (+)-mayolide A involved the stereoselective introduction of a C2-unit and repeated Claisen rearrangement to construct the side chain as key steps. Synthesis of the marine diterpenoid (+)-halimedatrial involved stereoselective formation of the cyclopropane moiety and formation of the diformylcyclopentane moiety as crucial steps. The marine sesterterpenoid dysidiolide was synthesized by intramolecular Diels–Alder reaction as the key step to obtain the decalin moiety.
Carbon Materials and the Surface Modification in View of Electrochemical Li Insertion/Extraction
Authors: Takamura Tsutomu 
Published: September 2002

Abstract
Carbon is an old, and at the same time, a new material. Carbon plays the leading part in the practical design of Li-ion secondary batteries, the most advanced secondary batteries, where as the negative electrode material it takes Li into the internal structure during the charging. This guarantees the reliability and safety by preventing the dangerous deposition of Li metal. In responding to a strong demand of the high power capability, the author has developed several surface modification methods.
This article describes the surface modification methods I have developed, together with several new findings in relation to the behavior of Li in the interior and on the surface of carbon. The following items are described and analyzed: (1) electrochemical reaction rate in relation to the battery reaction could be enhanced by surface modification such as (a) a simple heating in vacuum, (b) mild oxidation, and (c) vacuum deposition of a metal film on the carbon surface with such metals as Ag, Au, Bi, Cu, In, Pb, Pd, Sn, and Zn together with the oxidized ones. The cause of the enhancement was studied on the basis of SEI (solid-electrolyte-interphase); (2) use of a single fiber electrode enabled us to find what really occurs on the electrode surface, to determine the most reliable values of the Li diffusion coefficient in carbon; and to prevent decomposition of propylene carbonate on graphite; (3) electrical contact was demonstrated as a key factor to reduce the initial charging irreversibility and to enhance the cycleability; (4) underpotential deposition of Li on the carbon surface was pointed out; and (5) free movement of Li in metal at an ambient temperature was confirmed by the use of a bipolar cell.
In the final remarks I offer a new term of “carbon alloys” based on the nano-technology, which will be an attractive material both in science and technology in the new century.
A New Method for Oxidation of Various Alcohols to the Corresponding Carbonyl Compounds by Using N-t-Butylbenzenesulfinimidoyl Chloride
Authors: Matsuo Jun-ichi , Iida Daisuke , Tatani Kazuya , Mukaiyama Teruaki 
Published: September 2002

Abstract
Various primary and secondary alcohols were smoothly oxidized to the corresponding aldehydes and ketones by using a new oxidizing agent, N-t-butylbenzenesulfinimidoyl chloride (4a), in the coexistence of DBU or zinc oxide. The present oxidation proceeded under mild conditions via five-membered intramolecular proton-transfer of an alkyl arenesulfinimidate intermediate.
Ion-Transfer Processes across Liquid/Liquid Interfaces Promoted by a Convective Flux.
Authors: Wilke Natalia , Iglesias Rodrigo Alejandro , Chesniuk Sergio Gustavo , Dassie Sergio Alberto , Baruzzi Ana María 
Published: September 2002

Abstract
Convective flux produced by stirring either the aqueous or the organic phase is proposed as a mechanistic tool to study the ion-transfer processes at ITIES. The dependence of the voltammetric response on the sweep rate and the rotation frequency was used to differentiate the simple transfer of TEA+ from the assisted transfer of K+ by DB18C6 at a water 1,2-dichloroethane interface.
Mass-Spectrometric Study on Ion-Molecule Reactions of CH5+, C2H5+, and C3H5+ with C9–C19 Alkylbenzenes in an Ion Trap
Authors: Tanaka Yuki , Tsuji Masaharu 
Published: September 2002

Abstract
Chemical ionization of alkylbenzenes (PhCxH2x + 1 = M: x = 3–13) by the CH5+, C2H5+, and C3H5+ ions has been studied under a reactant-ion selective mode of an ion-trap type of GC/MS. The dominant product ions for short-chain reagents (x &lt; 7) were [M + H]+, [PhH + H]+, and CxH2x + 1+ ions, produced through proton-transfer to benzene ring. On the other hand, the dominant product ions for long-chain reagents (x ≥ 7) were CyH2y + 1+ (y &lt; x) and PhCyH2y+ (y ≤ x) ions. The former ions are produced through the attack of the reactant ions on the alkyl chain and/or the benzene ring, while the latter ones are exclusively formed through the attack of the reactant ions on the alkyl chain. Major formation processes of CyH2y + 1+ and PhCyH2y+ ions in each reaction were discussed on the basis of observed distributions and calculated thermochemical data.
Structural Characterization of Neptunyl(VI) Trinitrato Complexes: M[NpO2(NO3)3] (M = NH4+ and K+)
Authors: Wang Junhu , Kitazawa Takafumi , Nakada Masami , Yamashita Toshiyuki , Takeda Masuo 
Published: September 2002

Abstract
237Np Mössbauer spectra of two neptunyl(VI) trinitrato complexes, M[NpO2(NO3)3] (M = NH4+ 1 and K+ 2) were measured at 4.5 K, 10 K and 30 K, respectively. The spectra show magnetic hyperfine splittings similar to the spectrum of Rb[NpO2(NO3)3] 3 already reported. Since the SQUID data of 1 indicate that 1 is paramagnetic from 2 K to room temperature, the magnetic hyperfine splittings are due to slow paramagnetic relaxation. The crystal structures of 1 and 2 were refined by the Rietveld analysis, and the mean Np–O bond distances of 1 and 2 have been obtained. Almost the same Np–O bond distances of 1, 2 and 3 exhibit about the same δ values. This is consistent with the linear relationship between the δ values and the mean Np–O bond distances established for the neptunyl(VI) compounds.
Synthesis and Magnetic Properties of MnIIIMnIIMnIII Trinuclear Complexes with Hydroxo Bridges. Comparison of Magnetic Properties between Hydroxo- and Alkoxo-Bridged Complexes by Density Functional Calculations
Authors: Hirotsu Masakazu , Aoyagi Mutsumi , Kojima Masaaki , Mori Wasuke , Yoshikawa Yuzo 
Published: September 2002

Abstract
A hydroxo-bridged MnIIIMnIIMnIII trinuclear complex, [Mn3(L1)2(2,6-dcba)2(OH)2] (1), where H2L1 is N′,N′-bis-(2-hydroxybenzyl)-N′,N′-dimethylethylenediamine and H2,6-dcba is 2,6-dichlorobenzoic acid, was synthesized by the reaction of Mn(ClO4)2·6H2O with H2L1, H2,6-dcba, and a base in acetonitrile. The structure of 1 was determined by X-ray crystallography: 1 crystallizes in the monoclinic space group P21/c with a = 9.616(4) Å, b = 12.537(4) Å, c = 23.099(4) Å, β = 94.73(2)°, V = 2775(1) Å3, and Z = 2. The central MnII and terminal MnIII ions are bridged by phenolato, carboxylato, and hydroxo ligands to form a linear MnIII–MnII–MnIII arrangement. The bridging structure between MnIII and MnII is similar to that of analogous alkoxo-bridged complexes, [Mn3(L)2(carboxylato)2(alkoxo)2], where L is L1 or its derivatives. Most of the alkoxo-bridged complexes [Mn3(L)2(carboxylato)2(alkoxo)2] exhibit a weak ferromagnetic interaction between MnIII and MnII, while the hydroxo-bridged complex 1 exhibits a weak antiferromagnetic interaction. A comparison of the magnetic properties between the hydroxo- and alkoxo-bridged complexes was performed by density functional calculations of MnIIIMnII dinuclear model complexes.
Solvent-Dependent Formation of Di- and Trinuclear Rhodium and Iridium Complexes Bridged by N, N′-Donor Ligands
Authors: Yu Xiao-Yan , Maekawa Masahiko , Morita Tomonori , Chang Ho-Chol , Kitagawa Susumu , Jin Guo-Xin 
Published: September 2002

Abstract
Reactions of Rh and Ir hydrido complexes, [Rh(H)2(PPh3)2(solv)(EtOH)]ClO4 (solv = Me2CO, 1a; EtOH, 1b) and [Ir(H)2(PPh3)2(Me2CO)2]BF4 (2), with various N,N′-donor bridging ligands, such as pyrazine (pyz), 4,4′-trimethylenedipyridine (tmdp) and di(4-pyridyl) disulfide (dpds), in some solvents were examined, and their reaction products were characterized by X-ray crystal structure analysis, IR, 1H NMR and UV-vis spectra. Rh hydrido complexes, 1a or 1b, formed a dinuclear Rh complex, [Rh2(PPh3)2{(η6-C6H5)PPh2}2](ClO4)2·6CH2Cl2 (3·6CH2Cl2), in dichloromethane with a reductive elimination of hydrogen. The reactions of 1a or 1b with the pyz ligand in dichloromethane and tetrahydrofuran gave triangular Rh3 complexes, [Rh3(PPh3)6(pyz)3](ClO4)3·CH2Cl2 (5·CH2Cl2) and [Rh3(PPh3)6(pyz)3](ClO4)3·EtOH (5·EtOH), respectively, in contrast to the formation of a dinuclear Rh hydrido complex, [Rh2(H)4(PPh3)4(Me2CO)2(pyz)](ClO4)2·EtOH (4·EtOH), in acetone. The reactions of 1a or 1b with the tmdp ligand in dichloromethane and 3-methyl-2-butanone also afforded dinuclear Rh complexes, [Rh2(PPh3)4(tmdp)2](ClO4)2 (6) and [Rh2(PPh3)4(tmdp)2](ClO4)2·4MeCOCHMe2 (6·4MeCOCHMe2), respectively. On the other hand, Ir hydrido complex 2 reacted with pyz and dpds ligands in dichloromethane to afford dinuclear Ir complexes, [Ir2(H)4(PPh3)4(Me2CO)2(pyz)](BF4)2·3CH2Cl2 (7·3CH2Cl2) and [Ir2(H)4(PPh3)4(dpds)2](BF4)2·3CH2Cl2·H2O (8·3CH2Cl2·H2O), respectively, without any reductive elimination of hydrogen. Based on structural studies in solution and in the solid state, it was demonstrated that various Rh and Ir complexes were selectively produced depending on the choice of solvents and N,N′-donor bridging ligands.
Mössbauer and Infrared Studies of Reactions of Laser-Evaporated Iron Atoms with Methane
Authors: Yamada Yasuhiro , Katsumata Keiichi , Shimasaki Hideo , Ono Yuki , Yamaguchi Kayoko 
Published: September 2002

Abstract
The reaction of laser-evaporated iron atoms with methane gas was studied using a matrix-isolation technique, and the reaction products were observed by Mössbauer and infrared spectroscopy. The reaction produced CH3FeH in a CH4/Ar mixture, whereas Fe2H2(CH3)4 was also obtained in addition in a pure CH4 matrix. Molecular orbital calculations were performed in order to confirm the assignments.
Synthesis and Crystal Structure of {6-Amino-5-[6-amino-4-oxo-(1H)-pyrimidin-2-yl]thio-2-thioxo-pyrimidin-4-onato}[tris(2-aminoethyl)amine]cobalt(III) Perchlorate
Authors: Yamanari Kazuaki , Kida Makiko , Fuyuhiro Akira , Kaizaki Sumio 
Published: September 2002

Abstract
The novel tris(2-aminoethyl)aminecobalt(III) complex containing a dimerized ligand Hatuc-atuc (6-amino-5-[6-amino-4-oxo-(1H)-pyrimidin-2-yl]thio-2-thioxo-pyrimidin-4-onate(2-)) was prepared. The crystal structure revealed that Hatuc-atuc coordinates through the S/N donors and exhibits the intermolecular π–π stacking and the double N–H···O hydrogen bond interactions.
Effect of a Polymethylene Chain on the Intramolecular Hydrogen Bond between Adenine and Thymine
Authors: Itahara Toshio 
Published: September 2002

Abstract
The intramolecular hydrogen bond between the adenine and thymine rings of 9-[ω-(thymin-1-yl)alkyl]adenine was investigated in chloroform by means of NMR spectroscopy. The formation of the intramolecular hydrogen bond was dependent on the length of the polymethylene chains between adenine and thymine, and the thermodynamic parameters were estimated. The length of the polymethylene chains caused a marked difference in the physical properties of the compounds.
Protic Acid Catalyzed Stereoselective Glycosylation Using Glycosyl Fluorides
Authors: Jona Hideki , Mandai Hiroki , Chavasiri Warinthorn , Takeuchi Kazuya , Mukaiyama Teruaki 
Published: September 2002

Abstract
A catalytic and stereoselective glycosylation of various glycosyl acceptors, such as methyl glycosides, thioglycosides, or a disarmed glycosyl fluoride, with benzyl-protected armed glycosyl fluoride was successfully carried out by using various protic acids in the presence of MS 5A. In the cases when trifluoromethanesulfonic acid (TfOH) or perchloric acid (HClO4) was used in diethyl ether (Et2O), α-glycosides were obtained as major products, while β-stereoselectivity was observed when tetrakis(pentafluorophenyl)boric acid [HB(C6F5)4] was used in a mixed solvent of trifluoromethylbenzene (BTF)–pivalonitrile (tBuCN) = 5 : 1. Stereoselectivity of this glycosylation was controlled by the properties of counter anions of the catalyst as well as by those of solvents. Also, one-pot trisaccharide synthesis was performed by successive addition of NIS and third-sugar to afford Glcα or β1–6Glcβ1–6Glc and Glcα or β1–6GlcNβ1–6Glc in excellent yields.
Selective Oxidation of Phenols to Hydroxybenzaldehydes and Benzoquinones with Dioxygen Catalyzed by Polymer-Supported Copper
Authors: Takaki Ken , Shimasaki Yohei , Shishido Tetsuya , Takehira Katsuomi 
Published: September 2002

Abstract
Oxidation of 2,6-disubstituted 4-methylphenols with dioxygen by using a CuCl2-poly(4-methyl-4′-vinyl-2,2′-bipyridine) catalyst gave the corresponding 4-hydroxybenzaldehydes in high yields. The activity of the catalyst and the selectivity of the products significantly depended on the reaction conditions and the composition of the catalyst. When the molar ratio of the bipyridine unit of the polymer ligand to Cu was unity, i.e., N/Cu = 2, the best results were obtained. Moreover, the reaction is likely to be promoted by coordination of the products to the catalyst. Similarly, 2,3,6-trimethylphenol and related compounds were converted to p-benzoquinones selectively with a CuCl2-poly(4-vinylpyridine) catalyst. These polymer-supported catalysts were readily recovered and are reusable without noticeable decrease of their activity.
Structure Elucidation of 6-t-Butyl-6-phenylpentathiane Monoxides by X-ray Crystallography and DFT Calculations
Authors: Ishii Akihiko , Oshida Hideaki , Nakayama Juzo 
Published: September 2002

Abstract
6-t-Butyl-6-phenylpentathiane was oxidized with trifluoroperacetic acid (CF3CO3H) or dimethyldioxirane (DMD) at -20 °C. Oxidation with CF3CO3H yielded pentathiane 3-oxide as the main product, whereas that of DMD gave 1- and 3-oxides. The structures of 1- and 3-oxides were finally determined by X-ray crystallographic analysis. DFT calculations of the NMR chemical shifts were performed on the chair and twist forms of the pentathiane and sixteen isomers of the monoxides with the GIAO method at the B3LYP/6-31G* level. The calculated chemical shifts were verified to be in practical agreement with the experimental data of the pentathiane and the isolated 1- and 3-oxides.
Copper(II) Reagent-Promoted Degradation of N, N′-dialkyldiazenedicarboxamides
Authors: Yamaguchi Jun-ichi , Murayama Yukihito , Suyama Takayuki 
Published: September 2002

Abstract
Degradation of N,N′-dialkyldiazenedicarboxamides with a copper(II) reagent, which was prepared from lithium 4-nitrophenoxide and copper(II) bromide in tetrahydrofuran, proceeded via formation of isocyanate to produce the corresponding 4-nitrophenyl N-alkylcarbamate with the evolution of nitrogen. Further, it was also found that 4-nitrophenyl N-alkylcarbamate reacted with primary or secondary amines to give the corresponding multisubstituted urea. Based on the above results, we developed a new method for the one-pot preparation of multisubstituted ureas from N,N′-dialkyldiazenedicarboxamides.
Controlled Specific Ligand Substitution and Chiroptical Properties of Ruthenium Bis(bipyridine) Nitrosoarene Complexes
Authors: Hesek Dusan , Hembury Guy A , Drew Michael G B , Inoue Yoshihisa 
Published: September 2002

Abstract
Reaction of rac-cis-Ru(Cl)2(bpy)2 with N,N-diethyl-4-nitrosoaniline (2) yields the compound rac-cis-[Ru(Cl)-(bpy)2(2)]Cl in 90–95% yield. Irradiation at 420 nm results in the novel specific substitution of the equatorial chloride ligand for MeCN, leaving the nitrosoarene ligand unaffected. X-ray analysis shows that the nitrosoarene ligand does not participate in an intramolecular π–π interaction with a bipyridine; molecular modelling confirms the relative instability of such a conformation. High thermal stability allows the Δ and Λ enantiomers to be separated and the circular dichroism spectra to be obtained; the anisotropy, or g, factors that are subsequently derived are found to be unexpectedly large.
Efficient Method for the Preparation of Aromatic Bromides and Iodides by Ferrocenium Tetrakis[3,5-bis(trifluoromethyl)phenyl]borate-Catalyzed Halogenation with Bromine and Iodine Monochloride
Authors: Kitagawa Hideo , Shibata Tsuyoshi , Matsuo Jun-ichi , Mukaiyama Teruaki 
Published: September 2002

Abstract
Direct iodination and bromination of various aromatic compounds with 1.1–2.0 molar amounts of iodine monochloride (ICl) and 1.1–3.0 molar amounts of bromine proceeded smoothly to afford the corresponding aromatic iodides and bromides, respectively, in good to excellent yields by using 0.05 molar amount of ferrocenium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, Cp2FeB[3,5-(CF3)2C6H3]4 (1), in the presence of ZnO. Iodination of toluene in the coexistence of 0.5 molar amount of DDQ also proceeded to give iodotoluenes in high yield.
Preparation of Deoxygenated Derivatives of Neoanisatin, a Neurotoxic Sesquiterpenoid Having a β -Lactone
Authors: Obitsu Kazuyoshi , Maki Shojiro , Hirano Takashi , Niwa Haruki 
Published: September 2002

Abstract
Seven deoxygenated neoanisatin derivatives were prepared from anisatin and neoanisatin by utilizing methoxalyl ester/tributylstannane (n-Bu3SnH) deoxygenation procedure coupled with a novel dehydration reaction of neoanisatin.
Over 98% Optical Yield Achieved by a Heterogeneous Catalysis. Substrate Design and Analysis of Enantio-Differentiating Factors of Tartaric Acid-Modified Raney Nickel Hydrogenation
Authors: Sugimura Takashi , Nakagawa Satoshi , Tai Akira 
Published: September 2002

Abstract
Tartaric acid-modified Raney nickel (TA-MRNi) is a chiral heterogeneous catalyst for the hydrogenation of prochiral ketones. An optical yield (OY) of 86% with methyl acetoacetate (1) as a substrate was improved to 94–96% by employing β-keto esters having a proper bulkiness at the γ -position. The γ -bulkiness effect contributes to a high intrinsic enantio-differentiating ability (factor-i) of the TA-MRNi catalysis. Through the study, we found the best substrate, γ -cyclopropyl-β-keto ester, the hydrogenation of which resulted in 98.6% OY. This further improvement in the OY was ascribed to a smaller contribution of non-enantio-differentiating hydrogenation (N-site catalysis) due to the substrate-specific activation of the enantio-differentiating hydrogenation by the chiral modifier. The OY of the hydrogenation of 1 was analyzed by comparing with well-behaved β-keto esters, and the contribution of the factor-i and the N-site to the OY value was evaluated to deduce the origin of the enantiodifferentiation.
A Unified Con/Dis Approach to Assigning Stereogenic Axis Configuration
Authors: Mandal Dipak K 
Published: September 2002

Abstract
A new and unifying approach based on a directional relationship between two arcs joining two ligands at either end of the stereogenic axis is presented for assigning stereogenic axis configuration, which is specified as Con (when both arcs are clockwise or counterclockwise) or Dis (when one arc is clockwise and the other counterclockwise). Con and Dis correspond, respectively, to the descriptors axial R and axial S for a chiral axis, and to E and Z for an achiral alkene axis.
A Novel and Efficient Method for the Synthesis of Tetrahydropyranyl Ethers Catalyzed by Sc(OTf)3
Authors: Watahiki Tsutomu , Kikumoto Hisashi , Matsuzaki Masaya , Suzuki Takeshi , Oriyama Takeshi 
Published: September 2002

Abstract
Reaction of alcohols with dihydropyran in the presence of a catalytic amount of Sc(OTf)3 provides efficiently the corresponding tetrahydropyranyl ethers. After the reaction, the catalyst can be recovered quantitatively from the aqueous media and reused without loss of the activity.
Interpenetrating Polymer Networks Based on Hydrogenated Castor Oil–Isophorone Diisocyanate and Poly(butyl methacrylate)
Authors: Athawale Vilas D , Pillay Priti S 
Published: September 2002

Abstract
Hydrogenated castor oil was reacted with isophorone diisocyanate under different stoichiometric NCO/OH ratios to obtain polyurethanes. These polyurethanes were subsequently interpenetrated with butyl methacrylate monomer using ethylene glycol dimethacrylate as a crosslinker by radical polymerization using benzoyl peroxide as an initiator. Polyurethane/poly(butyl methacrylate) interpenetrating polymer networks (PU/PBMA IPNs) were obtained as tough films by casting in a glass mould. All IPNs were characterized for their resistance to thermal behavior, swelling (%), and mechanical properties. The morphology of the IPNs was studied by scanning electron microscopy. Enhanced mechanical properties were obtained with an increase in the NCO/OH ratios in addition to the regular trend obtained by increasing the polyurethane component in the blend.
Formation of Glyoxal by Oxidative Dehydrogenation of Ethylene Glycol
Authors: Ai Mamoru 
Published: September 2002

Abstract
Iron(III) phosphates doped with a very small amount of molybdenum(VI) were found to be effective as catalysts for a vapor-phase oxidative dehydrogenation of ethylene glycol to glyoxal. The effects of the molybdenum(VI) content and of the reaction variables on the conversion of ethylene glycol and selectivity to glyoxal were studied. The optimum Mo/Fe atomic ratio was in the range from 0.002 to 0.01. The highest selectivity to glyoxal was obtained in the temperature range of 290 to 310 °C. The rate of ethylene glycol consumption increased almost in proportion to the oxygen concentration, while the selectivity to glyoxal increased only slightly as the oxygen concentration was increased. The selectivity to glyoxal increased markedly as the concentration of water was increased. It reached 37 and 32 mol% at ethylene glycol conversions of 60 and 80%, respectively. The one-pass yield of glyoxal reached 26.5 mol%.
The Influence of Salt-Linkages on the Adhesion and Hardness Variance of Hydrogels
Authors: Tamagawa Hirohisa , Nogata Fumio , Umemoto Susumu , Okui Norimasa , Popovic Suzana , Taya Minoru 
Published: September 2002

Abstract
Adhesion between anionic and cationic gels was observed. This adhesion force varied according to the pH and the ionic strength of solutions bathing the gels. A quite strong adhesion was observed in neutral and the ionic-strength solutions. The cause of this phenomenon was suggested to be due to electrostatic interaction between the anionic and cationic fixed groups on the respective gel surfaces, that is, the formation of salt-linkages between the dissociated –COOH and –NH2 groups, –COO-···+H3N–. They were also found in an amphoteric gel body, thus suggesting a great influence on the degree of hardness. Salt-linkages serve as crosslinkings in amphoteric gel in addition to the permanently formed chemical crosslinkings of N,N-methylenediacrylamide. The degree of amphoteric gel hardness can be controlled reversibly by their formation and disruption. Since a reversible hardness change was also observed in real human muscle, the use of salt-linkages is a new principle used to design practical artificial gel muscles.