bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of [52](1,2)Ferrocenophane
Authors: Hisatome Masao , Yamashita Rin-ichi , Watanabe Jun , Yamakawa Koji 
Published: July 2006

Abstract
The title compound 1 has been synthesized via bridge enlargement of compound 2 which was formed by cyclization of [5]ferrocenophane-2-propionic acid. By this study the structure of 2, which was discrepantly described by two groups, has been established as [5]-α-oxo[3](1,2)ferrocenophane.
Halogenation Using Quaternary Ammonium Polyhalides. IX. One-Step Syntheses of Acylureas and Carbamates from Amides by Use of Tetrabutylammonium Tribromide and DBU
Authors: Fujisaki Shizuo , Tomiyasu Kazushi , Nishida Akiko , Kajigaeshi Shoji 
Published: July 2006

Abstract
The reaction of amides with tetrabutylammonium tribromide (TBA Br3) (0.5 equiv) and DBU (one equiv) in dichloromethane at room temperature gave N-substituted acylureas in fairly good yields. In the presence of alcohols, the reaction of amides with TBA Br3 (one equiv) and DBU (two equiv) gave N-substituted carbamates.
Effects of Aryl Substituents on Electron-Transfer-Mediated Photochemical Addition of Alcohol to 1,1,2-Triarylcyclopropanes
Authors: Tomioka Hideo , Inoue Osamu 
Published: July 2006

Abstract
Direct irradiation of 1,1,2-triarylcyclopropanes in alcohol resulted in the formation of all possible products arising from trimethylene biradicals, while DCB-sensitized irradiation gave a novel ”anti-Markownikoff“ addition product of alcohol almost exclusively. In order to get insight into the nature and fate of intermediates in the reactions, the effects of nucelophiles and aryl substituents are examined.
New Description of the Substituent Effect on Electronic Spectra by Means of Substituent Constants. V. n–π* Transition of Aliphatic Carbonyl Groups
Authors: Uno Bunji , Kano Kenji , Hosoi Noriya , Kubota Tanekazu 
Published: July 2006

Abstract
The substituent (X) effect on the carbonyl n–π* band of CH3COX is discussed on the basis of a general equation, theoretically derived in order to express the substituent effect on electronic spectra using substituent constants. The results have been successful and are supported by MO calculations.
Reactions of Cobalt Complexes of 5,10,15,20-Tetraphenylporphyrin with Peroxide Radicals Generated from Organic Peroxides and Unsaturated Fatty Acids
Authors: Kohno Masahiro 
Published: July 2006

Abstract
The title reactions in aerated benzene solutions were investigated by using ESR and optical-absorption spectrometers. It was found that (1) a benzyl peroxide radical, bpox·, generated photochemically from dibenzoyl peroxide (DBPO) oxidizes [CoII(tpp)] to produce, successively, a five-coordinate cobalt(III) complex, [CoIII(bpox)(tpp)]; a π cation radical, [CoIII(tpp)\underset.+](bpox)2, and isoporphyrin; (2) a t-butyl peroxide radical, bupox·, generated from di-t-butyl peroxide (DBuPO) oxidizes [CoII(tpp)] to give only a six-coordinate cobalt(III)complex, [CoIII(bupox)(tpp)(dbupo)]; (3) lipid peroxide radicals (lpox·: oapox·, lapox·, lnapox·, and aapox·) produced from unsaturated fatty acids, oleic acid (OA), linoleic acid (LA), linolenic acid (LNA), or arachidonic acid (AA), do not react with [CoII(tpp)]; (4) all the peroxide radicals (pox·: lpox·, bpox·, bupox·) react with [CoIII(Cl)(tpp)] to produce π cation radicals, [CoIII(tpp)\underset.+](Cl)(pox), and (5) bpox· and lapox· react further with the π cation radicals to give isoporphyrins. Finally, the present reactions were compared with the reactions of horseradish peroxidase.
Effect of Counterionic Species on the Adsorption of Tetradecyltrimethylammonium Ion at the Polarized Nitrobenzene–Water Interface
Authors: Kakiuchi Takashi , Kobayashi Miki , Senda Mitsugi 
Published: July 2006

Abstract
The effect of counterions, F−, Cl−, and Br− on the adsorption of the hexadecyltrimethylammonium ion (HTMA+) at the polarized nitrobenzene–water interface has been studied by measuring electrocapillary curves. The interfacial tension in the negative branch of the electrocapillary curve, where the interface is polarized such that the potential in the aqueous phase is negative with respect to that in the nitrobenzene phase, was lowered due to the specific adsorption of HTMA+ ion at the interface. The magnitude of interfacial tension depression in the negative branch became larger in the order F−, Cl−, and Br−, indicating a specific counterion binding at the interface in this order. The adsorption free energy of the HTMA+ ion, ΔGa0, for the adsorption of HTMA+ ion at the interface from the nitrobenzene phase was found to depend markedly on the anionic species present in the aqueous side of the interface. This ΔGa0 values can be taken as a quantitative measure of the counterion specificity at the interface. The meaning of the fact that the change in the shape of the electrocapillary curves depends on the counterion species is discussed in detail in terms of the thermodynamics of the oil–water interface.
An Ab Initio Molecular Orbital Study on the Conformations of Bicyclo[3.1.0]hexane Derivatives
Authors: Okazaki Renji , Niwa Jun , Kato Shigeki 
Published: July 2006

Abstract
Ab initio calculations have been carried out for 2,4-dithia- (5), 2,4-dioxa- (6), 6-oxa- (8), 6-thiabicyclo[3.1.0]hexanes (9), bicyclo[3.1.0]hexane (7), and some of the corresponding cyclohexane derivatives 10–12 using 3-21G, 3-21 G(*) and 6-13G* basis sets. Relative total energies and geometries have been obtained for both boat and chair forms of these compounds. The calculated geometries are in good agreement with observed ones for 7–9. The boat form is more stable than the chair form in the bicyclic systems 7–9, while both the forms have almost equal stability for 5 and the chair form of 6 is slightly more stable than the boat form. The relative stability of the boat form in the bicyclic systems compared with that in the monocyclic cyclohexane derivatives can be explained in terms of the stabilizing orbital interaction. Inversion barriers between the boat and chair forms for 5–7 have also been estimated and are briefly discussed. A similar calculation for bicyclo[3.2.0]hept-6-ene also shows that the boat form is much more stable than the chair form contrary to the conclusion derived from the analysis of experimental results.
Magnetism and Electronic Structure of a Cubane-Type Mo4S4 Cluster
Authors: Sugano Tadashi , Shibahara Takashi , Kobayashi Hanako , Uryû Norikiyo , Kinoshita Minoru 
Published: July 2006

Abstract
The static magnetic susceptibilities of the stable cubane-type compounds of [Mo4S4]m+ with a set of consecutive oxidation numbers have been measured in the temperature range from 2 to 300 K at the field strength of 0.5 T. Na3[Mo4S4(edta)2]·10H2O (m=5) has been found to be paramagnetic with S=1⁄2, whereas Mg2[Mo4S4(edta)2]·22H2O (m=4) and Mg[Mo4S4(edta)2]·12H2O (m=6) to be diamagnetic. The electronic structure of the [Mo4S4]m+ clusters is discussed on the basis of the MO theory from the magnetic properties of these compounds.
The Electrocapillary Curves of the Phosphatidylcholine Monolayer at the Polarized Oil–Water Interface. I. Measurement of Interfacial Tension Using a Computer-Aided Pendant-Drop Method
Authors: Kakiuchi Takashi , Nakanishi Masatoshi , Senda Mitsugi 
Published: July 2006

Abstract
The conditions for obtaining the electrocapillary curves of the dilauroylphosphatidylcholine (DLPC) monolayer formed at the polarized nitrobenzene–water interface have been studied using the pendant drop method. To facilitate the measurement, the system for the interfacial tension measurement, including the computer software for the data handling, has been developed based on digital image processing of the video image of a pendant drop. The 95% confidence interval of the measured interfacial tension value was ±0.06 mN m−1. The time required to measure an electrocapillary curve with 30 points was 30 min, while the time necessary to convert the image data to the interfacial tension was 1 min. The potential drop across the monolayer has been demonstrated to influence the stability of the monolayer strongly. The DLPC markedly lowered the interfacial tension by forming a stable monolayer when the interface was polarized so that the aqueous phase has a negative potential with respect to the nitrobenzene phase. On the other hand, when the aqueous phase became positively polarized, the adsorbed DLPC molecules started to desorb from the interface, giving rise to the disruption of the monolayer. The electrocapillary curves only in the former potential range were found to be thermodynamically meaningful.
Excited-State Reactions of Coumarins. VII. The Solvent-Dependent Fluorescence of 7-Hydroxycoumarins
Authors: Moriya Tetsuo 
Published: July 2006

Abstract
The excited-state reactions of 7-hydroxycoumarin (7HC) and 7-hydroxy-4-methylcoumarin (7H4MC) have been studied by measuring the absorption and fluorescence spectra in aqueous and organic solvents under acidic and basic conditions. Based on the solvent-dependent fluorescence of the fluorophores, the solvents could be classified into several groups: hydroxylic solvents, nonhydroxylic solvents with low dielectric constants, and those with high dielectric constants. In the hydroxylic solvent, protonation, deprotonation, and tautomerization were the main reactions, while in the nonhydroxylic solvent the formation of hydrogen bonding and ion pairs was essential. The fluorescence in water–ethanol mixtures and in aqueous sodium dodecyl sulfate solutions has also been examined in relation to the solvent-dependent spectra in pure hydroxylic and nonhydroxylic solvents.
Polarized Raman and Infrared Spectra of 2,6-Dichloro-, 2,6-Dibromo-, 3,5-Dichloro-, and 3,5-Dibromopyridines
Authors: Tanaka Katsuharu , Kasasaku Kinichi , Shimada Hiroko , Shimada Ryoichi 
Published: July 2006

Abstract
Assignments of the normal vibrations of 2,6-dichloro-, 2,6-dibromo-, 3,5-dichloro-, and 3,5-dibromopyridines were made based on the polarization behavior of the Raman and infrared spectra in single crystals and the normal coordinate calculations. The effect of halo-substitution on the vibrational frequencies of the normal modes was discussed.
The Structure of the Cyclodextrin Complex. XXI. Crystal Structures of Heptakis(2,6-di-O-methyl)-β-cyclodextrin Complexes with p-Iodophenol and p-Nitrophenol
Authors: Harata Kazuaki 
Published: July 2006

Abstract
Crystal structures of heptakis(2,6-di-O-methyl)-β-cyclodextrin complexes with p-iodophenol and p-nitrophenol were determined by the X-ray analysis. These two crystals were isomorphous with the space group P212121 and cell dimensions: a=14.796(3), b=18.853(5), and c=28.989(6) Å for the p-iodophenol complex, and a=14.779(2), b=18.965(3), and c=28.741(4) Å for the p-nitrophenol complex. The structures were solved by the heavy atom method combined with the phase refinement by the tangent formula and refined by the blockdiagonal least-squares method to the R-values of 0.12 (p-iodophenol complex) and 0.10 (p-nitrophenol complex). The host molecule has a round shape, which is maintained by the intramolecular hydrogen bonds between the O(3)H hydroxyl group and O(2)CH3 methoxyl group of the adjacent residue. The guest molecules in the both complexes are not included within the host cavity but located in the intermolecular space between host molecules. The host cavity includes water molecules and a methoxyl group of the adjacent host. Hydrogen bonds are formed only within the host cavity.
Accelerating Effect of Donor Solvents on Racemization of the Tris(1,10-phenanthroline)iron(II) Cation
Authors: Fujiwara Terufumi , Okamoto Yoshiharu , Yamamoto Yuroku 
Published: July 2006

Abstract
Rates of racemization of the tris(1,10-phenanthroline)iron(II) cation, [Fe(phen)3]2+, have been measured at 7.5 °C to 17.5 °C in 1,2-dichloroethane, o-dichlorobenzene, nitrobenzene, and nitromethane, and in 1,2-dichloroethane solutions containing dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), methanol (MeOH), acetone (Ac), and acetonitrile (AN). In the four pure solvents, the observed racemization rates are markedly smaller than those calculated by the Van Meter and Neumann equation, which relates the racemization rate to the solvation energy of the phen ligands and viscous resistance. Addition of donor solvents to 1,2-dichloroethane solutions of the iron complex enhances the racemization rates. The degree of enhancement increases in the order AN&lt;Ac&lt;MeOH&lt;DMF&lt;DMSO and the activation energy decreases in the same order. This sequence lies in the order of increasing Gutmann donor number of the solvents, indicating a nucleophilic interaction of the solvents with the iron metal in the transition state. These obsevations may be interpreted in terms of Kepert’ s model for solvent-assisted racemization of tris-chelated complexes and the molecular structure of a solvate complex determined previously, and allow us to modify the Van Meter and Neumann equation.
A Novel Synthesis of 2-Acyl Cyclic Ethers and 3-Keto Cyclic Ethers Including Spiro Cyclic Ethers via Intramolecular Ring-Opening of α,β-Epoxy Sulfoxides with Hydroxyl Group
Authors: Satoh Tsuyoshi , Iwamoto Ken-ichi , Sugimoto Atsushi , Yamakawa Koji 
Published: July 2006

Abstract
The α,β-epoxy sulfoxides 1 and 2 bearing ω-oxyalkyl group were synthesized from ω-oxyalkyl carbonyl compounds and 1-chloroalkyl phenyl sulfoxide. The intramolecular ring opening of the oxirane ring of these α,β-epoxy sulfoxides, through an attack of the terminal hydroxyl group, gave 2-acyl cyclic ethers or 3-keto cyclic ethers, including spiro-type cyclic ethers. This procedure is applicable to the preparation of five- and sixmembered cyclic ethers.
Synthetic Studies of Amphotericin B. III. An Enantiospecific Synthesis of the C-1–C-19 Segment of the Amphotericin B Aglycon
Authors: Kinoshita Mitsuhiro , Taniguchi Masato , Morioka Masahiko , Takami Hitoshi , Mizusawa Yasuhiro 
Published: July 2006

Abstract
The title compound, (3S,4S,5S,9S,11R,12R,15R,17S)-4-[(t-butyldimethylsilyloxy)methyl]-1,3,5,9,11,12,15,17,19-nonahydroxy-3,5:11,12:15,17-tri-O-isopropylidene-19-O-(4-methoxybenzyl)-9-O-[(2-methoxyethoxy)methyl]-7-nonadecanone (1) was effectively synthesized through the coupling of (3S,5R,8R,9R,11S)-12-iodo-3,5:8,9-di-O-isopropylidene-1-O-(4-methoxybenzyl)-11-O-[(2-methoxyethoxy)methyl]-1,3,5,8,9,11-dodecanehexol (2) and (3S,4R,5S)-4-[(t-butyldimethylsilyloxy)methyl]-3,5-O-isopropylidene-1,1-bis(methylthio)-1-trimethylstannyl-6-heptene-3,5-diol (36). The C-13–C-19 segment 36 was enantiospecifically synthesized from 1,2:5,6-di-O-isopropylidene-α-d-thero-d-glycero-3-hexofuranosulose (7) via (2S,4R,5S)-5,6-epoxy-3-[(t-butyldimethylsilyloxy)methyl]-1-hexen-3-ol (6a) in 11.6% overall yield.
Barium Ferrate Monohydrate BaFeO4·H2O, a Useful Oxidant for the Oxidation of Organic Compounds under Aprotic Conditions
Authors: Firouzabadi Habib , Mohajer Daryoush , Entezari-Moghadam Mohsen 
Published: July 2006

Abstract
Preparation of barium ferrate monohydrate with a slight modification is described. It is shown that this reagent is capable of oxidizing different organic compounds and could be used as a versatile reagent in organic synthesis. Primary and secondary alcohols are converted to their carbonyl compounds, α-hydroxy ketones to their diketones, and hydroquinones to their quinones. Aromatic amines are converted to their azo compounds, benzylamine to benzaldehyde, phenylhydrazones and oximes to their carbonyl compounds. Thiols are also converted to their disulfides in high yields. This reagent seems to be a non-toxic and a non-pollutant compound.
The Reaction of N″-Cyanoguanidine with Formaldehyde. II. Bis(N″-carbamoylguanidino)methane or N,N′-Methylenebis[N′-(diaminomethylene)urea]
Authors: Shiba Ryuichi , Takahashi Miyuki , Ebisuno Toichi , Takimoto Michiaki 
Published: July 2006

Abstract
The condensation product in the reaction of N″-cyanoguanidine with paraformaldehyde under strongly acidic conditions was identified as N,N′-methylenebis[N′-(diaminomethylene)urea] by X-ray analysis. This structure agreed with that estimated from the 1H NMR data.
Preparation of Novel N-Vinyl-, N-(1-Butylvinyl)-, and N-(1-Methyl-1-pentenyl)iminotriphenylphosphoranes and Their Reactions with α,β-Unsaturated Ketones
Authors: Iino Yukio , Nitta Makoto 
Published: July 2006

Abstract
The novel N-vinyl-(2a) and a mixture of N-(1-butylvinyl)-(2b) and N-(1-methyl-1-pentenyl) iminotriphenylphosphoranes (2c) were prepared by the reaction of azidoethylene and 2-azido-1-hexene with triphenylphosphine, respectively. The thermal reaction of 2a, 2b, and 2c with α,β-unsaturated ketones undergoes an enamine-type alkylation and the subsequent aza-Wittig reaction to give pyridine derivatives in modest yields.
Ion-Exchange Rate of Chromate and Dichromate Ions on Bis(triethylamine)zirconium
Authors: Rawat J P , Chitra  
Published: July 2006

Abstract
Kinetic studies of K2Cr2O7 and K2CrO4 have been performed on an inorganic anion exchanger, bis(triethylamine)zirconium in Cl− form. F values have been determined at four different temperatures 30, 40, 50, and 60 °C with ±1 °C variation and corresponding Bt values are evaluated and plotted as a function of temperature. The mechanism is found to be particle diffusion control. Various parameters viz. effective diffusion coefficient (Di), diffusion coefficient (Do), energy of activation (Ea), and entropy of activation (ΔS*) have been evaluated.
A Pulse Radiolysis Study of the Formation of Dimer Radical Cations of Aromatic Olefins
Authors: Chikai Yukio , Yamamoto Yukio , Hayashi Koichiro 
Published: July 2006

Abstract
The formation of dimer radical cations of several aromatic olefins has been studied by the pulse radiolysis technique. The aromatic olefins examined are 2-vinylnaphthalene (VN), 2-(1-propenyl)naphthalene (PN), 4-vinylbiphenyl (VBP), trans,trans-1,4-diphenyl-1,3-butadiene (1,4-DPB), and s-trans-2,3-diphenyl-1,3-butadiene (2,3-DPB). The formation of dimer radical cations were observed with all of them except 1,4-DPB, although it was very limited with VBP. Two types of dimer radical cations, bonded and associated ones, are formed with VN, whereas only the associated dimer radical cation is formed with PN. The influence of the aromatic substituents on the formation of the dimer radical cations is described.
Thermodynamic Studies on Order-Disorder Phase Transitions of p-Terphenyl and p-Terphenyl-d14
Authors: Saito Kazuya , Atake Tooru , Chihara Hideaki 
Published: July 2006

Abstract
The heat capacities of p-terphenyl and p-terphenyl-d14 were measured by adiabatic calorimetry between 3 and 300 K. The phase transition associated with a molecular conformation change was observed as a λ-shaped anomaly at (193.5±0.1) K and at (180.3±0.1) K. The enthalpies of transition are (304±20) J mol−1 and (288±20) J mol−1 and the entropies of transition are (1.63±0.10) J K−1 mol−1 and (1.63±0.10) J K−1 mol−1, respectively. The anisotropy of the intermolecular interaction is discussed and the anomalous portion of the heat capacities in the transition region was compared favorably with a two-dimensional Ising model.
Structure and Racemization of Optically Active mer-(3-Azapentane-1,5-diamine or 3-methyl-3-azapentane-1,5-diamine)(ethylenediamine-N-acetato)cobalt(III) Complexes
Authors: Kawaguchi Hiroshi , Fukaki Hironobu , Ama Tomoharu , Yasui Takaji , Okamoto Ken-ichi , Hidaka Jinsai 
Published: July 2006

Abstract
The crystal structure of (−)500CD-mer-[Co(edma)(dien)]Br2·2/3CH3OH·2/3H2O was determined by the X-ray diffraction method. The crystal is triclinic, space group P1, a=13.824(8), b=13.814(8), c=8.055(3) Å, α=101.18(6), β=101.17(6), γ=116.32(5)°, and Z=3. All of the crystallographically independent complex cations, in which the terdentate ligands coordinate meridionally, have a δ spiral configuration, and the asymmetric nitrogen donor atoms of the edma ligands take an S configuration. The racemization reactions due to the inversion at the secondary amine nitrogen atom of the edma ligand in (−)500CD-mer-[Co(edma)(dien)]2+ and (−)514CD-mer-[Co(edma)(mdien)]2+ were studied at 20–35 °C in the pH range of 6.10–7.24. The rate law for both complexes was described as R=k[OH−][complex]. The activation parameters at 30.0 °C were ΔH\eweq of 94.9 kJ mol−1 and ΔS\eweq of 126 J K−1 mol−1 for the dien complex and ΔH\eweq of 73.8 kJ mol−1 and ΔS\eweq of 62.0 J K−1 mol−1 for the mdien complex.
Total Synthesis of Elaiophylin (Azalomycin B)
Authors: Toshima Kazunobu , Tatsuta Kuniaki , Kinoshita Mitsuhiro 
Published: July 2006

Abstract
Antibiotic elaiophylin (1) has been first synthesized by a convergent route involving aldol coupling of (5R,6R,7R)-5-O-[2-deoxy-3,4-bis-O-(isopropyldimethylsilyl)-α-l-fucopyranosyl]-6-ethyl-7-O-(diethylisopropylsilyl)-5,7-dihydroxy-3-octanone (25f) and (7S,8S,15S,16S:3E,5E,11E,13E)-8,16-bis[(1R)-1-formylethyl]-7,15-dimethyl-1,9-dioxa-3,5,11,13-cyclohexadecatetraene-2,10-dione (3), followed by desilylation. The appropriately O-protected segment 25f and the macrocyclic dialdehyde 3 were synthesized from d-glucose and 2-deoxy-l-fucose.
Synthesis and Structure of 6,7-Dihydro-2,3-disubstituted 5H-2a-Thia(2a-SIV)-2,3,4a,7a-tetraazacyclopent[cd]indene-1,4(2H,3H)-dithione
Authors: Matsumura Noboru , Tomura Masaaki , Mori Osamu , Tsuchiya Yuko , Yoneda Shigeo , Toriumi Koshiro 
Published: July 2006

Abstract
Symmetrical tetraazapentalene derivatives 5 and 6 were synthesized by a convenient one-pot reaction using lithium thioureide/phenacyl chloride/alkyl (or allyl) isothiocyanate system. Unsymmetrical tetraazapentalene derivatives 8 were prepared by the reaction of various isothiocyanates with thiadiazolopyrimidine derivatives 7 which were derived from symmetrical tetraazapentalene derivatives. The structure of 5c was determined by a single crystal X-ray diffraction.
Intramolecular End-to-End Reactions of Photoactive Terminal Groups Linked by Poly(oxyethylene) Chains
Authors: Ashikaga Kazuo , Ito Shinzaburo , Yamamoto Masahide , Nishijima Yasunori 
Published: July 2006

Abstract
The triplet-sensitized photochemical reaction using a series of poly(oxyethylene) chains with a pair of photoactive terminal groups, dibenz[b,f]azepine (DBA) chromophores (DBA–COCH2CH2(OCH2CH2)nOCH2CH2CO–DBA, n=0–10) was examined. The photoirradiation of bichromophoric compounds caused either intra- or intermolecular reactions. These reactions were kinetically analyzed by two different methods: the measurement of deactivation processes of the reaction intermediates (excited triplet state of DBA) by nanosecond laser photolysis and the quantitative analysis of the reaction products by GPC. The intramolecular deactivation rate constant, kintra, showed a remarkable chain-length dependence; the maximum kintra value appeared at n=5 and it was found to be 5.9×104 s−1. On the other hand, the intramolecular cyclization rate also depends on the chain length; the maximum quantum yield, φdintra, was given at n=7 (φdintra=0.51). The chain length for the maximum cyclization yield shifted slightly to the longer region than that for the maximum kintra value due to the restriction of the terminal structure (anti-configuration). The results obtained for this reaction system are compared with those obtained for the previously reported polymethylene system and the effect of chain flexibility on the intramolecular ring-closure reaction is discussed.