bluuebunny/crossref_metadata_2025_split huggingface dataset:
Natural 2,6-Dialkyl-3-piperidinols. 9. Total Synthesis of (±)-Prosafrinine and 13C NMR Studies of Some Analogous Compounds
Authors: Paterne Michel , Dhal Robert , Brown Eric 
Published: July 2006

Abstract
1,7-Dibromoheptane was used to alkylate both ketoesters 2 and 4 successively. Hydrolysis and decarboxylation of the resulting intermediate afforded the ethylenic diketone (6). Ozonolysis of the double bond of 6 gave the diketonic aldehyde (8). Alkaline condensation of nitroethane on the aldehydic carbonyl of the latter, followed by hydrogenation using a Pd–Pt catalyst, afforded 3-r-hydroxy-6-c-(10-oxododecyl)-2-c-methylpiperidine [(±)-prosafrinine] (1a) and (±)-3-epiprosafrinine (1b). The structures of 1a, 1b, and some analogues were confirmed by 13C NMR studies.
The Photochemistry of Steroidal 6-Membered Cyclic α-Nitro Enones
Authors: Suginome Hiroshi , Kurokawa Yoshitaka 
Published: July 2006

Abstract
The products of the photolysis of two steroidal cyclic α-nitro enones, newly synthesized, were compared with those of the cyclic α-nitro ketones and cyclic enones. Direct irradiation of 2α-nitrocholest-4-en-3-one in protic solvents resulted in an unexpected α-cleavage of the carbonyl group and gave 3-alkoxy-2-nitro-2,3-secocholest-4-en-3-one while irradiation of 4α-nitro-5α-cholest-1-en-3-one gave the parent cholest-1-en-3-one which arose from the removal of the nitro group.
Studies of Liquid Water by Computer Simulations. VI. Transport Properties of Carravetta–Clementi Water
Authors: Kataoka Yosuke 
Published: July 2006

Abstract
The micro canonical molecular dynamics simulations of liquid water were performed at different temperatures and densities in order to investigate the anomalies of the transport coefficients. The nonempirical Carravetta–Clementi potential was used for the system with 216 molecules in a cubic cell. The order of magnitude of the nonempirically calculated self-diffusion coefficient, shear viscosity, bulk viscosity, and thermal conductivity were in agreement with experimental results. These transport properties were recognized as anomalous as in real liquid water. The temperature-dependence of these quantities was in agreement with the observed values under pressure of 50 MPa. The effects of compression on these transport coefficients were reproduced qualitatively. The obtained bulk viscosity was larger than the shear viscosity at low temperatures in accordance with experiments. The contribution of rotational motion to thermal conductivity seems to be responsible for the anomalous temperature-dependence of thermal conductivity. Several decay constants of the time correlation functions were obtained. The frequency spectra of the correlation functions were discussed. No marked molecule number dependence was observed in the calculated transport coefficients of Matsuoka–Clementi–Yoshimine water.
Adsorption of 2-(Octylsulfinyl)ethanol at Ethanol–Water Mixture/Air Interface
Authors: Iyota Hidemi , Motomura Kinsi 
Published: July 2006

Abstract
The surface tension of the solution of 2-(Octylsulfinyl)ethanol (OSE) in ethanol–water mixture was measured as a function of molality of OSE at constant composition of ethanol at 298.15 K under atmospheric pressure. The slope of surface tension vs. molality curve decreased with increasing composition. Two break points were observed on the curve: the break point at a low molality was attributed to the phase transition of the adsorbed film of OSE and the one at a high molality to the micelle formation of OSE. The surface excess numbers of moles per unit area of OSE and ethanol and their ratio were evaluated by applying the thermodynamic equations developed previously to the experimental results. It was clarified that the adsorbed film of OSE expels ethanol molecules from the surface region at a small composition of ethanol. The ratio of the excess number of molecules of ethanol per micelle particle to that of OSE was found to be similar to the corresponding ratio of the surface excess number of moles at the critical micelle concentration. This fact led us to the conclusion that the OSE molecules in the micelle behave similarly to those in the adsorbed film even in the mixed solvent.
Solvent Extraction of Various Metal Picrates with Benzo-18-crown-6 into CHCl3
Authors: Takeda Yasuyuki , Nishida Minoru 
Published: July 2006

Abstract
Overall extraction equilibrium constants (Kex) of various metal picrates (MAm) with benzo-18-crown-6 (B18C6) and distribution constant (KD,L) of B18C6 were determined at 25 °C between water and chloroform. The Kex values were analyzed by constituent equilibria, e.g., KD,L, formation constant in water and ion-pair extraction constant (Kex,ip) with a picrate anion of the B18C6–metal ion complex. Kex orders for univalent and bivalent metal ions are Tl+&gt;K+&gt;Rb+&gt;Ag+&gt;Cs+&gt;Na+ and Pb2+&gt;&gt;Sr2+&gt;Ca2+, respectively. Extraction selectivities of B18C6 for the alkali and alkaline earth metal ions are consistent with the size-fit concept; namely, the more closely a cation fits into a crown ether cavity, the more extractable the complex is. For a given B18C6–Mm+ system, Kex,ip value is much larger than values of the other constituent equilibria. Thus, the magnitude of Kex value is determined largely by that of Kex,ip value. Kex,ip value of B18C6 for univalent and bivalent metal ions increases in the order Na+&lt;Ag+&lt;Cs+&lt;K+&lt;Rb+&lt;Tl+ and Sr2+&lt;Ca2+&lt;Pb2+, respectively. Factors governing the magnitude of the Kex,ip value were discussed in detail.
The Spectrophotometric Determination of Phosphate Following the Collection of Ion Pair of Molybdophosphate with Bis[2-(5-chloro-2-pyridylazo)-5-diethylaminophenolato]cobalt(III) on an Organic Solvent-Soluble Membrane Filter
Authors: Taga Mitsuhiko , Kan Masahiko 
Published: July 2006

Abstract
A rapid and sensitive method of determining phosphate was described. The ion pair of molybdophosphate with bis[2-(5-chloro-2-pyridylazo)-5-diethylaminophenolato]cobalt(III) (Co-5-Cl-PADAP) formed in 0.075 mol dm−3 sulfuric acid, 0.225 mmol dm−3 ammonium molybdate, and 25 μmol dm−3 Co-5-Cl-PADAP was collected on an organic solvent-soluble membrane filter made of cellulose nitrate. The membrane filter with the ion pair was then dissolved into N,N-dimethylformamide, and the absorbance of the solution was measured for the determination of phosphate. The calibration curve was linear up to 0.4 μg as phosphorus, with the correlation coefficient of 0.999, and the apparent molar absorption coefficient of phosphate was 2.9×105 dm3 mol−1 cm−1. The relative standard deviation was 1.7% for 0.4 μg of phosphorus. Although dodecyl sulfate existing in an amount ten times that of phosphorus caused a positive error, no ions commonly existing in natural waters interfere with the determination of phosphate. The proposed method was applied to the determination of μg dm−3 levels of phosphate-phosphorus in natural waters, and satisfactory results were obtained.
Novel Synthesis of Carbamate Ester from Carbon Dioxide, Amines, and Alkyl Halides
Authors: Yoshida Yasuhiko , Ishii Shigeru , Watanabe Masayo , Yamashita Tadataka 
Published: July 2006

Abstract
A novel synthesis of carbamate ester using carbon dioxide as a direct material is reported in this article. The direct reaction of carbon dioxide, aliphatic amines, and alkyl halides was found to give the corresponding alkyl carbamate esters in good yields. Reactions using secondary alkyl bromides gave carbamate esters in higher yields than those using primary or tertiary alkyl bromides. The carbamate ester yields increased with the addition of N,N-dimethylformamide to the reaction system of carbon dioxide, amines and, alkyl halides. This reaction is considered to proceed by an SN2 displacement reaction of the alkyl halide by the carbamate anion formed from the reaction of carbon dioxide and the amine.
Novel Electron Acceptors Bearing a Heteroquinonoid System. II. Synthesis and Conductive Complexes of 2,5-Bis(dicyanomethylene)-2,5-dihydrothieno[3,2-b]thiophene, 2,6-Bis(dicyanomethylene)-2,6-dihydrodithieno[3,2-b:2′,3′-d]thiophene, and Their Derivatives
Authors: Yui Koji , Ishida Hideki , Aso Yoshio , Otsubo Tetsuo , Ogura Fumio , Kawamoto Atsushi , Tanaka Jiro 
Published: July 2006

Abstract
Novel heteroquinonoid compounds as potential electron acceptors, 2,5-bis(dicyanomethylene)-2,5-dihydrothieno[3,2-b]thiophene (4a), 3,6-dibromo derivative, 2,6-bis(dicyanomethylene)-2,6-dihydrodithieno[3,2-b:2′,3′-d]thiophene, 3,5-dibromo derivative, and 4,4-dioxide were synthesized by the action of tetracyanoethylene oxide or by a Pd(0)-catalyzed substitution reaction with sodium dicyanomethanide on the corresponding α,α′-dihalo-substituted fused thiophenes. They show effectively diminished on-site Coulomb repulsion owing to the extensive conjugation, and most of their molecular complexes with various electron donors exhibit very high electrical conductivities up to metallic region. In addition, X-ray crystallographic analysis of the complex of 4a with bis(ethylenedithio)tetrathiafulvalene has elucidated that sulfur atoms embedded in 4a molecule are capable of inducing a significant intermolecular interaction, forming a sheet-like network structure.
Oxetane Derivatives and Their Polymers for Designing Functional Polymers Containing a Soft, Somewhat Polar Polyether Network as a Polymer Support
Authors: Motoi Masatoshi , Nagahara Shinsuke , Yokoyama Mitsuru , Saito Eiichi , Nishimura Osamu , Kanoh Shigeyoshi , Suda Hiroshi 
Published: July 2006

Abstract
Several oxetane derivatives having functional groups, such as ester, ketone, ether, acetal, and azo, at the end of 2-oxapolymethylene spacers which were linked to the C-3 carbon of an oxetane ring were readily prepared by a substitution reaction of the corresponding bromide of the oxetane. These oxetanes were polymerized by cationic ring-opening polymerization to give their polymers with molecular weights ranging from 16000 to 1000, depending on the structure of the functional group of the monomer used. When using bisoxetanes as a cross-linking agent in the above polymerization, insoluble resins containing soft, somewhat polar polyether networks as a polymer support were obtained. Some chemical reactions of the pendant functional groups were also examined for the oxetane derivatives and their polymers.
Aryliminodimagnesium Reagents. XVI. Formation of o-Hydroxyazoarenes by Condensation with o-Hydroxynitroarenes. Favorable Role of o-Hydroxyl Group in the Reaction
Authors: Okubo Masao , Nakashima Takanori , Shiku Haruko 
Published: July 2006

Abstract
Hydroxy(HO)-azoxy- and -azoarenes were formed by condensation of ArN(MgBr)2 with o-, m-, and p-HO-nitrobenzenes; nuclear substitution took place as a minor or a major pathway. o-HO-azobenzene was obtained in sufficiently high yield. Relative yields of the products varied according to the position of HO group and reaction conditions. The yield variation was explained by the effects of relative efficiency of single electron transfer, σ-complexation, and cooperation of reagent molecules.
Solubilization of β-Carotene in Water by Water-Soluble Linear Macromolecules
Authors: Inamura Isamu , Isshiki Masayuki , Araki Takeo 
Published: July 2006

Abstract
β-Carotene was solubilized in water by the water-soluble linear macromolecules of poly(N-vinylpyrrolidone) (PVP), polyethylene glycol (PEG), poly(vinyl alcohol) (PVA), and dextran. Absorption of β-carotene in aqueous macromolecular solutions were red-shifted. The rate of photobleaching of β-carotene in water depended on the polymer species.
Selective Reduction of α,β-Unsaturated Carbonyl Compounds with Carbon Monoxide and Water Assisted by Selenium
Authors: Nishiyama Yutaka , Makino Yasuhiko , Hamanaka Sawako , Ogawa Akiya , Sonoda Noboru 
Published: July 2006

Abstract
Carbon–carbon double bond of α,β-unsaturated carbonyl compounds can be reduced selectively with hydrogen selenide, generated in situ by the reaction of elemental selenium with carbon monoxide and water in the presence of strongly basic tertiary amine.
Novel Ferroelectric Liquid Crystals Derived from n-Alkyl Esters of (R)-3-Hydroxybutanoic Acid (II), the Correlation between Their Ferroelectric Properties and Their Molecular Structure
Authors: Nakauchi Jun , Kageyama Yoshitaka , Hayashi Seiji , Sakashita Keiichi 
Published: July 2006

Abstract
The temperature dependence of the spontaneous polarization (Ps) and the optical tilt angle (θ) of the following series of novel ferroelectric liquid crystals, derived from normal alkyl esters of (R)-3-hydroxybutanoic acid, have been investigated.
(Remark: Graphics omitted.)
The magnitude of Ps and θ depends on the kind of linkage groups and their position in the core moiety as well as on the lengths of both terminal chains. The Ps’s for I(m,n) and II(m,n) show a maximum at (m,n)=(10, 3), whereas their θ’s increase with the m and do not change very much with n. In comparison with four analogues (I(10,3), II(10,3), III(10,3), and IV(10,3)), which have the same terminal chains, but which show a different phase sequence, the magnitudes of Ps and θ are in the orders of: III(10,3)&gt;IV(10,3)&gt;I(10,3)∼II(10,3) and III(10,3)&gt;I(10,3)&gt;II(10,3)&gt;IV(10,3) respectively. Among all the compounds, the III(10,3) shows the maximum Ps as high as 1100 μCm−2 in the chiral smectic C phase and as high as 1750 μCm−2 in the chiral smectic I phase.
Direct Determination of Hyperfine Coupling Constants from Complex and Poorly Resolved ESR Spectra with Numerical Decoupling Analysis
Authors: Nozaki Koichi , Naito Akira , Hatano Hiroyuki , Okazaki Satoshi 
Published: July 2006

Abstract
Numerical decoupling analysis (NDA) has been developed as a useful analytical method for determining accurate hyperfine coupling constants (hfccs) involved in isotropic ESR spectra with constant line-widths. NDA was found to have a number of advantages over other methods developed for the extraction of hfccs from ESR spectra. For example, the nuclear spin (e.g., I=1⁄2 or 1) can easily be distinguished and hfccs as small as a linewidth can be determined. Furthermore, false hfccs which often appear and lead to confusion in obtaining the true values in other methods are largely eliminated. Owing to these advantages NDA has enabled us to interpret not only complex but also poorly resolved ESR spectra. The practical use of NDA could be demonstrated by analyzing the ESR spectra of t-butyl 4-nitrophenyl nitroxide and t-butyl 2-chlorophenyl nitroxide radicals.
Syntheses, and Crystal and Molecular Structures of Tetramethylammonium[Aquamethanolhexakis(isothiocyanato)lanthanoidates(III)], [(CH3)4N]3[M(NCS)6(CH3OH)(H2O)] (M=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er), and Tetramethylammonium [Heptakis(isothiocyanato)lanthanoidates(III)], [(CH3)4N]4[M(NCS)7](M=Dy, Er, Yb)
Authors: Matsumoto Fumiko , Matsumura Naomi , Ouchi Akira 
Published: July 2006

Abstract
The title complexes were synthesized and their crystal and molecular structures were determined by the X-ray diffraction method using their single crystals. The crystals of the former ten hexakis(isothiocyanato) complexes of lanthanum through dysprosium(III) and erbiun(III) are isomorphous with each other: monoclinic, space group P21, Z=2. The central metal atom is octa-coordinated, in a square-antiprism geometry, to six nitrogen atoms of thiocyanato (SCN) ions and two oxygen atoms of methanol and water molecules. The two oxygen atoms take the positions of the most approaching apexes of two squares. The latter three heptakis(isothiocyanato) complexes of dysprosium, erbium, and ytterbium are in another isomorphous form with each other: orthorhombic, space group P21nb, Z=4. The central metal atom is hepta-coordinated, in a deformed pentagonal-bipyramidal geometry, to seven nitrogen atoms of SCN ions.
Stopped-Flow Kinetics of the Formation and Decomposition of 2,4- and 4,4-Disubstituted Meisenheimer Complexes in the Reaction of 4-Piperidino-1,3-dinitrophenanthrene with Potassium Methoxide in Dimethyl Sulfoxide–Methanol
Authors: Takahashi Hiroyuki , Hiraide Takao , Hashida Yohji , Sekiguchi Shizen 
Published: July 2006

Abstract
The formation of 2,4-disubstituted anionic σ complex, followed by the formation of 4,4-disubstituted one was confirmed by means of absorption and NMR spectra in the reaction of 4-piperidino-1,3-dinitrophenanthrene with potassium methoxide in DMSO–CH3OH. The rates and activation parameters were determined by kinetic studies using stopped-flow and conventional spectrophotometers. It was found, compared with the previous results on the naphthalene system that the presence of H5 of the title compound affects the rates differently.
Variable-Temperature and Variable-Pressure Nitrogen-14 NMR Studies on the Exchange Reaction of Different Nitriles at the Nickel(II) Ion
Authors: Ishii Masao , Funahashi Shigenobu , Ishihara Koji , Tanaka Motoharu 
Published: July 2006

Abstract
The activation parameters for the exchange reaction of several nitriles at the nickel(II) ion have been determined for the nickel(II) trifluoromethanesulfonate solutions by means of the 14N NMR line broadening method at various temperatures and pressures up to 220 MPa. Values of activation enthalpy (ΔH\eweq/kJ mol−1), activation entropy (ΔS\eweq/J mol−1 K−1), and activation volume at zero pressure (ΔV0\eweq/cm3 mol−1) for the exchange of various nitriles are respectively as follows: 41.4±0.5, −30±2, and +12.0±0.4 in acetonitrile; 42.0±0.4, −25±2, and +13.7±0.5 in propionitrile; 43.3±0.7, −23±2, and +13.1±0.5 in butyronitrile; 43.3±0.5, −19±2, and +12.4±0.6 in isobutyronitrile; 47.1±1.2, −10±4, and +14.4±0.4 in valeronitrile; 51.6±1.9, +4±6, and +13.1±0.6 in benzonitrile. The activation volume varies little in spite of the large variation of the molar volume of nitriles. The activation energy (EQ/kJ mol−1) and the activation volume at zero pressure (ΔVq\eweq cm3 mol−1) for the reorientation of nitrile molecules around the axis perpendicular to the C≡N bond were also determined to be respectively as follows: 7.4±0.1 and +8.3±0.4 for acetonitrile; 8.1±0.1 and +9.5±0.2 for propionitrile; 9.2±0.1 and +9.7±0.3 for butyronitrile; 9.1±0.1 and +11.3±0.2 for isobutyronitrile; 10.7±0.2 and +11.9±0.2 for valeronitrile; 12.5±0.2, and +13.5±0.2 for benzonitrile. Both EQ and ΔVq\eweq increase with increasing bulkiness of the substituent to the cyano group.
Thermal Ring-Splitting Reactions of Diarylcyclobutanes: Significance of Steric Effects on Orbital Interactions in Transition States and Biradical Intermediates
Authors: Yasuda Masahide , Yoshida Kouhei , Shima Kensuke , Pac Chyongjin , Yanagida Shozo 
Published: July 2006

Abstract
Regiochemistry and reactivities in the thermal ring-splitting reactions of diarylcyclobutanes (1–5) have been studied and shown to depend on the stable conformations and rotational mobilities of the aryl substituents. The reactions of 1 and 2 result in a regiospecific symmetric cleavage to give indene or styrene along with significant isomerization of 2 to 3. In the cases of 3–5 both the symmetric and unsymmetric cleavages competitively occur with decreasing symmetric-to-unsymmetric ratios with an increase in methyl substitution. The olefin products from 4 are mixtures of cis- and trans-2-butene, cis- and trans-β-methylstyrene, and trans-stilbene. Thermochemical analyses combined with product analyses indicate that the symmetric cleavage of 1 and the unsymmetric cleavage of 3 proceed with a concerted mechanism, whereas 1,4-biradicals are involved in the other reactions. Structure-reactivity relationships of the present reactions are discussed in terms of mixing of the σ* character in a bonding MO by specific π–σ* interactions, depending on the conformational situations of the aryl groups and in terms of the steric effects which destabilize 1,4-biradicals as well as transition states of the biradical fragmentation to the olefins.
Stopped-Flow Kinetics of Reactions of 1-Ethoxy-2,4-dinitronaphthalene with Pyrrolidine and Piperidine in Dimethyl Sulfoxide Solution
Authors: Fujinuma Hajime , Hosokawa Masaru , Suzuki Tohru , Sato Mitsuo , Sekiguchi Shizen 
Published: July 2006

Abstract
The reaction of 1-ethoxy-2,4-dinitronaphthalene (1) with pyrrolidine or piperidine in dimethyl sulfoxide occured in two stages (Stages I and II). In the stage I, a σ-adduct forms at such a rate as is measured by a stopped-flow technique, and in the stage II it decays at a slower and spectrophotometrically measurable rate. The pyrrolidine system is more reactive than the piperidine system in the stages I and II, with the former reactivity in the stage II being ca. 11000 times higher than the latter. This huge difference was found by NMR evidence to stem from the structure of transition state in the stage II. Further, the activation parameters were determined, which corresponded to such difference in reactivity very well.
The Crystal and Molecular Structure of Di-μ-hydroxo-bis[pentaaquascandium(III)] Benzenesulfonate Tetrahydrate, [{(H2O)5Sc}(OH)2{Sc(H2O)5}](C6H5SO3)4·4H2O: A Dimeric Complex in Pentagonal-Bipyramidal Hepta-Coordination
Authors: Matsumoto Fumiko , Ohki Yoshiyuki , Suzuki Yasuo , Ouchi Akira 
Published: July 2006

Abstract
The crystal and molecular structure of the mew title complex has been determined by means of a single crystal X-ray diffraction method. It is triclinic with the space group P\bar1, Z=2, a=15.518(5), b=19.827(7), c=7.493(2) Å, α=100.90(3), β=103.94(2), γ=82.85(3)°. Both of the metal atoms have almost the same coordination geometry, pentagonal bipyramidal which coordinates the oxygen atoms of five water molecules (2 axial and 3 equatorial ones) and the two hydroxide ions which bridge the both metal atoms. The Sc(1)···Sc(2) distance is 3.403(2) Å. The average Sc–O(H2O) bond length is 2.194 Å, which is much longer than that of Sc–O(OH), 2.072 Å. Benzenesulfonate ions and the other water molecules do not coordinate to the metal atoms, though their oxygen atoms as well as those of the coordinated water are connected with each other by a network involving hydrogen bonding.
Syntheses of 1β-Hydroxyvitamin D2 and D3
Authors: Tachibana Yoji 
Published: July 2006

Abstract
Reduction of 1-oxo-3,5-cyclovitamin D2 and D3 was carried out under various conditions. LiAlH4 reduction in ether preferentially afforded 1β-hydroxy-3,5-cyclovitamin D2 and D3, which were converted to 1β-hydroxyvitamin D2 and D3.
Studies on Aromatic Sesquiterpenes. XI. Synthesis of 7-Isopropyl-3,5-dimethyl-1-naphthol
Authors: Tanaka Juichi , Adachi Kazuo 
Published: July 2006

Abstract
Starting from m-cresol, the title new naphthol was synthesized through 4-methyl-3-(2-methoxy-4-methylbenzoyl)pentanoic acid as a key intermediate.
Stereoselective Synthesis of 3′-Deoxy-3′-fluoroadenosine
Authors: Morizawa Yoshitomi , Nakayama Toshiaki , Yasuda Arata , Uchida Keiichi 
Published: July 2006

Abstract
A new fluorinated nucleoside, 3′-deoxy-3′-fluoroadenosine(1), has been synthesized by a six-step synthesis from methyl 2-O-benzyl-5-O-t-butyldimethylsilyl-β-d-xylofuranoside (2a). Activation of O-3 by formation of a triflate followed by nucleophilic displacement allowed introduction of fluoride ion in a stereospecific manner at C-3.
Photoisomerization of Oxime Ethers and Efficiency of Triplet Formation via Exciplexes
Authors: Takeda Yoshihiko , Misawa Hiroaki , Sakuragi Hirochika , Tokumaru Katsumi 
Published: July 2006

Abstract
9,10-Dicyanoanthracene(DCA)-sensitized isomerization of (E)- and (Z)-isomers of an oxime ether of 2-acetylnaphthalene (E-1 and Z-1, respectively) was investigated in benzene by means of steady irradiation and laser flash photolysis. The excited singlet DCA was effectively quenched by E-1 and Z-1 to afford exciplexes, decay of which gave DCA triplets or 1 triplets. The triplet state of 1 was proposed as the isomerization intermediate and the formation efficiency of 1 triplets was estimated from isomerization quantum yields.