bluuebunny/crossref_metadata_2025_split huggingface dataset:
1,2-Migration of Perfluoroalkyl Groups in Anionotropic Rearrangement. The Acyloin Rearrangement of 4-Perfluoroalkyl-4-quinols
Authors: Uno Hidemitsu , Yayama Ayumi , Suzuki Hitomi 
Published: May 2006

Abstract
Treatment of 4-perfluoroalkyl-4-quinols with a catalytic amount of potassium t-butoxide gave 2-(perfluoroalkyl)hydroquinones or 5-perfluoroalkyl-2-cyclohexene-1,4-diones in good to moderate yields depending upon the substitution pattern of the quinols. Similarly, 2-hydroxy-3-methyl-2-perfluorooctyl-1-propyl-3-pyrrolin-5-one underwent the base-induced rearrangement to afford a perfluoroalkylated succinimide derivative.
Facile Preparation of Tetrabutylphosphonium Fluoride and Its HF Adducts. New Fluoride Anion Sources for Selective Nucleophilic Fluorination
Authors: Seto Hideharu , Qian Zhao-hui , Yoshioka Hirosuke , Uchibori Yukitaka , Umeno Masayuki 
Published: May 2006

Abstract
Anhydrous tetrabutylphosphonium hydrogen bifluoride (2), dihydrogen trifluoride prepared from aq. tetrabutylphosphonium hydroxide and aq. HF, and tetrabutylphosphonium fluoride prepared from 2 and BunLi were shown to be useful fluoride sources for selective nucleophilic fluorination of oxiranes, alkyl halides, alcohols and sulfonates of aliphatic and steroidal species.
Desing of the Catalyst for Partial Oxidation of Ethylene by Applying an Electrochemical Device
Authors: Otsuka Kiyoshi , Kobayashi Akihiko 
Published: May 2006

Abstract
The electrochemical device composed of the H3PO4-membrane on which various noble metals were attached, M/H3PO4/M′, was demonstrated as a probe of the catalysts for partial oxidation of C2H4. On the basis of the results, we have designed the catalyst (Pd–Ru–Graphite–H3PO4) for the selective synthesis of CH3CHO from C2H4.
Regioselective Synthesis and Polymerization of Substituted o-Trimethylsilylphenylacetylenes
Authors: Yamaguchi Masahiko , Tsukamoto Yukiharu , Ikeura Chinatsu , Nakamura Shigeo , Minami Toru 
Published: May 2006

Abstract
Substituted o-trimethylsilylphenylacetylenes were synthesized by o-metalation of phenylacetylenes with complex reagent of butyllithium and t-BuOK, and were polymerized in the presence of a tungsten catalyst giving deeply colored poly(arylacetylene)s. Relationship between the structure of monomers and polymers was examined.
Synthesis of Tetrakis(1,2-benzodithio)tetramethyleneethane Dication Salt and Its Two-electron Reduction
Authors: Sugimoto Toyonari , Kawachi Atsushi , Ikeda Kaoru , Yamauchi Jun 
Published: May 2006

Abstract
Tetrakis(1,2-benzodithio)tetramethyleneethane dication salt was obtained by two-electron oxidation of a head-to-head dimer of bis(1,2-benzodithio)allene. The dication was two-electron reduced at a comparatively low voltage into the corresponding diradical, whose ESR spectrum seemingly showed a fine structure. The characteristics of the diradical could not be obtained, since the signal intensity did not increase as a result of the preferential intramolecular radical coupling of the diradical into the original allene dimer.
Enantiodifferentiating Photoisomerization of 1,2-Diphenylcyclopropane Sensitized by Chiral Aromatic Esters
Authors: Inoue Yoshihisa , Shimoyama Hideo , Yamasaki Noritsugu , Tai Akira 
Published: May 2006

Abstract
Enantiodifferentiating cis-trans photoisomerization of 1,2-diphenylcyclopropane (1) in the presence of (−)-tetramenthyl 1,2,4,5-benzenetetracarboxylate as a chiral sensitizer gave (+)-(1S,2S)-1t in enantiomeric excesses (e.e.) of 10.4 and 2.8% in pentane and acetonitrile, respectively, while the photosensitization with the corresponding (−)-tetrabornyl ester afforded (+)-(1S,2S)-1t (3.8% e.e.) in pentane and, notably, the antipode (−)-(1R,2R)-1t (2.4% e.e.) in acetonitrile.
Diffusionless Electron Transfer of Xanthene Dyes in Nonpolar and Weakly Polar Donor- and Acceptor-Solvents
Authors: Kemnitz Klaus , Yoshihara Keitaro 
Published: May 2006

Abstract
Diffusionless electron transfer systems, comprised of excited xanthene dyes dissolved in nonpolar or weakly polar electron donor or acceptor, are distinguished by their direct access to the rate constant of electron transfer and by their potentiality for ultrafast electron transfer. We observed short fluorescence lifetimes of ≤ 6 ps for rhodamine 6G dissolved in p-benzoquinone, aniline and N,N-dimethylaniline.
Pig Liver Esterase-catalyzed Hydrolyses of Racemic Diacetates of Bicyclic Compounds and Interpretation of the Enantiomeric Specificity of PLE
Authors: Naemura Koichiro , Takahashi Nobuo , Ida Hirotsugu , Tanaka Shunsuke 
Published: May 2006

Abstract
Pig liver esterase-catalyzed hydrolyses of racemic diacetates of bicyclic compounds, bicyclo[2.2.1]heptanes, bicyclo[2.2.2]octanes, and bicyclo[3.2.1]octanes gave the optically active monoacetates and diacetates. The enantiomeric specificity of PLE toward diacetates of racemic diol substrates was analyzed by using the active site model.
Wavelength Dependence of Light-Induced Chemical Oscillation. Hexacyanoferrate(II)–Hydrogen Peroxide–Sulfuric Acid System
Authors: Mori Yoshihito , Srivastava Prem Kumar , Hanazaki Ichiro 
Published: May 2006

Abstract
We have measured the wavelength dependence of the light-induced chemical oscillation in the Fe(CN)64−–H2O2–H2SO4 system in a continuous-flow stirred tank reactor. The primary process for the induction of oscillation is suggested to be the photo-excitation of Fe(CN)63−.
Enantioselective Addition of Diethylzinc to Aldehydes Catalyzed by Chiral Hydroxy Aminal
Authors: Asami Masatoshi , Inoue Seiichi 
Published: May 2006

Abstract
Chiral secondary alcohols are obtained in high enantiomeric excesses (ee’s) by the enantioselective addition of diethylzinc to aldehydes in the presence of a chiral hydroxy aminal derived from (S)-2-(anilinomethyl)pyrrolidine.
Metal-ion-catalyzed Fluxionality of Pentadienyltins and Its Application to the Diels–Alder Reaction
Authors: Nishigaichi Yutaka , Takuwa Akio , Iihama Kenji , Yoshida Naofumi 
Published: May 2006

Abstract
(Z)-Pentadienyltins (PDT) as well as (Z)-allylic tins are isomerized to (E)-isomers most effectively by alkaline earth metal ions. The resulted (E)-PDT is trapped by 1,4-naphthoquinone to give the Diels–Alder adducts efficiently behaving as a reactive equivalent of 1,3-pentadiene.
New Addition Reactions of Cyclic Ethers with Esters and Thioesters Catalyzed by Quaternary Ammonium Salts or Crown Ether Complexes
Authors: Nishikubo Tadatomi , Sato Kazuya 
Published: May 2006

Abstract
A new addition reaction of 3-benzyloxymethyl-3-methyloxetane with S-phenyl thioacetate proceeded to give 3-benzyloxy-2-methyl-2-phenylthiomethylpropyl acetate catalyzed by 18-crown-6-potassium phenoxide complex. N-(2-Acetoxyethyl)-N-(2-phenoxyethyl)acetamide was also synthesized in high yield by the addition reaction of 5-methyl-4,6-dioxa-1-azabicyclo[3.3.0]octane with phenyl acetate, using tetrabutylammonium salts as catalysts.
Photoalkylation of α-Diketones with Tetraalkylstannanes via Electron Transfer
Authors: Kyushin Soichiro , Otani Shinju , Takahashi Tomoyuki , Nakadaira Yasuhiro , Ohashi Mamoru 
Published: May 2006

Abstract
Irradiation of α-diketones in the presence of tetraalkylstannanes gave α-ketols via electron transfer. The analogy between the photo-induced electron transfer reactions and mass spectrometry exists in the fragmentation of the radical cation of the stannanes.
Kinetic Evidence for the Existence of a Heterodinuclear Reaction Intermediate in the Mercury(II) Catalyzed Formation of Metalloporphyrins
Authors: Tabata Masaaki , Miyata Wakako 
Published: May 2006

Abstract
A reaction intermediate of a heterodinuclear metalloporphyrin involving mercury(II) and zinc(II) was kinetically observed as a two-step reaction pathway and confirmed by both the rate equation and the change in absorption spectra in the reaction of dimercury(II)porphyrin with aquazinc(II).
Synthesis of Heteropolyoxometalate Pillared Layered Double Hydroxides via Calcined Zinc-Aluminium Oxide Precursors
Authors: Narita Eiichi , Kaviratna Padmananda , Pinnavaia Thomas J 
Published: May 2006

Abstract
An amorphous zinc-aluminium oxide solid solution, Zn0.67Al0.33O1.17, Prepared by the thermal decomposition of the acidic layered double hydroxide (LDH), [Zn0.67·Al0.33(OH)2](CO3)1.17·0.33H2O, was found to react with Keggin-like heteropolyoxometalate anions such as α-[Si·W11O39]8− and α-1,2,3-[SiV3W9O40]7− in acid solution to form pillared LDH structures with gallery heights of 9.9 Å.
Preparation of Oxidation Catalysts by Immobilization and Isolation of Metal Complexes into Monolayer Matrix on Silica Surface
Authors: Miki Keiji , Sato Yoshiki 
Published: May 2006

Abstract
Immobilization and isolation of cobalt-pyridine complexes in the fence of monolayer matrix on silica surface provided the active catalysts for oxidation of 1,2,3,4-tetrahydronaphthalene.
Electrochemical Approach to Germenium and Silicenium Ions
Authors: Okano Mitsutoshi , Mochida Kunio 
Published: May 2006

Abstract
The reduction potentials for carbonium, silicenium, and germenium ions were determined by cyclic voltammetry of neutral precursor compounds. The reduction potential shifted to the negative direction as the center element changed from C to Ge.
Palladium(0)-catalyzed Dimerization/Allylation of 1-Alkynes with Allyl Carbonate
Authors: Inoue Yoshio , Ohuchi Kunihiro , Kawamata Tadanori , Ishiyama Jun-ichi , Imaizumi Shin 
Published: May 2006

Abstract
Palladium(0) complexes catalyzed a dimerization/allylation of 1-alkynes with allyl carbonate in which three carbon-carbon bonds were formed regio- and stereoselectively.
Surface Reaction of Methyl Sulfonates on Alumina Studied by Inelastic Electron Tunneling Spectroscopy
Authors: Hida Atsushi , Higo Morihide , Kamata Satsuo 
Published: May 2006

Abstract
Vibrational spectra of methyl sulfonates adsorbed onto an alumina surface have been measured by inelastic electron tunneling spectroscopy. The spectra indicate that the sulfonates react with OH groups of the alumina surface and are adsorbed dissociatively onto the alumina surface as sulfonate ions.
Image Formation Due to Thermo-chemical Decoloration in Blue Colored Organopolysilane/Titanylphthalocyanine Layered Film Patterned by Ultra-violet Light
Authors: Kakui Mikio , Yokoyama Kenji , Yokoyama Masaaki 
Published: May 2006

Abstract
Blue colored poly(methylphenylsilane) (PhMeSi)x/titanylphthalocyanine (TiOPc) layered films have been found to suffer thermo-chemical decoloration effectively by ultra-violet (UV) light irradiation followed by heat treatment at temperature of 250 °C. The decoloration has been confirmed to result from chemical destruction of TiOPc, which is initiated by thermo-decomposition of organopolysilane, and particularly accelerated by UV irradiation. The present thermo-chemical decoloration can be applicable as a new image recording.
New Langmuir–Blodgett Films Based on Substituted 1,2-Dithiolium-TCNQ Radical Anion Salts
Authors: Gionis Vassilis , Ficket Odile , Izumi Mitsuru , Garrigou-Lagrange Chantal , Amiell Jacques , Papavasseliou Georges , Delhaes Pierre 
Published: May 2006

Abstract
Based upon the synthesis of 3,4,5-tris(alkylthio)-1,2-dithiolium cation salts, we have realized new Langmuir–Blodgett films. They present either a centrosymmetrical or noncentrosymmetrical bilayer organization depending on the involved molecular association with iodine, tetracyanoquinodimethane or some other radical anion.
Distribution Map of the Main Peak of Nickel K-Edge X-Ray Absorption Near Edge Structure. Situations of the Nickels in Hydrogenases in the Map
Authors: Yamamura Takeshi , Nakamura Nobuhumi , Yasui Atsushi , Sasaki Kenju , Arai Hiroki 
Published: May 2006

Abstract
Nickel K edge XANES spectra of 27 compounds were observed. Energy and normalized height mapping of their main peaks has shown a characteristic area for square planar geometry, especially for the cases containing sulfur back scatterer. The coordination geometries of the nickels in hydrogenases and CO dehydrogenases were discussed by using their published data.
Novel Reduction of Carboxylic Acids with Samarium Diiodide
Authors: Kamochi Yasuko , Kudo Tadahiro 
Published: May 2006

Abstract
Carboxylic acids were immediately reduced with samarium diiodide in the presence of protic solvent under the basic medium at room temperature to the corresponding alcohols in good yields. The similar reaction of sodium benzoate in the absence of protic solvent afforded the reductive carbon–carbon coupling products.
Remarkable Changes in Catalytic Activity toward Testosterone of Engineered Cytochrome P-450d by Mutations at Putative Distal Site
Authors: Hiroya Kou , Shimizu Toru , Hatano Masahiro , Fujii-Kuriyama Yoshiaki 
Published: May 2006

Abstract
The catalytic activity, 6β-hydroxylation, toward testosterone of engineered cytochrome P-450d was three-times increased by Thr319Ala mutation at the putative distal site, While that was abolished Ala315Ser and important role the steroid of while that was abolished by mutations Thr322Ala at the same site, suggesting the of this region in catalytic activity toward cytochrome P-450d.
The Evaluation of Catalysts Generated from Lewis Acids and Silver Perchlorate in a Highly Stereoselective Glycosylation of 1-O-Acetyl-D-glucose
Authors: Mukaiyama Teruaki , Katsurada Manabu , Takashima Tohru 
Published: May 2006

Abstract
A catalytic cycle was effectively performed in highly stereoselective glycosylation of 1-O-acetyl-D-glucose by using active species generated from respective combinations of Lewis acids (SnCl4, GeCl4, SiCl4, GaCl3, InCl3, and HfCl4) and silver perchlorate.
Highly Enantioselective Synthesis of Propargylic Alcohols by Way of the Asymmetric Aldol Reaction
Authors: Mukaiyama Teruaki , Furuya Minoru , Ohtsubo Akihiro , Kobayashi Shu 
Published: May 2006

Abstract
In the presence of a catalytic amount of chiral diamine-coordinated tin(II) triflate, acetylenic aldehydes enantioselectively react with silyl enol ethers of thioesters to afford the corresponding aldol-type adducts, propargylic alcohols, in high yields. The products are easily converted to the corresponding optically active allene derivatives via effective chiral transfer.
Intercalation and Grafting of Vermiculite with Octadecylamine using Low-Temperature Melting
Authors: Weiss Zdeněk , Valášková Marta , Křístková Monika , Čapková Pavla , Pospíšil Miroslav 
Published: May 2006

AbstractOctadecylamine (ODA) was used to intercalate a fine-grained and a coarse-grained fraction of natural Mg-vermiculite (VER) using a low-temperature melting procedure. Mixtures of Mg-vermiculite fractions and powdered ODA in the molar ratios of 2:1, 1:1, 1:2 and 1:6 were homogenized and heated for 1, 3, 15 and 30 h at 80°C to prepare intercalated samples. X-ray powder diffraction analysis of intercalated samples was combined with molecular modeling to investigate their interlayer structure. Significant amounts of non-intercalated vermiculite and diffuse peaks with very low intensity and basal spacings close to 29 Å were identified when the lowest concentration (molar ratio VER:ODA = 2:1) was used. According to molecular modeling, this indicates the initial stage of a one-layer arrangement of distorted ODA molecules in the interlayer. If the concentration of ODA molecules and treatment time were increased, a two-layer arrangement of ODA molecules with a different ODA chain-disorder and interlayer-space saturation was identified. Interlayer ODA molecules were inclined to the vermiculite basal plane with an inclination angle for two-layer arrangements that ranged from 76 to 95°. Experimental basal spacings with these two-layer arrangements varied from 52 to 58 Å and were in agreement with molecular modeling results. A fully-saturated 58 Å two-layer ODA arrangement was identified when higher ODA concentrations (VER:ODA = 1:2 and 1:6) and 15 and 30 h treatment times were used. There was no significant difference between ODA-intercalated samples prepared using fine-grained and coarse-grained Mg-vermiculite fractions. A grafted ODA-chain nano-layer with a 49.6(2.1) Å average height was observed on the surface of thin ODA-intercalated micro-flakes using atomic force microscopy. Grafted ODA chains not only created an homogeneous surface nano-layer, but also variable-width channels between the ODA molecules.
Disorder in Layered Hydroxides: DIFFaX Simulation of the X-ray Powder Diffraction Patterns of Nickel Hydroxide
Authors: Ramesh T. N. , Jayashree R. S. , Kamath P. Vishnu 
Published: May 2006

AbstractLayered metal hydroxides exhibit non-uniform broadening of lines in their X-ray powder diffraction (XRPD) patterns, which cannot always be explained on the basis of crystallite size effects. In the case of hexagonal solids such as nickel hydroxide, DIFFaX simulations of the XRPD patterns show that: (1) stacking faults and turbostratic disorder at low (<30%) incidence selectively broaden the h0l reflections; (2) turbostratic disorder at high (>40%) incidence causes asymmetric broadening of the hk0 reflections and a complete extinction of the hkl reflections while leaving 00l unchanged; (3) interstratification selectively broadens the non-hk0 reflections; and (4) cation vacancies reduce the relative intensity of the 100 reflection. In contrast, a reduction in the thickness of the crystallites along the stacking direction of the layers selectively broadens the 00l reflections while a reduction in the disc diameter causes the progressive broadening and extinction of the hk0 reflections. Comparison with experimental data shows that several kinds of disorders have to be invoked to account for the observed broadening. DIFFaX simulations enable the quantification of the different kinds of disorder.
Consistent Modeling of the XRD Patterns of Mixed-Layer Phyllosilicates
Authors: Plançon Alain 
Published: May 2006

AbstractThe Markovian model of mixed-layering that has been used until now for the modeling of X-ray diffraction (XRD) patterns of 2:1 phyllosilicates describes the mixed-layer crystals as stacks of ‘layer units’ (LUs) that associate a 2:1 layer with an interlayer content. This model is not consistent when it is applied to a mixed-layer mineral (MLM) involving electrically charged layers, i.e. most of the mixed-layer phyllosilicates with 2:1 layers. Two consistent models can be proposed for these MLMs, which, instead of LUs, stack ‘interlayer units’ (IUs), composed of an interlayer content sandwiched between two half-layers. The IU-NPL model (interlayer units, non-polar layers) imposes non-polarity on the 2:1 layers resulting from the stack of these IUs, which implies restrictions on the succession of the IUs. In the other consistent model, the IU-PL one (interlayer units, polar layers), these restrictions are not imposed. These two models reproduce the Non-Polar 2:1 Layer Model and the Polar 2:1 Layer Model described by Altaner and Ylagan for illite-smectite mixed layering, and the second model corresponds to the stacks of O0.5 T I′ T O0.5 units described by Olives et al.The present work points out the similarities and discrepancies of the calculated XRD patterns by using computer programs designed for the three models of mixed-layering (LU, IU-NPL and IU-PL) and for two-and three-component MLMs. Illustrations are provided for some I-S and I-S-V MLMs.The IU-PL model leads to XRD patterns similar to those of the LU model. It is in agreement with lattice-energy calculations, expandability measurement, HRTEM imaging and NMR spectroscopy.
Predictors of Vitamin B6 and Folate Concentrations in Older Persons: The InCHIANTI Study
Authors: Gori Anna Maria , Sofi Francesco , Corsi Anna Maria , Gazzini Alessandra , Sestini Ilaria , Lauretani Fulvio , Bandinelli Stefania , Gensini Gian Franco , Ferrucci Luigi , Abbate Rosanna 
Published: May 2006

AbstractBackground: Low dietary intake and low serum concentrations of vitamin B6 and/or folate are associated with increased risk of vascular events, possibly because of their association with inflammation, which plays a crucial role in the pathogenesis of cardiovascular diseases.Methods: Using data from 1320 participants in the population-based InCHIANTI study (586 men and 734 women; median age, 69 years; range, 21–102 years) for whom complete data on folate, vitamin B6, inflammatory markers, 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T sequence variant, and important covariates were available, we evaluated the association of inflammatory markers with circulating concentrations of vitamin B6 and folate, independently of dietary vitamin intake, circulating vitamin concentrations, and MTHFR C677T sequence variant.Results: According to multiple linear regression analysis, C-reactive protein and interleukin-6 receptor were strongly and negatively associated with circulating vitamin B6 but not with folate concentrations, independent of age, sex, serum creatinine, serum albumin, total energy intake, smoking history, dietary nutrient intake, and circulating homocysteine and vitamin concentrations. Serum folate concentrations were related to MTHFR 677 TT genotype in persons with folate intake in the lowest tertile (&lt;221.2 μg/day). Vitamin C and retinol intakes were strongly and positively associated with serum folate concentrations independent of age, sex, serum creatinine, serum albumin, total energy intake, smoking history, homocysteine plasma concentrations, dietary nutrient intakes, serum vitamin B6 and vitamin B12 concentrations, and MTHFR C677T sequence variant.Conclusions: Low serum vitamin B6, but not serum folate, concentrations are independent correlates of the proinflammatory state, and both are influenced by antioxidant reserves.
UVB Dose‐toxicity Thresholds and Steady‐state DNA‐photoproduct Levels During Chronic Irradiation of Inbred Xenopus laevis Tadpoles
Authors: Pandelova Iovanna , Hewitt Stephen R. , Rollins‐Smith Louise A. , Hays John B. 
Published: May 2006

ABSTRACTEnvironmental stressors that severely impact some species more than others can alter ecosystems and threaten biodiversity. Genotoxic stress, such as solar UV‐B irradiance, may induce levels of DNA damage at rates that exceed repair capacities in some species but remain below repair capacities in other species. Repair rates would seem to establish toxicity thresholds. We used inbred Xenopus laevis tadpoles in the laboratory to test the hypothesis that balances between rates of induction of cyclobutane pyrimidine dimers (CPDs; the major UV‐B photoproduct in DNA) and rates of CPD removal (repair) can determine UV‐B toxicity thresholds. As rates of chronic UV‐B irradiance were progressively increased by decreased shielding of lamps, survival decreased sharply over a relatively narrow range of dose rates. Apparent toxicity thresholds were associated with large increases in steady‐state CPD levels. Induction at twice the measured removal (repair) rate produced sustained high CPDs and 100% mortality. Induction at one‐half the removal rate resulted in negligible CPD levels and low mortality. Increased intensity of visible radiation available to drive CPD photoreactivation, mimicking interspecies variation in DNA repair capacity, reduced steady‐state CPD levels and increased survival at UV‐B dose rates that were previously toxic, resulting in increased thresholds of apparent toxicity. We suggest that threshold effects due to DNA repair should generally be considered in assessments of effects of genotoxic agents on species‐specific population decreases and human health risks.