bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel [1, N]-Carbon to Carbon Rearrangement of an Ester Group via Organotitanium Intermediates Wherein the N Varies from 2 to 5. Full Scope and Limitation Leading Predominantly to the Rearrangement
Authors: Yamazaki Takanori , Urabe Hirokazu , Sato Fumie 
Published: June 2006

Abstract
Malonates and methanetricarboxylates having an unsaturated side chain such as 2, 12, 20, 22, 24, 31, or 37 underwent a new ester rearrangement reaction promoted by (η2-propene)Ti(O-i-Pr)2 to afford the succinate derivative 4 or α,β-unsaturated ester 17, 21, 23, 25, 34, or 38 via the migration of the ester group from its original bis- or tris-ester position to the acetylene- or olefin-titanium complex. It has been found that the side reactions competing with the desired migration are dealkylation of the side chain of the ester and a simple cyclization. The substrates and conditions which allow the ester migration a preferential path were determined as well as the scope and limitation of this reaction.
One-Step Synthesis of Naphthofurandione, Benzofurandione, and Phenalenofuranone Derivatives by the CAN-Mediated Cycloaddition
Authors: Kobayashi Kazuhiro , Uneda Tomokazu , Tanaka Koujirou , Mori Masako , Tanaka Hideo , Morikawa Osamu , Konishi Hisatoshi 
Published: June 2006

Abstract
The 3+2-type cycloaddition reaction of 2-hydroxy-1,4-naphthoquinones with various alkenes or phenylacetylene was mediated by ammonium cerium(IV) nitrate (CAN) to give the corresponding naphtho[2,3-b]furan-4,9-dione and naphtho[1,2-b]furan-4,5-dione derivatives. The reaction of 2-hydroxy-1,4-benzoquinones with alkenes in the presence of CAN similarly proceeded to give benzofuran-4,7-dione and benzofuran-4,5-dione derivatives. 3-Hydroxy-1H-phenalen-1-one also underwent the CAN-mediated cycloaddition with alkenes or phenylacetylene to give the corresponding 7H-phenaleno[1,2-b]furan-7-one derivatives.
In Vitro Selection of a DNA Aptamer Binding to Thyroxine
Authors: Kawazoe Naoki , Ito Yoshihiro , Shirakawa Masahiro , Imanishi Yukio 
Published: June 2006

Abstract
A DNA aptamer that selectively binds to a hormone, thyroxine, was isolated using the in vitro selection method. A pool of single-stranded DNAs consisting of random sequences was incubated with the thyroxine-immobilized agarose gel; bound DNAs were then collected and amplified by the polymerase chain reaction. This selection process was repeated nine times. The selected DNAs were cloned and sequenced. Some of the cloned DNA contained a consensus sequence. Several DNAs containing the sequence were chemically synthesized and the binding ratios to the thyroxine-immobilized gel were determined. Among them a DNA containing 14 nucleotides was found to bind selectively to thyroxine.
Intermolecular Hydrogen Bonds of 5-Benzylidene-2,4-thiazolidinedione Derivatives and Related Compounds in Crystalline State
Authors: Okazaki Masaki , Uchino Nobuhiko , Ishihara Makoto , Fukunaga Hiroo 
Published: June 2006

Abstract
From the viewpoint of noncentrosymmetric molecular arrangement design in crystalline state, which is indispensable to second order nonlinear optical materials, intermolecular hydrogen bond formation of eight 5-benzylidene-2,4-thiazolidinedione derivatives and related compounds were investigated by X-ray crystallography. 5-Benzylidene-2,4-thiazolidinedione (1) itself forms centrosymmetric head-to-head (or tail-to-tail) intermolecular hydrogen bonds and takes a centrosymmetric molecular arrangement in crystalline state. Introduction of 4-methoxy group into the phenyl moiety of 1 was the only useful means for head-to-tail type intermolecular hydrogen bond formation. 5-(4-Methoxybenzylidene)-2,4-thiazolidinedione shows head-to-tail type intermolecular hydrogen bonds and noncentrosymmetric molecular arrangement in crystalline state. Similarities in both hydrogen bond formation and molecular arrangement in crystalline state are obtained by conversion of 2,4-thiazolidinedione to 2-thioxo-4-oxazolidinone, but in the case of conversion to 2,4-oxazolidinedione only hydrogen bond formation is shown in a similar manner. In the case of conversion to rhodanine, no similarity in either hydrogen bond formation or molecular arrangement in crystalline state was shown. Such behaviors were considered from viewpoints of pKa and hydrogen bond energy.
Persistent Spectral Hole Burning of Phenoxazine and Phenothiazine Derivatives in Poly(vinyl alcohol) and the Effect of the Addition of N,N,N′,N′-Tetramethyl-p-phenylenediamine
Authors: Nishiyama Satoko , Machida Shinjiro , Yamashita Takashi , Horie Kazuyuki 
Published: June 2006

Abstract
The photochemical behavior at cryogenic temperatures of phenoxazine and phenothiazine dyes in poly(vinyl alcohol) was investigated by using persistent spectral hole burning. The importance of hydrogen-bondings has been confirmed by measuring the effects of the addition of N,N,N′,N′-tetramethyl-p-phenylenediamine on the holewidth and the hole area of various cationic dyes at 20 K. The hydrogen bonds around the ring-N atom affect the total dephasing time, while the hydrogen bonds around the amino groups as the substituents and around the ring-N atom control the efficiency of hole formation.
Functional Micropore Chemistry of Crystalline Metal Complex-Assembled Compounds
Authors: Kitagawa Susumu , Kondo Mitsuru 
Published: June 2006

Abstract
Syntheses of new porous frameworks with specific pore size and type are of considerable interest for the appearance of zeolite-like functionalities. It is useful to take advantage of metal complex-assembled compounds because of designable frameworks, high microporosity, and flexible frameworks based on a variety of coordination geometries of metal centers and multifunctionality of bridging organic parts. Many recent reports show that the synthesis procedures are developing from serendipitious to rational level. Therefore, the micropore chemistry of metal complex-based assemblages is directed toward not only new frameworks but also functionalities such as gas and small molecule adsorption, ion exchange, heterogeneous catalysis, photo-chemical and -physical properties. For chemical and physical functionalities robustness of a framework is required even in the absence of guest molecules in the cavity. The stability is largely dependent on the structural dimensionality of the assemblages. A wide variety of structures of metal complex-based assemblages are listed and recent findings in this functional chemistry are described.
Hydrogen Bonds of Poly[(n-alkyl methacrylate)-co-(methacrylic acid)]’s in Dilute Solutions
Authors: Noguchi Akihiro , Masui Yasusi , Oda Hirohisa , Kuzuya Masayuki 
Published: June 2006

Abstract
The nature of the association of poly[(n-alkyl methacrylate)-co-(methacrylic acid)]’s (poly(RMA-co-MAA)’s) in dilute chloroform solutions was investigated by Fourier transform infrared (FT-IR) spectroscopy and the solution viscosity. The proportions (Pfree) of free carboxyls increased with the length of the alkyl groups in RMA’s and with the decreasing MAA composition. From the relationships between Pfree and the effective concentration (Ceff) of carboxyls attached to the polymer chain, it was shown that the major substituent effects of the alkyl groups on the hydrogen bonds in the copolymers are the extension of the polymer chain and the steric effect on the association between carboxyls and ester groups. Also, from the features of the shrinkage of the polymer chains accompanied with the intrachain association of carboxyls it was suggested that the hydrogen bonds in the copolymers are formed chiefly between neighboring sites along the chain.
Spectral Characteristics of the Aggregation of α,β,γ,δ-Tetrakis(p-sulfophenyl)porphyrin in the Presence of Proteins
Authors: Huang Cheng Zhi , Li Yuan Fang , Li Na , Li Ke An , Tong Shen Yang 
Published: June 2006

Abstract
With the aid of absorption, fluorescence, and resonance light-scattering measurements, the aggregation of protonated water-soluble porphyrin, α,β,γ,δ-tetrakis(p-sulfophenyl)porphyrin, [H4tpps4]2−, in the presence of proteins has been characterized. At pH 1.86, proteins dissolved in water can form a positively charged microphase, which can neutralize the negative charges of [H4tpps4]2− distributed in it, leading to the J- and H-aggregation of [H4tpps4]2−. Exciton splitting signals, which are generally associated with the aggregation of porphyrins, as described by molecular-exciton theory, are observed at 436.1 nm on the resonance light-scattering spectra, supporting the porphyrin–porphyrin interactions in the positively charged microphase of proteins. It has been proved that positively charged microphase can protect aggregates of [H4tpps4]2− from water dilution and high temperature.
Coordination Polymers Self-Assembling from Cadmium(II) Ions and Flexible Pyridine-Based Bridging Ligands
Authors: Fujita Makoto , Aoyagi Masaru , Ogura Katsuyuki 
Published: June 2006

Abstract
This paper describes coordination polymers assembled from cadmium nitrate and flexible bridging ligands, py–X–py (py = 4-pyridyl, 1a: X = CH2, 1b: X = C(=CH2), 1c: X = CH2CH2). The X-ray structure analysis of these complexes showed that their infinite topologies are quite different from each other, despite the structural similarity of ligands 1a—1c. Upon treatment with Cd(NO3)2, 1a gave an infinite two-dimensional sheet structure with a stoichiometry of ML2 (M and L denote metal and ligand, respectively). Ligand 1b also afforded an infinite polymer possessing the same ML2 composition. However, the polymer structure is characterized by one-dimensionally bounded macrocyclic frameworks where adjacent Cd ions are linked by two ligand molecules. Interestingly, ligand 1c gave an infinite polymer of M2L3 composition whose structure was shown to be a unique one-dimensional framework having macrocyclic frameworks (M2L2) linked together by the third L molecules.
A Sulfur-Capped Triangular Cobalt–Tributylphosphine–Aminobenzenethiolato Complex: Synthesis, Structure and Properties of Co3(μ3-S)(abt)3(PBun3)3
Authors: Chen Zhong-Ning , Kang Bei-Sheng , Zhou Zhong-Yuan , Li Wen-Jie , Tong Ye-Xiang , Lu Zhong-Lin , Su Cheng-Yong 
Published: June 2006

Abstract
The reaction of CoCl2, Habt (2-aminobenzenethiol), NaOMe and PBun3 (tributylphosphine) in an equimolar ratio under anaerobic conditions, followed by the addition of an excess of Li2S led to the triangular cluster complex Co3(μ3-S)(abt)3(PBun3)3. It crystallizes in the triclinic space group , with a = 13.231(2), b = 14.201(2), c = 18.890(2) Å, α = 79.970(10)°, β = 87.560(10)°, γ = 67.040(1)°, V = 3216.6(12) Å3 and Z = 2. The molecule consists of three “Co(abt)(PBun3)” units with the Co3 plane capped by the bridging μ3-S atom to form an approximately equilateral triangle with an average Co–Co distance of 2.709 Å. The cobalt atoms located in distorted trigonal-bipyramidal environments are further bridged by μ2-S atoms from the three abt ligands and terminally coordinated by N and P donors. The cyclic voltammogram showed three quasi-reversible redox processes with E1/2 = 0.79, −0.07, and −0.81 V, vs. SCE. The variable-temperature magnetic susceptibility measurements showed an antiferromagnetic exchange interaction within the triangular spin cluster.
Chain Compounds of Molybdenum(II) Trifluoroacetate Linked by p-Quinones [Mo2(O2CCF3)4(p-quin)]n, p-quin = 9,10-anthraquinone, 2,6-dimethyl-1,4-benzoquinone, and 1,4-naphthoquinone
Authors: Handa Makoto , Matsumoto Hiroki , Yoshioka Daisuke , Nukada Ryoji , Mikuriya Masahiro , Hiromitsu Ichiro , Kasuga Kuninobu 
Published: June 2006

Abstract
A series of chain complexes of molybdenum(II) trifluoroacetate linked by p-quinones, [Mo2(O2CCF3)4(p-quin)]n, p-quin = 9,10-anthraquinone (9,10-aq), 2,6-dimethyl-1,4-benzoquinone (2,6-dmbq), and 1,4-naphthoquinone (1,4-nq) have been prepared. The X-ray structure analyses showed that the carbonyl oxygens of the p-quinones are coordinated to the Mo2 dimers with distances of 2.478(6) and 2.532(5) Å (for 9,10-aq), 2.619(9) and 2.596(10) Å (for 2,6-dmbq), and 2.522(8) Å (for 1,4-nq), respectively. The Mo–Mo bond distances are 2.107(1)—2.117(1) Å, which are slightly longer than that of Mo2(O2CCF3)4 (2.090(4) Å). Elongation of the C=O and C=C bonds of the 9,10-aq and 2,6-dmbq molecules on the coordination has been observed, but the bond distances of the coordinated and uncoordinated 1,4-nq molecules are similar to each other. The difference is discussed in terms of the oxidizing abilities and the symmetries of the p-quinones.
Kinetics and Mechanisms of the Reaction of PH2O2− with O2, Photocatalyzed by [Ru(bpy)3]2+* (bpy = 2,2′-bipyridine), Forming Peroxodiphosphate Ions in an Aqueous Solution
Authors: Kimura Masaru , Takahashi Aki , Sakata Tomomi , Tsukahara Keiichi 
Published: June 2006

Abstract
The formation reaction of peroxodiphosphate (denoted by PDP and meaning P2O84−, HP2O83− etc.) by the reaction of molecular oxygen (O2) with the phosphinate ion (PH2O2−) was extremely accelerated by irradiation with visible light of aqueous solutions containing the tris(2,2′-bipyridine)ruthenium(II) ion ([Ru(bpy)3]2+). The [Ru(bpy)3]2+ acted as a photocatalyst during the reaction. The reaction mechanism consists of a chain reaction being accompanied by the O2-quenching of a photoexcited ruthenium(II) complex ([Ru(bpy)3]2+*) to make the superoxide (O2−•) and [Ru(bpy)3]3+, followed by the reduction of [Ru(bpy)3]3+ by PH2O2− to make [Ru(bpy)3]2+ and PH2O2•. However, such PDP once formed in the presence of O2 began to decrease with a rate law of -d[PDP]/dt = kobsd[PDP] after the solution was saturated with N2 gas, and when the solution was again saturated with air, the PDP began to increase again with light irradiation and remained constant in the dark. Such behaviors are discussed while presenting the reaction mechanisms.
Study of Adsorption of Water-Soluble Porphyrin at Glass–Solution Interface in the Presence of Cationic Surfactant Admicelles by Means of Total Internal Reflection Spectroscopy
Authors: Kobayashi Junji , Hinoue Teruo , Watarai Hitoshi 
Published: June 2006

Abstract
Total internal reflection (TIR) spectra were measured in the visible region at an interface between glass and an aqueous solution of 1.00 × 10−6 mol dm−3 5,10,15,20-tetraphenylporphyrintetrasulfonic acid (TPPS) in the presence of admicelles of cetyltrimethylammonium bromide (CTAB). Comparison of the TIR spectra with transmission spectra of TPPS solutions with different CTAB concentrations revealed that the deprotonated ions, TPPS4−, are simultaneously adsorbed at the interface as two complexes with TPPS4-/CTA+ ratios of 1 : 4 and 1 : 7. Interfacial concentrations of the 1 : 7 complex were estimated by using a linear relation between the absorbance and the interfacial concentration derived from a theory of TIR spectroscopy. The concentration data indicated that the adsorption of TPPS hardly occurs below pH 3, is saturated at pHs between 4 and 6, and continuously decreases above pH 6. Assuming an aggregative structure of the admicelle, the pH dependence of the adsorption was mathematically treated with a model including the dissociation, complex formation, and adsorption equilibria.
Convenient Synthesis of the Central 3,6-Di(2-thiazolyl)-2-(4-thiazolyl)pyridine Skeleton of a Macrocyclic Antibiotic, GE 2270 A
Authors: Okumura Kazuo , Saito Hiroyuki , Shin Chung-gi , Umemura Kazuyuki , Yoshimura Juji 
Published: June 2006

Abstract
It was shown that 6-dimethoxymethyl-1,2-dihydro-2-oxo-3-pyridinecarbonitrile (5) is easily convertible into the titled ring system by a stepwise method. Both the 3-cyano and 6-dimethoxymethyl groups of 5 were converted into 2-thiazolyl groups via the thioamide and carbaldehyde groups by Hantzsch and Shioiri methods, respectively. The 2-pyridone function was changed to a bromoacetyl group via the coupling reaction between the corresponding triflate and ethyl vinyl ether, and then converted into the 4-thiazolyl group. Thus, the useful 3,6-di(2-thiazolyl)-2-(4-thiazolyl)pyridine derivative for the total synthesis of GE 2270 A was obtained. In fact, the method was recently applied to the total synthesis of an antibiotic, micrococcin P, which has a similar central skeleton.
Reactions in Solid and Constrained State. IV. Preparation and Solid-State Photoracemization of Optically Active Alkyl Cobaloxime Complexes
Authors: Arai Yoshifusa , Ohgo Yoshiaki 
Published: June 2006

Abstract
Various optically active 1-substituted and 1,2-disubstituted ethyl cobaloxime [bis(dimethylglyoximato)cobalt(III)] complexes including deuterium-labeled complexes were prepared. Their photoracemization was found to occur upon irradiation of visible light in the solid-state. The reaction rate was much greater than that of solid-state racemization by irradiation of X-rays. The rates were not controlled by the electronic character of axial base and alkyl group but by the crystal lattice: the volume and shape of the reaction cavity, flexibility of the cavity, and intermolecular interaction such as hydrogen bonding. The experiments using deuterium-labeled complexes revealed the main reaction path in which the racemization proceeds mainly through out-of-plane rotation of the alkyl radical.
Facile Preparation of Four Stereoisomers of 2,4-Thiazolidinedicarboxylic Acid
Authors: Shiraiwa Tadashi , Katayama Takashi , Kaito Takehiro , Tanigawa Hisashi , Kurokawa Hidemoto 
Published: June 2006

Abstract
(2R,4R)-2,4-Thiazolidinedicarboxylic acid [(2R,4R)-TDA] was diastereoselectively synthesized in 100% de by condensation of l-cysteine (l-Cys) with an equimolar amount of glyoxylic acid monohydrate (GLA·H2O) in acetic acid under reflux. The reaction employing a slight excess of GLA·H2O afforded (2S,4R)-TDA, as a single diastereomer, at 80 °C. (2S,4R)-TDA was also synthesized by reaction of l-Cys with dichloroacetic acid under alkaline conditions. These reactions starting with d-Cys yielded (2S,4S)- and (2R,4S)-TDA.
NMR Spectroscopic Studies on Complex Formation between Dimeric (R)-3-Hydroxybutanoic Acid and β-Cyclodextrin
Authors: Li Jun , Uzawa Jun , Doi Yoshiharu 
Published: June 2006

Abstract
Dimeric (R)-3-hydroxybutanoic acid (3HB) was found to form an inclusion complex selectively with β-cyclodextrin (β-CD) in aqueous solution. The complex formation was confirmed by the changes of 1H and 13C NMR spectra of both dimeric 3HB and β-CD in D2O solution. The continuous variation experiments showed the formation of a 1 : 1 inclusion complex. The dissociation constants at various temperatures between 15 and 47 °C were determined and the thermodynamic analysis of the complex formation was performed. The results indicated that the complex formation is enthalpically favorable but entropically unfavorable. We propose that the 3HB unit with carboxy end-group is located in the narrow side of the β-CD cavity.
Rearrangements of Tricyclo[5.3.1.01,7]undecatrienide Anion: Circumambulation and Cleavage of the Cyclopropane Ring
Authors: Oda Mitsunori , Masaki Yoshimi , Okazaki Yoshimi , Kajioka Takanori , Morita Yasufumi , Miyatake Ryuta , Kuroda Shigeyasu 
Published: June 2006

Abstract
Reaction of tricyclo[5.3.1.01,7]undeca-2,4,9-triene with butyllithium in tetrahydrofuran-hexamethylphosphoric triamide at −78 °C and subsequent quenching of the resulted dark red reaction mixture with water or methanol gave tricyclo[6.3.0.01,3]undeca-5,7,9-triene (4) as the sole isolable product. It was also found that quenching of the anion solution with deuterium oxide under the same conditions caused stereoselective incorporation of deuterium atom. On the other hand, quenching of the anion solution with water after it was warmed to 0 °C gave a mixture of dihydromethylazulenes. The cycloadduct of the rearranged hydrocarbon 4 with 4-phenyl-3H-1,2,4-triazoline-3,5(4H)-dione was obtained and its structure was confirmed by X-ray crystallographic analysis. A driving force of the circumambulation was thought to be the creation of conjugation between the cycloheptadienide part and the five-membered ring olefin in the product on the basis of the facts that a circumambulatory rearrangement in the opposite direction, which would lead to a different product via a less conjugated tricyclic anion, was not observed, and that the anion generated from tricyclo[5.3.1.01,7]undeca-2,4-diene was reluctant to undergo the rearrangement.
Novel Disaccharide Chiral Ligands Derived from α,α-Trehalose and Their Applications to Asymmetric Hydrogenation of Enamides
Authors: Yonehara Koji , Hashizume Tomohiro , Ohe Kouichi , Uemura Sakae 
Published: June 2006

Abstract
New chiral diphosphinite ligands such as 4,6 : 2′,3′ : 4′,6′-tri-O-cyclohexylidene-2,3-di-O-diphenylphosphino-α,α-trehalose (1), 3,3′-di-O-benzyl-4,6 : 4′,6′-di-O-benzylidene-2,2′-di-O-diphenylphosphino-α,α-trehalose (2), 4,6 : 4′,6′-di-O-benzylidene-2,2′-di-O-diphenylphosphino-3,3′-di-O-methyl-α,α-trehalose (3), and 2,2′-di-O-benzyl-4,6 : 4′,6′-di-O-benzylidene-3,3′-di-O-diphenylphosphino-α,α-trehalose (4) were prepared from α,α-trehalose which is an inexpensive natural reserve sugar. These ligands work as chiral ligands for Rh-catalyzed hydrogenation of α-acetamidoacrylic and cinnamic acid derivatives to afford both enantiomers of amino acids up to 84%ee (S) and 72%ee (R).
Solitons, Polarons, and Excitons in Quasi-One-Dimensional Halogen-Bridged Transition Metal Compounds
Authors: Okamoto Hiroshi , Yamashita Masahiro 
Published: June 2006

Abstract
We report the photogeneration of solitons and polarons in the quasi-one-dimensional (1-D) halogen (X)-bridged metal (M) compounds (simply abbreviated as the MX chain compounds). The most significant feature of this system is the remarkable tunability of the charge density wave (CDW) ground states. By substituting the metals (M = Pt, Pd, and Ni), the bridging halogens (X = Cl, Br, and I), the ligand molecules and the counter anions surrounding the 1-D chains, the amplitude of CDW, the optical gap energy, and the degeneracy of CDW can be widely controlled. On the basis of these controls, we have investigated the nature of photoexcited states. By comparing the results of photoinduced absorption (PA), ESR and photoinduced ESR measurements in the degenerate CDW states with those in the non-degenerate CDW states, we clearly characterized the photoinduced gap states as solitons and polarons. In the compounds having relatively large optical gap energies (ECT), spin-solitons and polarons are photogenerated. From a comparison of the excitation profiles of the PA signals with those of the luminescence of the self-trapped exciton (STE), it was demonstrated that the luminescence process strongly competes with the dissociation to spin–soliton pairs. An analysis of the temperature dependence of the luminescence decay time revealed that the conversion from an STE to a solitonic state occurs through a finite potential barrier, the magnitude of which depends on degeneracy of CDW. With decrease of ECT, the nature of the photoexcited states changes considerably; photogenerations of charged-solitons are observed instead of spin–solitons and the STE luminescence is remarkably quenched. While referring to the theoretical expectations based upon the Peierls–Hubbard model, we will discuss the overall view of the relaxation process of the photoexcited states related to solitons, polarons, and excitons in the MX compounds.
Theoretical Study of the Potential Energy Curves for the Ca–Ar and Sr–Ar Systems
Authors: Zhu Rong-Shun , Han Ke-Li , Huang Jian-Hua , Zhan Ji-Ping , He Guo-Zhong 
Published: June 2006

Abstract
The X1Σ ground state and the low-lying 1,3Σ, 1,3Π excited states of the Ca–Ar and Sr–Ar systems have been studied using pseudopotentials at MCSCF(CASSCF)-SDCI level. The results indicate that the 1,3Σ excited states are essentially repulsive, but the X1Σ ground state and the 1,3Π excited states have shallow potential minima at large equilibrium distance (Re) values. Spectroscopic constants of the X1Σ ground state and the 1,3Π excited states have been calculated and compared to those obtained by experiment.