bluuebunny/crossref_metadata_2025 huggingface dataset:
Action of Serine Carboxypeptidases on Endopeptidase Substrates, N-Acyldipeptideamides
Authors: Kunugi Shigeru , Tanabe Kazuo , Yamashita Kouji , Fukuda Mitsuhiro
Published: July 2006

Action patterns of two serine carboxypeptidases, one from yeast (Y) and the other from wheat bran (W), on N-[3-(2-furyl)acryloyl]-(Fua-) dipeptideamide substrates were examined by HPLC and amino acid analysis. In the reaction of the wheat enzyme the substrates were hydrolyzed to Fua-amino acid and no sufficient amount of Fua-dipeptides were detected on HPLC in the product mixtures. Very few or no free amino acids were observed by amino acid analysis. This indicates that the wheat enzyme exhibited carboxamidopeptidase activity on these substrates. On the contrary, carboxypeptidase Y gave Fua-amino acids and Fua-dipeptides as products, depending on the structure of the substrates. Accordingly, liberations of free amino acids were detected in some cases. This result shows that the yeast enzyme acts on some of the substrates in a two step manner: First by amidase and second by a carboxypeptidase activity. Based on these results the substrate binding mechanisms of these enzymes are discussed.
Partition Parameters for Three Redox Forms of Viologen in a Nonionic Micellar Solution
Authors: Hoshino Katsuyoshi , Sasaki Hiroaki , Suga Kosaku , Saji Tetsuo
Published: July 2006

The partition parameters of 1,1′-dimethyl-4,4′-bipyridinium (1), 1-decyl-1′-methyl-4,4′-bipyridinium (2), and 1-dodecyl-1′-methyl-4,4′-bipyridinium (3) between the micellar and water phases were determined by electrochemical methods. It was shown that 10, 2\underset.+, 20, and 32+ are almost completely solubilized in the micellar phase and that 12+, 1\underset.+ and 22+ are partitioned into two phases.
Determination of the Intrinsic Reaction Coordinate in the 2H+O(1D) System Near the Equilibrium H2O
Authors: Cho Seikichi
Published: July 2006

A normal coordinate analysis was applied to the 2H+O(1D) three atomic system, using the Schinke–Lester analytic expression for the adiabatic potential energy. Defining the reaction coordinates as the “infinitely slow motion trajectories,” the reaction coordinate of the heavy oxygen atom was calculated easily, while that of the light hydrogen atom was obtained with some difficulty. Several repeated corrections were needed to converge the reaction coordinates to the “intrinsic” reaction coordinate. The intrinsic reaction coordinate of a hydogen atom to the uphill side of H2O was found to be very difficult to follow. This fact might help to explain the low frequency factor of the decomposition reaction of H2O.
Asymmetric Hydrogenation Catalyzed by Bis(disubstituted glyoximato)cobalt(II)(L)-Chiral Cocatalyst System. Effect of Structural Variation of Ligands and Hydrogen Pressure
Authors: Ohgo Yoshiaki , Tashiro Yasuhisa , Takeuchi Seiji
Published: July 2006

The reaction rate was extremely enhanced by increasing the basicity of the axial ligand of [Co(dmgH)2(L)] and by increasing the hydrogen pressure without decreasing the enantioselectivity. Substituting one and two methyl groups of the dimethylglyoxime ligand in [Co(dmgH)2(L)] with a phenyl group enhanced and retarded the reaction rate, respectively. The chirality at the cobalt did not affect the enantioselectivity.
Insertion of Ketene and Diphenylketene to the Pnictogen-Heteroatom Bonds
Authors: Ando Fumio , Kohmura Yoshihiko , Koketsu Jugo
Published: July 2006

Ketene and diphenylketene insert across the heteroatom-metal bond of amino-, alkoxy-, and alkylthiopnictogens, R3−nMXn, to give the corresponding α-metallated acetamides, esters, and thioesters, R3−nM(CH2COX)n and R3−nM(CPh2COX)n (M=As, Sb, Bi; X=NR2, OR, SR; n=1,3), respectively.
The Oxidation of PbSO4 to PbO2 in Sulfuric Acid Solution
Authors: Takehara Zen-ichiro , Kanamura Kiyoshi
Published: July 2006

The interface between PbO2 and PbSO4 was considered to be the reaction site of the oxidation of PbSO4 to PbO2. The area of this site depended on the changing crystal size of PbSO4 with the discharge conditions. The oxidation rate of PbSO4 to PbO2 increased with a decrease in the crystal size of PbSO4 since the reaction site area per unit volume increased with a decrease in the crystal size of PbSO4. The oxidation of PbSO4 to PbO2 depended on the discharge current, the sulfuric acid concentration and the rest time after a discharge.
Hydrates of Organic Compounds. XII. Intercalation of Methyl and Ethyl Alcohols within the Clathrate-Like Hydrates of Tetrabutylammonium Fluoride and of Tetrabutylammonium Propionate
Authors: Nakayama Haruo , Tsunakawa Kiyoshi , Kan\={o} Mizue , Matsui Hiroshi
Published: July 2006

The amount of either methyl or ethyl alcohol intercalated within clathrate-like hydrates of tetrabutylammonium fluoride and of tetrabutylammonium propionate has been determined using 14C-labeled alcohols. It was found that (1) methyl alcohol could be intercalated within the tetrabutylammonium fluoride hydrate but not within the tetrabutylammonium propionate hydrate; (2) ethyl alcohol could be intercalated within both the tetrabutylammonium fluoride and tetrabutylammonium propionate hydrates; and (3) the amount of the alcohol intercalated increased with increasing concentration of alcohol in the initial solutions. These results were interpreted by taking into consideration the states of vacant pentagonal dodecahedra formed by hydrogen-bonded water networks.
The Reaction of N(24S3⁄2) with Hydrogen Halides and Deuterium Iodide
Authors: Umemoto Hironobu , Uchida Teruo , Tsunashima Shigeru , Sato Shin
Published: July 2006

The bimolecular rate constants for the reactions of ground state atomic nitrogen with hydrogen halides and deuterium iodide were measured by employing a pulse radiolysis-resonance absorption technique. As for the reactions of hydrogen iodide and deuterium iodide, the temperature dependence was also measured; it was found that the rate constants were well expressed by the following Arrhenius expressions: k(N+HI)=(3.6±0.6)×105 exp[−(1530±50)⁄T]; k(N+DI)=(1.0±0.4)×105 exp[−(1460±130)⁄T], in units of m3 mol−1 s−1. The preexponential factors for these reactions are much smaller than the semiempirically calculated ones. These small preexponential factors suggest that these reactions proceed non-adiabatically. The rate constants for hydrogen bromide and hydrogen chloride were found to be very small.
Electrochemical and Spectroelectrochemical Speciation of [5-phenyl-10,15,20-tris(4-sulfonatophenyl)porphinato]iron in Aqueous Solution
Authors: Arifuku Fumihiro , Nishino Rika , Ujimoto Kikujiro , Kurihara Hirondo
Published: July 2006

The equilibria among the species of [5-phenyl-10,15,20-tris(4-sulfonatophenyl)porphinato]iron (Fe–TPPS3) ion in aqueous solution and the redox reactions of the central metal were investigated by electrochemical and spectro-electrochemical methods. In the range of pH 3–12.5, the species formed by the reduction of Fe(III)–TPPS3 in solution was identified as the monomeric Fe(II)–TPPS3, while Fe(III)–TPPS3 exists in both monomeric and dimeric species in equilibrium. The monomeric Fe(III)–TPPS3 was demetallated at pH below 3 in the course of reduction of the Fe(III)–TPPS3 solution. The μ-oxo-dimer of Fe(III)–TPPS3 in highly basic solution was reversibly reduced to Fe(II)–TPPS3 and subsequently the monomeric Fe(I)–TPPS3. The formation of the stacking-type dimer of Fe(III)–TPPS3, significantly depending on the concentration of Fe(III)–TPPS3, was presumed to have a pH below 6.
Regio- and Stereoselectivity of the Intramolecular C–H Insertion by Cyclopropylidenes Bearing a Remote Oxido Substituent
Authors: Harada Toshiro , Yamaura Yasunari , Oku Akira
Published: July 2006

(ω-Oxidoalkyl)cyclopropylidenes generated from (2,2-dibromo-1-methylcyclopropyl)-CH2–X–(CH2)n–OH (X=CH2 or O, n=1, 2) by the reaction with methyllithium underwent a regioselective intramolecular insertion into the C–H bond at the δ position to the carbenic carbon. The activation effect of the oxido substituent on the reactivity of C–H bonds is discussed on the basis of (1) the ratio of the insertion products to the rearrangement product allenyl alcohol, and (2) the endo stereoselectivity of the present insertion reactions.
Chemo-Selectivity of Group-VIII Metal Catalysts in Hydrogenation of Nonconjugated Enones
Authors: Ishiyama Jun-ichi , Maeda Satoshi , Takahashi Kazuhiro , Senda Yasuhisa , Imaizumi Shin
Published: July 2006

The chemo-selectivity of group-VIII metal catalysts has been examined in the hydrogenation of nonconjugated enones at ambient temperature under an atmospheric pressure of hydrogen. A cobalt catalyst gave high yields of unsaturated alcohols from trialkylated olefinic ketones. Osmium showed the highest selectivity among platinum metal catalysts for the reduction of the carbonyl bond in the hydrogenation of trialkylated olefinic ketones. The hydrogenation of mono- and dialkylated olefinic ketone ordinarily proceeded with a preferential saturation of the olefinic function, regardless of the catalyst. The hydrogenation of 4-methylene- and 4-ethylidenecyclohexanone was accompanied by the formation of diethyl acetals over ruthenium, rhodium, and palladium black catalysts in an ethanol solvent. The acetals were not detected in the hydrogenation of the other enones and over the other catalysts. In addition, the chemoselectivity on the hydrogenation of acyclic enones was examined over nickel and cobalt catalysts treated with small amounts of alkali and carbon monoxide. The amount of unsaturated alcohols increased when the catalyst was treated with alkali in the case of di- and trialkylated olefinic ketones, whereas the characteristics of cobalt, which selectively reduces the ketonic function in trialkylated olefinic ketones, were completely missing when cobalt was treated with carbon monoxide.
Construction of an Optically Active 7-Oxabicyclo[4.3.0]non-4-en-3-one Skeleton from d-Glucose, and Its Transformation to Some Pseudo-Hexopyranoses
Authors: Tadano Kin-ichi , Ueno Yoshihide , Fukabori Chiyoko , Hotta Yukinori , Suami Tetsuo
Published: July 2006

A versatile chiral compound, (1R,6R,8R,9R)-8,9-isopropylidenedioxy-7-oxabicyclo[4.3.0]non-4-en-3-one (6), was efficiently synthesized from d-glucose. The synthesis featured an intramolecular aldol cyclization of 3-C-acetylmethyl-3-deoxy-1,2-O-isopropylidene-α-d-ribo-pentodialdo-1,4-furanose, which was readily derivatized from the known Wittig adducts of 1,2:5,6-di-O-isopropylidene-α-d-ribo-hexofuranos-3-ulose. The utility of this highly functionalized chiral synthon 6 was embodied by conversion to four optically active pseudosugars, these are pentaacetyl derivatives of pseudo-α-l-altropyranose, pseudo-β-d-glucopyranose, pseudo-2-amino-2-deoxy-β-l-altropyranose, and pseudo-2-amino-2-deoxy-α-d-glucopyranose (a derivative of pseudoglucosamine). The transformation of 6 to the pseudo sugars involved 1) a stereospecific epoxidation of the double bond in 6 providing (1R,4S,5S,6S,8R,9R)-4,5-epoxy-8,9-isopropylidenedioxy-7-oxabicyclo[4.3.0]nonan-3-one (8), and 2) an exclusive diaxial ring opening of the β-epoxy alcohols, which were derived from 8, providing (1R,3R,4S,5S,6S,8R,9R)-8,9-isopropylidenedioxy-7-oxabicyclo[4.3.0]nonane-3,4,5-triol (11) or (1R,3S,4S,5R,6S,8R,9R)-4-azido-8,9-isopropylidenedioxy-7-oxabicyclo[4.3.0]nonane-3,5-diol. Treatment of (1R,2S,3S,4S,5R)-3,4,5-tris(benzyloxy)-2-hydroxycyclohexanecarbaldehyde, which was derived from 11, with methanesulfonyl chloride, and successive sodium borohydride reduction provided (3S,4S,5R)-3,4,5-tris(benzyloxy)-1-cyclohexene-1-methanol (19). Hydroboration of 19 proceeded from the less hindered side stereoselectively.
Reaction of Olefins with α-Cyanoacetamide in the Presence of Manganese(III) Acetate
Authors: Sato Hidehiko , Nishino Hiroshi , Kurosawa Kazu
Published: July 2006

2-Butenamides and 2-buten-4-olides are formed by the reaction of phenyl or 4-chlorophenyl-substituted olefins with α-cyanoacetamide in the presence of manganese(III) acetate. On the other hand, aryl substituted olefins having electron-donating groups are oxidized under similar reaction conditions to give 1,5-dihydro-2H-pyrrol-2-ones and 3-ethenyl-2-pyrrolidones. All these reactions also produce glycols or ketones which are given by the direct oxidation of these olefins with manganese(III) acetate. The question whether an intermediate carbocation in the oxidation process cyclized on an oxygen or a nitrogen atom can be explained by the hard and soft acids and bases (HSAB) concept. A possible mechanism for the formation of 2-butenamides and 2-buten-4-olides is proposed.
Synthesis and Properties of Chiral Macrobicyclic and Macrotricyclic Cryptands Containing the trans-Tetrahydrofuran-2,5-diylbis(methylene) Subunit as the Chiral Center
Authors: Naemura Koichiro , Kanda Yuji , Iwasaka Hiroshi , Chikamatsu Hiroaki
Published: July 2006

The macrobicyclic and macrotricyclic cryptands containing the trans-tetrahydrofuran-2,5-diylbis(methylene) molecular framework as the chiral subunit were prepared in optically active forms. The enantiomer recognition property of the macrotricyclic tetracarboxamide (+)-6 in transport of enantiomeric molecules was examined, and the cation-binding abilities of the macrotricyclic and macrobicyclic amines 7, 10, and 13 were also investigated.
In-beam EIMS and Molecular SIMS of Quaternary Ammonium Chlorides of Benzylamine Derivatives
Authors: Shida Yasuo , Tsujimoto Kazuo , Ikeda Takashi , Ohashi Mamoru
Published: July 2006

The in-beam EIMS and SIMS of three quaternary ammonium chlorides of benzylamine derivatives have been examined, and their fragmentation processes have been clarified by means of the B⁄E costant and B2⁄E constant linked scanning techniques. The B⁄E constant linked scan of the benzyltrimethylammonium ion (m⁄z 150) in the in-beam EIMS indicated a fragment ion at m⁄z 126 as a daughter ion. A substitution reaction between the m⁄z 150 ion and a chlorine atom in the first field free region is proposed. The characteristics of SIMS of those compounds were demonstrated in comparison with those of EIMS and the fragmentation processes of the salts upon Xe+ bombardment were established based on the linked scanning techniques.
1,4-Dihydropyrrolo[3,2-b]pyrrole: The Electronic Structure Elucidated by Photoelectron Spectroscopy
Authors: Tanaka Shoji , Kumagai Tsutomu , Mukai Toshio , Kobayashi Tsunetoshi
Published: July 2006

The electronic structures of 1,4-dihydropyrrolo[3,2-b]pyrrole and some of its alkyl derivatives were studied by means of He(I) photoelectron spectroscopy combined with the MNDO calculation and a first-order perturbation theoretical method. The first five bands of the parent pyrrolopyrrole are assigned, from the top, to the π5(au), π4(au), π3(bg), π2(bg), and σ(ag) bands respectively. The MO model, which explains well the spectral data, indicates that the nitrogen lone-pair electrons are mainly delocalized in the π4, π2, and π1 orbitals. The ionization potentials of the HOMO levels of these compounds, which are characterized by the large pz contributions from the α-carbons, are the lowest among the hitherto known π-electron-excessive heteroaromatic compounds. 1,4-Dihydropyrrolo[3,2-b]pyrrole is concluded to be the system with the most efficient π-electron-donating ability among 10π-electron systems.
The Nucleophilic Reaction upon Electron-Deficient Pyridone Derivatives. VIII. Novel Fragmentation of 3,5-Dinitro-2-pyridone by Primary Amine
Authors: Tohda Yasuo , Ariga Masahiro , Kawashima Toshihide , Matsumura Eizo
Published: July 2006

Fragmentation of 3,5-dinitro-2-pyridone (1) by primary amine gave nitroacetamide (2) and nitromalonaldehyde diimine. In the case of N-methyl derivative (1c), the reaction was completely suppressed by the product 2 to give an anionic σ-adduct of 1c with 2. The mechanism of the reaction was discussed.
Stereoselective Synthesis of Anomers of 5-Substituted 2′-Deoxyuridines
Authors: Aoyama Hajime
Published: July 2006

The substitution reaction of 5-substituted 2,4-bis(trimethylsilyloxy)pyrimidines with 3,5-bis(O-p-chlorobenzoyl)-2-deoxy-α-d-ribofuranosyl chloride was investigated. In the presence of p-nitrophenol, β anomers were formed stereoselectively, whereas the addition of organic bases brought forth stereoselective formation of α anomers. Stereoselectivity of the reaction depends on the substituents at 5-position of disilylpyrimidines, additives, and the concentration of each reagent. The α and β anomers of 5-substituted 2′-deoxy-uridines were synthesized through the deacylation of α and β anomers of 5-substituted 3′,5′-di-O-(p-chlorobenzoyl)-2′-deoxyuridines.
The Reactions of Tropone Tosylhydrazone Sodium Salt with Acetylene Derivatives Possessing Electron-Withdrawing Groups: A Novel Method of Synthesis of 1H-1,2-Benzodiazepine Derivatives
Authors: Saito Katsuhiro
Published: July 2006

Reactions of tropone tosylhydrazone sodium salt with dimethyl and diethyl acetylenedicarboxylate gave dimethyl and diethyl 1H-1,2-benzodiazepin-3,4-dicarboxylate, respectively. The same reactions, but using ethyl acetylenecarboxylate and 3-butyn-2-one, afforded ethyl 1H-1,2-benzodiazepin-4-carboxylate and 4-acetyl-1H-1,2-benzodiazepine, respectively, accompanied by 8-azaheptafulvene derivatives derived from the sodium salt and the acetylene derivatives, and p-toluenesulfinic esters formed from p-toluenesulfinic acid and the acetylene derivatives. Reactions of the sodium salt with ethyl 2-butynoate gave the corresponding sulfinic ester but afforded no diazepine derivative.
A New Synthesis of 3-Amino-2-alkenoates. Novel Synthetic Route to Amino Sugars N-Benzoyl-l-daunosamine and -l-acosamine
Authors: Hiyama Tamejiro , Kobayashi Kazuhiro , Nishide Kiyoharu
Published: July 2006

Alkanoate esters are found to couple with various nitriles to give (Z)-3-amino-2-alkenoates in good yields with the aid of a magnesium amide prepared by the reaction of ethylmagnesium bromide and diisopropylamine. The C–C bond forming reaction was applied to (2S,3S)-2,3-(cyclohexylidenedioxy)butanenitrile and the resulting adduct was successfully converted into N-benzoyl-l-daunosamine in 41% overall yield through a sequence of functional group manipulation; acetylation, hydrogenation, hydrolysis and benzoylation, lactonization and finally reduction. By the similar process, (2R,3S)-2,3-(cyclohexylidenedioxy)butanenitrile was transformed to N-benzoyl-l-acosamine in 25% overall yield.
An Enantiospecific Synthesis of the C-21–C-37 Segment of the Aglycon of Amphotericin B
Authors: Kinoshita Mitsuhiro , Takami Hitoshi , Taniguchi Masato , Tamai Tetsuro
Published: July 2006

3-Deoxy-1,2-O-isopropylidene-3-C-methyl-α-d-allofuranose was stereoselectively converted into 3,5-dideoxy-4-O-(methoxymethyl)-3,5-di-C-methyl-6-O-pivaloyl-l-talose ethylene dithioacetal (31) via 3,5-dideoxy-4-O-(methoxymethyl)-3,5-di-C-methyl-l-talopyranuro-6,2-lactone ethylene dithioacetal (24) in 10 steps (23.6% overall yield). Desulfurization [Raney Ni W-4, 92% yield] of 31 followed by three-step transformation (91% yield) afforded 2,4,6-trideoxy-5-O-(diethylisopropylsilyl)-3-O-(methoxymethyl)-2,4-di-C-methyl-l-altrose, which was olefinated by using methyl (2E,4E)-6-(dimethoxyphosphinyl)-2,4-hexadienoate twice to give the target compound, all-trans-hexaenal 4 (12 steps, 38.6% overall yield from 31).
Chemical Synthesis of a Biosynthetic Precursor of Lipid A with a Phosphorylated Tetraacyl Disaccharide Structure
Authors: Imoto Masahiro , Yoshimura Hiroyuki , Yamamoto Michiharu , Shimamoto Tetsuo , Kusumoto Shoichi , Shiba Tetsuo
Published: July 2006

2,2′-N:3,3′-O-Tetrakis[(R)-3-hydroxytetradecanoyl]-β(1-6)-d-glucosamine disaccharide 1,4′-bis(phosphate) and its dephospho derivatives were synthesized. The bisphosphate prepared was shown to be identical with a natural biosynthetic precursor of lipid A which corresponds to the lipophilic part of lipopolysaccharide (LPS) in bacterial cell wall. The synthetic bis- and monophosphates exhibited many of typical endotoxic activities of LPS. Consequently, this work established the chemical structure of the biosynthetic precursor of lipid A and elucidated the fundamental structure required for the expression of these activities.
Total Synthesis of Escherichia coli Lipid A, the Endotoxically Active Principle of Cell-Surface Lipopolysaccharide
Authors: Imoto Masahiro , Yoshimura Hiroyuki , Shimamoto Tetsuo , Sakaguchi Nobuki , Kusumoto Shoichi , Shiba Tetsuo
Published: July 2006

Chemical syntheses are described of polyacylated β(1→6) glucosamine disaccharide 1,4′-bis(phosphate), which corresponds to the proposed structure of E. coli lipid A, and of its dephospho derivatives. The synthetic bisphosphate proved to be identical with the corresponding natural specimen. The chemical structure of lipid A was thus established.
Catalase-Like Activity of Anion-Exchange Resin Modified with Metalloporphyrin in the Oxidation of Methyl Alcohol and Its Application to the Determination of Hydrogen Peroxide
Authors: Saito Yutaka , Satouchi Mitsuko , Mifune Masaki , Tai Takaaki , Odo Junichi , Tanaka Yoshimasa , Chikuma Masahiko , Tanaka Hisashi
Published: July 2006

The catalase-like activity of anion-exchange resins (Amberlite IRA 900) modified with various metalloporphyrins in the acceleration of reaction (1) was evaluated by efficiency in color reaction (2) based on dye formation:

H2O2+CH3OH\oversetcatalase\ightharpoonup2H2O+HCHO (1)

HCHO+4-amino-3-hydrazino-5-mercapto-1,2,4-triazole+KIO4\oversetOH−\ightharpoonupDye(λmax=550 nm). (2)

Amberlite IRA 900 modified with Mn3+–tetrakis(sulfophenyl)porphine (MnTPPSr) was found to exhibit the highest catalase-like activity among the resins tested and was applied as a mimesis of catalase to the determination of hydrogen peroxide by the use of reactions (1) and (2). The molar absorption coefficient for hydrogen peroxide was found to be 2.37×104 mol−1 dm3 cm−1, which is larger than twice that in the control catalase method (0.97×104 mol−1 dm3cm−1). Interferences by common foreign substances tested were found to be small. MnTPPSr gave a better result than catalase in the determination of hydrogen peroxide.
The Synthesis of Ar-abietatrien-12,16-oxide and Its C-15 Epimer
Authors: Matsumoto Takashi , Imai Sachihiko , Yoshinari Takashi , Tsuruta Kazuaki
Published: July 2006

In order to elucidate the absolute configuration of C-15 in natural ar-abietatrien-12,16-oxide, (15R)-12,16-epoxy-8,11,13-abietatriene (1a) and its (15S)-epimer (1b) have been synthesized. Treatment of (15R)-8,11,13-abietatriene-12,16-diol with a mixture of chloromethyl methyl ether, dicyclohexano-18-crown-6, and potassium carbonate afforded 1a as a minor product and (15R)-12-methoxymethyl ether as a major product. The latter was further converted into 1a. A similar treatment of (15S)-8,11,13-abietatriene-12,16-diol gave 1b. Catalytic hydrogenations of 12,16-epoxy-8,11,13,15-abietatetraene, methyl 12,16-epoxy-8,11,13,15-abietatetraen-19-oate (5), and methyl 12,16-epoxy-8,11,13,15-abietatetraen-18-oate (7) afforded the corresponding (15R)-dihydrobenzofuran derivatives and their (15S)-epimers. Conversions of the hydrogenation products from 5 and 7 into 1a and 1b were also carried out. The synthetic 1a was identical with natural ar-abietatrien-12,16-oxide.
Preparation, Absolute Configuration and Conformation of Some α-Aryl-2-pyridylmethanols
Authors: Bojadziev Stefan E. , Tsankov Dimiter T. , Ivanov Petko M. , Berova Nikolina D.
Published: July 2006

The syntheses of five optically active α-aryl-2-pyridylmethanols 1–5 are described. It is shown by means of chemical correlation with the known (−)-(αR,2S)-α-phenyl-2-piperidylmethanol 6 that all levo-rotatory isomers of 1–4 are of R configuration. It is also found via the relative integral intensities in the infrared spectra of the bands due to free and intramolecularly bonded hydroxyl groups in the compounds 1–4 and the free hydroxyl groups in the model compounds 7–10, that the population of the conformers with an intramolecular OH···N bond in compounds 1–4 exceeds 80%.
Clay Montmorillonite-Catalyzed Aldol Reactions of Silyl Ketene Acetals with Carbonyl Compounds
Authors: Onaka Makoto , Ohno Ryosuke , Kawai Motomitsu , Izumi Yusuke
Published: July 2006

Al3+ ion-exchanged montmorillonite efficiently catalyzes the aldol reactions of silyl ketene acetals with carbonyl compounds and acetals. The optimum preparation of the effective montmorillonite catalyst is described.
63Cu High Resolution NMR of Cu(I) Halides in Aqueous Solution and Suspension
Authors: Endo Kazunaka , Yamamoto Kyonosuke , Deguchi Kenzo , Matsushita Kazuhiro
Published: July 2006

In an aqueous solution, 63Cu chemical shielding order ([CuCl4]3− \simeq[CuBr4]3−<[CuI4]3−) and line widths (10 to 30 kHz) for CuX–KX systems(where X=Cl, Br, I) have been obtained. The chemical shift(−694 ppm) between [CuCl4]3− and [Cu(CN)4]3− is interpreted by the paramagnetic term which depends mainly upon a 3d-hole on a Cu(I) atom by using perturbation theory with an average excitation energy approximation. The linebroadening of Cu(I) halide complexes in aqueous solution is explained dominantly by a Cu(I) nuclear quadrupole interaction with the electric field gradient which arises from a 3d-hole on a Cu atom. For the abnormal increasing metal shielding order of [MX4](4−i)−([MCl4](4−i)−≤[MBr4](4−i)−<[MI4](4−i)−), a possibility of the heavyatom effect in the metal shielding of [CuI4]3−(649 ppm, using the lowest excitation energy of the diatomic molecule) and [CdI4]3−(1941 ppm using the lowest excitation energy of the diatomic molecule), is evaluated.
The Photocycloaddition of N-Vinylcarbazole with 3-Cyanostyrene
Authors: Tsuchida Akira , Yamamoto Masahide , Nishijima Yasunori
Published: July 2006

The photocycloaddition reaction of N-vinylcarbazole (VCZ) as an electron donor, with 3-cyanostyrene as an electron acceptor, was studied. In nonpolar solvents, two cyclobutanes of cis-1-(9-carbazolyl)-2-(3-cyanophenyl)cyclobutane and trans-1-(9-carbazolyl)-2-(3-cyanophenyl)cyclobutane (in a ratio of 3 : 1) were obtained from an exciplex intermediate. The structure of cis cyclobutane seemed to originate from a sandwich conformation of the exciplex. In polar solvents, a photodissociation to free ion radicals was observed and trans-1,2-di(9-carbazolyl)cyclobutane was produced efficiently by means of a chain mechanism via a cation radical of VCZ. Transient intermediates were measured by means of nanosecond laser photolysis; the results supported the reaction scheme.
Silver–Gelatin Method for the Determination of Trace Amounts of Carbon Monoxide in Air
Authors: Pal Tarasankar , Ganguly Ashes , Maity Durga S
Published: July 2006

The use of silver–gelatin complex was found suitable for the determination of trace amounts of carbon monoxide in air. Silver–gelatin complex is reduced by carbon monoxide to give intensely colored sol. Measurement of the color intensity of the stable silver sol enables the determination of carbon monoxide successful under various environmental conditions. The detection limit is 2–100 ppm. The relative standard deviation for the determination of 10 ppm carbon monoxide is 2.6%.
The Effect of the Electrical Potential Difference on the Adsorption of the Hexadecyltrimethylammonium Ion at the Polarized Nitrobenzene–Water Interface
Authors: Kakiuchi Takashi , Kobayashi Miki , Senda Mitsugi
Published: July 2006

The adsorption of the hexadecyltrimethylammonium ion(HTMA+) at the polarized nitrobenzene–water interface has been studied using electrocapillary measurements. The adsorption of HTMA+ was found to be markedly dependent on the potential drop across the interface. HTMA+ exhibited no specific adsorption in the potential range where the aqueous phase is positive, whereas a strong adsorption occurred in the potential range where the electric potential in the aqueous phase is negative with respect to that in the nitrobenzene. The adsorption free energy depends linearly on the potential difference across the interface. The specific adsorption of HTMA+ significantly alters the double-layer structure. The outer Helmholtz potential in the nitrobenzene phase was inverted from negative to positive due to the adsorption of HTMA+ ions.
1,2-Migration of Fluorine Atom in CH2FCF2 Radical Produced by the Addition of a Hydrogen Atom to Trifluoroethylene
Authors: Kohida Tomoyuki , Kotaka Masahiro , Sato Shin , Ishida Toru , Yamamoto Keiji , Yamazaki Takashi , Kitazume Tomoya
Published: July 2006

The reaction of hydrogen atoms with trifluoroethylene has been studied at room temperature by using the mercury photosensitized decomposition of hydrogen as the source of hydrogen atoms. Product analyses using gas chromatography and 1H and 19F NMR spectroscopy confirmed the 1,2-migration of a fluorine atom in the CH2F\dotCF2 radical produced by the addition of a hydrogen atom to trifluoroethylene. The rate constant of the migration was estimated to be 2×1010 s−1 from the pressure dependence of the five kinds of hexafluorobutanes produced. NMR parameters for these fluorinated compounds were determined.
Mixed Alcohol Synthesis from CO–H2 by Use of KCl-Promoted Mo/SiO2 Catalysts
Authors: Muramatsu Atsushi , Tatsumi Takashi , Tominaga Hiro-o
Published: July 2006

Highly active Mo catalysts for mixed alcohol synthesis were prepared using Fuji Davison ID silica gel as a carrier. KCl promoted the selectivity to alcohols but reduced CO conversions in particular to hydrocarbons. Productivity of alcohols was largely affected by the reaction conditions. High pressure and short contact time enhanced space-time yield of alcohols, i.e. 420 g (kg-catalyst)−1 h−1 at 5.0 MPa, 573 K, and W/F=1.4 g-catalyst h mol−1. The presence of K effectively prevented the complete reduction of Mo to metal, resulting in the increase in the production of alcohols. The study on addition of ethene and ethanol to synthesis gas revealed that the other roles of K are to retard dehydration of alcohols to alkenes and their hydrogenation to alkanes.
Regio- and Stereoselective Introduction of Functional Groups into 1-Isoindolinone and 1(2H)-Isoquinolone Systems
Authors: Noguchi Michihiko , Yoshioka Manabu , Kakimoto Shinji , Kajigaeshi Shoji
Published: July 2006

The oxidation of 3a,4-dihydro-1-isoindolinone derivatives with MCPBA was carried out regio- and stereoselectively to afford the 5,6-epoxide products 2. The ring opening reaction of 2 with amines, alcohols, and sodium azide gave homoallyl alcohol type of products, derived from the ring opening at C-5 of 2. Lithium (cyano-C)methylcuprate reacted with 2 to give homoallyl and/or allyl alcohol, which is due to the conjugate addition to the C-7a position. This approach for selective introduction of functional groups into the heterocycles was extended for 3,4,4a,5-tetrahydro-1(2H)-isoquinolone system.
Synthesis, Properties, and Reactivity of (1H,1H-Perfluoroalkyl)- and (1H-Perfluoro-1-alkenyl)aryliodonium Triflates and Their Analogs
Authors: Umemoto Teruo , Gotoh Yoshihiko
Published: July 2006

(1H,1H-Perfluoroalkyl)phenyl- and -(p-fluorophenyl)iodoniurn triflates, fluorosulfate, sulfate (3)–(7) were synthesized in good yields by the oxidation of 1-iodo-1H,1H-perfluoroalkanes (RfCH2I) with trifluoroperacetic acid followed by treatment with triflic acid and benzene or fluorobenzene. (1H,1H,5H,5H-Perfluoropentane-1,5-diyl)bisphenylbisiodonium triflate was synthesized similarly. (trans-1H-Perfluoro-1-alkenyl)phenyliodonium triflates (11) were synthesized by dehydrofluorination of 3 with a base in good yields. Thermolysis of 3 produced 1H,1H-perfluoroalkyl triflate and iodobenzene, while 11 gave (Z)-1-iodo-1H-perfluoro-1-alkene and phenyl triflate. The thermolysis experiment, including (perfluoroalkyl)phenyliodonium triflate (17), demonstrated that the C–I bond strength of the trivalent iodine compounds increased in the order of RfCH2–I, Rf–I<Ph–I<RfCF=CH–I. The ionic mechanism containing RfCH2+, Ph+, and Rf+ for the thermal decomposition of 3, 11, and 17, respectively, was proposed. The reactivities of 3 and 11 to such nucleophiles as phenoxide, alkoxide, and alkanethiolate anions were studied and compared with that of 17. Remarkable changes in the reactivity were found depending on the nature of the fluoro-alkyl and -alkenyl groups. The reaction of 11 with the oxide anions yielded (2-phenoxy- and -alkoxy-1H-perfluoro-1-alkenyl)phenyliodonium triflates.
Peroxy Acid Oxidations. I. A Kinetic and Mechanistic Study of Oxidation of Acetylacetone by Peroxomonophosphoric Acid and Hydrogen Peroxide in Alkaline Medium
Authors: Patnaik Chakrapani P , Mohapatro Surendra Nath , Panigrahi Akhil Krishna , Panda Radhasyam S
Published: July 2006

The kinetics of oxidation of acetylacetone by peroxomonophosphoric acid and hydrogen peroxide have been investigated in the pH range 8–13.7. The oxidations by peroxomonophosphoric acid at 308 K and I=0.6 mol dm−3 follow the rate expressions,

(i) −\fracd[PMPA]Tdt={k1[A]+k2[A−]}[HPO52−]

in the pH range 8–10.63, where k1=1.96 dm3 mol−1 s−1 and k2=0.177 dm3 mol−1 s−1, and

(ii) −\fracd[PMPA]Tdt={k3[A]+k4[A−]}[HPO52−]+{k5[A]+k6[A−]}[PO53−]

in the pH range 11.5–13.7, where k3=30.4 dm3 mol−1 s−1 and k6≈0. The rate law for hydrogen peroxide oxidations in the pH range 9.2–13 at 308 K and I=0.1 mol dm−3 is given by,

 −\fracd[Hydrogen peroxide]Tdt={k7[A]+k8[A−]}[H2O2]+{k9[A]+k10[A−]}[HO2−]

the k7 and k10 values being 0.393 dm3 mol−1 s−1 and 0.143×10−2 dm3 mol−1 s−1 respectively. A and A− represent the diketo and enol form of acetylacetone respectively. The kinetic data and activation parameters are consistent with nucleophilic attack by peroxo species on both diketo and enol form of acetylacetone followed by oxygen–oxygen bond fission.
Palladium Catalyzed Hydrostannylation and Hydrogermylation of Acetylenes
Authors: Ichinose Yoshifumi , Oda Hiroji , Oshima Koichiro , Utimoto Kiitiro
Published: July 2006

Treatment of acetylenes with Ph3SnH or Ph3GeH in the presence of a catalytic amount of Pd(PPh3)4 provides the corresponding alkenyltriphenylstannanes or alkenyltriphenylgermanes in good yields.
The Phase Transitions of 1-Alkyl-1-azoniabicyclo[2.2.2]octane Bromides, Cn–ABCO–Br (10≤n≤22)
Authors: Imamura Kengo , Nogami Takashi , Shirota Yasuhiko
Published: July 2006

The phase transitions of a series of 1-alkyl-1-azoniabicyclo[2.2.2]octane bromides were studied on the basis of DSC, the measurements of the ionic conductivities of the bromide anion, and Raman spectroscopy. Most of the materials exhibited three endothermic signals at Tc1, Tc2, and Tc3 (Tc1<Tc2<Tc3) when they were heated. The temperature dependence of the ionic conductivities of the bromide anion showed conductivity jumps by a factor of 2–4 at around Tc3. In order to clarify the phase transition, the temperature dependences of the Raman spectra were measured. It was found that the phase transition at Tc1 is caused by the molecular rearrangement in the solid, while the transitions at Tc2 and Tc3 are caused by both the conformational change in the alkyl chain and the rotational motion of the ABCO portion.
Syntheses of 23-C-Substituted Derivatives of Mycaminosyl Tylonolide and 4′-Deoxymycaminosyl Tylonolide
Authors: Sakamoto Shuichi , Kajikawa Norio , Tsuchiya Tsutomu , Umezawa Sumio
Published: July 2006

23-C-Substituted derivatives of mycaminosyl tylonolide (MT) and 4′-deoxymycaminosyl tylonolide (DT) have been prepared by the reaction of protected 23-aldehyde derivatives, 2′,4′-di-O-acetyl-3-O-t-butyldimethylsilyl-23-deoxy-23-oxomycaminosyl tylonolide diethyl acetal (5) and 2′-O-acetyl-3-O-t-butyldimethylsilyl-23,4′-dideoxy-23-oxomycaminosyl tylonolide diethyl acetal (26), with several Grignard reagents and methyllithium. The final products were (23S)- and (23R)-23-C-methyl (13a, 13b), -ethyl (14a, 14b), -butyl (15a, 15b), -phenyl (16b, 16a), -allyl (17a, 17b), -vinyl (18a, 18b), -ethynyl (19b, 19a) derivatives of MT, and (23S)- and (23R)-23-C-methyl (28a, 28b), -vinyl (29a, 29b), and -ethynyl (30b, 30a) derivatives of DT. Their configurations at 23-position were determined by the NOE difference spectroscopy on 13a and 13b.
Battle River Coal Liquefaction and Its Co-Processing with Tar-Sand Bitumen
Authors: Yoshida Ryoichi , Miyazawa Makoto , Maekawa Yosuke
Published: July 2006

Battle River coal from Canada shows an excellent applicability to liquefaction. At 450 °C, anthracene oil and Cold Lake tar-sand bitumen show the solvent effect as a vehicle oil in the initial stage of liquefaction. A definite advantage is gained by tar-sand bitumen co-processing, where hydrogen consumption is comparatively lower than that of anthracene oil derived from coal to produce a similar yield of oil.
Structure, Properties, and Na+ Transport Membrane of Polyelectrolyte Complexes Consisting of Glycol Chitosan and Poly(vinyl sulfate)
Authors: Kikuchi Yasuo , Kubota Naoji
Published: July 2006

Glycol chitosan (GC) was allowed to react with poly(vinyl sulfate) (PVSK) to form many different water-insoluble polyelectrolyte complexes (PECs) in aqueous solution at various hydrogen ion concentrations. According to elemental analyses, IR spectroscopy, and solubilities of PECs, molecular structures of each PEC depend on [H+]. This result is attributable to change with [H+] in the degree of dissociation and conformation of GC and PVSK. PEC membranes were made by casting solutions of all kinds of PECs, and transport phenomena through a membrane of the PEC prepared in a solution of 4v/v% HCl were investigated under various conditions. The transport ratio of Na+ and the electric potential difference between the left and right sides of the membrane were measured, with a result that the higher value the membrane potential difference was long allowed to maintain, the higher the transport ratio became. According to this result, the driving force of transport is dependent on the membrane potential, Donnan potential and diffusion potential, between both sides of the membrane. The Cl− exclusion (Donnan exclusion), however, is small due to the small cation-exchange capacity, so that the membrane potential difference is caused to decrease rather rapidly by Cl− permeation.
The Microwave Spectra, Dipole Moments, and Two Isomers of Cyclopentadiene-1-carbonitrile
Authors: Sakaizumi Takeshi , Kikuchi Hiromi , Ohashi Osamu , Yamaguchi Ichiro
Published: July 2006

The microwave spectra of two isomers of cyclopentadiene-1-carbonitrile generated by the pyrolysis of 1H-benzotriazole have been observed in the frequency range from 8.0 to 40.0 GHz. The rotational constants (MHz) have been determined as A=8353.7(9), B=1904.24(1), and C=1565.38(1) for 1,3-cyclopentadiene-1-carbonitrile, and A=8235.0(13), B=1902.07(2), and C=1559.67(2) for 1,4-cyclopentadiene-1-carbonitrile. The dipole moments (Debye) obtained are μa=4.15(15), μb=0.27(3), and μtotal=4.16(17) for 1,3-cyclopentadiene-1-carbonitrile and μa=4.36(25), μb=0.77(10), and μtotal=4.42(35) for 1,4-cyclopentadiene-1-carbonitrile.
Preparation of Methyl 2-Arylpropanoates by the Reaction of 2-Hydroxypropiophenone Dimethyl Acetals with Sulfuryl Chloride in the Presence of an Amide or a Weak Base
Authors: Yamauchi Takayoshi , Hattori Kaneaki , Nakao Kenji , Tamaki Kentaro
Published: July 2006

Treatment of 2-hydroxypropiophenone dimethyl acetals [p-RC6H4C(OMe)2CH(OH)Me] (1; R=H, i-Bu, OMe, Ph, Br) with sulfuryl chloride in the presence of an amide or a weak base affords methyl 2-arylpropanoates (2) in good to excellent yields via 1,2-aryl migration of 1. The hydrolysis of 2 leads to the corresponding acids, some of which are pharmaceutically important compounds having nonsteroidal anti-inflammatory and analgesic activities. The aryl migration proceeds stereospecifically with complete inversion of configuration at the β-carbon atom.
Simple Generation of Nonstabilized Azomethine Ylides through Decarboxylative Condensation of α-Amino Acids with Carbonyl Compounds via 5-Oxazolidinone Intermediates
Authors: Tsuge Otohiko , Kanemasa Shuji , Ohe Masayuki , Takenaka Shigeori
Published: July 2006

Heating α-amino acids with a variety of carbonyl compounds generates N-unsubstituted or N-substituted azomethine ylides of nonstabilized types through the elimination of water and carbon dioxide. The ylides are captured by olefinic, acetylenic, and carbonyl dipolarophiles producing pyrrolidines, pyrrolines, and oxazolidines. The reaction involves intermediary 5-oxazolidinones which can be sometimes isolated. Some synthetic equivalents of parent azomethine ylide, methaniminium methylide, are accessible by this route.
Asymmetric Induction in the Base-Catalyzed Reactions Using Polymer-Supported Quinines with Spacer Groups
Authors: Inagaki Minoru , Hiratake Jun , Yamamoto Yukio , Oda Jun’ichi
Published: July 2006

New polymer-supported quinines having the spacer groups were synthesized and utilized for three types of base-catalyzed asymmetric reactions. Insertion of the spacer groups leads to improve the stereoselectivity in comparison with the polymer-catalyst with no spacer groups.
The Magnetic Field Effects on Electrolysis. The Anodic Oxidation of Phenylacetate Ion
Authors: Watanabe Takeshi , Tanimoto Yoshifumi , Nakagaki Ryoichi , Hiramatsu Mitsuo , Nagakura Saburo
Published: July 2006

In anodic oxidation of the phenylacetate ion, the formation yield of benzaldehyde increases by about 40% in the presence of a magnetic field (0.67 T), while 1,2-diphenylethane is insensitive to the field. The results are interpreted in terms of the magnetohydrodynamic mechanism.
Syntheses and Characterization of Dinuclear Manganese(II,II) and Manganese(II,III) Complexes with Phenolate and Two Carboxylate Bridges
Authors: Suzuki Masatatsu , Mikuriya Masahiro , Murata Shuji , Uehara Akira , Oshio Hiroki , Kida Sigeo , Saito Kazuo
Published: July 2006

Dinuclear manganese(II,II) and (II,III) complexes, [Mn2(L-py)(RCOO)2]ClO4·nH2O and [Mn2(L-py)(RCOO)2](ClO4)2·nH2O, were prepared, where L-py is 2,6-bis[bis(2-pyridylmethyl)aminomethyl]-4-methylphenolate(1–) and RCOO denotes CH3COO or C6H5COO. X-Ray structure analysis of the mixed valence complex [Mn2(L-py)(C6H5COO)2](ClO4)2·H2O revealed that the complex cation involves octahedral manganese(II) and manganese(III) centers with N3O3 donor sets and that the two metal ions are linked by phenolato and two benzoato groups. Magnetic susceptibility measurements over temperature range 80–300 K indicated that both manganese(II,II) and (II,III) complexes exhibit weak antiferromagnetic interaction with spinexchange coupling constant, J=−5–−7 cm−1. Cyclic voltammograms of the mixed valence complexes showed two quasi-reversible redox couples at ca. 0.5 and ca. 1.0 V (vs. SCE), assignable to the redox reactions of MnII–MnIII/MnII–MnII and MnIII–MnIII/MnII–MnIII, respectively. The comproportionation constants for the reaction (MnIII–MnIII)+(MnII–MnII)\ightleftarrows2(MnII–MnIII at 20°C were estimated as 2–3×109.
The Solid-Phase 13C NMR Spectra of Several Tropolone Derivatives
Authors: Mori Akira , Sugiyama Shigeru , Mametsuka Hiroaki , Tomiyasu Kazushi , Takeshita Hitoshi
Published: July 2006

The solid-phase 13C NMR spectra of o-, m-, and p-hydroxytropolones were measured. In the solid state, the hydrogen shift between the C-1 and C-2 oxygens was frozen under the NMR time-scale; the major tautomer of the o-hydroxytropolone was shown to the 2,7-dihydroxytropone form, which was parallel to the previous assignment deduced from the IR spectroscopy. In addition, the solid-phase 13C NMRg of o-bromotropolone showed it to be 7-bromo-2-hydroxytropone.
Practical, Stereocontrolled Synthesis of Polyfluorinated Artificial Pyrethroids
Authors: Fujita Makoto , Kondo Kiyosi , Hiyama Tamejiro
Published: July 2006

Practical and stereocontrolled approaches to polyfluorinated synthetic pyrethroids based on aldehyde addition of CF3CCl2ZnCl are described. The zinc reagent was allowed to react with 3-formyl-2,2-dimethylcyclopropanecarboxylates (6) to give the corresponding adducts. These were acetylated and then reduced again with zinc to afford (1R*, 3S*)-3-(2-chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethylcyclopropanecarboxylates (12). The (1R*, 3R*)-isomer was derived from 2,2-dichloro-1,1,1-trifluoro-5-methyl-4-hexen-3-ol by diazoacetylation, Cu(II)-catalyzed intramolecular carbene addition, and finally by the zinc reduction. An alternative access to 12 and its halogen homologues of the (Z)-pyrethroids involves addition of 1-halo-2,2-difluoroethenyl group across the CHO group of 6 and subsequent regio- and stereoselective halogenation.
Synthesis of Pyrano[4,3-c]pyrazol-4(1H)-ones and -4(2H)-ones from Dehydroacetic Acid. Homo- and Heteronuclear Selective NOE Measurements for Unambiguous Structure Assignment
Authors: Cantos Albert , March Pedro de , Moreno-Mañas Marcial , Pla Anna , Sanchez-Ferrando Francisco , Virgili Albert
Published: July 2006

Cyclization of dehydroacetic acid N-substituted hydrazones furnished 1-substituted 3,6-dimethylpyrano[4,3-c]pyrazol-4(1H)-ones, together with varying amounts of N,N′-disubstituted 5-hydroxy-3-methyl-4-(3-methyl-1H-pyrazol-5-yl)-1H-pyrazoles. The same pyranopyrazolones were obtained regioselectively without side reactions from N-alkylhydrazines and 4-chloro-3-(1-chlorovinyl)-6-methyl-2H-pyran-2-one, (“Dehydroacetchlorid”), while N-arylhydrazines gave the 2-aryl-3,6-dimethylpyrano[4,3-c]pyrazol-4(2H)-ones. NMR NOE methods, including long-range selective heteronuclear 13C{1H} NOE enhancement measurements, allowed unambiguous distinction between -4(1H)-ones and -4(2H)-ones.
Reactions of Tropone Tosylhydrazone Sodium Salt with 2-Pyrone Derivatives: Nucleophilic Addition of 1,2,4,6-Cycloheptatetraene to 2-Pyrone Derivatives
Authors: Saito Katsuhiro , Ishihara Hiraku
Published: July 2006

The reaction of tropone tosylhydrazone sodium salt with 3- or 5-methoxycarbonyl-2-pyrones afforded benzotropilidene derivatives. These products are considered to be formed via addition reactions of the 2-pyrone derivatives with 1,2,4,6-cycloheptatetraene derived from cycloheptatrienylidene, which is the initial product of the decomposition of tropone tosylhydrazone sodium salt.
The Solvation Effect on the Reactions in Solution. I. The Solvation Model for the Interpretation of Entropy Changes in the Complex Formation of Dichlorodimethylstannane with Pyridine
Authors: Fujiwara Hideaki , Arakawa Hiroyuki , Murata Saburo , Ohtaku Ikuzi , Ishii Motoko , Sasaki Yoshio
Published: July 2006

A complex-formation reaction has been studied for the Me2SnCl2 plus pyridine system in dimethyl phthalate (DMP) and dioctyl phthalate (DOP) by means of titration calorimetry. The resulting entropy changes in the reactions of A+B=AB and AB+B=AB2, with A=Me2SnCl2 and B=pyridine, were compared with those calculated for the gas-phase reactions. The values in solution amounted only to 1/3–1/4 of the gas-phase values. Correction for the entropy of solution of each component failed to explain the observed values in the absence of a strong solvation. The solvation model is presented to allow for such a discrepancy, assuming a strong solvation for Me2SnCl2 as well as for the 1:1 pyridine complex by definite numbers of solvents. To test the applicability of the model, calculations were made based on molecular statistical thermodynamics. The results obtained were reasonable, indicating that a free molecule, Me2SnCl2, is solvated by 1.3 molecules of the solvent of DMP, which are released about half by half on the formation of the 1:1 and 1:2 complexes with pyridine.
Oxygen-17 NMR Study of the Uranyl Ion. IV. 17O Nuclear Magnetic Relaxation and Chemical Shifts of Uranyl Oxygen Atoms and Coordinated Water
Authors: Jung Woo-Sik , Tomiyasu Hiroshi , Fukutomi Hiroshi
Published: July 2006

17O nuclear magnetic relaxation times and chemical shifts of uranyl oxygen atoms (hereafter uranyl oxygens) and solvent water have been measured with changing concentration of the uranyl ion in aqueous solution. The 17O resonance of the water molecule in the first-coordination sphere is determined to be at 90.1±1.2 ppm relative to free water at 25 °C. The effective correlation time for the 17O quadrupolar relaxation of the coordinated water, which corresponds to the reorientation time for the hydrated uranyl ion, is about 8.7 times that of free water. The 17O spin-lattice relaxation times (T1) of uranyl oxygens have been measured at 25 °C. From the 17O T1 values the 17O nuclear quadrupole coupling constant of uranyl oxygens has been estimated to be 0.44 MHz. This small value implies the high symmetry of electron distribution around uranyl oxygens.