bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies of Unusual Amino Acids and Their Peptides. VII. The Syntheses and the Reactions of Iminopeptides
Authors: Yamada Takashi , Suegane Kazuko , Kuwata Shigeru , Watanabe Hiroshi 
Published: July 2006

Abstract
As a basic study for synthesis of bottromycin, the syntheses and the reactions of iminodipeptides were investigated. Nine N-benzyloxycarbonyl(Z) iminodipeptides were prepared by the condensation of ethyl Z-amino carboximidates with amino acids according to the method of Ried et al. All the imidates were prepared from the corresponding nitriles, and ethyl N-Z-2-pyrrolidinecarboximidate (IIIf) was also successfully obtained from Z-proline thioamide by the method of Suydam et al. Though Z-(iminoprolyl)glycine was easily deprotected or esterified, its C-terminal could not be elongated because it was likely to cyclize into an imidazolone ring. This side reaction could be avoided by locating a carboxyl group further apart from an imino group in a molecule; i. e., the imidate (IIIf) could be coupled with methyl glycylphenylalaninate, thus affording the desired iminotripeptide, Z–ImPro–Gly–Phe–OMe, in a good yield.
A New Synthesis of Pyrocin and Related Compounds
Authors: Takeda Akira , Sakai Takashi , Shinohara Shohei , Tsuboi Sadao 
Published: July 2006

Abstract
A new synthesis of pyrocin (1) and related compounds is described. The reaction of 2-benzoyl-4,4-dimethyl-2-buten-4-olide (5b) with 2-methyl-1-propenylmagnesium bromide (6) in the presence of CuCl gave α-benzoylpyrocin (7b) in 90% yield. The product of 7b with a specific rotation of +2.43° was obtained when the reaction was carried out in the presence of (−)-sparteine. α-Acetylpyrocin (7a) was prepared in the similar manner in 63% yield. The treatment of 7a and that of 7b with ethanolic sodium ethoxide gave 1 in 65% and 81% yields, respectively. The reaction of 1 with large excess of SOCl2 in absolute ethanol gave ethyl 3-(1-chloro-1-methylethyl)-5-methyl-4-hexenoate (8) in 82% yield. Similar treatment of 7 with SOCl2 gave ethyl 2-substituted-4-(2-methyl-1-propenyl)-5,5-dimethyl-4,5-dihydrofuran-3-carboxylate (12). Compound 8 was transformed to ethyl trans-(±)-chrysanthemate (2) in 75% yield.
Substituent Effects on the Photo-ethoxycarbonylation of Monosubstituted Ferrocenes
Authors: Akiyama Takeo , Kitamura Taro , Kato Takao , Watanabe Haruo , Serizawa Toshio , Sugimori Akira 
Published: July 2006

Abstract
The effect of the substituent in the ferrocene nucleus on the photo-ethoxycarbonylation of monosubstituted ferrocene in carbon tetrachloride–ethanol solution is described. The electron withdrawing substituents, such as chloro, bromo, iodo, cyano, and acetyl, retarded the photo-ethyoxycarbonylation, whereas the electron releasing substituents, such as ethyl accelerated the reaction. The electronic effects which affect the formation of the charge transfer complex and those which affect the reactivity of the cyclopentadienyl ring toward the attack of a trichloromethyl radical can be considered for the photo-ethoxycarbonylation.
ESR Studies of Nitrogen-centered Free Radicals, N-Aryl-N-phenylthioaminyls
Authors: Miura Yozo , Kinoshita Masayoshi 
Published: July 2006

Abstract
A variety of substituted N-phenyl-N-phenylthioaminyls (2), Ar–\dotN–S–Ar′, were generated by the photolysis of benzenesulfenanilides (1) in benzene in the presence of di-t-butyl peroxide or by the oxidation of 1 in benzene with lead dioxide. The ESR spectra of the radicals were completely analyzed by labeling some radicals with deuterium and with the aid of a computer simulation technique. The unpaired electron is distributed mainly on the nitrogen atom and the N-phenyl ring. The values of an were plotted against the σ or σ− in the Hammett equation, and it was found that 2, in terms of Walter’s criteria, belong to class S.
Intramolecular Cyclization of 3,4-Epoxy Alcohols; Oxetane Formation
Authors: Murai Akio , Ono Mitsunori , Masamune Tadashi 
Published: July 2006

Abstract
1-(2,3-Epoxypropyl)-1-cyclohexanol (1) and its methyl analogues (2 and 3), when treated with base in 75% aqueous dimethyl sulfoxide, gave the corresponding oxetanes (9–11) as the main products, while treatment of compound 1 under anhydrous conditions afforded the oxolane dimer (17) as the sole identified product.
Production of 61Cu by α and 3He Bombardment on Cobalt Target
Authors: Homma Yoshio , Murakami Yukio 
Published: July 2006

Abstract
In order to determine the optimum irradiation conditions to produce the 61Cu for nuclear medical use, excitation curves and thick-target yield curves were determined for the α reactions producing 61Cu, 57Co, and 58Co, and 3He reactions producing 61Cu, 56Co, 57Co, and 58Co, both from natural cobalt. The 59Co(α, 2n) 61Cu and the 59Co(3He, n) 61Cu reactions give cross section peaks of 340 mb and 6 mb at 25 MeV and 35 MeV, respectively. The 61Cu thick-target yields for these reactions at 40 MeV were 6 mCi/μAh and 110 μCi/μAh, respectively. A simple and reliable anion-exchange method was developed to provide carrier-free 61Cu. The purity of 61Cu was determined with a Ce(Li) spectrometer. Photopeak efficiencies have been calculated at principal γ-ray energies of 61Cu, 64Cu, and 67Cu, for a 1/2 in. NaI scintillation camera. Alternative nuclear reactions and the methods for producing 61Cu are compared.
Binuclear Metal Complexes. XVI. Hetero Metal Binuclear Complexes with N,N′-Bis(3-carboxysalicylidene)ethylenediamine
Authors: Okawa Hisashi , Nishida Yuzo , Tanaka Mitsunori , Kida Sigeo 
Published: July 2006

Abstract
Hetero metal binuclear complexes, MM′ (fsaen)·nH2O (M=Cu(II) and Ni(II); M′=Cu(II), Ni(II), Co(II), Fe(II), and Mn(II); n=1–3), with N,N′-bis(3-carboxysalicylidene)ethylenediamine (H4fsaen) have been synthesized and characterized, where M and M′ denote the metal ion coordinated by the N2O2-coordinating atoms and the O4-coordinating atoms, respectively. The magnetism of CuNi(fsean)·3H2O and CuCo(fsaen)·3H2O is explained in terms of the Heisenberg model. The magnetism of NiCu(fsaen)·H2O, NiCo(fsaen)·2H2O, and NiMn(fsaen)·2H2O obeys the Curie-Weiss law, demonstrating the binuclear structure to be composed of one diamagnetic nickel(II) and one paramagnetic M′(II) ions. CuFe(fsaen)·2H2O, NiFe(fsaen)·2H2O, and CuMn(fsaen)·H2O each shows unusual magnetic property.
A Shock Tube Study of the Decomposition Mechanism of Chloroform in the Presence of Deuterium or Methane
Authors: Yano Takayuki 
Published: July 2006

Abstract
Chloroform was pyrolyzed in the absence and in the presence of one of three additives—D2, CH4, and CD4, over the temperature range of 1000–1200 K in a single-pulse shock tube. The main products of the decomposition of chloroform by itself were tetrachloroethylene and hydrogen chloride. On the other hand, tetrachloroethylene, trichloroethylene, dichloromethane, and hydrogen chloride were the major products in the presence of D2, while in the chloroform–methane systems they were tetrachloroethylene, trichloroethylene, 1,1-dichloroethylene, vinyl chloride, ethane, and hydrogen chloride. From the deuterium distribution of the products, as determined by mass spectrometry, it is found that the hydrogen atoms of trichloroethylene and 1,1-dichloroethylene mainly came from chloroform and methane respectively, while the hydrogen atoms of vinyl chloride came from both chloroform and methane. The change in the product distribution resulting from the addition of deuterium or methane and the hydrogen isotopic distribution suggest that the mechanism is composed of Cl atom elimination in the initiation step and successive reactions involving “hot” molecule reactions. The hydrogen isotopic distribution of vinyl chloride may indicate that the three-centered hydrogen elimination (αα) process competes with the four-centered (αβ) process in the decomposition of “hot” 1,1-dichloroethane.
Activity Coefficients of Glycylglycine and α-Aminobutyric Acid in Aqueous Sucrose Solutions
Authors: Uedaira Hatsuho 
Published: July 2006

Abstract
The activity coefficients of glycylglycine and α-aminobutyric acid in aqueous sucrose solutions have been measured by the isopiestic vapor pressure method at 25 °C. α-Aminobutyric acid is salted-out by sucrose, the effect increasing with an increase in the concentration of sucrose and a decrease in the concentration of amino acid. However, in the glycylglycine–sucrose–water system at lower concentrations of solutes salting-in of glycylglycine by sucrose takes place and then salting-out predominates at concentrations higher than 1 mol kg−1 glycylglycine and 2 mol kg−1 sucrose. The pairwise interactions and the free energy of the transfer of amino acids from water to various concentractions of sucrose solutions are calculated. The results account for the stabilizing effect of sucrose on the higher structure of globular proteins.
Luminescence of Aminopyridines and Related Molecules
Authors: Kimura Ko , Takaoka Hideko , Nagai Ryo 
Published: July 2006

Abstract
Quantum yields and lifetimes of fluorescence and phosphorescence were measured for 2-, 3-, 4-aminopyridines, 2-, and 4-(dimethylamino)pyridines in ethanol–methanol, in an acidic ethanol–methanol mixture, and in a mixture of triethylamine and 2-methyltetrahydrofuran at 300 K and at 77 K. Quantum yields of fluorescence of 2- and 3-substituted pyridines are appreciable, while those of 4-substituted pyridines are as low as or less than 0.01 at 77 K. In view of the significant quantum yields of fluorescence for 2- and 3-substituted pyridines in the aprotic solvent, it may be concluded that the higher excited 1(nπ*) or 3(nπ*) states are not so close in energy to the lowest excited 1(ππ*) states.
The Effect of Crown Ethers on the Reaction of Alkali Metal Trichloroacetate with Cyclohexene under Decarboxylative Conditions
Authors: Idemori Kenjiro , Takagi Makoto , Matsuda Tsutomu 
Published: July 2006

Abstract
The reaction between alkali metal trichloroacetate and cyclohexene was studied in an aprotic medium in the presence and also in the absence of crown ethers. The crown ethers catalyzed decarboxylation but reduced the yield of the dichlorocarbene adduct.
The Preparation of 3,5-Diacetoxy-1-cyclopentene
Authors: Kurozumi Seizi , Toru Takeshi , Tanaka Toshio , Miura Shuji , Kobayashi Makiko , Ishimoto Sachio 
Published: July 2006

Abstract
The phase-transfer reaction of 3,5-dibromo-1-cyclopentene with potassium acetate was studied using trialkylamines and a trialkylphosphine as catalysts. Various metal acetates were examined for their effects in this reaction.
The Structure of the Cyclodextrin Complex. V. Crystal Structures of α-Cyclodextrin Complexes with p-Nitrophenol and p-Hydroxybenzoic Acid
Authors: Harata Kazuaki 
Published: July 2006

Abstract
α-Cyclodextrin (α-CDx) forms a 1 : 1 complex with p-nitrophenol (p-NP) and p-hydroxybenzoic acid (p-HB). The crystal structures were determined by the X-ray method. The crystals of both complexes are orthorhombic, and the space group is P212121 with Z=4. The cell dimensions are a=13.455(1), b=15.296(1), and c=24.740(3) Å for the p-NP complex, and a=13.356(1), b=15.342(1), and c=24.896(2) Å for the p-HB complex. The crystal structures were determined on the basis of the isomorphous structure of the p-iodophenol complex by using 4811 reflections for the p-NP complex and 4692 reflections for the p-HB complex, and refined by the block-diagonal least-squares method to the final R-values of 0.066 and 0.067 respectively. In both complexes, the guest molecule is included in the α-CDx cavity, and the α-CDx ring is deformed from the regular hexagonal symmetry as a result of the inclusion of the planar molecule. The nitrophenyl or carboxyphenyl group is located in the cavity, while the phenolic hydroxyl group protrudes from the secondary hydroxyl side of the cavity. Several intermolecular hydrogen-hydrogen contacts shorter than the ideal van der Waals contact are observed between α-CDx and guest molecules, indicating that the guest molecule is rigidly fixed in the cavity. The nitro or carboxyl group is situated on the O(6) side and is hydrogen-bonded to water or a hydroxyl group of the adjacent α-CDx molecule. The geometry of the complex gives a reasonable model for the α-CDx-substrate complex in the hydrolysis of p-nitrophenyl acetate and p-carboxyphenyl acetate catalyzed by α-CDx.
Photolysis of Ethyl Azidoformate in Ethers and in Alcohols
Authors: Torimoto Noboru , Shingaki Tadao , Nagai Toshikazu 
Published: July 2006

Abstract
Ethoxycarbonyl nitrene, generated by the photolysis of ethyl azidoformate (I), was inserted preferentially into the α C–H bonds of acyclic ethers. Each of the reactions with acyclic ethers gave N-alkoxyurethane via a cleavage of the C–O bond, indicating that an O–N ylide is an intermediate of the nitrene reaction. Comparing sensitized photolysis with direct photolysis of I in ethers and in alcohols, it was found that the nitrene insertion into the α C–H bonds of ethers proceeds for both singlet and triplet and that the insertion into the β and γ C–H bonds of ethers and the O–H bonds of alcohols proceeds only for the singlet.
Formose Reactions. III. Evaluation of Various Factors Affecting the Formose Reaction
Authors: Shigemasa Yoshihiro , Fujitani Takashi , Sakazawa Chikahiro , Matsuura Teruo 
Published: July 2006

Abstract
By an analytical method using oxidation-reduction potential measurements of the formose reaction, which were previously shown to be useful for separately analyzing the induction and the formose-forming steps, the influence of various factors on each step and on the sugar yield were examined. It was found for the batchsystem formose reaction that the rate of both steps and the sugar yield are affected by the concentration of formaldehyde, the amount of calcium hydroxide, and also by the ratio of the two. The dissolved calcium ion is believed to be an essential catalyst for either the induction or the formose-forming step, with the hydroxy anion playing significant role as the catalyst for the latter step. The optimum conditions necessary for obtaining the sugars in high yields are discussed.
Asymmetric Reactions. II. Asymmetric Synthesis of Methyl α-Phenylpropionate by Means of Chiral Polymers
Authors: Yamashita Tetsushi , Yasueda Hiroshi , Miyauchi Yasushi , Nakamura Nobuo 
Published: July 2006

Abstract
The asymmetric addition of methanol to phenylmethylketene was carried out in the presence of propionylcinchonine and poly(acryloylcinchonine). The use of poly(acryloylcinchonine) produced additional products with higher optical yields than that of propionylcinchonine. The highest optical yield (35%) was obtained with the above polymeric catalyst at −78 °C. An insoluble, cross-linked polymer obtained by the co-polymerization of acryloylcinchonine with N,N′-diacryloylhexamethylenediamine, was also used as a catalyst. The products obtained for the cross-linked polymer showed a linear correlation between logkR/ks and 1/T while those with non-cross-linked poly(acryloylcinchonine) exhibited a relationship deviating somewhat from linearity. A linear relationship was also observed using insoluble, cross-linked poly(acryloylquinine).
Reduction by a Model of NAD(P)H. XIV. Mechanistic Consideration on the Role of Metal Ion
Authors: Ohno Atsuyoshi , Kimura Takahide , Yamamoto Hiroyuki , Kim Seung Geon , Oka Shinzaburo , Ohnishi Yutaka 
Published: July 2006

Abstract
The driving force for the catalytic activity of metal ions on the reduction of α-keto esters with an NAD(P)H-model compound has been discussed. The scope of the reaction and spectroscopic investigations as well as molecular orbital consideration have revealed that the transition state of the reaction consists of a ternary complex in analogy with a coenzyme–enzye–substrate complex in an enzymic system. It is concluded that, at the transition state, one electron migrates from a model compound to a substrate through a metal ion, which is followed by the transfer of a proton.
The Highly Selective Sulfonylation of Cycloheptaamylose and Syntheses of Its Pure Amino Derivatives
Authors: Tsujihara Kenji , Kurita Hironori , Kawazu Mitsutaka 
Published: July 2006

Abstract
Mesitylenesulfonyl chloride reacted selectively with primary hydroxyl groups of cycloheptaamylose to give hexakis (6-O-mesitylsulfonyl)cycloheptaamylose (II) and heptakis(mesitylsulfonyl)cycloheptaamylose (I). The selectivity of mesitylenesulfonyl chloride in the preferential sulfonylation is 24 times larger than that of tosyl chloride. Pure hexakis(6-azido-6-deoxy)cycloheptaamylose (III) and hexakis(6-amino-6-deoxy)cycloheptaamylose (IV) were synthesized from II. Pure heptakis(6-amino-6-deoxy)cycloheptaamylose (VII) and mixture of positional isomers of hexakis(6-amino-6-deoxy)mesitylsulfonylcycloheptaamylose (VIII)* were obtained by the catalytic hydrogenation of the corresponding azido compounds V and VI,* which were themselves given by the reaction of I with sodium azide. These amino derivatives, IV, VII, and VIII,* showed significant antimicrobial activities against such gram-negative bacteria as Escherichia, Shigella, and Pseudomonas. These compounds also exhibited hypocholesterolemic effects in the chick when added in the diet for two weeks, probably through sequestration of intestinal bile acids.
A Convenient Synthesis of (±)-Taxodione, (±)-Ferruginol, and (±)-Sugiol
Authors: Matsumoto Takashi , Usui Shuji , Morimoto Toshitaka 
Published: July 2006

Abstract
The condensation of β-cyclocitral (4); with 3-isopropyl-4-methoxybenzyl chloride (5) in the presence of lithium naphthalenide gave an alcohol (6), which was then oxidized to the corresponding α,β-unsaturated ketone (7). The Intramolecular cyclization of 7 with polyphosphoric acid yielded (±)-12-methoxyabieta-8,11,13-trien-6-one (8) and its cis-isomer (9), which was then successfully converted into 8 via an enol acetate (11). The 8 ketone was dem ethylated with boron tribromide to give a phenol (18), and this was then reduced with lithium aluminium hydride to yield the corresponding alcohol (19). The oxidation of the C-11 position in 19 with benzoyl peroxide gave (±)-12-benzoyloxyabieta-8,11,13-trien-6β,11-diol (20), which, on reduction with lithium aluminium hydride and subsequent oxidation with Jones reagent, afforded (±)-taxodione (1). The reductive cleavage of the hydroxyl group in 6 with dichloroaluminium hydride, followed by cyclization, gave (±)-ferruginyl methyl ether (12), which was then demethylated with boron tribromide to produce (±)-ferruginol (2). Further, the oxidation of 12 with chromium trioxide, followed by demethylation, gave (±)-sugiol (3).
X-Ray Diffraction Studies of the Metal Soaps of Fatty Acids of Odd Carbon Numbers
Authors: Ogino Keizo , Saito Toshio 
Published: July 2006

Abstract
X-Ray diffraction patterns have been observed for metal soaps of fatty acids with odd carbon numbers. The soaps of Pb, Cd, Ba, and Zn were prepared from the fatty acids of hexanoic, heptanoic, nonanoic, decanoic, undecanoic, dodecanoic, tridecanoic, tetradecanoic, pentadecanoic, hexadecanoic, heptadecanoic, and octadecanoic, the long spacings of which were studied in comparison with those of sodium soaps. The most prominent characteristic of these soaps is the presence of a definite order of long spacing which is directly proportional to the number of carbon atoms in the hydrocarbon chains, this is in contrast to the sodium soaps, which show a zigzag relation.
The Detection of Hg(63P1 and 63P0) Atoms by an Atomic Absorption Method and Their Quenching Cross Sections
Authors: Horiguchi Hiroyuki , Tsuchiya Soji 
Published: July 2006

Abstract
The absorption intensities of the 435.8- and 404.7-nm lines by Hg(63P1 and 63P0) atoms were calculated taking into account the hyperfine structure under the assumption of a Doppler spectral line shape. The calculated values were tested by comparison with experimental absorption of the line in an Ar+N2+Hg mixture illuminated by 253.7-nm radiation. This procedure led to the conclusion that the ratio of the spectral half-width of the 404.7-nm line from a low-pressure Hg lamp to that of the Hg(63P0) absorption line should be 2.25±0.25 instead of the value of 5 determined in the previous experiment. On the basis of this value, the quenching cross sections of the excited Hg atoms reported in the previous paper were revised. The corrections are generally less than 20%, so that it is not necessary to change the previous conclusions.
Electronic Interactions in Triple Exciplex of the 1,4-Dicyanobenzene and Naphthalene System
Authors: Mimura Tsutomu , Itoh Michiya , Ohta Toshiaki , Okamoto Toshihiko 
Published: July 2006

Abstract
Semiempirical SCF-MO-CI caluculation was carried out for the 1,4-dicyanobenzene (DCB) and naphthalene system which is known to form exciplex (DA)* and triple exciplex (D2A)*. Potential energy curves of the electronic interactions between excimer and electron acceptor molecule, and between exciplex and electron donor molecule were constructed. The results show that the array of component molecules in the triple exciplex is DDA, and the stabilization energy of triple exciplex is ≈0.4 eV from the excimer and ≈0.2 eV from the exciplex. They are in line with results reported on the experiment of exciplex and triple exciplex formation.
The Effect of Added Inorganic Salts on the Micelle Formation of Nonionic Surfactants in Aqueous Solutions
Authors: Nishikido Nagamune , Matuura Ryohei 
Published: July 2006

Abstract
In order to divide the inorganic salt effect on the micelle formation of nonionic surfactants into the effects on the hydrocarbon and on the hydrophilic moieties of the surfactant, the critical micelle concentrations(CMC) of nonionic surfactant homologs (8,10,12 methylene and 6 oxyethylene groups) were determined in aqueous salt solutions. The salt-effect parameters of methylene and hexa(oxyethylene) groups were calculated from the CMC data. The orders of both the parameters with respect to the anion obeyed the Hofmeister series. The variation in the extent of the parameters with respect to the cation was much less than that with respect to the anion. These phenomena were discussed in terms of the direct and indirect effects of ions on the water structure around the hydrocarbon and hydrophilic moieties of the surfactants. In addition, the salt effect on the cloud point (CP) and the amount of solubilization toward the Yellow OB dyestuff in aqueous solutions were discussed in connection with the salt effect on the hydrophilic moiety.
The Effective π-Electron Hamiltonian for the Excited State. The Effect of Σ-Π Interaction
Authors: Maki Izumi , Kitaura Kazuo , Nishimoto Kichisuke 
Published: July 2006

Abstract
The effective π-electron Hamiltonian for the excited molecule has been derived from the singly excited configuration interaction method (SECI) considering Σ-Π interaction. In this paper, the zero-differential overlap (ZDO) approximation has been employed. Then, in SECI scheme, π-π* and σ-σ* configurations interact through the exchange type MO-integrals over π- and σ-MO’s. As the result, only the excited singlet states are modified by Σ-Π interaction. So that the triplet states remain unchanged by this type of interaction.
When the ZDO approximation is employed, the effective electron interaction over AO’s, \ ildeγμν, can be derived. It is found that \ ildeγμν’s are represented approximately in terms of topological matrix, so named ‘bond index matrix’.