bluuebunny/crossref_metadata_2025 huggingface dataset:
A Novel Skeletal Rearrangement of 2-Azabicyclo[2.2.1]hept-5-ene-3-carboxylic Acid Derivatives into 2-Oxabicyclo[3.3.0]-oct-7-en-3-ones under Acidic Conditions
Authors: Kobayashi Tomoshige , Ono Katsuhiko , Kato Hiroshi
Published: July 2006

The reaction of ethyl 2-azabicyclo[2.2.1]hept-5-ene-3-carboxylate with aroyl chloride and the subsequent hydrolysis of the ester group provided 2-aroyl-2-azabicyclo[2.2.1]hept-5-ene-3-carboxylic acid derivatives, which underwent a stereospecific rearrangement giving 4-aroylamino-2-oxabicyclo[3.3.0]oct-7-en-3-ones by treatment with trifluoroacetic acid. On the other hand, the reaction of 2-benzoyl-2-azabicyclo[2.2.1]hept-5-ene with trifluoroacetic acid in heated benzene afforded 1-[(benzoylamino)methyl]-1,3-cyclopentadiene which afforded a Diels–Alder cycloadduct with N-phenylmaleimide. A plausible mechanism for the rearrangement is presented.
Synthesis and Antimicrobial Activity of Bactenecin and Its Analogs
Authors: Uchida Yoshiki , Shindo Mitsuno
Published: July 2006

Bactenecin and four analogs were synthesized by Merrifield’s solid phase method. The antimicrobial activity and conformation of the synthetic peptides were studied by the microplate dilution of the synthetic peptides were studied by the microplate dilution method and CD spectroscopy, respectively. The results suggest that the original sequence and cyclic structure are important for the expression of the potent antimicrobial activity of bactenecin. The CD spectrum of bactenecin revealed a profile corresponding to that of the random coil conformation.
Intramolecular [2+2] Photocycloaddition. 14. Cycloreversion of Cyclophanes Possessing a Cyclobutane Ring at Their Tether
Authors: Nishimura Jun , Wada Yasuhiro , Sano Yukari
Published: July 2006

Thermal cycloreversion of ten cyclophanes possessing a cyclobutane ring at their tether was examined. The rates were affected not only by their strain but also by their structural characteristics, such as meta- or para-configuration. The relative rate difference covered a range of the order of 106.
The Effect of the CCl3F-Treatment on Wettability of Silica Glass Surface by Water and Organic Liquid
Authors: Kurosaki Akito , Okazaki Susumu , Nishiyama Yoshiyuki
Published: July 2006

The wettability of silica glass plate by water and some organic liquids was varied by vapor-phase treatment of the surface with CCl3F at temperatures higher than 450 °C. The critical surface tension γc of the treated surface was found to be about 49 dyn cm−1 (1 dyn = 10−5 N).
A Systematic Study on the Bakers’ Yeast Reduction of 2-Oxoalkyl Benzoates and 1-Chloro-2-alkanones
Authors: Sakai Takashi , Wada Kou , Murakami Takahiko , Kohra Kiichiro , Imajo Norihisa , Ooga Yukihiro , Tsuboi Sadao , Takeda Akira , Utaka Masanori
Published: July 2006

The bakers’ yeast reduction of a series of 2-oxoalkyl arenecarboxylates [R(C=O)CH2O(C=O)C6H4-p-X] (1a–f) (R = CH3 to n-C6H13; X = H) and the phenyl-modified derivatives (1g–l) (R = n-C5H11, X = OH, CH3, F, Cl, Br, or I) as well as 1-chloro-2-alkanones R(C=O)CH2Cl (6a–f) (R = CH3 to n-C6H13) were systematically investigated. The substrate specificities, configuration and %ee of the reduction products were found to be highly dependent on the length of the alkyl group (R) and the α substituent. Thus, the benzoates 1a–f gave optically active 2-hydroxyalkyl benzoates (2a–f) (R, configuration, %ee) (a: CH3, S, 99; b: C2H5, S, 98; c: C3H7, S, 26; d: n-C4H9, R, 55; e: n-C5H11, S, 15; f: n-C6H13, S, 63) in 11–91% yields. Among the modification experiments of the phenyl group, 1g–l, the p-iodo substituent markedly increased the ee from 15 to 71%, although the yield was rather lowered (22% yield). The reduction of α-chloro ketones 6a–f also gave optically active 1-chloro-2-alkanols (7a–f) [(R, configuration, %ee) (a: CH3, S, 83; b: C2H5, S, 54; c: C3H7, R, 49; d: n-C4H9, R, 80; e, n-C5H11, R, 65; f, n-C6H13, R, 41)] in 16–69% yields.
The Spectroscopic Properties and Organometallic Reactivities of Cobalt(III) Porphyrins
Authors: Setsune Jun-ichiro , Saito Yasushi , Ishimaru Yoshihiro , Ikeda Mitsuhiro , Kitao Teijiro
Published: July 2006

Chlorocobalt(III) porphyrins showed novel UV-vis and 1H NMR spectra in a non-coordinating solvent to suggest displacement of the cobalt out of the porphyrin plane toward the axial ligand in solution. They underwent insertion of alkynes into the Co–Cl bond to generate σ-(trans-2-chlorovinyl)cobalt(III) complexes. In a special case, novel [4+2]cycloaddition reaction between the Co–N–C(pyrrole-α)-C(meso) moiety of [CoIIICl(oep)] [oep = octaethylporphyrin dianion] and dimethyl acetylenedicarboxylate took place. The reaction behavior of chlorocobalt(III) porphyrins was compared with that of diaquaperchloratocobalt(III) porphyrins which also reacted with alkynes in the presence of 2,6-lutidine to give analogous σ-vinylcobalt(III) porphyrins with a 2,6-dimethyl-1-pyridinio substituent occupying the trans-β-position of the σ-vinyl group. While the methoxycarbonyl group of methyl propiolate was directed to the α side of these σ-vinylcobalt(III) complexes, the phenyl group of phenylacetylene was found to be directed to the α side of σ-(2-chlorovinyl)cobalt(III) porphyrin and to the β side of σ-[2-(2,6-dimethyl-1-pyridinio)vinyl]cobalt(III) porphyrin.
Radical Intermediates in the Thermal Decomposition of 1,1-Bis(t-butyldioxy)cyclohexane
Authors: Sugihara Yasushi , Watanabe Yasumasa , Kumura Hiromi , Nakamura Tomoyuki , Suyama Shuji , Sawaki Yasuhiko
Published: July 2006

The thermolysis mechanism of 1,1-bis(t-butyldioxy)cyclohexane (6) has been studied in solutions. The activation parameters obtained in cumene are ΔH≠ = 139.5 kJ mol−1 and ΔS≠ = 44.8 J K−1 mol−1, and the volatile products are t-butyl alcohol, t-butyl peroxyhexanoate, and 2,3-dimethyl-2,3-diphenylbutane along with minor products of acetone, cyclohexanone, and t-butyl 1-methyl-1-phenylethyl peroxide. The thermolysis of 6 in benzene gave acetone and t-butyl alcohol as major volatile products. The polyester of 2-hydroxyhexanoic acid was obtained both in cumene and benzene as a non-volatile product, and the yield was as high as 76% in benzene. These facts indicate that [1-(t-butyldioxy)cyclohexyl]oxyl radical (7) undergoes a facile ring-opening reaction yielding 5-(t-butyldioxycarbonyl)pentyl radical (8). The resulting radicals abstract hydrogen atoms either intra- or intermolecularly. The former reaction is predominant in the absence of good hydrogen donors, affording 2-hexanolide and ultimately the corresponding polyesters.
One-Step Hydroamidation of 2-Aza-1,3-pentadienes
Authors: Okamoto Hidenori , Kobutani Tadashi , Kato Shozo
Published: July 2006

Various N-(1-aryl-1-alkenyl)-2-chloroacetamides bearing alkoxymethyl or alkylthiomethyl group on amide nitrogen were synthesized by a one-step hydroamidation of 2-aza-1,3-pentadienes. Some N-(1-aryl-1-alkenyl)-2-chloroacetamides were found to have high herbicidal activities against upland farm weeds.
Action of Fatty Acid Esters of l-Ascorbic Acid as Antioxidants in Phosphatidylcholine Liposomal Membranes
Authors: Takahashi Mareyuki , Komuro Erika , Niki Etsuo , Tanaka Kunihiko
Published: July 2006

The antioxidant activities of saturated fatty acid esters of l-ascorbic acid were studied in the oxidations of soybean phosphatidylcholine liposomes in aqueous dispersions aiming at elucidating their action as antioxidants in the liposomal membranes, especially the effects of number and length of the fatty acid ester side chains at either 6- or both 5- and 6-positions. Ascorbic acid esters were found to act as radical-scavenging antioxidants in the oxidations initiated by either aqueous free radical attacking from outside of the membrane or by lipophilic radical generated within the membranes. They inhibited the oxidation cooperatively with α-tocopherol in the membranes and reduced the rate of α-tocopherol consumption, their sparing effects on α-tocopherol being greatest for the monoesters and for the esters with the shortest fatty acid chains within the diester group. It was concluded that the intramembrane and intermembrane mobilities of ascorbic acid esters decreased with increasing number and length of fatty acid chains.
The Reactions of Monoalkylthio- or Monoarylthio-Substituted Cyclopropenium Salt with Nitrogen Nucleophiles: Formation of Polyfunctionally Substituted Pyrroles or Pyrazoles
Authors: Yoshida Hiroshi , Utsumi Fumitaka , Suzuki Hideki , Ito Satoru , Sakashita Shin-ichi , Ogata Tsuyoshi , Matsumoto Kiyoshi
Published: July 2006

The reactions of monoalkylthio- or monoarylthio-substituted cyclopropenium salt (1) with a number of secondary amines were studied. The amines, such as N-methylaniline, yielded indenes, whereas N-alkyl- or N-arylbenzylamines gave 1-alkyl- or 1-aryl-2-phenylpyrroles in low-to-moderate yields, depending on the kinds of substituents of the amines and 1. The reaction with N-isopropylbenzylamine-α,α-d2 (i-PrNHCD2Ph) resulted in the formation of the 1-isopropyl-2,3,5-triphenylpyrrole-4-d, clearly indicating the intramolecular H-abstraction mechanism via vinylcarbene intermediates for the formation of pyrroles. The reaction of 1 with tosylhydrazones afforded the ring opend hydrazide, while with phenyl-, methyl-, and t-butylhydrazines gave 1,4,5-trisubstituted pyrazoles in small yields.
NMR Relaxation Studies for Sodium and Potassium Ions and Water Molecules in Concentrated Aqueous Solutions of Dibutyl Phosphate
Authors: Iida Masayasu , Hata Yukari
Published: July 2006

The hydration and alkali-ion binding of an aggregate of the dibutyl phosphate (DBP) ion in its isotropic aqueous solution were investigated by measuring the nuclear magnetic relaxation times for 17O of H2O, and 23Na and 39K of hydrated alkaline metal ions at various temperatures. The relaxation rates for the 17O of H2O showed that the rotational motion of the water molecule is more restricted in the sodium system than that in the potassium system. Arrhenius plots also showed that the activation energy for the relaxation rate of the water molecule is larger in the sodium system. The dependences of the longitudinal relaxation rates for the alkali ions on the DBP concentrations in these systems showed that the sodium ion has an enhanced tendency, over the potassium ion, to interact with the dibutyl phosphate ion and to form ion-aggregates.

Viscosity measurements showed that the appreciable restriction of the motion of the water molecules in DBP solutions corresponds to a great extent in the aggregation of DBP.
Fluorescence Spectra of 1-Naphthol During the Sol-Gel Process of a Mixed Aluminum-Silicon Alkoxide (Si : Al = 94 : 6)
Authors: Fujii Tsuneo , Mabuchi Toshiaki , Kitamura Hiroshi , Kawauchi Osamu , Negishi Nobuaki , Anpo Masakazu
Published: July 2006

The fluorescence and fluorescence-excitation spectra of 1-naphthol during sol to gel to xerogel transitions of a mixed solution comprising silicon and aluminum alkoxides (Si : Al = 94 : 6) catalyzed by a small amount of NaOH aqueous solution have been observed as a function of time. During the reaction of the system, the spectrum shifted to the red in the first stage and shifted to the blue in the next stage. This behavior reflects the changes of polarity and microviscosity of the matrix surrounding the doped 1-naphthol molecules during the sol to gel to xerogel transitions of the mixed metal alkoxide. The gelation occurred at 10 d. On the other hand, the most remarkable red-shift in the fluorescence spectrum was observed at 9 d. Comparing the fluorescence and fluorescence-excitation spectra of 1-naphthol in typical solvents with those of the sol–gel process, it has become apparent that a part of the doped 1-naphthol molecules in the ground state form a contact ion pair on the surface in cages of the prepared gel.
Surface Alkoxylation of Silicas by Mild Reactions with Alcohols
Authors: Shioji Shuhei , Tokami Kenjirou , Yamamoto Hideo
Published: July 2006

The surface alkoxylation reaction of silicas was investigated under mild reaction conditions with some low-molecular-weight saturated aliphatic alcohols. Silica gels and porous silica glass were treated with liquid alcohols using a Soxhlet extractor below their boiling points. The number of formed alkoxyl groups was examined by both thermal analyses and infrared spectra. It was shown that some of the surface hydroxyl groups were easily esterified to alkoxyl groups, even by contact with the alcohols under mild reaction conditions. The degree of alkoxylation was higher for the silica gels than for porous silica glass. The adsorption isotherms of methanol vapor at room temperature were measured on silica gel samples which were previously activated at various temperatures. The adsorption equilibrium strongly depends on the pretreated temperature. The surface methoxylation reaction took place not only on the surface hydroxyl groups, but also on the siloxane bridges, even at room temperature.
The Crystal Structures of Cyanide Metmyoglobins Reconstituted with Iron(III) Complexes of Porphyrin, 5,10,15,20-Tetramethylporphyrin, and 5,10,15,20-Tetraethylporphyrin
Authors: Sato Takao , Tanaka Nobuo , Moriyama Hideaki , Matsumoto Osamu , Takenaka Akio , Neya Saburo , Funasaki Noriaki
Published: July 2006

The structures of three mimic myoglobins reconstituted with synthesized iron(III) meso-substituted porphyrins have been studied by X-ray crystallography. Although the overall structure of each globin was the same as that of the native, apart from a few terminal residues, the Cα atom of Arg45 in each crystal was displaced by 2.7 Å from that in the native. This large displacement opens a channel for the ligand penetration, formed by His64, Thr67, Val68, and heme. The movement of each porphyrin was estimated from the refined anisotropic temperature factors of its atoms, which showed that the root-mean-squares amplitude of the vibration about the normal to the porphyrin plane was significantly larger than the globin’s movement.
Simulation of Vibrational Spectra of Acetic Acid By an Extended Molecular Mechanics Method and Half Band Width Parameters
Authors: Yokoyama Isao , Miwa Yoshihisa , Machida Katsunosuke
Published: July 2006

The molecular mechanics simulation of the infrared absorption and Raman spectra of acetic acid in the solution or liquid phase has been carried out by using an empirically estimated force field which includes the equilibrium charges and the charge fluxes as the Coulomb potential parameters. The variation of the observed band widths among different normal modes has been taken into account by introducing the half band width parameters empirically assigned to individual internal coordinates. The half widths of more than 20 bands observed in the infrared absorption and the Raman spectra are well reproduced in terms of five half band width parameters. The thermodynamic properties and the structures of acetic acid monomer and dimer are successfully simulated. The overall features of the simulated spectra of acetic acid are in good agreement with the observed ones.
“Syn-Effect” in the Conversion of (E)-Vinylic Sulfones to the Corresponding Allylic Sulfones
Authors: Hirata Takaki , Sasada Yoshihiro , Ohtani Takashi , Asada Takahiro , Kinoshita Hideki , Senda Hitoshi , Inomata Katsuhiko
Published: July 2006

It was found that (E)-vinylic sulfones preferentially afford (Z)-allylic sulfones as kinetically-controlled products by treatment with a base under mild conditions, while (Z)-vinylic sulfones give (E)-allylic sulfones. Such stereochemical relationship was rationalized by “syn-effect”, and its relative degree for various substituents was determined by observation of E/Z ratios of the allylic sulfones resulted from the corresponding γ-mono- or γ,γ-disubstituted vinylic sulfones as follows: RO– (R = CH3, C2H5) ArO– (Ar = p-CH3OC6H4, p-CH3C6H4, C6H5, p-NO2C6H4) ≥ AcO– > Cl– ≥ Br– > CH3– > CH3S– ≥ –CH2– (cyclic and acyclic) > (CH3)2CH– >> (CH3)3C–, C6H5–. X-Ray crystallography was performed for some vinylic sulfones to reveal the origin of the “syn-effect”.
Solvent Extraction of Divalent Metals as Dihydrobis(1-pyrazolyl)borate Chelates
Authors: Yasuda Noriyasu , Kokusen Hisao , Sohrin Yoshiki , Kihara Sorin , Matsui Masakazu
Published: July 2006

The extraction behavior of divalent metals (M2+) with dihydrobis(1-pyrazolyl)borate ligand (H2B(pz)2−) has been studied. Divalent transition metals form [M{H2B(pz)2}2] chelates readily and are extracted into the organic phase. The extraction constants of the first-row transition metals increase in the order Mn(II) < Fe(II) < Co(II) < Ni(II) < Cu(II) > Zn(II), which is in accordance with the Irving and Williams’ order for complex stability. Although Be2+ is slightly extracted by H2B(pz)2−, Mg2+, Ca2+, Sr2+, and Ba2+ are not extracted, whether a synergistic agent such as trioctylphosphine oxide and tetrabutylammonium chloride is added or not. The characteristics of H2B(pz)2− in the extractability of metal ions are ascribed to that the basicity of coordinating nitrogen atoms is increased by negative charge of the molecule and inductive effect of the boron atom, and that adduct formation is restricted by the steric hindrance.
Copper(II)-Thioether Bondings in Multidentate N,S-Donor Ligand Complexes. Structural Dependence of the Chemical Properties of the Copper(II) Complexes of 1,5-Bis(2-pyridylmethylamino)-3-thiapentane and 2,6-Bis(2,6-dithiaheptyl)pyridine
Authors: Masuda Hideki , Sugimori Tamotsu , Kohzuma Takamitsu , Odani Akira , Yamauchi Osamu
Published: July 2006

With a view to understanding the factors affecting the chemical properties of the copper sites in proteins, model copper(II) complexes of two multidentate ligands with nitrogen and sulfur atoms, 1,5-bis(2-pyridylmethylamino)-3-thiapentane (pmtp) and 2,6-bis(2,6-dithiaheptyl)pyridine (dthp), have been isolated as [Cu(pmtp)][Cu(pmtp)ClO4](ClO4)3 (1) and [Cu(dthp)(NO3)2] (2), respectively, and studied by X-ray diffraction, spectroscopic, and electrochemical methods. Complex 1 crystallizes in space group P21/a of the monoclinic system with four [Cu(pmtp)]2+ ions and four [Cu(pmtp)(ClO4)]+ ions in a cell of dimensions a = 24.180(7), b = 31.855(7), c = 9.760(3) Å, and β = 143.84(1)°. The coordinations around the coppers in the two independent complexes are square-pyramidal and octahedral, respectively, with an amine nitrogen, two pyridine nitrogens, and a thioether sulfur at the equatorial positions (eq) and an amine nitrogen (and a perchlorate oxygen in addition in the octahedral complex) at the axial position(s) (ax); Cu–Neq = 1.991(10), 2.001(14), and 2.009(9) Å, Cu–Seq = 2.353(6) Å, Cu–Nax = 2.276(8) Å for [Cu(pmtp)]2+, and Cu–Neq = 1.994(7), 2.002(6), and 2.013(14) Å, Cu–Seq = 2.355(6) Å, Cu–Nax = 2.306(10) Å, Cu–Oax = 2.698(14) Å for [Cu(pmtp)(ClO4)]+. Complex 2 crystallizes in space group P21/c of the monoclinic system with four [Cu(dthp)(NO3)2] molecules in a cell of dimensions a = 18.492(5), b = 14.375(3), c = 8.554(2) Å, and β = 101.19(2) Å. The coordination around copper is distorted trigonal-bipyramidal with two thioether sulfurs and a nitrate oxygen in the trigonal plane and a pyridine nitrogen and a nitrate oxygen at the axial positions; Cu–Seq = 2.344(2) and 2.402(2) Å, Cu–Oeq = 2.244(6) Å, Cu–Nax = 1.982(6) Å, Cu–Oax = 1.927(5) Å. The structures of these complexes in aqueous solution were concluded to be square-pyramidal from ESR and electronic spectra. Their reduction potentials (E1⁄2 vs. NHE) were +0.062 V for 1 in CH3CN with one coordinated S atom and +0.678 V for 2 in CH2Cl2 with two coordinated S atoms. The higher E1⁄2 value for 2 has been interpreted as due to the presence of the two coordinated sulfur atoms and the flexibility of the ligand which can accomodate the structural changes accompanying the Cu(II)/Cu(I) redox reaction.
Stereoselective Formation and Some Properties of Polynuclear Cobalt(III) Complexes with d-Penicillaminate
Authors: Okamoto Ken-ichi , Yonemura Toshiaki , Konno Takumi , Hidaka Jinsai
Published: July 2006

The novel mononuclear, dinuclear, and trinuclear cobalt(III) complexes with d-penicillaminate(d-pen), ΛDdd-fac(S)-[Co(d-pen-N,S)3]3−, ΛDdd-[Co{Co(d-pen-N,S)3}(dien)], ΛDdd-[Co{Co(d-pen-N,S)3}(d-pen-N,O,S)]2−, and ΛDddΔDdd-[Co{Co(d-pen-N,S)3}2]3− were prepared. These complexes were characterized from their electronic absorption, CD, and 13C NMR spectra. These complexes formed selectively each one isomer. The stereoselectivity for the d-pen complexes is discussed in comparison with that of the corresponding l-cys ones. The d-pen polynuclear complexes exhibited characteristic absorption spectral behaviors in the visible region. The 13C NMR spectral behaviors for the d-pen complexes are connected with those of the corresponding l-cys ones.
Synthesis of Optically Active Polymethacrylates Bearing Axially Dissymmetric 1,1′-Binaphthalene Skeleton as a Pendant Group and Their Optical Resolution Ability as Chiral Adsorbent for HPLC
Authors: Tamai Yasufumi , Qian Pu , Matsunaga Ken’ichi , Miyano Sotaro
Published: July 2006

Optically active polymethacrylates 6 and 8, which have pendant axially dissymmetric 1,1′-binaphthalene moiety, were synthesized by radical polymerization of (S)-2-methacryloyloxy- and (S)-2-(3-methacryloyloxypropoxy)-2′-methoxy-1,1′-binaphthalene, respectively. Specific rotation and CD spectrum of 6 are rather different from those of the model compound 2-(2,2-dimethylpropanoyloxy)-2′-methoxy-1,1′-binaphthalene (7), while the chiroptical properties of 8 are almost the same as those of the corresponding model compound. The difference of the chiroptical properties between 6 and 7 was attributed to the difference of the dihedral angles between the naphthalene planes of the 1,1′-binaphthalene skeleton. The polymethacrylates 6 and 8 were coated on a spherical silica gel to give HPLC chiral stationary phases (CSP-6 and CSP-8). These CSPs differentiated several enantiomeric 1-aryl-1-alkanols and 1,2-diols as the 3,5-dinitrophenylcarbamates, CSP-8 showing better resolution than CSP-6. Furthermore, (S)-2-(5-carboxypentyloxy)-2′-methoxy-1,1′-binaphthalene, a model compound of 8, was prepared and covalently bonded to an aminopropylsilanized silica gel to afford CSP-16, which also resolved these racemates. Thus, the chiral discriminating ability of the polymethacrylate 8 would be based not on the secondary and/or higher-ordered structure, but mainly on the interaction between the individual 1,1′-binaphthalene units of 8 and the racemates.
Efficient Six-Electron Photoreduction of Nitrobenzene Derivatives by 10-Methyl-9,10-dihydroacridine in the Presence of Perchloric Acid
Authors: Fukuzumi Shunichi , Tokuda Yoshihiro
Published: July 2006

Photoreduction of nitrobenzene derivatives by 10-methyl-9,10-dihydroacridine (AcrH2) occurs efficiently in the presence of perchloric acid in acetonitrile containing H2O (0.50 mol dm−3) to yield the corresponding six-electron reduced products (aniline derivatives) and 10-methylacridinium ion efficiently. The initial two-electron reduction of PhNO2 to PhNO by AcrH2 in the six-electron reduction of nitrobenzene (PhNO2) is started by electron transfer from AcrH2 to the n,π* triplet state (3PhNO2*), followed by acid-catalyzed thermal reduction of PhNO to PhNHOH by AcrH2 and the subsequent photoreduction of PhNHOH to PhNH2 by AcrH2.
Photochemical Reactions of 4-Acylstyrenes. Effects of Acyl Substituents on Photocyclodimerization via an Excited Triplet State
Authors: Tsubakiyama Kyoji , Miyagawa Kohji , Kaizaki Kiyotaka , Yamamoto Masahide , Nishijima Yasunori
Published: July 2006

The photochemical reactions of 4-acylstyrenes (1a–e; acyl = acetyl, benzoyl, 1-naphthoyl, 2-naphthoyl, and 9-phenanthrylcarbonyl, respectively) were investigated, and their excited state behavior and photoreactivities are discussed in relation to the aryl ketone structures. Photoirradiation of 1a–e in benzene gave two isomeric cyclodimers of trans- and cis-1,2-bis(4-acylphenyl)cyclobutanes(2a–e and 3a–e) as main products, accompanied by the formation of some oligomers and polymers. The fractions of the trans-form in the cyclodimers were ca. 80%; this indicated that the cyclodimerization proceeded via the π,π* triplet state. The quantum yields of the photodimerization for 1a–e were almost the same irrespective of the acyl substituents (Φ = 0.03–0.04 at [1a–e] = 0.1 mol dm−3). Phosphorescence spectra of 1c (τ = 0.48 s) and 1d (τ = 0.91 s) observed in a rigid solution at 77 K, which coincided with those of the respective model aryl ketones, were ascribed to the low-lying excited π,π* triplet states localized on the naphthalene moiety of the molecules. Phosphorescence emissions of 1a and 1b could not be detected. The transient absorption spectrum of 1d (τ = 23 ns) observed in a fluid solution at 293 K was tentatively assigned to the π,π* triplet state mainly localized on the styrene moiety of the molecule. The photoreaction mechanism is discussed in terms of the intramolecular triplet energy transfer.
Synthesis and Radical Polymerization of Itaconates Containing an Adamantyl Ester Group
Authors: Matsumoto Akikazu , Watanabe Hiroyuki , Otsu Takayuki
Published: July 2006

Itaconates containing a 1-adamantyl or a 3,5-dimethyl-1-adamantyl ester group were prepared and polymerized in the presence of a radical initiator. The polymerization reactivity has been investigated in relation to the structure of ester alkyl groups of the monomer. It has been clarified that the adamantyl-containing polyitaconates show high thermal stability, i.e., high glass transition temperatures and decomposition temperatures. The relationship between polymer structures and thermal properties of polymers from some α- and β-substituted acrylic esters, i.e., acrylates, methacrylates, crotonates, fumarates, and itaconates was discussed.
Preparation of Poly(2,5-diheptyl-1,4-phenylenevinylene) by Sulfonium Salt Pyrolysis
Authors: Sonoda Yoriko , Kaeriyama Kyoji
Published: July 2006

Poly(2,5-diheptyl-1,4-phenylenevinylene) (1) was prepared by the sulfonium salt pyrolysis procedure. Tough films of 1 were obtained by pyrolysis of its sulfonium salt precursor film. Due to flexible side chains, 1 was soluble in organic solvents such as chloroform. The molecular weights were Mn = 3.8−4.7 × 104 and Mw = 1.4−1.8 × 105. The ratio of trans to cis olefinic units was found to be 93 : 7 from the 1H NMR spectrum. Two arylmethylene peaks suggested that there were two kinds of stereochemically different methylene groups. Although the peak energy in the absorption spectra was almost identical to those of poly(1,4-phenylenevinylene) (PPV), the electrical conductivity of 1 was much lower than that of PPV.
Surface Adsorption and Micelle Formation of Dodecyltrimethylammonium Chloride and Dodecylammonium Chloride Mixture
Authors: Ikeda Norihiro , Sanefuji Norihiko , Abe Koji , Todoroki Natsuko , Aratono Makoto , Motomura Kinsi
Published: July 2006

The miscibility of dodecyltrimethylammonium chloride (DTAC) and dodecylammonium chloride (DAC) in the adsorbed film at water/air interface and in the micelle was investigated by measuring the surface tension of the aqueous solution of surfactant mixture as a function of the total molality and composition of surfactants. The compositions of surfactants in the adsorbed film and micelle were evaluated by use of the thermodynamic equations developed previously. The results indicated that DTAC and DAC molecules mix slightly nonideally in the adsorbed film and micelle. Furthermore, the composition of DAC in the micelle was found to be remarkably smaller than that in the adsorbed film at the critical micelle concentration. It was concluded that the bigger hydrophilic group of DTAC is geometrically favorable for the micelle formation.
Evaluation of Melting and Crystalline Relaxation Temperatures of Fatty Acid Monolayers on the Water Surface and Their Importances for Molecular Aggregation States in Monolayers
Authors: Kajiyama Tisato , Oishi Yushi , Uchida Motoko , Morotomi Naoaki , Ishikawa Jun-ichi , Tanimoto Youichi
Published: July 2006

The melting temperature, Tm and the crystalline relaxation temperature, Tαc of fatty acid monolayers on the water surface were evaluated by a combination of two kinds of measurements, the subphase temperature, Tsp dependence of monolayer modulus based on a π-A isotherm and also, the Tsp dependence of the electron diffraction, ED patterns of monolayer. Tms of myristic, palmitic, and stearic acid monolayers were evaluated to be 278, 301, and 317 K, respectively, on the basis of both apparent decrease in the Tsp vs. modulus curve and the change of the ED pattern from a crystalline Debye ring to an amorphous halo. The crystalline relaxation process corresponds to a change from elastic to viscoelastic characteristics in a crystalline phase due to a considerable contribution of anharmonic thermal molecular vibration. Tαcs of palmitic and stearic acid monolayers were evaluated to be 291 and 298 K, respectively, from both apparent decrease in the Tsp dependence of modulus and appearance of the break in the thermal expansion coefficient of crystalline lattice constant. This break may be attributed to a remarkable increase in contribution of the anharmonic term with respect to the intermolecular potential energy. The magnitude of Tm and Tαc of monolayers on the water surface is an important factor to decide the structure or aggregation state in the crystalline and amorphous monolayers and also, the formation process of a large-area monolayer, that is, the fusion or sintering behavior among crystalline monolayer domains.
Effect of Ascorbic Acid on the Desorption of Gold in Graphite Furnace Atomic Absorption Spectrometry
Authors: Imai Shoji , Hayashi Yasuhisa
Published: July 2006

In the graphite furnace atomic absorption spectrometry of gold, signals with a single peak were observed with a pyrolytic graphite (PG) furnace, while signals with a shoulder on the tailing edge were observed with a nonpyrolytic graphite (NPG) furnace. A thermal shift of the atomic absorption signals for gold occurs in response to changes in the concentration of ascorbic acid without any loss for each furnace. When the pre-pyrolysis of a 5% (m/V) ascorbic acid solution was carried out at 1270 K, although the background signal due to the release of amorphous carbon was not observed, a thermal shift of the gold signal was confirmed. At a pre-pyrolysis temperature over 1460 K, the peak absorbance was reduced by increasing the pre-pyrolysis temperature, while absorbance at the position of the signal for gold only was increased. The values of the Arrhenius activation energy for the desorption of gold were obtained to be 60 ± 2 kcal mol−1 for gold only, 93 ± 3 kcal mol−1 for gold with 5% (m/V) ascorbic acid and 99 ± 2 kcal mol−1 after a pre-pyrolysis of ascorbic acid at 1270 K.
Preparation of Cu Thin Films by the Decomposition of Copper Acetylacetonate on Catalytically Active Substrate Surfaces
Authors: Miura Hiroshi , Oki Kazuo , Ochiai Hisayoshi , Higuchi Hiroshi , Terasaka Michio , Matsuda Tsuneo
Published: July 2006

A selective CVD system used to deposit the central metal of a volatile complex preferentially on catalytically active substrate surfaces was examined. Copper(II) acetylacetonate was vaporized in a flow of hydrogen and decomposed on Ni, Pd, and Al plates in order to deposit metallic copper. When a Ni plate was used as the substrate, deposition of metallic copper occurred at temperatures in the range 13O–180 °C only on the substrate surfaces. The formation of an ultrathin film of Cu of uniform thickness was confirmed. On a Pd substrate, the formation of an ultrathin Cu film of uniform thickness was also observed. On an Al substrate, however, deposition occurred nonselectively at temperatures above 160 °C, not only on the substrate surface, itself, but also on the wall of the glass tube as well as the quartz wool surrounding the Al plate. In addition, the formation of fine particles of Cu, instead of thin film, was found to exist on the substrate. Because the deposition of Cu took place on catalytically active surfaces selectively, the deposition was considered to proceed by a catalytic hydrogenation of the C=O bond of the ligand, thus detaching it from the Cu ion and allowing it to decompose the complex and deposit Cu metal.
Mechanism on the Efficient Formation of Singlet Oxygen by Energy Transfer from Excited Singlet and Triplet States of Aromatic Hydrocarbons
Authors: Usui Yoshiharu , Shimizu Noriyo , Mori Satoshi
Published: July 2006

The formation efficiencies of singlet oxygen for the oxygen quenching in excited singlet of aromatic hydrocarbons; A and for the quenching in the triplet T1; B were estimated. The hydrocarbons were classified into three types: (i) A = 1 and B = 1 for dicyanoanthracene i.e., total 200% efficiency, (ii) A ≈ 0.3 and B = 1 for anthracene, (iii) A ≈ 0 and B = 1 for pyrene, as examples. It is suggested that the energy levels of T2 and a dissociative exciplex; (T11Δg) correlated to A and B values from the energetic considerations.
Preparation of 1,4,2-Dithiazolium Salts
Authors: Yonemoto Katsumi , Shibuya Isao , Taguchi Yoichi , Tsuchiya Tohru , Yasumoto Masahiko
Published: July 2006

N-(Substituted formyl)dialkylamino(thioxo)methanesulfenamides (R2NCSSNHCOR′ 3: R = alkyl, R′ = alkyl, dialkylamino, alkoxy, and heterocyclic substituent) were treated with a strong acid (HBF4 or HClO4) in Ac2O to afford 1,4,2,-dithiazolium salts (7) and/or 3,5-bis(dialkyliminio)-1,2,4-trithiolanes (9). The reactivity is markedly dependent on the nature of substituents (NR2 and R′) and the acid used. For R′ = MeO, the sulfenamides reacted successively with NaH and p-toluenesulfonyl chloride to give methyl bis(dialkylthiocarbamoylthio)carbamates (10). The mechanisms for the formation of 9 and 10 are discussed.
Generation and Cycloaddition Reactions of 3-Styryl-1,2-thiaphosphole 2-Sulfide and 1,5-Diphenyl-2,4-pentadiene-1-thione
Authors: Motoki Shinichi , Sakai Takaya , Matsuo Yoshihisa , Kametani Shunichi , Saito Takao
Published: July 2006

The cycloaddition reaction of 3-styryl-1,2-thia phosphole 2-sulfide and 1,5-diphenyl-2,4-pentadiene-1-thione derivatives generated by the thermolysis of 5,6-distyryl-3,8-diaryl-2,9-dithia-1-phosphabicyclo[4.3.0]nona-3,7-diene 1-sulfides have been described. Methacrylonitrile, methyl methacrylate, α-methylstyrene, norbornene, methyl acrylate, styrene, and mehyl vinyl ketone afforded the cycloadducts or their rearranged products with the thiaphosphole 2-sulfides, whereas diethyl azodicarboxylate, dimethyl acetylenedicarboxylate, and N-(p-methoxyphenyl)maleimide gave the cycloadducts with the thioketone.
Citreobenzofurans A, B, and C, First Isolation of Sesquiterpene-Type Metabolites of a Hybrid Strain KO 0031 Derived from Penicillium Citreo-viride B. IFO 4692 and 6200
Authors: Kosemura Seiji , Nagamatsu Harutoshi , Yamamura Shosuke
Published: July 2006

Three new sesquiterpene-type metabolites, citreobenzofurans A, B, and C, have been isolated ftrom the mycelium of the hybrid strain KO 0031 derived from Penicillium citreo-viride B. IFO 4692 and 6200. Their stereostructures have been also elucidated on the basis of their spectral data.
Synthesis of (±)-Isopiperitenol by Fluoride Ion Mediated Cyclization of Allylsilane Moiety Incorporated in Terpene Aldehydes
Authors: Nakamura Hideshi , Oya Toyohisa , Murai Akio
Published: July 2006

Fluoride ion mediated cyclization of aldehydes (1 and 2) having regioisomeric allylsilane functionalities give a mixture of cis- and trans-isopiperitenol (3). The aldehydes (1) reacted faster and showed better stereoselectivity than the regioisomeric aldehydes (2) regardless of geometry of the double bond at an unsaturated aldehyde.
A Novel Isobenzofuran Derivative Undergoing Photovalence Isomerization
Authors: Miki Sadao , Yoshida Masahiro , Yoshida Zen-ichi
Published: July 2006

4,5,6-Tri-t-butylisobenzofuran (1) and 4,5,7-tri-t-butylisobenzofuran have been synthesized. They were stable infinitely in solutions at room temperature. Upon irradiation, 1 undergoes photovalence isomerization to afford 2,3,4-tri-t-butyl-8-oxatetracyclo [4.3.0.02,4.03,5]nona-1(9),6-diene.
Semi-preparative Purification and Crystallization of Synthetic Analogs of Heat-stable Enterotoxins of Enterotoxigenic Escherichia coli
Authors: Sato Takashi , Ito Hideaki , Takeda Yoshifumi , Shimonishi Yasutsugu
Published: July 2006

The purification by high-performance liquid chromatography of synthetic analogs of heat stable enterotoxin (ST) of enterotoxigenic Escherichia coli from large amounts of their dilute solution on a laboratory scale is described. These analogs were also crystallized by gradually decreasing the temperature of their warm aqueous solution.
Intramolecular [2+2] Photocycloaddition. 15. Synthesis of 1,2-Ethano-9,10-methano[2.2]paracyclophanes
Authors: Nishimura Jun , Horikoshi Yoichiro
Published: July 2006

The title compounds were prepared in 30% yield by the sequence of photocycloaddition of styrene derivatives, followed by bromination and elimination. The isomer raito of the products was 5 : 4.
Reactivity of Lithium Alkylamide toward Vinylsilane Derivatives
Authors: Nagasaki Yukio , Morishita Shinya , Kato Masao , Kihara Yasuharu , Tsuruta Teiji
Published: July 2006

Kinetic studies concerning the addition reactions of lithium diethylamide (Et2NLi) to several vinylsilane derivatives, such as H2C=CH–Si(CH3)2X [X: methyl, phenyl, ethoxy, 2-(diethylamino)ethyl and vinyl], and H2C=CH–Si(CH3)2OSi(CH3)2X [X: 2-(diethylamino)ethyl and vinyl], were carried out. The reactivity of vinylsilane derivatives toward nucleophile was strongly influenced by the nature of the substituents on the Si atom. The reactivity of trimethylvinylsilane [rate constant k (trimethylvinylsilane; cHx; 50 °C) = 2.9 ± 0.2 · 10−4 dm3 mol−1 s−1] was found to be of the same order of magnitude as that of para-alkyl-substituted styrenes, such as 4-methylstyrene [k (4-methylstyrene; cHx; 50 °C) = 3.2 · 10−4 dm3 mol−1 s−1]. The reactivities of vinylsilane compounds having an aryl substituent, e.g. dimethylphenylvinylsilane [k (dimethylphenylvinylsilane; cHx; 50 °C) = 14.8 ± 0.3 · 10−4 dm3 mol−1 s−1] and dimethyldivinylsilane [k (dimethyldivinylsilane; cHx; 50 °C) = 14.8 ± 0.6 · 10−4 dm3 mol−1 s−1], were higher than that of trialkyl-substituted vinylsilane. This fact may be explained by a π-conjugation between the phenyl (or vinyl) and vinyl groups through an empty d-orbital of the Si atom. A vinylsilane compound having a 2-(dialkylamino)ethyl substituent, [2-(diethylamino)ethyl]dimethylvinylsilane, showed unique reactivity toward lithium diethylamide, indicating that the β-nitrogen atom plays an important role regarding the reactivity of the vinyl group. In the reaction between lithium diethylamide and vinylsilane having an ethoxyl group, an addition reaction to the vinyl group and a cleavage reaction of the Si–O linkage proceeded concurrently. No cleavage reaction, however, proceeded in the reaction of lithium diethylamide with vinylsilane compounds having a disiloxane linkage. 1,1,3,3-Tetramethyl-1,3-divinyldisiloxane exhibited a much higher reactivity than did the other vinylsilane compounds.
Footprint Catalysis. IV. Structural Effects of Templates on Catalytic Behavior of Imprinted Footprint Cavities
Authors: Shimada Toyoshi , Nakanishi Kiyoko , Morihara Kensaku
Published: July 2006

Footprint catalysts are silica(alumina)gel catalysts with tailored specificities. Their catalytic sites are “molecular footprint-like” cavities formed by a molecular imprinting procedure with templates, which are referred to as transition-state or reactive-intermediate analogs of the catalyzed reactions. To clarify the relationship between the structural feature of template molecules and catalytic behavior, seven footprint catalysts were prepared by imprinting with templates of several types closely related to the substrates, benzoic anhydride and acetic anhydride; their catalytic activity and thermodynamic parameters for 2,4-dinitrophenolysis were then estimated. Among these catalysts, a catalyst imprinted with N,N′-dibenzoylbenzenephosphonediamide, a tetrahedral intermediate analog for benzoic anhydride substrate, showed a 10-fold higher catalytic activity than did the other imprinted catalysts.
Racemization of Optically Active Aromatic N-Acetylamino Acids and Asymmetric Transformation of N-Acetyl-2-(4-hydroxyphenyl)glycine via Salt Formation with Optically Active α-Methylbenzylamine
Authors: Shiraiwa Tadashi , Sakata Shinji , Natsuyama Hisashi , Fujishima Keiko , Miyazaki Hideya , Kubo Satoru , Nitta Tomohisa , Kurokawa Hidemoto
Published: July 2006

The racemization rates of N-acetyl-(S)-tyrosine, N-acetyl-(S)-phenylalanine, N-acetyl-(R)-2-(4-hydroxyphenyl)glycine [(R)-AcHpg], N-acetyl-(R)-2-phenylglycine, and N-acetyl-(S)-alanine were measured by use of (RS)-α-methylbenzylamine [(RS)-MBA] as a base-catalyst. The first-order rate constant for racemization tended to increase with an increase in the polar substituent constant of the N-acetylamino acid side chain. The racemization appeared to be subject to the inductive effect by the side chain. An asymmetric transformation of (RS)-AcHpg by using (R)-MBA, based on the result of racemization, gave an optically pure salt of (R)-AcHpg with (R)-MBA by successive use of the filtrate as the solvent. Optically pure (R)-2-(4-hydroxyphenyl)glycine [(R)-Hpg] was separated from the salt in 87–90% yield based on the starting (RS)-AcHpg. In addition, the asymmetric transformation of (R)-AcHpg was achieved by using (S)-MBA to give optically pure (S)-Hpg in 80% yield after purification of the salt of (S)-AcHpg with (S)-MBA followed by hydrolysis.
Efficient Synthesis of 2-Vinyl-γ-butyrolactones and 2-Vinyl-γ-butyrolactams by Palladium-Catalyzed Decarboxylative Carbonylation
Authors: Bando Takashi , Tanaka Shuji , Fugami Keigo , Yoshida Zen-ichi , Tamaru Yoshinao
Published: July 2006

4-Vinyl-1,3-dioxan-2-ones (cyclic carbonates) undergo decarboxylation-carbonylation by the catalysis of Pd(0) species under CO (in most cases, 1 atm) to provide 2-vinyl-γ-butyrolactones in good yields. The course of the reaction of 6-vinyltetrahydro-2H-1,3-oxazin-2-ones (cyclic carbamates) depends on the substituent on the nitrogen atom. When it is H or Ts (and COPh), 2-vinyl-γ-butyrolactams or 6-amino-3-hexenoic acid esters are obtained. Cyclic N-benzylcarbamates are unreactive. trans-2,3-Disubstituted lactones and lactams arise stereoselectively from carbonates and carbamates, irrespective of their stereochemistry, respectively.
A Novel Configuration-Controlled Stereoselectivity in Enol Silylation of Ketones. Stereochemistry of Amine-Promoted Enol Silylation of Meso and Racemic α,α′-Dichloro Ketones and of Ketonization of the Resultant Enol Silyl Ethers
Authors: Shimizu Nobujiro , Matsuno Sho-ichiro , Tanaka Masayuki , Tsuno Yuho
Published: July 2006

Stereochemistry in amine-promoted enol trimethylsilylation of meso- and dl-α,α′-dichloro ketones, RCHClCOCHClR (1a; R = Me and 1b; R = i-Pr), and in ketonization of the resultant enol silyl ethers (2a and 2b) has been studied. The Et3N-promoted silylation of 1 in benzene shows a marked diastereoselectivity; the racemic isomer exhibits 84% and 98% (E)-selectivities for 1a and 1b, while the meso isomer, 97% and 98% (Z)-selectivities respectively. Both stereo- and diastereo-selectivities markedly depend upon solvent polarity and base strength. For example, both meso- and dl-1a showed small (Z)-selectivities in DMF. The diastereoselectivity markedly decreased with increasing base strength; both 1a and 1b exclusively gave the (E)-isomer of 2 irrespective of the configuration of the ketone when treated with lithium diisopropylamide in the presence of chlorotrimethylsilane at −78 °C. The ketonization of 2a and 2b was also diastereoselective in the direction opposite that observed in the forward reaction; the (E)-isomer predominantly gave the meso ketone (24% d.e.), while the (Z)-isomer, the racemic ketone (ca. 70% d.e.) upon protonation with concd hydrochloric acid in THF.
Total Synthesis of Siastatin B and Its Enantiomer Using Carbohydrate as a Chiral Educt
Authors: Nishimura Yoshio , Wang When-mei , Kudo Toshiaki , Kondo Shinichi
Published: July 2006

The enantioselective synthesis of siastatin B, an inhibitor of neuraminidase and its antipode from d-ribono-γ-lactone has stereospecifically been achieved. The total synthesis elucidated the absolute configuration of siastatin B as (3S,4S,5R,6R)-6-acetamido-4,5-dihydroxy-3-piperidinecarboxylic acid.
FeS2-Catalyzed Hydrocracking of Di(1-naphthyl)methane. Efffects of Hydrogen Pressure, Catalyst Feed and Reaction Temperature, and Kinetic Study
Authors: Wei Xian-Yong , Ogata Eisuke , Niki Etsuo
Published: July 2006

Hydrocracking of di(1-naphthyl)methane (DNM) in the temperature range of 150–300 °C was studied. In the presence of FeS2 and pressurized hydrogen, DNM hydrocracking took place over 175 °C. FeS2 selectively catalyzed the cleavage of C–C linkage in DNM to give 1-methylnaphthalene and naphthalene. The rate for DNM hydrocracking strongly depended on hydrogen pressure, FeS2 feed and reaction temperature. Kinetic study indicates that DNM hydrocracking in the temperature range of 200–300 °C could be considered as a first order reaction. Under the reaction condition (DNM 7.5 mmol, decalin 30 ml, FeS2 0.5 g, sulfur 0.05 g, initial hydrogen pressure 10 MPa), the activation energy and frequency factor for DNM hydrocracking were 19 kcal mol−1 and 5.3 × 107 h−1, respectively.
Sequence Dependent Cyclization-Cleavage of Dipeptides from the Oxime Resin and Its Prevention
Authors: Nishino Norikazu , Xu Ming , Mihara Hisakazu , Fujimoto Tsutomu
Published: July 2006

The rates of cyclization-cleavage of dipeptides with various sequences assembled on the Kaiser’s oxime resin were determined. cyclo(–Ala–Ala–) was liberated from the H–Ala–Ala–oxime resin with the apparent first-order rate constant, kapp, 1.8 × 10−1 min−1 under basic conditions. While cyclo(–Ala–Pro–) was much more rapidly formed (kapp = 1.5 min−1) from the H–Ala–Pro–resin, cyclo(–Ala–Val–) was produced with kapp, 2.2 × 10−2 and 5.5 × 10−2 min−1 from H–Ala–Val–resin and H–Val–Ala–resin, respectively. During the coupling reaction for tripeptides by the dicyclohexylcarbodiimide/1-hydroxybenzotriazole or the symmetrical anhydride method was observed significant loss of dipeptides by cyclization, which was successfully prevented by the [(benzotriazol-1-yl)oxy]tris(dimethylamino)phosphonium hexafluorophosphate (BOP) method except in the case of H–Ala–Pro–resin. In consequence of elucidating the defect and describing the method for the prevention, the reliability of the oxime resin was increased to be widely used in the practical synthesis of protected peptides.