bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation of 2-Nitromethyl-2-cycloalkenol and 2-Nitromethyl-2-cycloalkenone
Authors: Sakakibara Tohru , Manandhar Mangala devi , Ohkita Noriaki , Ishido Yoshiharu
Published: July 2006

oxidation of 1-nitromethylcycloalkenes with m-chloroperbenzoic acid afforded the corresponding 2-nitromethyl-2-cycloalkenols, which were further converted into 2-nitromethyl-2-cycloalkenones.
Ordering of Cations in Ba(Mg1⁄3Nb2⁄3)O3 and Ba(Zn1⁄3Nb2⁄3)O3
Authors: Yoshioka Hideki
Published: July 2006

The ordering of B-site cations in Ba(Mg1⁄3Nb2⁄3)O3 (BMN) and Ba(Zn1⁄3Nb2⁄3)O3 (BZN) was studied from superlattice reflections in X-ray diffraction patterns. The degree of ordering in BMN increases with increasing sintering temperature. While in BZN an ordered structure was observed up to 1673 K, and an order-disorder phase transition was found below 1773 K.
Solid-Phase Thermal Reactions of Chromium(III) and Copper(II) Complexes Containing Pentadentate Ethylenediaminetetraacetate and 1,2-Propanediaminetetraacetate Ions
Authors: De Goutam , Suzuki Masatatsu , Uehara Akira
Published: July 2006

Thermal reactions of the solid complexes [Cr{Hedta or (RS)-Hpdta}(H2O)] and [Cu{H2edta or (RS)-H2pdta(H2O)] were investigated under quasi-isothermal and -isobaric conditions (Q-conditions) and under open dynamic conditions (D-conditions), where Hedta and H2edta, and Hpdta and H2pdta denote mono- and diprotonated ethylenediaminetetraacetate and 1,2-propanediaminetetraacetate ions, respectively.
Syntheses of New Multi-Sulfur 1,2-Dithiolene Complexes. Ni- and Pd-Complexes of 1,4-Dithiin-2,3-dithiolate
Authors: Nakamura Tadashi , Nogami Takashi , Shirota Yasuhiko
Published: July 2006

The title dithiolene complexes possessing eight sulfur atoms were synthesized. They are expected to give highly conductive organic salts. The improved synthesis of 4,5-(vinylenedithio)-1,3-dithiole-2-thione is also reported.
Ruthenium Complex-Catalyzed N-Heterocyclization. Syntheses of N-Substituted Pyrroles and Pyrrolidines from 1,4-Diols and Primary Amines
Authors: Tsuji Yasushi , Yokoyama Yasuharu , Huh Keun-Tae , Watanabe Yoshihisa
Published: July 2006

2-Butyne-1,4-diol reacts with aliphatic amines in the presence of a catalytic amount of [RuCl2(PPh3)3] at 150 °C to give N-alkylpyrroles in good yields. 1,4-Butanediol reacts with aromatic or aliphatic amines to give N-substituted pyrrolidines in excellent yields; [RuCl2(PPh3)3] and [RuCl3·nH2O–3PBu3] are the best catalysts for aromatic and aliphatic amines, respectively. The reaction of 2-butene-1,4-diol with alkyl amines gives a 1:1 mixture of N-substituted pyrroles and pyrrolidines in high yield.
Preparation and Some Properties of Acyltin Compounds
Authors: Kosugi Masanori , Naka Hiroyuki , Sano Hiroshi , Migita Toshihiko
Published: July 2006

According to Quintard’s method, acyltin compounds were prepared by the reaction of tributylstannylmagnesium chloride with an excess of aldehyde, and their physical data were described. These compounds were sensitive to oxygen air to give the corresponding tributyltin carboxylates. Free radical chain mechanism was suggested.
Synthesis of α-Methylene-γ-butyrolactones via Addition of Tin Hydride to Enynes Induced by Triethylborane
Authors: Nozaki Kyoko , Oshima Koichiro , Utimoto Kiitiro
Published: July 2006

Et3B induced addition of Ph3SnH to suitably constituted enynes provides (triphenylstannylmethylene) oxolanes stereoselectively in one pot. Destannylation followed by oxidation affords α-methylene-γ-butyrolactones in fair yields.
An NMR Study of Phenyl- and Diphenylphosphine Alkali Metal Salts
Authors: Yokoyama Yukihiro , Takahashi Kensuke
Published: July 2006

The 1H, 13C, and 31P NMR spectra were observed for the title salts in several solvents. The formation of the salts by the deprotonation of the neutral precursors causes significant changes in their NMR parameters. First, the delocalization of the excess charges into the phenyl ring of the salts was confirmed from the 1H and 13C chemical-shift data. Second, the parameters concerned with the center of the anions are dependent on the circumstances of the center atom, phosphorus, such as the hybridization. The results are discussed in terms of the effects of the counter cations and the solvents. Third, a strong polar solvent, HMPA, exerts significant effects on the chemical shifts and the one-bond 13C–31P coupling constants. These parameter changes are explained in terms of an equilibrium between two kinds of ion-pairs (contact ion-pairs and solvent-separated ion-pairs). The parameters obtained in this solvent, HMPA, correspond to those of the solvent-separated ion-pairs or the free anions.
Synthesis of Dichlorocyclobuta[b]benzofuran-2a-carboxylic Derivatives and 3-(Trichloroethenyl)coumarin through Cross Photocycloadduct of Coumarin and Tetrachloroethylene
Authors: Nonoyama Shinji , Yonezawa Noriyuki , Saigo Kazuhiko , Hasegawa Masaki , Iitaka Yoichi
Published: July 2006

Photoirradiation of coumarin and tetrachloroethylene with a high-pressure mercury lamp through Pyrex filter in the presence of benzene and benzophenone gave cross cycloadduct (3) in a moderate yield. By treatment with bases or nucleophiles at room temperature, 3 underwent ring-contraction reaction through lactone-opening, cyclobutene formation, and intramolecular SN2′ displacement to yield dichlorocyclobuta[b]benzofurancarboxylic derivatives exclusively. By use of a non-nucleophilic base, 3-(trichloroethenyl)coumarin was alternatively obtained through [2+2] cycloreversion of cyclobutene intermediate in a good yield.
New Discogenic Compounds: N,N′-Dialkanoyl-2,3,5,6-tetrakis(alkanoyloxy)-1,4-benzenediamines
Authors: Kobayashi Yukio , Matsunaga Yoshio
Published: July 2006

A series of N,N′-dialkanoyl-2,3,5,6-tetrakis(alkanoyloxy)-1,4-benzenediamines has been prepared and found to be mesogenic over a wide temperature range. The transformation into an isotropic liquid at a temperature between 189 and 209 °C is followed by thermal decomposition. The X-ray diffraction pattern of unoriented specimens in the mesophase consists of two sharp inner peaks and a broad outer one assignable to 100, 110, and 001 reflections respectively, indicating that the phase is hexagonal columnar.
Stereochemistry of a Porphyrin Atropisomer. The Molecular and Crystal Structure of Six-Coordinate [5α,10β-bis(o-nicotinamidophenyl)-15,20-diphenylporphinato]zinc(II)
Authors: Scheidt W Robert , Eigenbrot C W , Ogiso Motoyasu , Hatano Keiichiro
Published: July 2006

The synthesis and molecular structure of the title complex was investigated as part of our work into the chemical significance of atropisomerism in porphyrin compounds. The complex crystallizes in the triclinic system, space group P\bar1, a=11.707 (2) Å, b=12.744 (5) Å, c=9.521 (2) Å, α=102.60 (3)°, β=101.31 (2)°, and γ=100.29 (2)°, Z=1. A total of 3737 reflections (average of two forms) were considered observed and used in the solution and refinement of the structure. The structure was refined to a final R=0.081. The molecule, with a crystallographically imposed inversion center, has disordered nicotinamide side chains. This disorder leads to some ambiguity in defining the relative substitution pattern of the phenyl rings. Independent of the assumptions used to define the disorder, the nicotinamide side chains are found to coordinate the zinc ions of adjacent molecules to form a polymeric, linear chain containing six-coordinate zinc ions. The average equatorial Zn–N bond distance is 2.052 (3) Å and the unique axial bond distance is 2.432 (5) Å.
Surface Properties and Catalytic Activities of Niobic Acid Treated with Diluted Phosphoric Acid
Authors: Kurosaki Akito , Okuyama Tetsuhiro , Okazaki Susumu
Published: July 2006

A surface treatment of niobic acid using about l mol dm−3 of phosphoric acid was effective for the enhancement of the surface acidity and the catalytic activity for some acid-catalyzed reactions such as cyclohexanol dehydration and alkylation of benzene with methanol. However, a treatment with phosphoric acid of higher concentration might form a deposit on the surface, which would prevent the penetration of reactants and/or products and, thus, decreased the catalytic activity of niobic acid. The P component added to the niobic acid was hardly removed by steaming at 400 °C, although it could be taken off by soaking in water at room temperature for twelve hours.
Syntheses and Characterization of Dinuclear Iron(II, II) and Iron(II, III) Complexes with a Dinucleating Ligand, 2,6-Bis[bis(2-pyridylmethyl)aminomethyl]-4-methylphenolate (1—)
Authors: Suzuki Masatatu , Uehara Akira , Oshio Hiroki , Endo Kazutoyo , Yanaga Makoto , Kida Sigeo , Saito Kazuo
Published: July 2006

Dinuclear iron(II, II) complexes, [Fe2(L-py)(RCOO)2]BF4·nH2O (RCOO : CH3COO (1a) and C6H5COO (2a)), and two types of dinuclear mixed valence iron(II, III) complexes [Fe2(L-py)(RCOO)2](BF4)2·nH2O (RCOO : CH3COO (1b) and C6H5COO (2b)) and [Fe2(L-py)(CH3COO)(OH)](BF4)2·2H2O (3) were prepared, where L-py represents 2,6-bis[bis(2-pyridylmethyl)aminomethyl]-4-methyl-phenolate(1–). Only one of the two iron(II) ions in the iron(II, II) complexes is easily oxidized with molecular oxygen in methanol to form the mixed valence complexes, [Fe2(L-py)(RCOO)2](BF4)2·nH2O, which were characterized by chemical analyses and Mössbauer measurements. Magnetic susceptibility measurements over the temperature range 80–300 K revealed that high-spin iron(II) and iron(III) ions are antiferromagnetically coupled with the spin-exchange coupling constants J=−3–−8cm−1. The complexes exhibited an ESR signal of gav≈1.7 near liquid helium temperature. Such an ESR signal arises from an antiferromagnetically spin-coupled high-spin iron(II, III) dimer. An inter-valence charge-transfer transition was observed in the region 7000–8500 cm−1. The electron delocalization parameter α is estimated to be ca. 0.08, which corresponds to the class II mixed valence type in the classification of Robin and Day. Cyclic voltammogram of the complex 2b in acetonitrile showed two reversible couples at +0.05 and +0.73 V (vs. SCE), which were assigned to the redox reactions of Fe(II, III)/Fe(II, II) and Fe(III, III)/Fe(II, III), respectively. The comproportionation constants of 1b and 2b at 20 °C are 1.6×1012 and 5.0×1011, respectively, implying that the present mixed valence complexes are significantly stabilized.
Inhibition of Dimerization of Copper(II) Carboxylates by Cyclohexane Ring in Extraction of Copper(II) with Cyclohexanecarboxylic Acid
Authors: Yamada Hiromichi , It\={o} Miyuki , Mizuta Masateru
Published: July 2006

The extraction of copper(II) with cyclohexanecarboxylic acid in benzene was carried out at 25 °C and at the aqueous ionic strength of 0.1 mol dm−3 (NaClO4). The partition constant, KD,HA of cyclohexanecarboxylic acid between benzene and water, and the dimerization constant, K2,HA of cyclohexanecarboxylic acid in benzene were determined: logKD,HA=0.90 and logK2,HA=1.54, respectively. The monomeric and dimeric copper(II) cyclohexanecarboxylates were responsible for the extraction:

Cu2++(HA)2,o \ightleftharpoons (CuA2)o+2H+

Cu2++2(HA)2,o \ightleftharpoons (CuA2(HA)2)o+2H+

2Cu2++2(HA)2,o \ightleftharpoons (Cu2A4)o+4H+

2Cu2++3(HA)2,o \ightleftharpoons (Cu2A4(HA)2)o+4H+

with the extraction constants, logKex(10)=−8.34, logKex(12)=−7.33, logKex(20)=−12.47, and logKex(22)=−11.73, respectively. By comparing the overall formation constant of the dimeric copper(II) cyclohexanecarboxylate, Cu2A4(HA)2 in the aqueous phase with that of copper(II) decanoate and lipoate, the cyclohexane ring was found to inhibit the formation of the dimeric copper(II) carboxylate.
Studies on the Interaction of Molybdate Ion and Magnesium Ion Observed in the Raman Spectra of the Mixture Solutions
Authors: Ozeki Toru , Murata Kazuko , Kihara Hiroshi , Hikime Seiichiro
Published: July 2006

When alkali metal or alkaline earth metal chloride, (except magnesium chloride) was added to a solution of sodium molybdate, similar Raman spectra were observed. When magnesium chloride was added to the molybdate solution, however, the intensity of the peak (ν1) based on the symmetric stretching vibration of the tetrahedral molybdate decreased and a new peak (νx) appeared at a higher wavenumber than ν1. The wavenumber of the new peak is almost equal to that observed for solid magnesium molybdate. This suggests that the new peak can be ascribed to the molybdates of the distorted octahedral structure, since the molybdate ion exists as an octahedral in the solid state of magnesium molybdate. The tetrahedral and the octahedral molybdates seem to be in equilibrium in the solution.
13C and 1H NMR of Arylnitrones. Substituent Effects of α-Phenyl-N-(p-substituted phenyl)nitrones
Authors: Suda Kohji , Tsujimoto Toshio , Yamauchi Masashige
Published: July 2006

Substituent effects on the chemical shifts of the conjugation sites in α-phenyl-N-arylnitrones (2) have been investigated. Resonance effects predominate at these positions. The electronic effects of the substituents should be treated separately between electron-donating groups and electron-withdrawing ones. A plausible mechanism for the transmission of the substituent effects in 2 has been proposed.
Enzymatic Reactions in Aqueous-Organic Media. II. Effects of Reaction Conditions and Selectivity in the Esterification of Aromatic Amino Acids by α-Chymotrypsin in Alcohols
Authors: Kise Hideo , Shirato Hitoshi , Noritomi Hidetaka
Published: July 2006

N-Acetylated aromatic amino acids were esterified by α-chymotrypsin suspended in alcohols. The reaction rate and the yields of the esters depended primarily on the amount of the aqueous buffer solution in which α-chymotrypsin was dissolved. The reaction rate increased but the equilibrium yield of the esters decreased with increasing concentration of water. High substrate selectivity and stereospecificity were observed for l-aromatic amino acids; and therefore, in this system α-chymotrypsin was considered to be an effective catalyst which maintains its native conformation. When the amount of the substrate was increased, the present reactions gave higher yields of the esters than the reactions in chloroform (two-phase method).
Excimer Formation and Induced-Fit Type of Complexation of β-Cyclodextrin Capped by Two Naphthyl Moieties
Authors: Moriwaki Fumio , Kaneko Hiromi , Ueno Akihiko , Osa Tetsuo , Hamada Fumio , Murai Koichi
Published: July 2006

Host–guest complexation of β-Cyclodextrin bearing two naphthyl moieties (1) has been studied by circular dichroism and fluorescence spectroscopic methods. The circular dichroism spectrum exhibits a positive band around 225 nm while the fluorescence spectrum exhibits a predominant monomer peak with a shoulder of excimer emission. These data suggest that 1 can take two forms, one of two naphthyl moieties being included in the cavity of the predominant form (A) while both naphthyl moieties being located outside of the cavity in another form (B). With increasing concentration of guests, the dichroism intensity diminishes but the excimer intensity increases. This result indicates that 1 moves the included naphthyl moiety outward from the interior of the cavity during guest binding and then the two naphthyl moieties act as hydrophobic caps. The binding of 1 was stronger for cyclohexanol and 1-adamantanecarboxylic acid but weaker for cyclododecanol than that of the corresponding γ-cyclodextrin derivative in correspondence with size-fitting between the guests and hosts.
Stereoelectronic Effects in Serine Proteases: Ab Initio Molecular Orbital Calculations
Authors: Taira Kazunari , Gorenstein David G
Published: July 2006

Ab initio molecular orbital calculations have been performed on the reaction profile for the addition/elimination reaction between ammonia and formic acid, proceeding via a tetrahedral intermediate: NH3+HCO2H→H2NCH(OH)2→NH2CHO+H2O. For the addition of ammonia two transition state conformations, of which one possesses a lone pair, on the hydroxyl oxygen of formic acid, antiperiplanar to the attacking nitrogen (T1 conformer) and the other possesses a hydrogen atom, of the OH group, antiperiplanar to the nucleophile ammonia (T1′ conformer), have been identified as characteristic transition state structures. Calculated transition state energies for the first addition step of the reaction revealed that a lone pair on the oxygen of the OH group, which is antiperiplanar to the attacking nitrogen (T1 conformer), stabilized the transition state by 7.4 kcal mol−1 compared to the T1′ conformer. Similarly, for the second water elimination step of the reaction, two conformers (T2 and T2′) have been identified as transition state structures, of which the T2 conformer possesses a lone pair on the nitrogen, antiperiplanar (app) to the leaving water and the T2′ conformer possesses a hydrogen atom, of the NH2 group, app to the leaving water molecule. Again, calculated transition state energies for the T2 and T2′ structures revealed that a lone pair on the nitrogen of the NH2 group, which is app to the scissile C–O bond (T2 conformer), stabilized the transition state by 3.1 kcal mol−1, thus supporting the hypothesis of stereoelectronic control for this reaction. The significance of these stereoelectronic effects for the mechanism of action of serine proteases is discussed and a novel mechanism is proposed.
Transformation of d-Xylose to (1R,2R,3R,4R)-2,3,4-Trihydroxy-1-(hydroxymethyl)cyclopentane, Pseudo-β-d-arabinofuranose
Authors: Tadano Kin-ichi , Kimura Hiroshi , Hoshino Masahide , Ogawa Seiichiro , Suami Tetsuo
Published: July 2006

The known 3-O-benzyl-d-xylose was converted into methyl (4R,5R,6R)-4,6,7-triacetoxy-5-benzyloxy-2-(methoxycarbonyl)heptanoate (8) by employing Knoevenagel condensation of 2,4,5-tri-O-acetyl-3-O-benzyl-aldehydo-d-xylose with dimethyl malonate as a key reaction. O-Deacetylation of 8 and successive glycol cleavage followed by acetylation gave a mixture of (1S,4R,5R,6R)-5-acetoxy-6-benzyloxy-4-methoxycarbonyl-2-oxobicyclo[2.2.1]heptan-3-one and dimethyl (2R,3R,4S)-2,4-diacetoxy-3-benzyloxy-1,1-cyclopentanedicarboxylate (12), which was converted into 12 exclusively. This enantiomerically pure highly oxygenated cyclopentane dicarboxylate 12 was converted into (3S,4S)-3-benzyloxy-1-(t-butyldiphenylsilyloxymethyl)-4-hydroxy-1-cyclopentene (15) by 1) thermal demethoxycarbonylation accompanied by β-elimination of the acetoxyl group, 2) diisobutylaluminium hydride reduction, and 3) selective protection of thus formed 1-cyclopentene-1-methanol. Pyridinium chlorochromate oxidation of 15 followed by reduction with sodium borohydride gave a 6.4:1 mixture of (3S,4R)-3-benzyloxy-1-(t-butyldiphenylsilyloxymethyl)-4-hydroxy-1-cyclopentene (18) and 15. Hydroboration of O-desilyl derivative of 18 proceeded stereoselectively from the less hindered α-face, and (1R,2R,3R,4R)-2,4-diacetoxy-1-acetoxymethyl-3-(benzyloxy)cyclopentane (21) was obtained after acetylation. Deprotection of 21 gave pseudo-β-d-arabinofuranose.
Influence of Hexasulfonated Calix[6]arenes on the Reactivities of Arenediazonium Ions in an Aqueous System
Authors: Shinkai Seiji , Mori Seiichi , Araki Koji , Manabe Osamu
Published: July 2006

The pKa of Phenol Blue shifted from 4.6 to 6.2 because of complexation of protonated Phenol Blue in the cavity of hexasulfonated calix[6]arene with dodecyl substituents (2C12). The finding stimulated us to examine whether the analogs (2C) suppress the dediazoniation of arenediazonium ions in an aqueous system as crown ethers do in organic solvents. We have found that 2C can suppress the dediazoniation in an aqueous system where neither 18-crown-6 nor anionic micelles are effective. The magnitude of the inhibition effect was 4–5 fold. The reaction rate of the diazo coupling with N,N-dimethylaniline was significantly suppressed in the presence of 2C, suggesting that arenediazonium ions are deactivated through complexation with 2C. The novel stabilization effects were explained by the strong anionic reaction field which neither 18-crown-6 nor anionic micelles have: that is, 2C has a peculiar architecture that six sulfonato groups are circularly arranged on the edge of the calixarene cavity.
The Effect of Phosphoric Acid Treatment on the Catalytic Property of Niobic Acid
Authors: Okazaki Susumu , Kurimata Masao , Iizuka Tokio , Tanabe Kozo
Published: July 2006

The effects of the treatment of niobic acid with phosphoric acid, sulfuric acid, and hydrofluoric acid on its surface area, structure, acidic property, and catalytic activity have been studied. The treatment with phosphoric acid was found to be most effective for maintaining a large surface area and a large amount of strong acid sites and for preventing niobic acid from crystallizing even after the heat treatment at higher temperatures above 600 °C. The XPS study revealed that a large amount of phosphorous exists on niobic acid after high temperature heat treatment. In accordance with these results, niobic acid treated with phosphoric acid and heat-treated at higher temperatures exhibited high catalytic activities for methanol conversion and ethylene hydration, whereas the activities of niobic acid containing no phophoric acid were very low when heat-treated at high temperatures.
Oxidation of (CD3)2\dotCX Radicals. I. Reaction of Propane and Isopropyl Radicals with Atomic Oxygen
Authors: Washida Nobuaki
Published: July 2006

The reaction of oxygen atoms with propane-1,1,1,3,3,3-d6, (CD3)2CH2, in a fast-flow system was studied with a photoionization mass spectrometer. Isopropyl-d6 radicals, (CD3)2\dotCH, formed by the initial hydrogen abstraction at the 2-position were detected directly.

(CD3)2CH2+O(3P)→(CD3)2CH+OH (3)

The subsequent reaction of (CD3)2\dotCH radicals with atomic oxygen proceeds by both an deuterium abstraction (61%) and an oxygen addition reaction (39%). The product in the deuterium abstraction was CD2CHCD3 and those in the oxygen addition were (CD3)2CO (18%) and CD3CHO (21%).

(Remark: Graphics omitted.)

Competition experiments show that (CD3)2\dotCH radicals react (0.029±0.004) times as fast with O2 as with O(3P). In the presence of an excess of O2, CD2CHCD3 was observed in decreased yield (20%) and (CD3)2CO and CD3CHO increased to 32 and 44%, respectively. The rate data for Reaction 3 were fitted by an Arrhenius expression:

k 3=(2.0−0.7+1.0)×10−10exp[−(6086±392 cal mol−1)⁄RT]

cm3 molecule−1 s−1 (381–627 K). The rate constant of Reaction 3 obtained from the yields of products was 7.9×10−15 cm3 molecule−1 s−1 at 298K.
Heat Capacity and Thermodynamic Properties of Bismuth in the Range 333 to 923 K
Authors: Badawi Walid Ahmad , Brown-Acquaye H A , Eid Ali Esa
Published: July 2006

Calorimetric studies on the behavior of the heat capacity of bismuth have been carried out in the range 333 to 923 K. Values of the enthalpy and entropy have been determined for selected temperatures. The enthalpy and entropy of fusion at 544.54 K are 11.360±0.014 kJ mol−1 and 20.86±0.03 JK−1 mol−1, respectively. Appropriate polynomial temperature functions of the Cp for solid and liquid bismuth are given. Earlier reported increasing Cp at temperatures above 800 K proved not to be reliable. The heat capacity at constant volume decreased from 25.80 to 21.14 JK−1 mol−1 over the region 544.54 to 873 K. Due to beginning of higher-order transformation, the Cv of solid bismuth showed an excess over the harmonic value (3R).
Behavior of the Enthalpy of Formation in the Tin–Antimony System
Authors: Badawi Walid Ahmad , Eid Ali Esa
Published: July 2006

Calorimetric studies on the behavior of the enthalpy of formation in the tin–antimony system have been carried out at five different compositions (43.3–55 at -% Sb). The enthalpy of dissolution has been determined at 796.15 and 768.15 K. The enthalpy of formation is negative and takes a maximum value (2.906±0.002 kJ mol−1) at 298.15 K for 50 at-% Sb. The molar enthalpy of mixing is more positive than that of formation. On comparing with partial molar enthalpy of mixing, the partial molar enthalpy of formation of tin is shifted to more negative values, while that of antimony to more positive values.
Aryliminodimagnesium Reagents. XII. The Distribution of Products in the Condensation with Nitrobenzothiazoles. Reduction of Electron-Donating Ability of Reagent by the Interaction with Thiazolyl Group
Authors: Okubo Masao , Asao Keiko , Hyakutake Hiroyuki
Published: July 2006

The 4-, 5-, 6-, and 7-nitro derivatives of benzothiazole condense with ArN(MgBr)2 giving unsym-azoxy and -azo products. The product distribution indicated the mild nature of the reaction, and could be explained in terms of a reduced electron-donating ability of the reagent due to an interaction with thiazolyl group.
Theoretical Estimation of the Solubilities of Lanthanoid Iodates in Dimethyl Sulfoxide–Water Mixtures
Authors: Abe Takehiro
Published: July 2006

By using a Modified Born equation, the solubilities of sparingly soluble lanthanoid iodates in dimethyl sulfoxide–water mixtures have been successfully estimated.
Effects of CH3···O Hydrogen Bond on the Rotamer Populations in 9-(Alkoxymethyl)-1,4-dimethyltriptycenes
Authors: Tamura Yoshio , Yamamoto Gaku , Oki Michinori
Published: July 2006

Rotamer populations in 9-(alkoxymethyl)-1,4-dimethyltriptycenes, where the alkyl is an ethyl, a methyl, or a 2,2,2-trifluoroethyl, were examined by 1H NMR spectra. The populations of the sc isomer decreased as the alkyl group becomes electronegative. The population ratio, sc/ap, of the methyl compound was almost the same with that for 1,4-dimethyl-9-(phenoxymethyl)triptycene to indicate that the populations of the rotamers in this and related series of compounds are determined on a delicate balance of various factors such as van der Waals repulsive and charge-transfer attractive interactions.
(E)-2-Tridecyl-2-heptadecenal, an Unusual Metabolite from the Red Alga Laurencia Species
Authors: Suzuki Minoru , Kurosawa Etsuro , Kurata Kazuya
Published: July 2006

The structure of an unusual α,β-unsaturated aldehyde isolated from the red algae Laurencia undulata and L. papillosa was established as (E)-2-tridecyl-2-heptadecenal by synthetic method.
Autoxidation of Indolo[3,2,1-de][1,5]naphthyridines
Authors: Irikawa Hajime , Okumura Yasuaki
Published: July 2006

The yellow keto lactam and the blue dimeric pigment were formed by the autoxidation of indolo[3,2,1-de][1,5]naphthyridines.
Measurement of Concentration Profile of Dye at Glass-Solution Interface by Photoacoustic Spectrometry Coupled with Total Internal Reflection Technique
Authors: Hinoue Teruo , Kawabe Masaaki , Yokoyama Yu
Published: July 2006

Photoacoustic signals were measured as a function of a penetration depth by changing an angle of incidence of an excitation beam. Concentration profiles were obtained from a relationship between the signal magnitude and the penetration depth by an inverse Laplace transformation. The smallest value of the penetration depth used was 34 nm.
Synthetic Polyether Dicarboxylic Acids Exhibiting Lithium Ion-Selective Transport
Authors: Hiratani Kazuhisa , Taguchi Kazuhiro
Published: July 2006

Polyether dicarboxylic acid carriers with several alternate units of oxytrimethylene and oxy-o-phenylene groups have been synthesized. They exhibit lithium ion selectivity in the competitive cation transport among lithium, sodium, and potassium ions through liquid membranes. On the basis of the cation extraction and the spectroscopic behavior, it is proposed that these carriers form a coiled structure into which the lithium ion becomes selectively incorporated to exhibit lithium ion-selective transport.
The Trapping and Release of Injected Hydrogen Isotopes in Vitreous Silica
Authors: Azuma Naoto , Miyazaki Tetsuo , Fueki Kenji , Furukawa Katsutoshi , Aratono Yasuyuki , Ohno Shin-ichi , Saeki Masakatsu , Tachikawa Enzo
Published: July 2006

The behavior in vitreous silica of hydrogen isotopes, which had been introduced by 80-keV D+-ion implantation, thermal D2 doping, or recoil tritium implantation (2.7 MeV), was studied by means of FT-IR spectroscopy, ESR spectroscopy, and radioassay with a liquid scintillation counter. The hydrogen isotopes are trapped by forming hydroxyl bonds (OD, OT). In the D+-ion implantation, OD bonds are formed mainly by the rupture of the ≡Si–O–Si≡ bonds. In the thermal D2 doping, however, OD bonds are formed mainly by the isotope-exchange reaction between the preexisting OH bonds and D2 molecules. When vitreous silica implanted by recoil tritium is heated to about 1150 K, HTO and HT are released. The OD bonds produced by D+ implantation decrease upon annealing at 1150 K. The OD bond-rupture is controlled by the diffusion of hydrogen isotopes trapped as OD(OT) bonds to the surface of vitreous silica. The mechanism of the diffusion of the hydrogen isotopes through vitreous silica was explained in terms of a repetition of the chemical reaction of ≡SiOD(OT)+≡SiOSi≡→≡SiOSi≡+SiOD(OT). The diffusion coefficient (DTHTO)) of tritium according to the above mechanism was obtained as:

D T(HTO)=2.3×10−4exp[−1.7×102(kJ mol−1)⁄RT]cm2s−1
Pressure Dependence of the Reaction of Thiolane with H and D Atom
Authors: Tang Jie , Kamo Tohru , Yamada Muneyoshi , Amano Akira
Published: July 2006

The title reaction was investigated at room temperature and under pressures ranging from 133 to 2660 Pa, using a conventional discharge flow reactor. 1-Butanethiol, butane, and 1-butene were the main products, whose compositions varied according to the pressure. In the reaction with deuterium atom, 1-butene was monodeuterated, while 1-butanethiol and butane were dideuterated. The following mechanism was proposed to account for the product compositions and their pressure dependencies as well as the deuterium labeling of the products.

(CH2)4S+H → CH2(CH2)3SH (1)

CH2(CH2)3SH+H → CH3CH2CH2CH2SH* (2)

CH3CH2CH2CH2SH* → CH3CH2CH2CH2SH (3)

→ CH3CH2CHCH2+H2S (4)

→ CH3CH2CH2CH2+HS (5)

CH3CH2CH2CH2+H → CH3CH2CHCH2+H2 (6)

→ CH3CH2CH2CH3 (7)
The Molecular Structure of Thioxanthone as Studied by Gas Phase Electron Diffraction
Authors: Iijima Kinya , Oonishi Isao , Fujisawa Shoji , Shibata Shuzo
Published: July 2006

The molecular structure of thioxanthone has been determined from gas electron-diffraction data. The molecular parameter values and their uncertainties are rg(C–C)=1.401±0.001 Å, rg(C–H)=1.099±0.007 Å, rg(C–S)=1.751±0.002 Å, rg(C–Cc)=1.498±0.004 Å, rg(Cc–O)=1.232±0.006 Å, ∠CSC=103.4±0.3°, ∠CCcC=119.4±0.6°, and θ(dihedral angle)=169.0±1.6°, where the angle parameters are rα parameters. The dihedral angle of thioxanthone is much larger than those of related molecules.
A Kinetic Study of Pressure Effect upon an Outer Sphere Electron-Transfer Reaction Involving Free Radicals
Authors: Ebihara Masahiro , Sasaki Yoichi , Tero-Kubota Shozo , Saito Kazuo
Published: July 2006

Volume of activation for the redox reaction between [(en)2CoIII(μ-NH2,O2(−))CoIII(en)2]4+ (en, ethylenediamine) and 2,2,6,6-tatramethyl-1-piperidinyloxyl radical is zero. The result endorses our previous discussion that the changes in solvation and in intrinsic volume of reactants are respectively responsible for determining the precursor and transition state.
Crystal Structures of the Configurationally Isomeric Dimers of 4(e)-Bromo-8-oxa-6-azabicyclo[3.2.1]octan-7-one
Authors: Yamane Takashi , Honda Mitsuharu , Ashida Tamaichi , Hashimoto Kazuhiko , Sumitomo Hiroshi
Published: July 2006

The crystal structures of the major(Major) and minor(Minor) components of the dimer obtained from the anionic reaction of the racemates of 4(e)-bromo-8-oxa-6-azabicyclo[3.2.1]octan-7-one (Br-BOL) have been determined by X-ray method. Crystal data are: (Major) P21/c, a=10.852(3), b=5.207(3), c=22.146(5) Å, β=92.75(2)°, Z=4, R=0.083 for 1744 reflections; (Minor) P21/c, a=16.825(5), b=7.844(3), c=11.483(3) Å, β=121.40(2)°, Z=4, R=0.038 for 2026 reflections. The structure of each dimer is constructed of an original Br-BOL skeleton at a terminus and an rearranged bicyclic skeleton at another terminus. The configuration of the chiral C atom contained in the rearranged skeleton of Major is different from that of Minor, when the chirarity of a terminal Br-BOL skeleton in Major is coincided with that in Minor.
Molecular Structure of (+)550CD·(+)370CD(2-Aminoethanesulfenato)bis(1,3-propanediamine)cobalt(III) Perchlorate
Authors: Okamoto Ken-ichi , Konno Takumi , Einaga Hisahiko , Hidaka Jinsai
Published: July 2006

The molecular structure of the title complex, (+)550CD·(+)370CD-[Co(aese)(tn)2](ClO4)2, has been determined by the X-ray analysis. This isomer having the Λ configuration takes S configuration for the sulfur donor atom and one of the two 1,3-propanediamine chelate rings takes a chair form and the other an asymmetric skew-boat one.
The Formation of β-LiFe5O8 from Aqueous Suspensions and Its Properties
Authors: Kiyama Masao , Kurata Tokihiro , Takada Toshio
Published: July 2006

Alkaline suspensions containing iron(III) hydroxide and excess LiOH were subjected to aging at temperatures between 40 and 90 °C or to autoclaving at 120 °C or above. The resulting products, identified by X-ray analysis as a spinel phase, were further subjected to magnetic examination at 300 K, BET surfacearea measurements, and electron-microscopic observation. The ferromagnetic precipitates of β-LiFe5O8 were formed at lower temperatures and less excess LiOH concentrations than those at which the nonferromagnetic precipitates of α-LiFeO2 were formed. Their saturation magnetization increased near 60 emu g−1 (1 emu g−1=4πρ10−4 T, where ρ=specific gravity) with the increase in their mean particle size, D, their coercive force depending on the D. With a rise in the temperature of the suspension, superparamagnetic particles with vacancies of the Li ion, intermingled with the ferromagnetic cubic particles, slowly grew to ferromagnetic particles and the composition approached LiFe5O8
Catalytic Behavior of Optically Active Amino Alcohol–Borane Complex in the Enantioselective Reduction of Acetophenone Oxime O-Alkyl Ethers
Authors: Itsuno Shinichi , Sakurai Yoshiki , Ito Koichi , Hirao Akira , Nakahama Seiichi
Published: July 2006

In the presence of the optically active amino alcohol–borane complex, an oxime ether was reduced with various hydride reducing agents to give a chiral primary amine of high optical purity. Catalytic use of the chiral complex was also investigated.
Regioselective Addition of Organic Chlorides to Epoxides in the Presence of Quaternary Ammonium Chloride
Authors: Gu Xue-Ping , Ikeda Isao , Okahara Mitsuo
Published: July 2006

By a reaction of epoxides with organic chlorides in the presence of dodecyltrimethylammonium chloride as a catalyst, a series of 2-substituted 1-(chloromethyl)ethyl ethers were synthesized regioselectively in high yields under mild conditions.
Fe3O4-Catalyzed Halogen-Exchange Reactions of Polyhalomethanes
Authors: Nakada Masahiro , Tokumoto Sei-ichi , Hirota Minoru
Published: July 2006

Triiron tetraoxide pretreated by polyhalomethane was shown to catalyze the halgen-exchange reactions of polyhalomethanes CHlBrmCln(l=1 or 2). The exchange proceeds consecutively giving, for example, CHBrCl2, CHBr2Cl, and CHBr3 as the main products from CHCl3. The mechanism of the reaction is discussed briefly.
Mechanism of Photochemical Reaction from Benzyl Chloride to Toluene in Solution
Authors: Takemura Takeshi , Fujita Masahisa
Published: July 2006

The photochemical reaction from benzyl chloride to toluene has been investigated in rigid glasses and fluid solutions. The experimental results indicate that toluene formation from benzyl chloride in 2-methylpentane proceeds via hot benzyl radicals or higher triplet states that are isoenegitic to the vibrationless level of the S1 state of BzCl and proceeds negligibly from stable benzyl radicals.
Mathematical Analysis of Noncatalytic Coal Dissolution Using Tetralin and the Prediction of Coal Conversion, SRC Yield and Aromatidty of SRC
Authors: Tagaya Hideyuki , Sugai Masayuki , Ito Kazuo , Ando Hisako , Chiba Koji
Published: July 2006

Mathematical analyses of noncatalytic coal dissolution using tetralin at 350–460 °C were carried out. Coal conversion, SRC yield and aromaticity of SRC could be predicted fairly well by regression equations using liquefaction conditions as explanation variables. The equation derived from coal conversions in 67 experiments using the C% and volatile matter of 6 coals and liquefaction conditions could predict coal conversions fairly well (R=0.972). The conversions predicted by the proposed equation were also compared with those reported by previous investigators. Although it was suggested that long heating-up period was detrimental to coal conversion, the equation was a good indication of the conversion in solvent extract liquefaction.
Viscosity Behavior of Poly(2-vinylpyridine) of a Low Molecular Weight
Authors: Yoshida Masafumi , Itoh Kikuo , Sakamoto Noriyuki , Arichi Shizuo
Published: July 2006

For the data of the limiting viscosity number of poly(2-vinylpyridine) of a low molecular weight Mw=2.26–0.21×104 in benzene and methanol, the value of the thickness parameter, b, and the energy difference, E, between the gauche and trans state were discussed in terms of the theory of Rossi and Perico. It is possible to use this theory for the viscosity data in the molecular weight range of 0.35–1.30×104. The values of E and b were thus estimated; E depended on the nature of the solvent for this polymer, while b was constant (0.3 nm). The temperature dependence of the calculated limiting viscosity number, dln[η]⁄dT, in benzene and dioxane was discussed, together with the measured values.
Simple Generation of Ester-Stabilized Azomethine Ylides from 2-Amino Esters and Carbonyl Compounds. Stereochemistry of Their Cycloadditions
Authors: Tsuge Otohiko , Kanemasa Shuji , Ohe Masayuki , Yorozu Kiyotaka , Takenaka Shigeori , Ueno Kazunori
Published: July 2006

Condensation of 2-amino esters with carbonyl compounds leads to simple generation of ester-stabilized azomethine ylides which are trapped by olefinic dipolarophiles as cycloadducts. Anti ylides are exclusively involved in the cycloadditions when N-substituted 2-amino esters are employed for the ylide generation, while syn ylides from N-unsubstituted 2-amino esters. Relative stability among all possible ylide isomers has been inspected and the selective involvement of particular ylidic forms has been explained on the ground of 1,5-dipole interaction or hydrogen bonding stabilization. Endo- and exo-selectivity of the cycloadditions is also discussed.
The Structure of μ-Aquabis(μ-trichloroacetato)bis[aquabis(trichloroacetato)erbium(III)] Hydrate, [{Er(CCl3CO2)2(H2O)}2(CCl3CO2)2(H2O)]n·nH2O
Authors: Imai Takashi , Ouchi Akira
Published: July 2006

The structure of the title complex has been determined by the single-crystal X-ray diffraction method. A crystal of Er2C12H8O16Cl18, F. W. 1380.86 is triclinic, with the space group of P\bar1, a=12.787(8), b=15.209(7), c=11.685(7) Å, α=102.24(5), β=114.43(5), γ=70.59(4)°, Z=2 (for the dimer formula), Dx=2.36, Dm=2.34(3) Mg m−3, and μ(MoKα)=5.74 mm−1. All the carboxylate ions act as bidentate bridges, and each pair of the side-by-side metal atoms is bridged by four carboxylate ions, or by two carboxylate ions and one water-oxygen atom, alternately, forming a polymeric chain approximately parallel to the [011] axis. The chains are arrayed in layers parallel to the (100) plane, and the respective layers are separated by the trichloromethyl groups.
Total Syntheses of Indicine N-Oxide, Intermedine N-Oxide, and Their Enantiomers Using Carbohydrate as a Chiral Educt
Authors: Nishimura Yoshio , Kondo Shinichi , Takeuchi Tomio , Umezawa Hamao
Published: July 2006

The first completely enantioselective syntheses of indicine N-oxide, intermedine N-oxide, and their enantiomers have been achieved stereospecifically. A synthetic analogue modeled on indicine N-oxide showed the superior activity to indicine N-oxide itself against cancer cell in vitro test.
Surface Tensions of Molten Binary PrCl3–NaCl, PrCl3–KCl, and PrCl3–CaCl2 Systems
Authors: Igarashi Kazuo , Mochinaga Junichi
Published: July 2006

The surface tensions of molten binary PrCl3–NaCl, PrCl3–KCl, and PrCl3–CaCl2 systems were measured by a maximum bubble pressure method, and the results were expressed as linear functions of the temperature. The isotherms of surface tension of the PrCl3–MCl (M=Na and K) systems had minimum; however, such behavior was not observed in the isotherm of the PrCl3–CaCl system.
The Magnetic Field Effects on Electrolysis. II. The Anodic Surface Oxidation of Gold
Authors: Watanabe Takeshi , Tanimoto Yoshifumi , Nakagaki Ryoichi , Hiramatsu Mitsuo , Sakata Tadayoshi , Nagakura Saburo
Published: July 2006

In the anodic oxidation of gold in an acidic solution, the electrode surface is covered with a black deposit. It dissolves immediately after the application of an external magnetic field (1 T). The results are discussed in terms of a magnetohydrodynamic mechanism.
Stoichiometry Determination of Cation–Macrocyclic Complexes Based on the 1H NMR Chemical Shift of the Cation-Coordinated Water Molecules
Authors: Iwachido Tadashi , Shibuya Koichi , Nakamura Naoki , Motomizu Shoji
Published: July 2006

The stoichiometries of alkali and alkaline earth metal complexes with macrocyclic ligands were determined in a water-containing nitrobenzene solution by means of 1H NMR. The chemical shift of the water protons was more sensitive to the complexation than that of the methylene protons of the ligands.
Terpenoids. IX. Permanganate Oxidation of Thujopsene. Neutral Products
Authors: Nagahama Shizuo , Tazaki Masato
Published: July 2006

Permanganate oxidation of thujopsene 1 in dry and aqueous acetone was reexamined with a careful separation of the neutral part of the products. In dry acetone, the major products were Δ9-thujopsen-8β- and 8α-ols (2 and 3) which easily decomposed to thujopsadiene 6. In aqueous acetone, 1 gave 8β-hydroxythujopsan-9-one 8 and thujopsane-8α,9α-diol 11 as main products, besides 8β,9β-diol 10, 8α-hydroxythujopsan-9-one 9, and epimeric allyl alcohols 2 and 3. The hydroxy ketone 8 was isomerized to a ring contracted compound, 4α-acetyl-4β-hydroxy-6α,10,10-trimethyltricyclo[4.4.0.01,3]decane 4 during alumina chromatography. 8β,9-Epoxy-10-thujopsanone 5 was isolated as a minor product. Kawamura’s glycol was an eutectic mixture of 10 and 11.
Asymmetric Diels–Alder Reaction of Acrylamides Having trans-2,5-Disubstituted Pyrrolidines as Chiral Auxiliaries
Authors: Kawanami Yasuhiro , Katsuki Tsutomu , Yamaguchi Masaru
Published: July 2006

The asymmetric Diels–Alder reaction between chiral acrylamides derived from (2R,5R)-2,5-disubstituted pyrrolidines and cyclopentadiene gave (1R,2R,4R)-5-norbornene-2-carboxylic acid amides 3a–c with excellent diastereoface selectivity. The amides 3a–c were converted into the corresponding carboxylic acid by an iodolactonization-reduction sequence and 2,5-disubstituted pyrrolidines were recovered intact.
81Br NQR and 119Sn Mössbauer Spectra for SnBr3− Anions
Authors: Yamada Koji , Hayashi Tomoko , Umehara Takako , Okuda Tsutomu , Ichiba Sumio
Published: July 2006

The structures of the SnBr3− anions in MSnBr3 (M=(CH3)2NH2, (CH3)3NH) and MSnBr3·H2O (M=K, NH4) were deduced by means of 81Br NQR spectroscopy. The former compounds have three 81Br NQR lines in the frequency range 73–80 MHz at 77 K, indicating the presence of pyramidal SnBr3− anions. The anion structure of the latter hydrate, on the other hand, was presumed to be square-pyramid with one terminal and two bridging Br atoms, because two of the 81Br NQR frequencies were considerably low compared with that of the terminal atom. Phase transitions were observed for the latter hydrates. Associated with these, drastic increases of the NQR frequencies were observed only for the bridging atoms, suggesting significant changes in the bridging network.
Influences of Lewis Acids on the Photochemical Cyclodimerization of Cyclopentenone
Authors: Ogawa Takuji , Masui Yoshiyuki , Ojima Shoshi , Suzuki Hitomi
Published: July 2006

In the presence of tin(IV) chloride, photochemical dimerization of cyclopentenone gave a cis-transoid-cis head-to-head dimer as predominant product. Other Lewis acids such as zinc(II) bromide, boron trifluoride etherate, tin(II) chloride, and silver(I) trifluoromethylsulfonate, however, showed little influence. Tris(2,2,6,6-tetramethyl-3,5-heptanedionato)lanthanum(III) andtris(2,2,6,6-tetramethyl-3,5-heptanedionato)europium(III) affected regiochemistry of the reaction in a way to favor a head-to-tail dimer.
Thermal and Ferroelectric Properties of (S)-2-Methylbutyl Esters of α-Substituted 4-(4-Alkoxybenzoyloxy)cinnamic Acid
Authors: Nakauchi Jun , Kageyama Yoshitaka , Uematu Mioko , Minami Shunsuke
Published: July 2006

Three homologous series of (S)-2-methylbutyl esters of α-substituted 4-(4-alkoxybenzoyloxy)cinnamic acid Ia (α-H), Ib (α-CH3), and Ic (α-CN) have been synthesized and their thermal and ferroelectric properties have been investigated. The mesomorphic transition temperatures for the homologous series (Ia, Ib, and Ic) depend on the α-substituents as well as the terminal alkoxyl chain length. In comparison with Schiff base analogues, the transition temperatures from the isotropic phase to smectic A for all the homologous series are a little lower; however, their transition temperatures from the smectic A phase to chiral smectic C show significantly different features. The thermal stability of the chiral smectic C phase has been discussed from the view point of the local intermolecular dipole–dipole interaction in the homologous series (Ia, Ib, and Ic) and the Schiff base analogues. The spontaneous polarization for the homologous series is in the order of the homologues: Ib>Ia>Ic and their polarity is negative for Ia and Ib and positive for Ic homologues, respectively. These results have also been discussed in terms of the α-substituent effect on the spontaneous polarization.
Treatment of Tetraalkoxysilanes with Amberlyst 15 Cation-Exchange Resin in Presence of Hexamethyldisiloxane
Authors: Hasegawa Isao , Sakka Sumio
Published: July 2006

Tetraalkoxysilanes were treated with Amberlyst 15 cation-exchange resin in hexamethyldisiloxane at 40 °C in order to substitute the trimethylsilyl group for the alkyl group in a tetraalkoxysilane partially. Tetramethoxy-, ethoxy-, propoxy-, and butoxysilanes were used for the experiments. After the treatment, SiO4R4−nXn(1≤n≤4, R=CH3, C2H5, n-C3H7, and n-C4H9, X=Si(CH3)3) were detected by gas chromatography and were identified by combined gas chromatography-mass spectrometry. The degree of trimethylsilylation of tetraalkoxysilane changed with the molar ratio of hexamethyldisiloxane to tetraalkoxysilane and quantities of the reaction products in the system depended mainly on the ratio.
The Kinetic Evidence of the Concerted [1,9] Sigmatropy for the Acetyl Migration in the 2-Acetoxytropones. The NMR Spectral Analysis of the Seven-Fold Degenerated Acetotropy of Hexaacetoxytropone
Authors: Takeshita Hitoshi , Mori Akira , Watanabe Hiroyasu , Kusaba Tomoyuki , Sugiyama Shigeru , Kodama Mitsuaki
Published: July 2006

“The acetotropy” of 2-acetoxytropones was shown to be a concerted [1,9] sigmatropic process on the basis of a kinetic analysis. A little substituent effect for the activation free energy of the acetyl migration was recognized. Preferred tautomers of polyacetoxytropones were those having the carbonyl group at inner positions. As an extreme case, a “Merry-Go-Round”-type rearrangement was operative in hexaacetoxytropone.
Peptide Synthesis in Aqueous Solution. II. Synthesis and Biological Activity of a Molluscan Neuropeptide, FMRFamide (Phe–Met–Arg–Phe–NH2) Analogs for N-Terminal Moiety
Authors: Kouge Katsushige , Soma Haruko , Katakai Yukari , Okai Hideo , Takemoto Mayumi , Muneoka Yojiro
Published: July 2006

In order to elucidate the contribution of the N-terminal moiety (Phe1 or Met2) of FMRFamide to the activity, 16 kinds of FMRFamide analogs were synthesized and their structure-activity relations are discussed. From the results, it was found that hydrophobic or bulky group in N-terminal contributes to the contractile effect, while the precise length of the side chain of amino acid at 2-position is due to a relaxing effect.