bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Chelating Agents on the Preparation of Benzenediols by Oxidation of Phenol with Peracetic Acid
Authors: Tsuchiya Tohru , Ikehira Kazuhiro , Imamura Juichi
Published: July 2006

The oxidation of phenol with peracetic acid has been investigated in connection with the industrial preparation of benzenediols. The effects of 25 additives, such as derivatives of monomeric and condensed phosphoric acid, chelating agents, and salts of polybasic carboxylic acids, were examined; derivatives of condensed phosphoric acid were found to be most effective. The oxidation of phenol (213 mmol) with peracetic acid (21 mmol) in the absence of the additives gave 1,2- and 1,4-benzenediols in only 5.8% and 7.6% yields, respectively. But in the presence of 2.0×10−7 mol of potassium diphosphate the yields of 1,2- and 1,4-benzenediol were 47% and 31%, respectively. The improvement in the yields by the additives is attributable to the masking of a trace of metals, especially iron and cobalt, present in the reaction mixture. These metals tend to catalyze the further oxidation of the benzenediols formed.
Liquid-phase Oxidation of Anthracene in Acetic Acid by Use of Copper(II) Chlorocomplexes. II. Kinetic Study
Authors: Koshitani Jinya , Kado Toshio , Ueno Yoshio , Yoshida Takatoshi
Published: July 2006

A kinetic study was performed on the oxidation of anthracene by use of copper(II) chlorocomplexes, which were produced in reactions of copper(II) acetate with lithium chloride in acetic acid. When the pressure of oxygen was high enough that the rate of oxidation was not affected, the result was as follows:

−\fracdO2dt∝[RH]1[Cu2(OAc)4]01⁄2[LiCl]01⁄2−0.

Akineticapproximationtotheexperimentalresultwasattempted.
Application of Regular Solution Theory to Extraction of Salicylaldehyde Oxime Chelates
Authors: Narayanan S , Rao G N
Published: July 2006

The distribution coefficients of salicylaldehyde oxime and its metal chelates, namely of Co(II), Cu(II), and Zn(II) were determined between aqueous acetate phase (μ=0.1) and eight ‘inert’ organic solvents at 25 °C. On the basis of regular solution theory, the correlation between the distribution coefficients of the ligand (PHA) and that of the metal chelates (PM) expressed by logPM=nlogPHA+ const, was shown to be valid satisfactorily in most of the systems. Hexane and cyclohexane showed abnormal behaviour in extraction with Cu(II), while with Zn(II) extraction to the desired level was not possible with these two solvents. A good correlation was also observed between the distribution coefficient of salicylaldehyde oxime and the ‘solubility parameter’ of the solvents and the solutions are shown to be regular.
The Gibbs Free Energy of the Formation of the Al(OH)4− Ion at Elevated Temperatures
Authors: Chang Byong-Tae
Published: July 2006

The Gibbs free energy of the formation of the Al(OH)4− ion, ΔGf°[Al(OH)4−], has been determined from the solubility data of alumina hydrates at temperatures up to 300 °C. According to the results of thermodynamical calculations, ΔGf°[Al(OH)4−] is −1305.3 kJ/mol at 25 °C, and it decreases almost linearly with an increase in the temperature. Its temperature dependence between 25 and 300 °C can be expressed as follows: ΔGf°[Al(OH)4−]=−1152.7–3.318T−5.64×10−4T2+1.202TlogT.
Isotope Effect on Hydrogen Atom Abstraction Reaction by Recoil T Atoms in Solid n-C10D22–n-C10H22 Mixtures. Comparison of Recoil T Atoms with D Atoms in γ-Radiolysis
Authors: Aratono Yasuyuki , Taghikawa Enzo , Miyazaki Tetsuo , Fueki Kenji
Published: July 2006

An isotope effect on the hydrogen atom abstraction reaction by recoil T atoms in the n-C10D22–n-C10H22 mixtures in the solid phase is compared with the reaction by D atoms in the γ-radiolysis. A small isotope effect for the recoil T atoms is explained by a track model.
Selective Transport of Potassium Ions against Their Concentration Gradient by Pentaethylene Glycol Derivative Containing Both 8-Quinolyl and o-Carboxylphenyl Terminal Groups
Authors: Hiratani Kazuhisa
Published: July 2006

A pentaethylene glycol derivative containing both 8-quinolyl and o-carboxylphenyl terminal groups can transport potassium ions selectively against the concentration gradient in liquid membrane systems containing more than one alkali ion species in aqueous solution. Uptake of cations by this synthetic ionophore from the aqueous solution into the organic layer is confirmed to be important for exhibiting this excellent selectivity toward potassium ions.
Extraction of Lead(II) in Aqueous Halide-Perchlorate Solutions with Trioctylphosphine Oxide in Hexane
Authors: Kusakabe Satoshi , Sekine Tatsuya
Published: July 2006

The stability and the extractability with trioctylphosphine oxide(L) in hexane of lead(II) halide complexes in 1 mol dm−3 Na(ClO4) were studied. The complexes were stable and more extractable in the following order of the ligands: Cl−<Br−<I−. The maximum numbers of the ligand (n) in the complexes PbXn2−n were 2(Cl−), 3 (Br−), and 4 (I−). The chemical forms of the extracted species with L were in all cases Pb(ClO4)2L2, PbX(ClO4)L3, and PbX2L2.
Preparation and Molecular Structure of cis-Diaqua[(7S, 14S)-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclo-tetradecane]nickel(II) Chloride
Authors: Ito Haruko , Sugimoto Masako , Ito Tasuku
Published: July 2006

A six-coordinate diaqua nickel(II) complex with the title macrocyclic ligand, [Ni(H2O)2(S,S-L)]Cl2, has been synthesized and its structure has been determined by the X-ray analysis. Coordination geometry about the Ni is of cis-NiO2N4 type with the macrocyclic ligand folded.
Application of the Water-gas Shift Reaction. III. Reduction of Oxidized Nitrogen Compounds with CO and H2O Catalyzed by [Ru(cod)py4](BPh4)2
Authors: Okano Tamon , Fujiwara Kensuke , Konishi Hisatoshi , Kiji Jitsuo
Published: July 2006

The ruthenium(II) complex, [Ru(cod)py4](BPh4)2 (cod=1,5-cyclooctadiene, py=pyridine) has been shown to catalyze the reduction of oxidized nitrogen compounds with CO and H2O. In this reaction, primary, secondary, and tertiary nitroalkanes are converted into amides, ketones, and amines, respectively. Nitrosobenzene and picoline N-oxides are also reduciable to amines in good yields.
Stereoselective Micellar Catalysis. II. Kinetic Properties of Optically Active Micellar Catalysts for Cleavage of Amino Acid Ester Derivatives
Authors: Ihara Yasuji , Hosako Reiko
Published: July 2006

Stereoselective reactions of the enantiomers of N-acylamino acid p-nitrophenyl esters with N-decanoyl-(d or l)-histidine (DecHis) in an optically active surfactant (DMEBr) derived from (l)-ephedrine were studied at 25 °C and pH 7.30 in comparison with those of simple surfactant, hexadecyltrimethylammonium bromide (CTABr). The mixed micelles of DecHis and DMEBr are effective stereoselective catalysts and the catalytic effects are determined mainly by the nucleophilic reactivity of the optically active histidine residue of DecHis.
Adsorption of Ethylene Oxide on Cab–O–Sil Silica, Reactive Silica, and Oxygen-treated Reactive Silica
Authors: Sotani Noriyuki
Published: July 2006

Ethylene oxide reacted with surface Si–OH of Cab–O–Sil silica to form Si–O–CH2–CH2–OH, while ethylene oxide was adsorbed on the silicon radicals of the reactive silica, and the oxygen radicals of the oxygen-treated reactive silica on which the adsorbed species polymerized to form (–CH2–O–CH2–)n.
Molecular Structure of [2](2,5)(7,7,8,8-Tetracyanoquinodimethano)[2](1,4)naphthalenophane
Authors: Mizuma Takashi , Miki Kunio , Kai Yasushi , Tanaka Nobuo , Kasai Nobutami
Published: July 2006

Molecular structure of [2.2](1,4)naphthalenophane containing 7,7,8,8-tetracyanoquinodimethan moiety as an electron acceptor has been determined by means of X-ray diffraction. Crystals belong to monoclinic system, space group Cc with four molecules per unit-cell; a=9.770(1), b=15.176(2), c=13.299(2) Å, β=98.43(1)°. The structure was established by the direct method and refined by the full-matrix least-squares to R=0.035 for 1217 non-zero reflections. The [2.2]paracyclophane skeleton has the usual structure; a half of the naphthalene moiety has a boat-form, the six-membered ring of the TCNQ, moiety also has a boat-form, and two C(CN)2 portions in the TCNQ, moiety are bent out and slightly twisted from the six-membered ring. The other half of the naphthalene ring free from the bridging is planar and are slightly bent out from the [2.2]paracyclophane skeleton.
The Discrimination of the Oxidation States of Neptunium in Sodium Hydroxide Solutions by Means of Chromatography on Alumina
Authors: Shiokawa Yoshinobu , Yamana Hajimu , Sat\={o} Akiko , Suzuki Shin
Published: July 2006

A method of discriminating the oxidation states of Np in a NaOH solution by means of chromatography on alumina is proposed. In a NaOH solution of 0.5–1.7 M(1 M=1 mol dm−3), the separation of Np(VI) from Np(VII) can be made effectively by means of chromatography on alumina. Only a little Np(VI) is adsorbed on alumina the Np(VII) adsorbed to some extent, and the Np(V), strongly, under the same conditions. By applying this chromatographic method, the method of preparing Np(VI) and Np(VII) of a tracer quantity in 1 M NaOH is established.
Voltammetric Studies of the Use of the Rotated Oxide Electrode as an Indicator Electrode and as a View to the Determination of EDTA and Other Complexanes
Authors: Yoshimura Tadayosi
Published: July 2006

The accessible potential ranges of rotated lead dioxide (PbO2) and manganese dioxide (MnO2) electrodes were investigated in supporting electrolyte solutions of 0.1 mol/1 (mol/dm3) KNO3 at various pH values, by measuring the base currents of these oxide electrodes. The anodic and cathodic ascending potentials of both the oxide electrodes are pH-independent in a neutral solution. In each neutral system of KNO3, KClO4, K2SO4, and KCl, the accessible potential range of the PbO2 electrode was from +1.4 to +0.2 V vs. SCE, while that of the MnO2 electrode was from +1.2 to +0.3 V, and the lower manganese oxide electrode from +0.3 to −0.9 V. Furthermore, the applications of these electrodes to the determination of EDTA and other complexanes were examined. Both the oxide electrodes gave a good calibration curve which could establish a linear relationship to the EDTA concentration, passing through the point of origin. The rotated PbO2 and MnO2 electrodes seem to be useful for determining depolarizers such as the EDTA-type complxanes.
Kinetic Studies of the Oxidation of l-Ascorbic Acid by the Peroxodisulfate Ion, and of Copper(II)-catalysis
Authors: Kimura Masaru , Kobayashi Akiko , Boku Keiko
Published: July 2006

Kinetic studies of the oxidation reaction of l-ascorbic acid by the peroxodisulfate ion(S2O82−) are carried out in an aqueous solution over the pH range of 3.4–4.6 at various ionic-strengths from 0.071 to 1.07 M (1 M= 1 mol dm−3) with NaClO4, and at four temperatures between 15 and 30 °C, at an ionic-strength of 1.07 M. The variations in the rate of the oxidation with the hydrogen-ion concentrations are consistent with the reaction schemes involving two pH-related species; ascorbic acid H2A (k1=0.032 M−1 s−1 at 25 °C, ΔH1\eweq=17 kJ mol−1, ΔS1\eweq=−220 J deg−1 mol−1) and the ascorbic anion HA− (k2=0.43 M−1 s−1 at 25 °C, ΔH2\eweq=45 kJ mol−1, ΔS2\eweq=−102 J deg−1 mol−1). A relationship of logk2=−1.47+2.17I1⁄2⁄(1+I1⁄2) is found with the ionic-strength (I) at 25 °C. The reaction rate is greatly catalyzed by the presence of trace amounts of the copper(II) ion; the mechanisms of the copper(II)-catalyzed reaction are discussed.
Spectrophotometric Determination of Iron(III) after Separation by Adsorption of Its 5-Chloro-7-iodo-8-quinolinol Complex on Microcrystalline Naphthalene
Authors: Satake Masatada , Mehra Mool C , Fujinaga Taitiro
Published: July 2006

A procedure is described for the spectrophotometric determination of iron(III) at ppm levels with 5-chloro-7-iodo-8-quinolinol. Iron(III) reacts with the reagent in an acidic solution to form a water-insoluble blue-black complex, which can be quantitatively adsorbed on the surface of freshly precipitated microcrystalline naphthalene at room temperature. The separated iron(III) complex is dissolved in N,N-dimethylformamide, together with the naphthalene, and the absorbance of the resulting solution is measured at 480 nm. Beer’s law is obeyed over the range of 5–88 μg of iron in 10 ml of the solvent. The molar absorptivity of the complex was found to be 6.3×103 l mol−1 cm−1 at 480 nm. The effects of various factors, such as the pH, the amounts of the reagent and naphthalene, and diverse ions, were also examined. The proposed method was satisfactorily applied to the determination of iron in several selected samples, including standard reference materials, aluminum metal, and natural water.
Synthesis of dl-3-Hydroxycuparene by a Claisen Rearrangement of Allyl Aryl Ether
Authors: Inouye Yoshinobu , Inomata Satoru , Ishihara Yasumasa , Kakisawa Hiroshi
Published: July 2006

The Claisen rearrangement of 1-methyl-2-[(3-methylphenoxy)methyl]cyclopentene in N,N-dimethylformamide gave 5-methyl-2-(1-methyl-2-methylenecyclopentyl)phenol(5) via its trimethylsilyl ether. The methylation of 5, followed by a Simmons-Smith reaction and by the catalytic hydrogenolysis, afforded 3-hydroxycuparene.
Studies on the High-pressure Reaction of Rare-earth Sesquioxides with Vanadium Dioxide
Authors: Shin-ike Tsutomu , Adachi Gin-ya , Shiokawa Jiro , Shimada Masahiko , Koizumi Mitsue
Published: July 2006

The reaction of rare-earth sesquioxides (Ln2O3 with vanadium dioxide (VO2) at 1400 °C and 50 kbar and 30 kbar was studied. Quadrivalent vanadium ions were reduced to the trivalent state, rare-earth vanadates(III) (LnVO3) being obtained. For LnVO3 a typical transformation of the ABO3-type compounds, one from the aragonite-type to the perovskite-type via the vaterite- or calcite-type structure was observed with a decrease in the ionic radius of the rare-earth ions. The magnetic properties of the vaterite-type LnVO3 were studied.
A Kinetic Study of the Anation Reactions of Some Cobalt(III) Complexes Containing Macrocyclic Quadridentate Amine Ligands
Authors: Tsukahara Keiichi , Oshita Hiroshi , Emoto Yasunobu , Yamamoto Yasuo
Published: July 2006

The kinetics of the anation of trans-[Co(OH)(N4)(H2O)]2+ by acetate ions (OAc−) have been studied at 25 °C and at an ionic strength of 0.10 mol dm−3 (LiClO4), and over the pH range from 3.62 to 5.17; N4 represents a macrocyclic ligand. The reaction is considered to proceed through a dissociative mechanism. The rate constants of the loss of the coordinated water of [Co(OH)(N4)(H2O)]2+ are estimated to be (1.4±0.2)×10−2 s−1, (8.9±1.6)×10−2 s−1, (1.0±0.1)×10−1 s−1, and (4.0±0.1)×10−1 s−1 for [14]aneN4, Me6[14]4,11-dieneN4, ms-Me6[14]aneN4, and rac-Me6[14]aneN4 complexes respectively. These represent the steric acceleration by the methyl groups of the macrocyclic ligands. The anation of the [14]aneN4 complex by chloride and bromide ions in acetate-buffer solutions has also been investigated. The relative effectiveness of entering groups for the coordination to the pentacoordinate intermediate follows the order: H2O<OAc−<Cl−<Br−. The substitution reaction of [Co(OH)(N4)(H2O)]2+ is slower than the ascorbate reduction of this complex reported previously. It is concluded that the electron-transfer reaction does not proceed through an inner-sphere mechanism, but through an OH-bridged mechanism.
Binuclear Metal Complexes. XLV. Synthesis and Magnetic, Spectral, and Electrochemical Studies of Strati-bis Copper(II) Complexes of Some Schiff Bases Derived from Primary Tetraamines and Salicylaldehydes
Authors: Izumitani Tatsuo , Nakamura Masaaki , Okawa Hisashi , Kida Sigeo
Published: July 2006

New Schiff base ligands, 1,2,3,4-tetrakis(R-salicylideneamino)-2,3-dimethylbutane (abbreviated as H4(R-sata); R (substituent on the ring)=H, 5-Me, 5-But) and 1,2-bis(R-salicylideneamino)-1,2-bis(salicylideneaminomethyl)cyclohexane (H4(R-sacta)), which are capable of forming “strati-bis” type binuclear copper(II) complexes, have been synthesized. Magnetic, spectral and electrochemical properties of the binuclear copper(II) complexes, Cu2(R-sata) and Cu2(R-sacta), were investigated in comparison with those of mononuclear copper(II) complexes Cu(R-salpn) and Cu(R-sacda), where H2(R-salpn) is N,N′-bis(R-salicylidene)-1,2-propanediamine and H2(R-sacda) 1-(R-salicylideneamino)-1-(R-salicylideneaminomethyl)cyclohexane. ESR spectra of Cu2(sata), Cu2(sacta) and Cu2(5-Me-sacta) showed a seven-lined hyperfine structure whose hyperfine coupling constant (A||≈85 G, 1 G=10−4 T) was about one half of that of the corresponding mononuclear copper(II) complex. Each electronic spectrum of these binuclear complexes showed the π-π* transition originated from the azomethine group at a low frequency compared with that of the corresponding mononuclear complex. Cyclic voltammograms of these three complexes involved two redox couples. The first redox couple attributable to the Cu(II, II)/Cu(II,I) process is higher in potential than the Cu(II)/Cu(I) process of the corresponding mononuclear complex. These characteristics were discussed in terms of the electron-delocalization through the π-π interaction between the two [CuN2O2]-chromophores.
C,O-Chelates of the Trifluoroacetylacetonate Dianion with Palladium(II). Molecular Structure of [Pd(tfac(2–)-C,O)(PPh3)(2,6-Me2-py)]
Authors: Okeya Seichi , Kawakita Yasuo , Matsumoto Shinichi , Nakamura Yukio , Kawaguchi Shinichi , Kanehisa Nobuko , Miki Kunio , Kasai Nobutami
Published: July 2006

Reactions of bis(trifluoroacetylacetonato)palladium(II), [Pd(tfac)2], with tertiary phosphines followed by pyridine or its derivatives afforded a series of the [Pd(tfac(2–)-C,O)LL′]-type complexes which contain a C,O-chelating trifluoroacetylacetonate dianion and a couple of tertiary phosphine and/or heterocyclic nitrogen base ligands (L and L′). Their structures in solution were studied by 1H, 13C, 19F, and 31P NMR spectroscopy and the molecular structure in a crystal of [Pd(tfac(2–)-C,O)(PPh3)(2,6-Me2-py)]·C6H6 containing triphenylphosphine and 2,6-dimethylpyridine as L and L′ was determined by means of X-ray diffraction.
Preferential Introduction of a Pyridylmethyl Group into Sulfonamides as an Approach to an Intramolecular Transimination
Authors: Iwata Masaaki , Kuzuhara Hiroyoshi
Published: July 2006

N,N′-Bis(p-tolylsulfonyl)-α-ω-alkanediamine disodium salts (n=3, 4, 5, 6, 7, 8, 9, 10) were subjected to monopyridylmethylation by the reaction with 5′-deoxy-5′-chloro- or 5′-deoxy-2′-chloro-3,4′-O-isopropylidenepyridoxine hydrochloride, accompanied by the corresponding bispyridylmethylation. Monopyridylmethylation became remarkable for longer methylene chains of the diamine. Thus, introduction of an amino group protected by a sulfonyl group at the end of either the C2- or the C5-side chains of pyridoxine derivatives was achieved.
The Reaction of 2,4,6-Triphenyl-1,3,5-thiadiazin-1-ium Salt with Active Methylene Compounds
Authors: Shibuya Isao
Published: July 2006

The reaction of 2,4,6-triphenyl-1,3,5-thiadiazin-1-ium tetrafluoroborate with several active methylene compounds was studied. Nitromethane and nitroethane gave 2H-1,3,5-thiadiazines. The compounds possessing a benzoyl group reacted with this salt to give 5-substituted 2,4,6-triphenylpyrimidines, while those possessing a carbamoyl group afforded 5-substituted 4-hydroxy-2,6-diphenylpyrimidines or 4(3H)-pyrimidinone. On the other hand, malononitrile and ethyl cyanoacetate gave 5-substituted 4-mercapto-2,6-diphenylpyrimidines, with the liberation of benzonitrile. It was thus found that 2,4,6-triphenyl-1,3,5-thiadiazin-1-ium tetrafluoroborate reacts with active methylene compounds in fashions similar to that of 2,4,6-triphenyl-1,3-thiazin-1-ium salt.
Oxidizing Action of Hydroperoxides. Oxidation of Alkyl Aryl Ketones by Hydroperoxides
Authors: Maruyama Kazuhiro , Iwamoto Hidetoshi , Soga Osamu , Takuwa Akio
Published: July 2006

The oxidation of alkyl aryl ketones by t-butyl hydroperoxide under basic conditions gave products which resulted from the fission of the carbon-carbon bond between carbonyl carbon and alkyl carbon. The reaction was investigated using chiral alkyl aryl ketones. On the basis of the results, a probable reaction mechanism is proposed.
The Synthesis of Highly Strained Buttaflanes with Aromatic Rings
Authors: Kimura Koji , Ohno Hideki , Morikawa Kiyoshi , Hiramatsu Yasuhiro , Odaira Yoshinobu
Published: July 2006

Dibenzo[4.4.2.2]buttaflanes, syn-13,14:15,16-dibenzopentacyclo[6.4.2.22,7.01,8.02,7]hexadeca-13,15-diene, and syn-13,14:15,16-dibenzohexacyclo[6.4.2.22,7.01,8.02,7.03,12]hexadeca-13,15-diene were synthesized by the intramolecular photocycloaddition of the dibenzo[a,e]cyclooctene derivatives, syn-13,14:15,16-dibenzotricyclo[6.4.2.22,7]hexadeca-1,7,13,15-tetraene and syn-13,14:15,16-dibenzotetracyclo[6.4.2.22,7.03,12]hexadeca-1,7,13,15-tetraene, which had themselves been derived by the catalytic hydrogenation of the biphenylene photodimer, syn-13,14:15,16-dibenzotricyclo[6.4.2.22,7]hexadeca-1,3,5,7,9,11,13,15-octaene, and the pentacyclic compound, syn-13,14:15,16-dibenzopentacyclo[6.4.2.22,7.03,12.04,11]hexadeca-1,5,7,9,13,15-hexaene, respectively.
Applications of Homogeneous Water-gas Shift Reaction. IV. Hydrocarbonylation and Dimerization of Methyl Acrylate with CO and H2O
Authors: Murata Kazuhisa , Matsuda Akio
Published: July 2006

Hydrocarbonylation of methyl acrylate with CO and H2O forms dimethyl 4-oxopimelate in 94% yield based on H2O, the Co2(CO)8-1,2-bis(diphenylphosphino)ethane (diphos) catalyst system being used as in the case of ethylene or propylene. Increasing temperature tends to promote the dimerization and/or hydrodimerization of methyl acrylate to give 1,3-bis(methoxycarbonyl)-1-butene and/or dimethyl 2-methylglutarate. Effects of CO pressure and H2O concentration on the hydrocarbonylation and dimerization were examined at 135 and 165 °C. Catalytically active intermediates for the hydrocarbonylation take part in the dimerization of methyl acrylate.
Photosensitized cis-trans Isomerization of β-Alkylstyrenes
Authors: Arai Tatsuo , Sakuragi Hirochika , Tokumaru Katsumi
Published: July 2006

Triplet sensitized isomerization of a series of β-alkylstyrenes has been investigated with the use of various sensitizers. Among the olefins employed β-t-butyl- and β-t-pentylstyrene were found to give remarkably high ratios of the cis-isomers (>80%) at the photostationary state. This fact is reasonably attributed to lower rate constants for energy transfer from the triplet sensitizers to the cis-isomers than to the trans-isomers.
Bitter Diterpenoids from Rabdosia shikokiana (Makino) Hara
Authors: Ochi Masamitsu , Okamura Mitsuyuki , Kotsuki Hiyoshizo , Miura Iwao , Kubo Isao , Kubota Takashi
Published: July 2006

Three new bitter diterpenoids, shikokianoic acid, shikokianal acetate, and 16,17-epoxyshikokianal acetate, have been isolated from the leaves of Rabdosia shikokiana (Makino) Hara. Their structures were established on the basis of spectral and chemical evidence.
Methylation of a Benzene Ring as a Chemical Signal. Marked Changes in the Pattern of Temperature Dependence of the Selectivity in Oxidation of a Pair of Associating Thiols
Authors: Endo Tadashi , Okubo Akihiro , Kaneko Yuji , Uehara Masatoshi , Tasai Hidetoshi , Sato Akiyoshi , Nikki Kunio , Nakagawa Naoya , Kamei Shinichi
Published: July 2006

Temperature dependence of the selectivity [the ratio of an unsymmetrical disulfide to symmetrical one] has been studied in oxidation of a pair of associating thiols, each with the recognition site [C6H4N(CH3)2 and R1], with O2 in 80% (v/v) acetonitrile–20% water in the range of −10 to 70 °C. The selectivity for R1=C6H4CH3 shows a minimum at 35 °C, whereas for R1=C6H5 the selectivity exhibits a maximum at 35 °C; for R1=C6H4C2H5 plots of the selectivity against temperature shows a sigmoid-like curve. The selectivity in oxidation of a pair of non-associating thiols, 2-(dimethylamino)ethanethiol and a para-substituted benzenethiol, remains practically unaltered with temperature in the same solvent. Though thiol-disulflde exchange reaction proceeds slowly below 35 °C, the selectivity in the exchange differs entirely from that in the oxidation. It has been found that changes in hydrophobicity with R1 and temperature cannot explain dramatic alterations in the selectivity with R1 and temperature.
Syntheses of 2-Amino-3,4-dimethyl-3H-imidazo[4,5-f]quinoline and Its Related Compounds
Authors: Kasai Hiroshi , Nishimura Susumu
Published: July 2006

The strongly mutagenic compound, 2-amino-3,4-dimethyl-3H-imidazo[4,5-f]quinoline (Me-IQ), isolated from broiled sardines was synthesized from 6-amino-7-methylquinoline. Several structurally related compounds were also synthesized to clarify the structure-activity relationship. Some of them also showed strong mutagenic activity towards Salmonella typhimurium TA98.
The Effect of Quaternary Phosphonium Halides on the Temperature of the Maximum Density of Water
Authors: Takaizumi Katsuko , Wakabayashi Toshiki
Published: July 2006

The shifts in the temperature of the maximum density(tmd) of water produced by quaternary phosphonium halides, (n-Bu)4−nPhnPX(n=0–4), were measured dilatometrically, and the Despretz constants, KD, were determined. The KD, which is positive when the tmd is lowered by a solute, increases nearly linearly with increasing n from 1.16 kK for (n-Bu)3PhPCl to 1.57 kK for Ph4PCl, while the KD for Bu4PCl, 0.933 kK, is considerably lower than that to be expected from those for other members. Since the standard partial molal volumes of the cations have been found to be nearly the same, the variation in KD with n would originate from the difference in ion-water interaction between the cations. Some estimation was made for the contribution of the structural effect of the cations on the solvent water (Kst). The Kst is largely negative for the Bu4P+ ion, indicating that the cation is a structure maker. The Kst becomes less negative as n increases, indicating that the structure-making ability decreases with an increase in n.
Monolayers of Alkylammonium Alkanesulfonates
Authors: Shibata Osamu , Kaneshina Shoji , Nakamura Makoto , Matuura Ryohei
Published: July 2006

The surface pressure-area (π-A) curves for monolayers of cation-anion double long-chain salts, alkylammonium alkanesulfonates, were determined at the air-water interface by the Langmuir method. When the total chain length of cation and anion was constant, the transition pressure from the expanded to the condensed state in the monolayer was lowered as the chain length of cation elongated, and the lowest pressure at the transition point was observed in the case of the equal chain length of cation and anion. The lower the pressure at the transition point, the larger the value of the mean area per molecule at that point. The apparent molar entropy, enthalpy, and energy of transition from the expanded to the condensed phase were calculated from the temperature dependence of the transition pressure on the π-A curve. All the values calculated were negative. The magnitude in the changes of the apparent molar quantities was greatest when both a cationic and an anionic chain had the same length. These results were interpreted in terms of the orientation of double long-chain salt in the condensed state of monolayer. The increase in the chain length of cation and anion tends to increase the values of apparent molar quantity changes. The contributions of long-chain anion and cation to the phase transition of monolayer are not equivalent; the condensing effect of long-chain cation is larger than that of long-chain anion.
High Performance Liquid Chromatography Using Polymer Gels for Direct Analyses and Characterizations of Soluble Organic Pollutants in Water
Authors: Urano Kohei , Furuune Hiroyuki , Hayashi Koji
Published: July 2006

The optimum conditions in HPLC separations using columns packed with polymer gels were investigated for analyzing and characterizing directly various organic pollutants in water without complicated pretreatment. Experimental results showed that polystyrene gel column was unsuitable for direct analyses of water samples. Direct analyses of various organic compounds in water could be achieved on polyacrylester and polyhydroxystyrene columns by using 0.02 mol L−1 phosphoric acid and acetonitrile (85:15) as a mobile phase. At 40 °C, these systems of column and mobile phase gave values of height equivalent to a theoretical plate ranging from approximately 0.10 to 0.25 mm and retention times ranging from approximately 8 to 60 min for various compounds in water. Separation characteristics of these polymer column systems were discussed by taking into account solubilities, functional groups, aromaticities, or molecular weights of organic compounds in water. Furthermore, several wastewaters and their treated waters were directly analyzed for examples.
The Effect of the Vanadium Component on the Life of the WO3–TiO2 Catalyst Used for the Reduction of NOx, with NH3
Authors: Morikawa Shigeru , Takahashi Kazumasa , Mogi Junichi , Kurita Satoru
Published: July 2006

The 5000-h life test of the WO3–TiO2 catalyst for the reduction of NOx with NH3 has been investigated in real flue gases containing vanadium and SOx on a pilot plant. When the present catalyst was used in a residual-oil-fired-boiler flue gas, steady activities over 90% of NOx reduction were achieved for 5000 h at 400 °C (space velocity: 2700 h−1). On the other hand, when the catalysts were taken out of the reactors at certain intervals and studied by means of a laboratory reactor, they were much more active than fresh catalyst at lower temperatures (250–350 °C). Also, the SO2 oxidation efficiency increased with the reaction time. This activation was considered to be due to the vanadium component in the flue gas.
Concentration Dependence of Ketone Hydrogenation Catalyzed by Ru, Pd, and Pt. Evidence for Weak Ketone Adsorption on Pd Surface
Authors: Sungbom Choi , Tanaka Kazunori
Published: July 2006

As the ketone (cyclohexanone, 4-heptanone) concentration in cyclohexane was increased, the hydrogenation rate saturated even below 0.05 mol dm−3 on Ru and Pt, but at a much higher concentration of around 0.5 mol dm−3 on Pd. This result suggests that ketone adsorption on Pd is weak in comparison with other platinum group metals.
The Formation of Anion Radicals in Glassy N-Propyl and N-Benzyldimethacryloylamines γ-Irradiated at 77 K
Authors: Kodaira Toshiyuki , Taniguchi Makoto , Hase Hiroaki , Matsuyama Tomochika
Published: July 2006

N-Propyl- and N-benzyldimethacryloylamines irradiated by γ-rays from 60Co in their glassy state at 77 K yield anion radicals of their methacryloyl groups. These anion radicals afford a triplet with a coupling constant of 1.1 mT on measurement of the ESR and are bleached by a high-pressure mercury lamp at 77 K.
The MoO3–SnO2 Catalysts. Acid-Base Properties and Catalytic Activities for 2-Butanol Decomposition and 1-Butene Isomerization
Authors: Jin Tuo , Hattori Hideshi , Tanabe Kozo
Published: July 2006

Acidic and basic properties of MoO3–SnO2 catalysts with different compositions of MoO3 were measured by adsorption of NH3, CO2, and acid-base indicators. Acidic property prevailed over basic property for all catalysts. Catalytic activities for 2-butanol dehydration and 1-butene isomerization correlated with the acidities measured under the reaction conditions.
Electrophoretic Behavior of Adenine, Adenosine, and Adenosine Nucleotides in Ion Exchange Cellulose Paper as a Support
Authors: Kitaoka Yoshinori
Published: July 2006

Studies have been carried out on the effects of cationizable and anionizable groups of ion exchange cellulose papers on an electroosmotic flow over a range of pH=5–10 and on the electrophoretic migrations of adenine, adenosine, and adenosine nucleotides. The ionizable groups strongly affected the mobilities of adenosines.
Studies of Lead-complex Formation in Sea Water by Anodic Stripping Methods
Authors: Nakata Ryuji , Okazaki Satoshi , Fujinaga Taitiro
Published: July 2006

For the purpose of the determination and chemical speciation of trace lead in sea water by the use of an electrolytic concentration technique, the effects of the pH on the reduction potential of lead ions in the presence of various organic and inorganic ligands were investigated. In the pH range below ca. 5, the lead–chloro complex is dominant in sea water. Even in the presence of organic model ligands such as nitrilotriacetic acid (NTA), the electroactive species of lead was also its chloro complex when the sample solution was acidified enough below pH 2.
The Synthesis and Reactions of 2,6-Dimethyl-4-silaspiro[3.4]oct-6-ene
Authors: Terunuma Daiyo , Shibuya Noriyuki , Nohira Hiroyuki
Published: July 2006

A new silaspiro compound, i.e., 2,6-dimethyl-4-silaspiro[3.4]oct-6-ene, was synthesized by treating 1,1-dichloro-3-methyl-1-silacyclobutane with isoprene in the presence of magnesium in tetrahydrofuran. The reactions of the silaspiro compound with LiAlH4, H2PtCl6, dimethyl acetylenedicarboxylate in the presence of PdCl2(PPh3)2, and the Simmons-Smith agent were investigated.
A Convenient Synthesis of 2-Deuterio-1,3-benzodithiolylium Salts. Useful Synthon for the Preparation of One-carbon Homologated 1-Deuterio Aldehydes
Authors: Nakayama Juzo
Published: July 2006

2-Deuterio-1,3-benzodithiolylium salt, a useful synthon for preparation of one-carbon homologated 1-deuterio aldehydes, can be prepared in excellent overall yield in three steps starting from easily accessible 2-isopentoxy-1,3-benzodithiole.
The Stereoselective Diels-Alder Reaction of Bicyclo[3.2.0]nona 3,6-dien-2-one with Several Dienes
Authors: Takeshita Hitoshi , Hatsui Toshihide , Shimooda Isao , Mametsuka Hiroaki
Published: July 2006

The endo-cis adducts were selectively obtained by the Diels-Alder reaction of several dienes with bicyclo[3.2.2]nona-3,6-dien-2-one, prepared from tropone and ethylene. This selective formation from the bicyclic dienophile, the isolated C=C and ethano C–C bonds of which are situated in similar sterical environments within the molecule, was supported by an Extended Hückel calculation.
Synthesis of a 6-Methylpyridoxine Hydrochloride Derivative as an Electrophilic Precursor for Pyridoxal-like Functionalization
Authors: Iwata Masaaki , Kuzuhara Hiroyoshi
Published: July 2006

Through a key step of regioselective rearrangement of 5′-O-acetyl-3,4′-O-isopropylidene-6-methylpyridoxine 1-oxide, stable 5′-deoxy-2′,5′-dichloro-3,4′-O-isopropylidene-6-methylpyridoxine hydrochloride, which is expected to be a strong electrophile in an HCl free form, was synthesized from Dl-alanine in good yield.
X-Ray Microanalysis of Uranium on Fibrous Amidoxime-type Adsorbent
Authors: Kitamura Takao , Sakane Koji , Katoh Shunsaku
Published: July 2006

The adsorption process for uranium from sea water was studied by X-ray microanalysis on polyacrylamidoxime fiber, whose functional group was found to distribute uniformly. Uniform distribution of uranium was observed on cross sections of the adsorbents, which had contacted with sea water for 14 and 55 d. It was deduced that intrafiber diffusion of uranium is not the rate determining step in adsorption.
Crystal Structure of Mixed-valence Compound 1′,1'″-Dipropylbiferrocenium Triiodide with Averaged-valence Type Irons at 298 K and with Trapped-valence Type Irons at 110 K and Thermal Electron Transfer Process of Mono-oxidized Binuclear Ferrocene Derivatives
Authors: Konno Michiko , Hyodo Shi-aki , Iijima Sei-ichiro
Published: July 2006

The crystal structure of 1′,1'″-dipropylbiferrocenium (PrFcFcPr)+I3−, which shows averaged-valence irons at 298 K and trapped-valence irons at 110 K, was determined by X-ray diffraction. The crystal at 298 K is triclinic, space group P\bar1, a=8.5148(8), b=8.5482(5), and c=10.9032(13) Å, α=89.546(9), β=115.582(9), and γ=108.488(7)°, U=671.10(9) Å3, and Z=1. The crystal at 110 K is triclinic, space group P1, a=8.431(2), b=8.478(2), and c=10.816(3) Å, α=88.58(3), β=117.39(2), and γ=108.65(2)°, U=643.4(3) Å3, and Z=1. Structures were refined to R=0.042 at 298 K and R=0.050 at 110 K. At 298 K cation (PrFcFcPr)+ sits on the symmetry center and the two Fc units are crystallographically equivalent, whereas at 110 K the symmetry center is lost and ferrocene-like and ferrocenium-like Fc units are distinguished. A three-dimensional hydrogen-bond network is clearly found between the cation and iodine atoms at 110 K, in contrast to the result at 298 K. Infrared spectra of 1′,1'″-diethyl- and 1′,1'″-dipropylbiferrocenium+I3− and μ-(as-indacenyl)-bis(cyclopentadienyliron)+I3−0.5I2 salts measured at 294 and 78 K indicate that a remarkable change in peak intensity is observed at 680 and 1525 cm−1 in the dialkyl salts, whereas no change is found in the remainder.
Transient Species in Picosecond Pulse Radiolysis of Liquid Carbon Tetrachloride
Authors: Sumiyoshi Takashi , Sawamura Sadashi , Koshikawa Yoshio , Katayama Meiseki
Published: July 2006

Formation and decay of transient species produced in pure liquid carbon tetrachloride by ionizing radiation were studied by using a stroboscopic pulse radiolysis technique in the time region 35–350 ps. Optical absorption spectra show two principal bands. One narrow band centered at 325 nm, which is formed during each fine structure electron pulse and decayed after pulse with t1⁄2=6.5 ns, is attributed to CCl4+ cation. The other broad band centered at 470 nm built up after electron pulse is assigned to (CCl4+·Cl−). A consideration on effects of cation scavengers on these bands furnishes a support for the above assignment.
Pulse Radiolysis Studies on Methyl Methylthiomethyl Sulfoxide in Aqueous Solutions
Authors: Sumiyoshi Takashi , Miura Nobuyuki , Aikawa Masayuki , Katayama Meiseki
Published: July 2006

Reaction mechanisms between methyl methylthiomethyl sulfoxide (MTMSO) and hydrated electron (eaq−) or hydroxyl radical (OH· radical) have been studied in aqueous solutions with various pH values by means of pulse radiolysis technique. The acid and basic components of equilibrium

(Remark: Graphics omitted.)

and

(Remark: Graphics omitted.)

are formed for the reaction of eaq−+CH3SCH2SOCH3 and OH· +CH3SCH2SOCH3, respectively. The pKa values of the respective equilibrium are 10 and 9. The anion (I) and (II) have absorption maxima at 375 nm and 360 nm, respectively. The sulfinic acid CH3SCH2SO2− is also formed in the reaction of CH3SCH2SOCH3+OH·. The rate constants have been determined to be k(eaq−+MTMSO)=1.3×108 M−1 s−1 and k(OH· +MTMSO)=3.1×109 M−1 s−1 (1 M=1 mol dm−3). Relative reactivities of OH· radical with thio-methyl bond and sulfinyl group are also discussed.
Dynamic Studies on Electron Transport Across Micellar Phase. Intermicellar Migration of Hydrated Electrons
Authors: Aikawa Masayuki , Sumiyoshi Takashi , Miura Nobuyuki , Katayama Meiseki
Published: July 2006

The dynamics of hydrated electrons generated by pulsed electron beams was studied for micellar systems with a series of halogenated naphthalenes as substrates exclusively dissolved in micellar phase. Time behavior of absorption for hydrated electrons, displayed as a curve consisting of two exponential decays, affords evidence that two different routes exist in advance of dissociative electron attachement: 1) direct penetration of electrons through micellar phase with substrates, and 2) migration of hydrated electrons between micells in the absence and presence of substrates, prior to the penetration of electrons into the reactive center in the micelle. Electrostatic interaction of hydrated electrons with positively charged surface of micelles is also discussed.
Structures of Cys-containing Peptide Complexes of Pd(II) in Organic Solvents
Authors: Ueyama Norikazu , Sasaki Kazuko , Nakata Michio , Nakamura Akira
Published: July 2006

Cysteine-containing peptide (pep) complexes of Pd(II) have been synthesized and their structures in organic solvents such as dimethyl sulfoxide (Me2SO) and N,N-dimethylformamide (DMF) were examined by use of 1H-, 13CNMR, visible, and CD spectroscopies. In all cases of the Pd(II) complexes, only the thiolato group of the peptides coordinates to the metal. Upon mixing [PdCl4]2− and the peptide, a trans(S) isomer [PdCl2(pep)2]2− immediately forms, which gradually isomerizes to the cis(S) isomer at 20 °C in DMF. The reactivity of Pd(II)–S bonds in these complexes was examined by addition of 2,2′-bipyridyl, 2-mercaptoethanol, or 3,4-toluenedithiol.
Syntheses, Structure, and Properties of Several Bis(O,O′–dialkyl dithiophosphato)cobalt(II)Adducts
Authors: Shimoi Mamoru , Ouchi Akira , Uehiro Takashi , Yoshino Yukichi , Sato Shoichi , Saito Yoshihiko
Published: July 2006

Several amine or phosphine adducts of bis (O,O′-dialkyl dithiophosphato)cobalt(II), which were hardly oxidized in air at room temperature, were obtained as crystalline solids. The crystal and molecular structure of one adduct, Co(Me2dtp)2(triphenylphosphine) (Me2dtp=O,O′-dimethyl dithiophosphato group), was determined by means of the X-ray diffraction method. The crystal is monoclinic: space group P21/n, a=26.712(4), b=9.495(1), c=11.180(5) Å, β=95.43(3)°, Z=4, Dx=1.495, Dm=1.45 g cm−3, μ(Mo Kα)=1.17 mm−1, and the final R value obtained is 0.062 for 4466 observed reflections. The coordinated atoms around the cobalt atom are in a trigonal bipyramidal configuration. The approximate first formation constants of the adducts, K=[Co(II)(R2dtp)2·X]/{[Co(II)(R2dtp)2][X]} (R=alkyl group, and X=donor) in solution, were obtained by means of the spectrophotometric as well as the NMR technique.
Theoretical Prediction of Cotton Signs in CD Spectra of Λ-[Co(N)2(O)4]−- and Λ-[Co(N)4(O)2]+-type Complexes
Authors: Fujinami Shuhei , Tsuji Kenshi , Shibata Muraji
Published: July 2006

The crystal field model of d-d optical activity has been applied to complexes with cis(N)-[Co(N)2(O)4]− and cis(O)-[Co(N)4(O)2]+ chromophores, and the Cotton signs of these complexes have been predicted. The model has shown that the Cotton signs in CD spectra of the complexes depend upon: 1) the energy difference between Ega and A2g states, 2) the coordination angle in a bidentate chelate, and 3) the effective charge of the ligating atoms. The CD spectral difference between an optically active carbonato complex and the corresponding diaqua complex derived from the carbonato complex has been understood in terms of the effective charge of the ligating O atoms.
Cobalt(III) Complexes with Tripodlike Quadridentate Ligands. III. Absorption and Circular Dichroism Spectra of Cobalt(III) Complexes Containing N-(2-Aminoethyl)iminodiacetate and Amino Carboxylate or 1,2-Diamine
Authors: Akamatsu Keiji , Komorita Takashi , Shimura Yoichi
Published: July 2006

Glycinato, l-alaninato, ethylenediamine, N,N-dimethylethylenediamine, (R)-propylenediamine, (R,R)-1,2-cyclohexanediamine and meso-2,3-butanediamine cobalt(III) complexes of a tripodlike ligand, N-(2-aminoethyl)iminodiacetate have been prepared. The geometrical configurations are assigned on the basis of their absorption, circular dichroism, and 1H-NMR spectra. The trans(O) isomer of meso-2,3-butanediamine complex is optically resolved and the relationship between the absolute configurations of the chiral 1,2-diamine complexes and their circular dichroism is discussed.
Rapid Differential Determination of Mixtures of Hydrazine and Hydroxylamine by Potentiometric Titration with an Iodide Ion-selective Electrode
Authors: Motonaka Junko , Ikeda Sanae , Tanaka Nobuyuki
Published: July 2006

A rapid method has been established for determination of mixtures of hydrazine and hydroxylamine by potentiometric titration using an iodide ion-selective electrode. Accurate values are obtainable when nitric acid is added to the sample solution. A recommended procedure is proposed in which the sum of hydrazine and hydroxylamine is titrated with an aliquot of sample solution and another aliquot is titrated to the end point for hydrazine after hydroxylamine has been decomposed with nitric acid. Hydrazine and hydroxylamine in mixture can be determined in the concentration range of 0.01–0.5 mmol/dm3. The best result, with relative error and relative standard deviation both of less than 0.7%, may be obtained on 0.5 mmol/dm3 hydrazine and hydroxylamine.
Structure of Epilubimin, Epioxylubimin, and Isolubimin, Spirovetivane Stress Metabolites in Diseased Potato
Authors: Katsui Nobukatsu , Yagihashi Fujio , Murai Akio , Masamune Tadashi
Published: July 2006

The isolation and structure elucidation of the title spirovetivane sesquiterpenes, stress metabolites produced in diseased potato tubers, are described.
Synthesis and Reactions of o-Naphthothioquinone Methides
Authors: Okazaki Renji , Sunagawa Kazuhiko , Kotera Mitsuharu , Kang Kyung-Tae , Inamoto Naoki
Published: July 2006

Photochemical reactions of naphtho[1,2-c][1,2]dithiole-3-thione (7), naphtho[2,1-c][1,2]dithiole-1-thione (10), and naphtho[2,3-c][1,2]dithiole-3-thione (16) with cyclohexene and 2,3-dimethyl-2-butene afford the corresponding naphthothioquinone methides. The thioquinone methide from 7 exists only as a monomeric form and is the first isolable o-thioquinone methide, while that from 16 exists as a dimer of [4+4] type in the solid state although the chemical behavior suggests the presence of a monomeric form in solution to a very minor extent. In the case of the thioquinone methide from 10, there exists an equilibrium between a monomer and a dimer of [4+2] type. Some cycloadditions of these thioquinone methides are also described.
Synthesis of Paracyclo(1,8)napthalenophane and Paracyclo(5,6)acenaphthenophane
Authors: Kasahara Akira , Izumi Taeko , Shimizu Iwao , Satou Masahiro , Katou Takao
Published: July 2006

[2]Paracyclo[2]paracyclo[2](1,8)naphthalenophan-9-ene-1,17-diyne, [0]paracyclo[2]paracyclo[0](5,6)acenaphthenophan-7-ene, and [2]paracyclo[2]paracyclo[2](5,6)acenaphthenophan-9-ene-1,17-diyne, were synthesized by intramolecular reductive coupling reaction of the corresponding carbonyl compounds with low-valent titanium reagent. The structures of the compounds were elucidated by NMR analyses, and the transannular π-electronic interactions between two benzene rings were examined on the basis of electronic spectra.
The Transition Metal-catalyzed N-Heterocyclization. A Reductive Transformation of Aminonitroarenes and Dinitroarenes into Phenanthroline Derivatives Using Aliphatic Aldehydes under Carbon Monoxide Pressure
Authors: Watanabe Yoshihisa , Suzuki Naoki , Tsuji Yasushi
Published: July 2006

The Catalytic N-heterocyclization of aminoarenes and dinitroarenes using aliphatic n-C3–C5 aldehydes was carried out at 180 °C under the pressure of carbon monoxide (70 atm at room temperature) in the presence of RhCl(PPh3)3 and PdCl2 as a binary catalyst system. The reaction of p-nitroaniline with propanal, butanal, and pentanal gave 3,8-diethyl-2,9-dimethyl-4,7-phenanthroline, 2,9-diethyl-3,8-dipropyl-4,7-phenanthroline, and 3,8-dibutyl-2,9-dipropyl-4,7-phenantroline in 43, 57, and 54% yields respectively. On the other hand, m-nitroaniline and o-nitroaniline gave 1,7-phenanthroline and imidazole derivatives in rather low yields (21 and 24%) under the reaction conditions employed.
Studies on Heteropentalenes. V. Cycloadditions of 5-Aryl-3-methylimidazo[5,1-b]thiazoles with Acetylenic Esters Leading to 5-Aryl-3-methylthiazolo[2,3-c]benzimidazoles and Related Heterocycles
Authors: Abe Noritaka , Nishiwaki Tarozaemon , Ikeda Kotaro
Published: July 2006

Cycloaddition of 5-aryl-3-methylimidazo[5,1-b]thiazoles with dialkyl acetylenedicarboxylate in an aprotic nonpolar solvent gives a number of products including epimeric thiazolo[2,3-c]benzimidazoles (3 and 4) [1:2-cycloadducts], epimeric 5,10b-ethenothiazolo[3′,2′:3,4]imidazo[1,5-a]-pyridines (5 and 6) [1:3-cycloadducts], and thiazolo[3′,2′:3,4]imidazo[1,2-a]pyridines [1:3-adducts]. At higher temperature, formation of the 1:2-cycloadducts is favored over the 1:3-adducts, whereas the latter predominates at room temperature. In an aprotic polar medium, the 1:3-cycloadducts (5 and 6) and tetraalkyl 6-arylpyridine-2,3,4,5-tetracarboxylates are substantially produced. Epimerization of 3 and 4 has been found to compete well with fragmentation to 4H-1,4-benzothiazine.