bluuebunny/crossref_metadata_2025_split huggingface dataset:
How Do Proton Chemical Shifts Reflect Aromaticity ? Graph Theory of the Secondary Magnetic Field Due to Ring Currents
Authors: Aihara Jun-ichi 
Published: July 2006

Abstract
A secular determinant for a polycyclic conjugated molecule, combined with a test dipole, is definable as a function of the applied magnetic field. It was found that this determinant can be expanded graph-theoretically into a characteristic polynomial. A secondary magnetic field is brought about by so-called ring currents. A new formula for evaluating the secondary field was derived by applying Newton’s method to this polynomial. This formula indicates that the secondary field at any point in the molecular plane is given exactly as a sum of the contributions of all π-electron circuits. The contribution of each π-electron circuit is expressible in terms of a pure geometric factor and an aromatic stabilization energy assigned to the circuit. The secondary field and then the proton chemical shifts can thus be related to aromaticities of individual π-electron circuits. Magnetotropism of most polycyclic conjugated molecules can be rationalized in this manner. π-Electron circuits which share the conjugated atom nearest to a given proton dominate the chemical shift. In general, a peripheral π-electron circuit contributes modestly to the overall thermodynamic stability of a molecule, but contributes much to the secondary fields at attached protons.
A Model of Crystal Defects in Calcite by Sodium and Potassium Uptake
Authors: Ishikawa Masamichi , Ichikuni Masami 
Published: July 2006

Abstract
Crystal defects in calcite containing Na and K ions were investigated by means of a model based on statistical thermodynamics and measurements of thermoelectric power. The varying amount of Na and K ions in the crystal was interpreted on an assumption of ideal solution of the ions as Ca1−x−y\squarex+y[Na2x, K2y]CO3, where \square and [ ] means Ca-vacancy and interstitial ion, respectively. In the model, the excess charge of Na and K ions is balanced with Ca-vacancy to form interstitial-vacancy pairs ([Na, K]2\square). Measurements of thermoelectric power in calcite showed the cationic transport which resulted from Na and K interstitials and/or Ca-vacancies. From the ideal mixing of Na and K ions at interstitial sites, the K/Na molar ratio in calcite was correlated with that in aqueous solution at 20 °C and pH 8.5 by the formula,
\fracKSNaS=0.20\fracKLNaL,
where S and L refer to solid- and aqueous-phase, respectively.
The Specific Effects of Tetraalkylammonium and Alkali Metal Ions on the Polarographic Reduction of Nitroalkanes and Nitrobenzenes in Acetonitrile
Authors: Hojo Masashi , Nishikawa Kazukiyo , Akita Yoshihiro , Imai Yoshihiko 
Published: July 2006

Abstract
The polarographic behavior of 2-methyl-2-nitropropane ((CH3)3CNO2) was examined at DME in acetonitrile with various supporting electrolytes. The addition of Et4N+ or n-Bu4N+ caused the half-wave potential (E1⁄2) of (CH3)3CNO2 to shift negatively in the presence of a fixed concentration of NaClO4. The negative shift was explained in terms of the interaction between tetraalkylammonium cations and the unreduced molecule of (CH3)3CNO2. The formation of (CH3)3CNO2\ewdot(Na+)2 was also suggested, and the conditional formation constants of the species were obtained by the positive shift in the E1⁄2 of (CH3)3CNO2 with increasing concentration of Na+ at certain concentrations of Et4N+ and n-Bu4N+. Other nitroalkanes and nitrobenzenes were also examined. The effect of water on the half-wave potentials of the first waves of the nitro compounds suggested the formation of RNO2\ewdot(H2O)2-type species.
Superconductivity and Characterization of the High-Pressure Reaction Products of Carbon Diselenide, CSe2
Authors: Kobayashi Akiko , Sasaki Yukiyoshi , Watanabe Tokuko , Ikehata Seiichiro , Kishida Haruo , Kawamura Haruki , Kato Reizo , Kobayashi Hayao 
Published: July 2006

Abstract
The physical properties and the structure of black solids obtained by the high-pressure reaction of CSe2 were examined by IR, X-ray diffraction, scanning electron microscope, electron diffraction, thermal analyses and magnetic experiments. The crystalline solid, which was metallic (σ(RT)≈50 S cm−1) at ambient pressure became superconductor above 20 GPa(Tc(onset)=6 K), while the amorphous solid was insulating. Contrary to the previously proposed one- or two-dimensional polymerization structure of (CSe2)x, it has been revealed that the metallic CSe2 sample have a rather complex structure that is composed of the crystalline hexagonal Se, graphite and some amorphous parts. Thus, the high conductivity and the diamagnetism of the crystalline solid at ambient pressure seems to come from graphite part and the superconductivity seems to come from hexagonal Se part. The superconducting transition behavior depended on the path of the pressure-cooling steps. The superconducting state was observed only when the pressure was increased at the low temperature.
Extraction Equilibria of Mercury(II) from Hydrochloric Acid with Trialkylphosphine Sulfides
Authors: Baba Yoshinari , Umezaki Yukihiro , Ueda Takashi , Inoue Katsutoshi 
Published: July 2006

Abstract
The extraction of mercury(II) from hydrochloric acid was compared using five kinds of sulfur-containing extractants. Mercury(II) was extracted most effectively by trialkylphosphine sulfides. Subsequently, the distribution equilibria of mercury(II) from hydrochloric acid with triisobutylphosphine sulfide (TIBPS=\barS) and trioctylphosphine sulfide (TOPS=\barS) in toluene have been measured at 303 K in order to clarify the concentration dependencies of the reactant species. It was found that mercury(II) is extracted according to the solvation reaction by TIBPS or TOPS as a mercury(II): extractant 1:2 complex, HgCl2S2, in the range of low loading ratio of mercury(II) to the extractants, and as a 1:1 binuclear complex, (HgCl2)2S2, in the region of high loading ratios, as follows:
HgCl2+2\barS\ightleftharpoons‾HgCl2S2 Ke
2HgCl2+2\barS\ightleftharpoons‾(HgCl2)2S2 Ke′
The extraction equilibrium constants, Ke and Ke′, were evaluated as Ke=4.0×105 (dm3 mol−1)2 and Ke′=2.0×108 (dm3 mol−1)3 for TIBPS and as Ke=7.2×106 (dm3 mol−1)2 for TOPS.
Solvation and Ionic Association of Bis(2,4-pentanedionato)(diamine)cobalt(III) Perchlorates in 1-Propanol, Acetone, and Their Mixtures
Authors: Ito Kazuaki , Iwamoto Etsuro , Suehisa Shigehito , Isono Hiroyuki , Yamamoto Yuroku 
Published: July 2006

Abstract
The conductances of bis(2,4-pentanedionato)(diamine)cobalt(III) perchlorates ([Co(acac)2(diamine)]ClO4, diamine: en=ethylenediamine, pn=1,2-propanediamine, N,N-dmen=N,N-dimethylethylenediamine, N,N′-dmen=N,N′-dimethylethylenediamine, N,N,N′-trimen=N,N,N′-trimethylethylenediamine, N,N,N′,N′-tmen=N,N,N′,N′-tetrametnylethylenediamine) were measured in isodielectric solvents, 1-propanol (n-PrOH), acetone (Me2CO), and 60 and 80 mol% acetone in 1-propanol (n-PrOH–Me2CO) at 25 °C. In spite of the increase in size of [Co(acac)2(diamine)]+ due to the introduction of N-methyl groups, the Walden products (λ0+·η) of the chelate cations were found to increase in all solvents. The contribution per N-methyl group was large in n-PrOH. The variation in the ionic association constants (Ka) with the number of NH protons in the chelate cations was small in all solvents. The Ka values for [Co(acac)2(N,N′-dmen)]ClO4 were larger than those for other chelate salts in all solvents. These results could be explained in terms of the solvation of the NH protons (diamine in [Co(acac)2(diamine)]+) by oxygen atoms of n-PrOH and Me2CO, and of oxygen atoms (acac) by the OH proton of n-PrOH owing to hydrogen bonding interactions and desolvation resulting from the introduction of the N-methyl groups. For [Co(acac)2(en)]+ in n-PrOH a solvation model to form a six-membered ring was proposed.
Pyrolyse und Massenspektren von 5-(Hydroxyphenoxymethyl)-2-oxazolidinon und p- oder m-Bis(2-oxooxazolidin-5-ylmethoxy)benzol
Authors: Shimasaki Choichiro , Wakabayashi Mariko , Yoshida Shizuo 
Published: July 2006

Abstract
5-(Hydroxyphenoxymethyl)-2-oxazolidinone (1) and p- or m-bis(2-oxooxazolidin-5-ylmethoxy)benzene (2 or 3) were prepared by the reaction of tris(2,3-epoxypropyl)-1,3,5-triazin-2,4,6(1H,3H,5H)-trione with hydroquinone and resorcinol. These compounds were found by the thermal analysis to be thermally stable. The activation energies of the pyrolysis for 1, 2, and 3 were calculated from the DTA curves to be 142.7, 158.8, and 130.0 kJ mol−1, respectively. The mechanism of the main fragmentation of the linkages between the benzene and oxazolidinone rings by electron impact was found to consist of two processes; a simple cleavage and a rearrangement reaction. Further, each process had the three cleavage modes. In mass spectra of 2 and 3, the fragment ion which corresponded to the molecular ion peak for 1 was detected. High resolution mass spectrometry established the composition of many peaks in the low resolution spectra of the compounds studied.
The Lithium Diisopropylamide-Induced Fragmentation of 2,2-Diphenyl-1,3-dithiolane S-Oxide and Several 2,2-Diaryl-1,3-dithiolane S,S′-Dioxides
Authors: Inoue Yoshihiko , Tanimoto Shigeo , Oida Tatsuo 
Published: July 2006

Abstract
The reaction of 2,2-diphenyl-1,3-dithiolane S-oxide with lithium diisopropylamide results in fragmentation to thiobenzophenone followed by further conversion leading to alkyl diphenylmethyl sulfide on trapping with alkyl halide. The reaction of 2,2-diaryl-1,3-dithiolane S,S′-dioxides with lithium diisopropylamide proceeded smoothly to afford 1,1-diaryl-N,N-diisopropylmethanesulfinamides in moderate yields via the intermediate diaryl thioketone S-oxides.
The Preparation and Properties of the Manganese(II) Ion-Selective Electrode
Authors: Motonaka Junko , Nishioka Hiroshi , Ikeda Sanae , Tanaka Nobuyuki 
Published: July 2006

Abstract
For the measurement of manganese(II)-ion activity, manganese(II) ion-selective electrodes were prepared and tested. As electrodes, heterogeneous membranes were prepared by dispersing sensitive materials, such as manganese sulfide, manganese borate, or manganese dibenzyldithiocarbamate, in silicone rubber, poly(vinyl chloride), or poly(vinyl acetate). A manganese chloride solution (0.1 mol dm−3) was used as the internal reference solution, along with an Ag/AgCl internal reference electrode. The manganese(II) ion-selective electrodes thus made were then examined in terms of their response curves, response times, the effect of the pH, the variation in the response slopes with the temperature, and selectivity coefficients. The response time of the manganese dibenzyldithiocarbamate electrode was within 15 s in the concentration range of 10−8–10−1 mol dm−3. The response slope was 33.14 mV/pMn2+ in the linear part, and the coefficient of correlation was 0.999. The selectivity coefficients were examined by the separate-solution method.
Exo/Endo Stereoselectivity in 1,3-Dipolar Cycloaddition of Trifluoroacetonitrile Oxide and -nitrilimine with Bicyclic Olefins
Authors: Tanaka Kiyoshi , Masuda Hideyuki , Mitsuhashi Keiryo 
Published: July 2006

Abstract
Trifluoroacetonitrile oxide and N-phenyl-C-(trifluoromethyl)nitrilimine cycloadded with norbornenes, resulting in the exclusive formation of the exo-adducts, while the concomitant formation of the endo-adducts was observed in their cycloadditions with norbornadienes. The nitrile oxide was subjected to the cycloaddition with 2,3-disubstituted norbornadienes to evaluate the effect of the substituents on the exo/endo stereoselectivity. The electron-withdrawing substituents tend to favor the formation of the exo-adducts.
Radiation-Induced Alkylation of Quinoline Derivatives with Alcohol
Authors: Sugimori Akira , Yamada Tetsuo , Ishida Hiroaki , Nose Masayuki , Terashima Keiko , Oohata Noriko 
Published: July 2006

Abstract
Gamma-irradiation of quinoline and its derivatives in alcohols brings about alkylation at the 2- or 4-position of pyridine ring. Hydroxyalkyl radicals play important roles in the radiation-induced alkylation with alcohol. The radiation-induced substitution of CF3CH2– and CF3CH(OH)– for H in pyridine and pyrimidine rings occurs in low yields.
Reactivity of (Porphinato)aluminum Phenoxide and Alkoxide as Active Initiators for Polymerization of Epoxide and Lactone
Authors: Yasuda Tomokazu , Aida Takuzo , Inoue Shohei 
Published: July 2006

Abstract
Reactivity of the axial aluminum-phenoxyl and -alkoxyl bond (Al-X) of aluminum porphyrin (1, (TPP)AIX, (TPP): (5,10,15,20-tetraphenylporphinato)) toward epoxide, β-lactone, and ε-lactone was examined in relation to the ring-opening polymerization of these cyclic compounds catalyzed by 1. The reactivity of
(Remark: Graphics omitted.)
aluminum phenoxide was in the order, epoxide&gt;β-lactone&gt;ε-lactone, while that of the alkoxide, ε-lactone&gt;β-lactone.
Solvation of Carboxylic Acids in Nonaqueous Binaries. Solvation Models for Butyric and Trichloroacetic Acids in Nitrobenzene–Toluene Mixtures
Authors: Hegazi Mohamed M Fahmi 
Published: July 2006

Abstract
The partitions of trichloroacetic and butyric acids between aqueous solutions and various nitrobenzene–toluene mixtures have been carried out at 25.0 and 30.0 °C, respectively. The observed nonlinearities for both acids of the monomer partition constants and the dimerization constants with the nitrobenzene mole fraction are interpreted in terms of the fractionation factors of effective exchangeable solvation sites of the involved species. Butyric acid monomer is concluded to have three sites for the solvation of the carboxylic hydrogen, carboxylate region, and alkyl chain. Desolvation of the former two sites is necessary for the formation of the dimer for which only two sites corresponding to its two alkyl chain are identified. The solvation sites of trichloroacetic acid monomer and dimer are identical and a singly hydrogen-bonded structure for the dimer is deduced. Dimerization of this acid in the organic phase proceeds by desolvation of what is equivalent to the sites of only one monomer.
Structural Study of the Methylnaphthazarins. X-Ray Structure of the Tetramethylnaphthazarin, a Charge Transfer Complex
Authors: Rodriguez José-Gonzalo , Pablo Alfonso De , Smith-Verdier Pilar , Florencio Feliciana , Garcia-Blanco Severino 
Published: July 2006

Abstract
The synthesis and analysis by 1H NMR of the methyl substituted naphthazarins were attempted. The chemical shifts of the substituents and of the ring protons were compared with those in their diacetates and were then correlated with the quinonoid or benzenoid nature of the rings. X-Ray diffraction analysis of tetramethylnaphthazarin, 2,3,6,7-tetramethyl-5,8-dihydroxy-1,4-naphthoquinone, has shown that this exists, in solid state, as a centrosymmetric charge-transfer complex with itself. The compound crystallizes in the Ibam space group, with an orthorhombic cell of dimensions a=17.479(1), b=9.983(1), c=6.752(1) Å, and four molecules in the unit cell. The crystal is built from molecules stacked up the c-axis and the interplanar distance between two overlapping molecules is 3.38 Å.
Photoinduced Hydrogen Evolution with Viologen Linked Porphyrin in a Micellar System
Authors: Okura Ichiro , Kaji Naruhiko , Aono Shigetoshi , Nishisaka Tsuyoshi 
Published: July 2006

Abstract
Viologen linked porphyrins, ZnP(CnV)4, with various methylene chain lengths (n=2–5) between the porphyrin and the viologen have been synthesized. These compounds were applied to photoinduced hydrogen evolution in a system containing NADPH–ZnP(CnV)4–hydrogenase under steady state irradiation. On the addition of surfactant to the system, a remarkable rate increase of hydrogen evolution was observed in the case of ZnP(C5V)4.
Size Effects of Small Platinum Particles on the Electrocatalytic Oxidation of Methanol
Authors: Takasu Yoshio , Fujii Yuichi , Matsuda Yoshiharu 
Published: July 2006

Abstract
A cyclic voltammetry study of a platinum-glassy carbon model catalyst-electrode (Pt/GC) in an aqueous solution of H2SO4 revealed that the peak potentials for the anodic oxidation of methanol shifted a little to the negative potential and that the current densities decreased greatly with the decrease in the size of the platinum particles.
Synthesis of Substituted Crown Ether Acetals
Authors: Oshima Takumi , Nagai Toshikazu 
Published: July 2006

Abstract
Reactions of phenyldiazomethane with chloranil and of 1-phenyldiazoethane and 9-diazofluorene with 2,3-dichloro-5,6-dicyano-p-benzoquinone in the presence of oligoethylene glycols and its monomethyl ethers gave the corresponding substituted crown ether acetals and open-chain analogues.
The Structure of Isoaplysin, a Brominated Rearranged Cuparane-Type Sesquiterpenoid from the Red Alga Laurencia okamurai Yamada
Authors: Suzuki Minoru , Kurata Kazuya , Kurosawa Etsuro 
Published: July 2006

Abstract
The structure of isoaplysin isolated from the red alga Laurencia okamurai Yamada has been established by the spectral and chemical methods.
Conductometric Determination of the Association Constants of β-Cyclodextrin with Amphiphilic Ions
Authors: Satake Iwao , Yoshida Shoji , Hayakawa Katumitu , Maeda Tamaki , Kusumoto Yoshihumi 
Published: July 2006

Abstract
The association constants (K) of β-cyclodextrin with 13 amphiphilic ions were determined. For a homologous series 1-alkanesulfonate ions, the saturation phenomenon of K occurred at the number of carbon atoms of 10. The values of K for amphiphilic ions with dodecyl chain were similar to one another.
The Crystal and Molecular Structure of Inner Triple-Layered Paracyclophanequinone
Authors: Toyoda Toshihiro , Tatemitsu Hitoshi , Sakata Yoshiteru , Kasai Nobutami , Misumi Soichi 
Published: July 2006

Abstract
The molecular structure of inner quinone isomer of two triple-layered paracyclophanequinones has been determined by means of X-ray diffraction. C26H24O2, M 368.5, orthorhombic, space group Pbcn, a=12.923(1), b=11.507(1), c=12.550(1) Å, V=1866.2(3) Å3, Z=4. The structure was solved by the direct method. Anisotropic refinement by the block-diagonal least-squares procedure gave R=0.042 for non-zero reflections. The molecule has a two-fold symmetry. The benzoquinone moiety is sandwiched by two donor benzene rings, and the two-fold axis passes through the O=C···C=O bonds of the twisted benzoquinone moiety. The outer benzene rings take a boat-form and the central benzoquinone ring is twisted.
α-d-Glucosylation by 6-O-Acetyl-2,3,4-tri-O-benzyl-d-glucopyranose Using Trimethylsilyl Triflate and Pyridine. Synthesis of α-Maltosyl and α-Isomaltosyl α-d-Glucosides
Authors: Koto Shinkiti , Yago Kazuo , Zen Shonosuke , Tomonaga Fumiya , Shimada Shigehiko 
Published: July 2006

Abstract
The d-glucosylation of methyl 2,3,4-tri-O-benzyl-α-d-glucopyranoside and methyl 2,3,6-tri-O-benzyl-β-d-glucopyranoside by 2,3,4,6-tetra-O-benzyl-α-d-glucopyranose using pyridine and excess trimethylsilyl triflate was carried out in dichloromethane, 1,2-dimethoxyethane, and acetonitrile. In a given solvent, the selectivity of the reaction varied depending on the type of hydroxyl group of the glucosyl acceptors. The d-glucosylation of these acceptors with 6-O-acetyl-2,3,4-tri-O-benzyl-d-glucopyranose employing this reagent system in dichloromethane proceeded with good α-selectivity irrespective of the type of the hydroxyl group. This α-d-glucosylation was applied for the synthesis of O-α-d-glucopyranosyl-(1→4)- and -(1→6)-α-d-glucopyranosyl α-d-glucopyranosides from α,α-trehalose.
A Simple and Efficient Synthesis of Optically Active (+)-4-Demethoxydaunomycinone
Authors: Kimura Yoshikazu , Suzuki Michiyo , Matsumoto Teruyo , Abe Rumiko , Terashima Shiro 
Published: July 2006

Abstract
Diels-Alder reaction of 2-chloro-1,3-butadiene with anthracene-1,4,9,10-tetrone was found to occur exclusively at the external (C2,3) double bond, giving the adduct in an excellent yield. The adduct was elaborated to 5,12-dihydroxy-1,2,3,4-tetrahydro-2,6,11-naphthacenetrione. The conventional cyanohydrin formation of this sample followed by acid hydrolysis gave (±)-2,5,12-trihydroxy-6,11-dioxo-1,2,3,4-tetrahydro-2-naphthacenecarboxylic acid. The racemic acid was found to be cleanly resolved by forming a salt with (−)-N-methylephedrine, furnishing optically pure (R)-carboxylic acid. Successive treatments of the (R)-carboxylic acid with N,N′-carbonyldiimidazole and methylmagnesium bromide in the presence of trimethylsilyl triflate readily produced optically pure (R)-(−)-7-deoxy-4-demethoxydaunomycinone, the key synthetic intermediate of (+)-4-demethoxydaunomycinone.
Perfluoroalkylations of Carbanions with (Perfluoroalkyl)phenyliodonium Triflates (FITS Reagents)
Authors: Umemoto Teruo , Gotoh Yoshihiko 
Published: July 2006

Abstract
FITS reagents reacted with primary alkylmagnesium halides in THF at −78 °C to give the corresponding perfluoroalkyl(Rf)-alkanes in moderate to good yields. But an alkyl-lithium or -copper gave a poor yield of the Rf-product. The reaction of FITS with secondary or tertiary alkylmagnesium halides resulted in low yields of the products. Alkynyl-lithiums or -magnesium halides produced Rf-alkynes in favorable yields. The reaction with aryl or vinylmagnesium halide was complex and the yields of Rf derivatives were low. FITS also reacted smoothly with enolate anions of active methylene compounds such as 2-methyl-1,3-cyclopentanedione, ethyl 2-methylacetoacetate, and ethyl 2-oxocyclopentanecarboxylate in a polar solvent to afford O- and C-perfluoroalkylation products in moderate yields, ratios O-/C-Rf products depending on the reaction temperature. Anions of diethyl 2-methylmalonate and 2-nitropropane afforded C-Rf-compounds only.
Addition Reaction of 1,4-Dibromo-2,5-piperazinedione with 3,4-Dihydro-2H-pyran
Authors: Itoh Kuniaki , Sera Akira 
Published: July 2006

Abstract
Reaction of 1,4-dibromo-2,5-piperazinedione (1) with 3,4-dihydro-2H-pyran (2) under irradiation gave 1 : 1 and 1 : 2-addition products (3,4) and corresponding secondary products (5–7). The adducts were considered to be produced separately by photoinduced free radical addition as well as concomitant ionic addition reactions.
Preparation of Sydnone Compounds Substituted by Thio and Seleno Functional Groups at the 4-Positions
Authors: Fuchigami Toshio , Chen Ching-Sy , Nonaka Tsutomu , Yen Mou-Yung , Tien Hsien-Ju 
Published: July 2006

Abstract
The introduction of thio and seleno functional groups to the 4-position of a sydnone ring was successfully attempted using 4-lithiosydnones (2) and 4-bromosydnones (3) as starting compounds. The reaction of 2 with tetraalkylthiuram disulfides, bis[alkoxy(thiocarbonyl)] disulfides, and bis[alkylthio(thiocarbonyl)] disulfides provided 4-sydnonyl dithiocarbamates, O-alkyl S-(4-sydnonyl) dithiocarbonates, and dialkyl 4-sydnonyl trithiocarbonates, respectively in good yields. In addition, treatment of 2 with thiocyanogen and selenocyanogen gave rise to bis(4-sydnonyl) sulfides (11) and bis(4-sydnonyl) selenides (12), respectively. These products, 11 and 12 were also formed by the reaction of 3 with potassium thiocyanate and selenocyanate, respectively. Furthermore, it was found that 3 reacted with selenourea and potassium O-ethyl dithiocarbonate under heating to provide 12 and 11, respectively. It was also found that the reactivity of these sydnone compounds 2 and 3 was quite different in many cases from that of the corresponding ordinary aromatic analogues, though the sydnone ring has a somewhat aromatic nature.
The Cerium(IV) Ammonium Nitrate Oxidation of 5-Hydroxy-2-methoxytropone to Bitropolonyl Derivatives and One-Step Synthesis of 3-Methoxy-p-tropoquinone
Authors: Mori Akira , Isayama Yasutoshi , Takeshita Hitoshi 
Published: July 2006

Abstract
Unlike the benzenoid equivalent, p-methoxyphenol, the cerium(IV) ammonium nitrate (CAN)-oxidation of 5-hydroxy-2-methoxytropone gave C–C coupling products. On the other hand, either by thallium(III) nitrate (TTN) or CAN at 50 °C, 5-hydroxytropolone, a free tropolone, gave 3-methoxy-p-tropoquinone together with p-tropoquinone and 8-oxabicyclo[3.2.1]octenone derivatives, but no dimeric product.