bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and Characterization of Chemically Bound Tartrate‐Sillca Gel as Sorbent for Ligand Exchange Chromatography
Authors: Chyueh Sun‐Dsong , Liu Chuen‐Ying 
Published: May 2015

AbstractTartrate‐based sorbents of two kinds for ligand‐exchange chromatography were prepared by covalent bonding of functional groups to silica gel through an amide bond. The structure and conversion of functional groups of the resin were confirmed with IR spectral and elemental analysis. The influence of pH on adsorption of metal ions to the resin was examined. The coordination behaviour of the sorbent was investigated by means of IR, EPR and electronic absorption spectroscopy. The results indicate that the affinity of metal ions toward the synthesized resins decreased in the order Cu(II) > Zn(II) > Cd(II). The conformation of the copper(II)‐sorbent complexes may be distorted tetragonal, whereas those of zinc(II) and cadmium(II) may be tetrahedral. These complexes between metal ion and sorbent were investigated as a stationary phase for enantiomeric separation of underivatized amino acids. Factors affecting the retention and the sample selectivity were examined. The interactions between sorbent metal complexes and analytes in this ternary system were also investigated.
A Novel Reaction of Ruthenium Carbonyl and Tetrafluorodisila‐3,5‐cyclohexadlene
Authors: Cheng W. S. , Huang C. Y. , Liu C. S. , Lec C. Y. 
Published: May 2015

AbstractIn hexane solution, the decomposition of (1,1,6,6‐tetrafluoro‐3,4‐di‐t‐butyl‐1, 6‐disila‐2,4‐hexadiene)ruthenium (II) tetracarbonyl 2, led to formation of compound (η4‐1,1‐difluoro‐3,4‐di‐t‐butyl‐sila‐2,4‐cyclopentadiene)ruthenium(O)tricarbonyl 3 and monomeric SiF2 that added to cyclic diene compound 1,1,2,2‐tetrafluoro‐4,5‐di‐t‐butyl‐disila‐3, 5‐cyclohexadiene 1, to form bicyclic compound 4. SiF2 was for the first time generated at such a low temperature and trapped with a conjugated diene.
Crystal Structure Refinement of Gaivinoxyl Radical, C29H41O2, Based on Synchrotron X‐ray Powder Diffraction and Rietveld Method
Authors: Sbeu Hwo‐Shuenn , Lee Chih‐Hao , Wang Yu , Chiang Long Y. 
Published: May 2015

AbstractHigh‐resolution X‐ray powder diffraction with synchrotron radiation coupled with Rietveld analysis has been used recently as one of the best way to obtain structural information from a powder specimen. Molecular and crystal structures of Che gaivinoxyl radical (C29H41O2) were studied by means of powder diffraction using NSLS (National Synchrotron Light Source) with λ = 1.5855 A and a rotating anode with Cu Kα radiation. The space group of the crystal is C 2/c with refined lattice parameters a = 23.786(1), b = 10.8611(4), c= 10.6766(4) Å, β = 106.634(3)° Z = 4. The peak shape was fitted with a pseudo‐Voigt profile function. The preferred orientation is along the >011< direction of the needle‐like crystals. Final refinements were converged to give agreement indices Rp 0.08 and 0.17 respectively for synchrotron radiation and rotating anode data. The fitting of the peak profile and refined parameters from the synchrotron radiation data are significantly better than those from rotating anode data. No significant differences are found between single crystal results and those in this work. This work provides evidence that powder diffraction, especially with synchrotron radiation, could be used as one means of structural analysis even for such a weakly scattering organic material.
Formation of Pyrrole Derivatives from Heteroatom‐Substituted Acetonitriles
Authors: Jeng Huey‐Jiuan , Fang Jim‐Min 
Published: May 2015

AbstractAminomalononilrile reacted with conjugated carbonyl compounds to give 3H‐pyrrolines. Treatment of 2‐cbloro‐2‐phenyllhioacetonitrile with alkenes in the presence of potassium t‐butoxide afforded 1‐pnenylthiocyclopropanecarbonitriles, which reacted with nucleophiles in 1,2‐, 1,4‐ or 1,6‐addition modes. The 1,2‐adducts (cyclopropylimines) rearranged in situ to give substituted pyrroles.
Bromination of 3‐Aryl‐4‐acetylsydnones with Potassium Bromide and Sulfuric Acid
Authors: Tien Hsien‐Ju , Lin Shaw‐Tao , Ong Geok Ton 
Published: May 2015

AbstractBromination of 3‐aryl‐4‐acetylsydnones with alkali bromide and sulfuric acid yielded 3‐aryl‐4‐dibromoacetylsydnones (R=H, Me, C1, NO2) and 3‐(3‐bromoaryl)‐4‐dibromoacetyIsydnones (R=OH, OMe, OEt) in good yields. The resultant dibromoacetylsydnones were converted to the corresponding 3‐arylsydnones with alcoholic NaOH solution.
Photopolymerization of Styrene and Methyl Methacrylate with Poiy(methylphenylsilane) as Photoinitiator
Authors: Chang T. C. , Chin Y. S. , Chen H. B. , Ho S. Y. 
Published: May 2015

AbstractThe rate of photochemical polymerization of styrenc (St) and methyl methacrylate (MMA) with polymcthylphenylsilane (PMPS) as initiator were measured. Polymethylphenylsilane is photodegraded to form silyl radicals that may initiate polymerization of St and MMA. The kinetic orders of polymerization reactions of initiator PMPS in St and in MMA systems are 0.49 and 0.29, respectively. The rate coefficients kp and kt are 38.1 and 0.71 × 107 Lmol‐−1s−1 in the St/PMPS system and 249.5 and 6.71 × 107 Lmol−1s−1 in the MMA/PMPS system. A polymerization reaction mechanism is proposed.
Stereoselective Hydroiodination of 3‐Substituted Derivatives of Propynoic Acid
Authors: Luo Fen‐Tair , Hsieh Li‐Chen 
Published: May 2015

AbstractThe hydroiodination of 3‐substituted propynoic acids and their derivatives with sodium iodide/trimethylsilyl chloride/water in acetonitrile at 25 °C gives stereoselectively (Z)‐3‐iodopropenoic acid derivatives in good yields.
Reactions with Naphthoylhydroxlmoyl Chlorides: Synthesis of Derivatives of Isoxazole, Pyrrolidino[3,4‐d]isoxazoiin‐4,6‐dione, lmidazo[1,2‐a]pyridine, lmidazo[1,2‐a]pyrimidine, Benzotriazine and Benzothiadiazine
Authors: Abdelhamid Abdou O. , Al‐Hamidi Abdulaziz A. 
Published: May 2015

AbstractHydroximoyl chlorides 3 react with acrylonitrile, N‐arylmaleimide and maleic anhydride to give isoxazolines 5, pyrrolidino[3,4‐d]isoxazolines 8, and furolidino[3,4‐d]isoxazolines 9, respectively. 3 reacted with 2‐aminopyridine, 2‐aminopyrimidine, o‐phenylenediamine and o‐aminothiophenol to yield 3‐ni‐trosoimidazo[1,2‐α]pyridines 20, 3‐nitrosopyrimidines 22, 3‐naphthoyl‐1,4‐dihydrobenzo‐1,2,4‐triazines 24, and 3‐naphthoyl‐4H‐1,3,4‐benzothiadiazine 27, respectively. Compound 3 reacted with benzoylacetonitrile, acetoacetanilide, thiophenol, benzencsulfinic acid in ethanolic sodium ethoxide solution to give the corresponding isoxazoles 12–13 and oximes 16–17, respectively. The structures of these products were confirmed by elemental analyses, spectral data and, wherever possible, alternative synthesis.
Chemical Components from Triumfetta bartramia
Authors: Ho Li‐Kang , Chang Chiann‐Rong , Chang Yuan‐Shiun 
Published: May 2015

AbstractTriumfetta bartramia Linn. is a folk medicine used in Taiwan. From this plant we identified β‐sitosterol, friedelin, friedelinol, quercetin, 2,6‐dimethoxy‐1,4‐benzoquinone, and rosmarinic acid. The identification of these compounds was confirmed by spectral methods and comparison with authentic samples.
Chemical Constituents from Berchemia formosana
Authors: Lee Shoei‐Sheng , Tsai Fang‐Yen , Chen Ih‐Sheng 
Published: May 2015

AbstractCentrifugal partition chromatography, Sephadex LH‐20 and flash chromatography were applied to separate flavonoids and coumarins from Berchemia formosana. This first chemical investigation led to the isolation of ten compounds. Based on spectral analysis, they were determined to be quercetin (1), rutin (2), (+)‐dihydroquercetin (3), (+)‐dihydrokaempferol (4), naringenin (5), 2‐hydroxy‐naringenin (6), 2‐hydroxy‐naringenin‐7‐O‐β‐glucoside (7), (‐)‐catechin (8), (‐)‐gallocatechin (9) and scopoletin (10). Among these 7 is a novel natural product and was found to be composed of two inseparable diastereoisomers. The presence of the rare 2‐hydroxyflavanones 6 and 7 in B. formosana is of interest for chemotaxonomy.
Inversionless Amplification in a Three‐Level System Driven by a Single Field
Authors: Fain Benjamin , Khidekel Vadim 
Published: May 2015

AbstractThe three‐level system subjected to electromagnetic fields is investigated. It is shown that when one of two fields is strong (the pumping field), the system can amplify the second (probe) field even if no population inversion is created, but some phase relations are satisfied. The conditions necessary for inversionless amplification to take place are discussed. The connection between this effect and stimulated Raman emission is shown. Numerical simulations for each one of the discussed cases were performed.
Dual Mechanism for CO(A1Π)‐CO(X1 ∑+) Rovibronic Energy Transfer: An OODR‐MP1 Spectroscopic Study
Authors: He Jinbao , Sha Cuohe , Jiang Bo , Zhang Cunhao 
Published: May 2015

AbstractThe highly versatile OODR‐MPI technique is used, mostly without resort to isotope tagging, to study the quantum state specific rovibronic energy transfer between molecules of the same species, specifically CO(A)‐CO(XJ. Two types of rovibronic energy transfer mechanisms are found to be prevailing and are differentiated experimentally, i.e., the long range near resonant dipole‐dipole interactions and the short range exciplex formation. The first type is characterized, at first unexpectedly, by its compliance to the selection rules of optical dipole transitions, ΔJ = 0, ±1 and parity + ⟷ −. Numerical computation procedures are presented for the calculation of rovibronic energy transfer cross‐sections when the two types of mechanism are operating concurrently. The computed results and their variation with J are in good accord with the experiments.
Vibrational Spectroscopy As a Probe of Surface Heterogeneity: CO on NaCl(100)
Authors: Chang Huan‐Cheng , Dai David J. , Ewing George E. 
Published: May 2015

AbstractThe fundamental (Δv = 1 ← 0) and the first overtone (Δv = 2 ← 0) transitions of monolayer physisorbed CO on NaCl(100) single crystal surfaces at 5 K have been investigated using polarized Fourier transform infrared spectroscopy. Comparisons of the transition frequencies, bandwidths and absorbances for these two transitions together with those of dilute isotopes allow us to isolate the contribution of dynamic and static coupling effects of molecules within the monolayer. Homogeneous and heterogeneous effects can also be distinguished from band profiles of these various transitions. We conclude that the residual line broadening of 0.1 cm−1 at 5 K for the isolated CO isotopes arises from heterogeneous surface effects. We set an upper limit of 0.07 cm−1 for the linewidth of single CO molecules on NaCl(lOO) due to surface heterogeneity. A lower limit of × 10−8 cm−1 is provided by the vibrational lifetime of adsorbed CO molecules. Sharpness of the vibrational features shows that infrared spectroscopy of adsorbate is a sensitive method for probing surface and adlayer irregularities of adsorbed molecules on a single crystal.
TEA CO2‐Laser Induced SF6 + Ba Beam‐Surface Ionization
Authors: Castaño J. , Zapata V. , Makarov G. , Ureña A. González 
Published: May 2015

AbstractA TEA CO2‐laser induced SF6 + Ba beam‐surface ionization process has been studied when vibrational excitation of SF6 molecules was carried out at (and near) the polished surface of the electrically heated up to 675 K polycristalline Ba. Electron emission and negative molecular ion signal were detected. The dependence of the molecular ion signal on laser fluence and frequency (on SF6 molecular absorption) as well as on the SF6 gas pressure in the nozzle were studied. The results reveal a nonlinear, probably multiphoton character of the molecular ion formation and a clear vibrational selectivity i.e. vibrational enhancement, of the SF6 + Ba beam‐surface ionization process. Possible mechanisms of the negative molecular ion formation in the IR laser induced SF6 + Ba beam‐surface ionization process are discussed.
A Study on the Reaction of O(1D) and N2O by Trajectory Calculation and Time‐Resolved FTIR Spectroscopy
Authors: Wang Xuebin , Li Hongzhi , Zhu Qihe , Kong Fanao , Yu Huagen 
Published: May 2015

AbstractO(1D) atoms, generated via the laser photodissociation of N2O at 193 nm, reacting with N2O was studied by Time‐Resolved Fourier Transform Infrared (TR‐FTIR) Spectroscopy. The IR emission from NO(v1–11.) was collected at 30 μs after the laser was fired. Several instrumental corrections were made to obtain reliable experimental results. The vibrational temperature of the nearly‐nascent NO product was estimated to be Tv  9,000 K. A Quasi‐Classical Trajectory (QCT) calculation of the reaction was performed. The calculated results, corresponding to a head‐on attack mechanism, agree with the experimental data. Additional reaction channel with side‐on attack producing N2 and O2 was also studied by QCT, where vibrationally hot O2(a 1 Δg) and cold N2(X1∑g+) products are predicted.
Molecular Beam Studies on the Laser‐Enhanced Surface Reaction of GaAs(100) with Chlorine
Authors: Qin Qizong , Zhang Kangzhan , Lu Pinghe , Zheng Qike 
Published: May 2015

AbstractA cw supersonic Cl2 molecular beam coupled with an angle‐resolved time‐of‐flight (TOF) technique has been used to investigate the laser‐enhanced surface reaction of GaAs(100) with chlorine. The mass and velocity distributions of the major reaction products under 1064 nm laser irradiation have been measured as a function of laser fluence, detection angle, surface temperature and normal component of the translational energy of the incident chlorine molecules. It has been found that increasing both laser fluence and the translational energy of incident chlorine molecules markedly enhance mis surface reaction. The measured flux angular distributions of major reaction products can be fit satisfactorily with a bi‐cosine function. Measurements of the mass and angular distributions of reaction products by a modulated molecular beam mass spectrometry show that the surface temperature effect is obvious for the Cl2/GaAs(100) “dark” thermal reaction. A direct activated dissociative chemisorption is proposed for the mechanism of Cl2 chemisorption on the GaAs(100) surface.
Formation and Photodissociation of Transition Metal‐Sulfur Binary Cluster Ions
Authors: Shi Yang , Yu Zhong‐De , Zhang Nan , Gao Zhen , Kong Fan‐Ao , Zhu Qi‐He 
Published: May 2015

AbstractTransition metal‐sulfur binary cluster ions were produced by direct laser ablation and analyzed with the first stage time‐of‐flight mass spectrometer (TOF‐MS). It was found that the distribution of the strong peaks of the stable cluster ions in the TOF‐MS were not appreciably affected by the composition of the sample. The composition of the most stable metal‐sulfur cluster ions, MnSm are different for various transition metals: Cu, n = 2m + I and n = 2m; Zn, m = n; Mn, m = n; Fe, m = n, m = n −1 and m = n − 2; Co, m = n − 1, m = n − 2, m = n − 3, m = n − 4 and m = n − 5; Cr, m = n and m = n + 1; Ta, m = n + 1 and m = n + 2. Cluster ions can be selected by a mass gate, and photolyzed by an excimer laser. The photodissociation product ions were analyzed with the second stage TOF‐MS. These product ions were mainly the more stable cluster ions as those given in the first stage TOF‐MS.
Aggregation Behaviour of Some Reactive Dyes
Authors: Mostafa O. I. , Abd El‐Aal A. Y. , El Bayaa A. A. , Sallam H. B. , Mahmoud A. A. 
Published: May 2015

AbstractThe absorption spectra of aqueous solutions of monochlorotriazine reactive dyes, C.I. Reactive Red 9 and Reactive Orange 13 were measured in the presence of 5, 10, 25 and 50% (v/v) of ethanol, pyridine and dioxane‐water mixtures and in varied concentrations of KCl, NaCl and LiCl. The varying position, intensity and shape of absorption bands are interpreted in terms of aggregation and disaggregation of dyes in solutions. The aggregation behaviour of the reactive dyes in solutions and in the presence of additives is related to their apparent deviations from Beer's law and aggregation numbers (N). The aggregation constant (K.) of the monomer/dimer equilibrium is calculated.Dyes in ethanol‐water mixtures record a larger aggregation number and aggregation constant than in the presence of pyridine. Dioxane is classified as anon‐polar solvent and hence has a more disaggregating influence. The value of the aggregation number and constant are increased with increasing salt conentration and the order of degree of aggregation is KCl > NaCl > LiCl related to the order of ionic radii of K+, Na+ and Li+ ions.
Reactivity of Iminophosphoranes. Formation of the Piperazine Ring
Authors: Lin Tu‐Chen , Cheng Ming‐Chu , Peng Shie Ming , Liu Shiuh‐Tzung , Kiang Fu‐Mei 
Published: May 2015

AbstractReaction of 3‐azidopropyl methanesulfonate with triphenylphosphine produced the 1,4‐bis(triphenyl‐phosphino)piperazine 5 by intermolecular cyclization, instead of formation azidine derivatives by an intramolecular pathway. Structural formulation of 5 was achieved by both spectral and X‐ray crystal analysis. Hydrolysis of 5 under basic condition gives piperazine, whereas reaction of lithium diphenylphosphide with 5 produced 1,2‐bis(diphenyl‐phosphino)ethane (dppe) exclusively.
Synthesis of α‐Methyldopa Prodrugs Containing Dipeptide Moieties as Tools for Intestinal Delivery
Authors: Wang Hui‐Po , Cheng Chih‐Yuan , Ma Jin‐Ran , Lee Jia‐Shuai 
Published: May 2015

AbstractDipeptides containing D‐phenylglycine or D‐p‐hydroxyphenylglycine were attached onto the antihypertensive agent α‐methyldopa to form prodrugs 1a, 1b and 1c. The nonessential amino acids were introduced into the prodrug molecules as tools of chemical delivery to improve the intestinal absorption of the parent drug. Preliminary tests revealed that the prodrugs were stable in phosphate buffer solutions at pH 7.4 (t1/2 > 10 h). These compounds also demonstrated satisfactory stability toward enzymatic degradation in a mucosa preparation isolated from rat intestine, indicating that they might be feasibly formulated as an oral prodrug of α‐methyldopa.
Mechanistic Studies of the Biosynthesis of 3,6‐Dideoxysugars in Bacteria: Exploration of a Novel C‐O Bond Cleavage Event
Authors: Liu Hung‐Wen , Thorson Jon S. , Miller Vaughn P. , Kelley Theresa M. , Lei Yenyoung , Ploux Olivier , He Xuemei , Yang Ding‐Yah 
Published: May 2015

AbstractDeoxy sugars are ubiquitous in nature and contribute to diverse biological activities. Attempts to design systems to control or to mimic their functions are hampered, however, by the lack of biosynthetic knowledge of these unique sugars. To elucidate the mechanism by which the sugar deoxygenation is effected, we have initiated a study to explore the biosynthesis of CDP‐ascarylose, a 3,6‐dideoxyhexose found in the lipopolysaccharides of Yersinia pseudotuberculosis, and our initial focus centered on C‐3 deoxygenation catalyzed by E1 and E3. We have now purified the wild‐type enzymes, cloned the corresponding genes (ascC for E1 and ascD for E3), and overexpressed the gene products in Escherichia coli. The purified E3 is a flavoprotein comprising an iron‐sulfur center and E1 is an iron‐sulfur containing, pyridoxamine 5′‐phosphate‐de‐pendent enzyme. Since these iron‐sulfur clusters are well known one‐electron carriers, reactions mediated by E1 and E3 must proceed via a radical mechanism. Recently, EPR analysis of E1/E3 catalysis indicated a potential new redox role for pyridoxamine as a cofactor. These findings make this system unique from two perspectives: E1 is the only coenzyme B6‐dependent catalyst that interacts with a sugar and not with an amino acid, and it is the first example in which coenzyme B6 may facilitate one‐electron redox chemistry. Thus, the unprecedented mechanisms of E1 and E3 distinguish this system as a novel radical deoxygenation with potentially interesting future developments.
Enantioselective Aldol Type Reactions of Acetate Titanium Enolate with α,β‐Unsaturated Aldehyde‐TiCl4 Complex
Authors: Yan Tu‐Hsin , Hung An‐Wei , Lee Hui‐Chun , Liu Wen‐Hung , Chang Chii‐Shin 
Published: May 2015

AbstractThe camphor‐derived N‐acetyloxazolidinethione has been used to effect enantioselective aldol type reaction of the derived thioimide titanium enolate with unsaturated aldehyde‐TiCl4 complex. The observed facial selectivity is best explained by an open transition state model.
P‐C Bond Cleavage in Platinum Complexes Containing bis (Diphenylphosphino) Methane Promoted with a Phase‐Transfer Catalyst
Authors: Lin Ivan J. B. , Shen H. I. , Feng And Da‐Fa 
Published: May 2015

AbstractWith a phase‐transfer catalyst, Pt‐dppm (dppm = Ph2PCH2PPh2) complexes undergo basic hydrolysis, in which a dppm ligand is hydrolyzed to produce PPh2Me and PPh2OH (or PPh2O). The ease of this hydrolysis reaction depends partly on the molecular charges of the metal complexes. Hydrolysis of neutral [Pt(dppm)(L‐L)] (L‐L = S2CO2, S2P(O)(OEt)2− and mnt = S2C2(CN)22−) is slower than that of monocationic [Pt(dppm)(L′‐L′)]Cl (L′‐V = S2CNEt2‐, (CH2)2S(O)Me and acetylacetonate) compounds. Among the neutral compounds, hydrolysis of [Pt(dppm)(mnt)] is more rapid than that of the other two. These results are rationalized according to the ease with which partial positive charges are induced on the dppm phosphorus atoms. The steric effect due to ligands trans to dppm also influences the rate of hydrolysis of Pt‐dppm compounds. When trans ligands are Ph2P(CH)2PPh2, Ph2P(CH2)3PPh2 and (Ph2PO2)H, no hydrolysis of dppm occurs. Hydrolysis of Pt‐dppm compounds depends further on the concentrations of both the phase‐transfer catalyst and OH− ions. All these results are consistent with nucleophilic attack of OH− on dppm phosphorus atoms to release strain in the Pt‐dppm ring.
Oxidation of Alkenes and Sulfides with Transition Metal Catalysts
Authors: Liao Jen‐Hai , Cheng Kuang‐Yuan , Fang Jim‐Min , Cheng Ming‐Chu , Wang Yu 
Published: May 2015

AbstractAlkenes and sulfides were oxidized with transition‐metal catalysts. The oxidant sources include molecular dioxygen, air and iodosylbenzene. The metal ions Mn(III), Fe(III), Co(II) and Ni(II) were used. The Catalysts 1‐18 of 1,3‐dioxo‐, β‐ketoimine‐ or salen‐types were prepared and their efficacy was examined. 1,2‐Dihydronaphthalene is most efficiently epoxidized with O2/Me2CHCHO or PhIO in the presence of Mn(III)‐salen catalysts. The Ni(II)‐, Co(II)‐ and Fe(III)‐catalysts of either β‐ketoimine‐ or salen‐types are useful for epoxidation of styrene, (E)‐stilbene and (E)‐benzalacetone in the O2/Me2HCHO system; these epoxidations are stereospecific without formation of corresponding diastereomeric epoxides. Oxidation of methyl p‐tolyl sulfide with O2/Me2CHCHO is facilitated by the 1,3‐dioxo‐catalyst Co(II)‐1. Monooxidation is achieved with Me2CHCHO in equimolar proportions to give the corresponding sulfoxide, whereas overoxidation is realized with excess Me2CHCHO to give the sulfone. These epoxidation and sulfide oxidations all occur at 25 °C and are complete in less than a day.
Cyanation of the Seven‐Membered Ring of Diethyl Azulene‐1,3‐Dicarboxylate
Authors: Morita Tadayoshi , Sasaki Kazuo , Lin Bing Bing , Lin Yuan‐Shan 
Published: May 2015

AbstractReaction of diethyl azulene‐1,3‐dicarboxylate with potassium cyanide in dimethoxyethane gave diethyl 4‐cyano‐, 6‐cyano‐, and 4,6‐dicyanoazulene‐1,3‐dicarboxylates. This cyanation involved addition of acyanide ion to the seven‐membered ring of azulene to form a cyclopentadienide ion, followed by oxidation.