bluuebunny/crossref_metadata_2025_split huggingface dataset:
Efficient Preparation of a Valuable Intermediate in the Synthesis of (−)-Swainsonine
Authors: Bermejo Gonzalez Francisco , Lopez Barba Ana , Ruano Espina Myriam 
Published: July 2006

Abstract
The preparation of the octahydropyrano[3,2-b]pyridine-6,7,8-triol derivative 22, a highly valuable intermediate in the synthesis of (−)-swainsonine, has been achieved by application of a fifteen-step sequence starting from d-mannose with 20% overall yield.
Stereochemical Outcome of Aldol Reaction of a 6-C-Substituted d-Mannose Derivative
Authors: Bermejo Gonzalez Francisco , Ruano Espina Myriam 
Published: July 2006

Abstract
The base-promoted cyclization of the diketose 3 has been studied. The structural assignments of the aldol products 4a, 4b, and 4c were based on the spectroscopic analysis and the chiroptical properties.
Synthesis of a Series of Acodazole and Naphthothiophene-Deuterioporphyrins and Metalloporphyrins
Authors: Sondhi Sham M , Magan Archana , Lown J William 
Published: July 2006

Abstract
The design and synthesis of several hybrid intercalator-linked porphyrins and their corresponding metalloporphyrin derivatives designed as cellular DNA targetted anticancer agents is described. 9-Chloro-7-methylimidazo[4,5-f]quinoline was condensed with ethylenediamine, 1,4-phenylenediamine and 2,5-toluenediamine to give compounds Ia–c. Naphtho[2,1-b]thiophene-4-carboxylic acid was condensed with 1,6-hexanediamine, 1,10-decanediamine, and 1,12-dodecanediamine to give compounds IIa–c and IIIa–c. Compounds Ia–c and IIa-c were condensed with deuterioporphyrin monomethyl ester and deuterioporphyrin to yield compounds IVa–j. Compounds IVa–h were refluxed with MnCl2 or CoCl2 in DMF to give metalloporphyrins Va–j. Compounds Ia–c, IIa–c, IIIa–c, IVa–j, and Va–j were characterized by IR, NMR, and MS (FAB) spectral data. Kassoc value for intercalative binding of these porphyrin derivatives to calf thymus DNA is in the range 1.9−3.0 × 106 L M−1.
Photoinduced Electron Transfer between Zinc Protoporphyrin Reconstituted Myoglobin and Methylviologen
Authors: Aono Shigetoshi , Nemoto Shuzo , Okura Ichiro 
Published: July 2006

Abstract
Photoinduced electron transfer proceeded between zinc protoporphyrin reconstituted myoglobin and methylviologen. The reduced methylviologen formed by electron-transfer quenching was observed by means of laser flash photolysis. The quenching rate constants were affected by the change in the surface charges of myoglobin.
Electrochemical Studies of Poly(mercaptohydroquinone) and Poly(mercapto-p-benzoquinone) Films Prepared by Electrochemical Polymerization. VI.Electroreduction of l-Cystine on Thiolates Fixed in the Polymer Film
Authors: Arai Gorou , Sugaya Toshiaki , Sakamoto Mika , Yasumori Iwao 
Published: July 2006

Abstract
Electrocatalytic reduction of l-cystine (CySSCy) was examined on glassy carbon electrodes coated with the title conductive polymer in which Pt, Pd, Cu, Ag, and Hg thiolates were fixed. Pt and/or Pd thiolate fixed in the polymer behaved as excellent electrocatalytic active sites for reductive cleavage of the sulfur–sulfur bond in CySSCy.
Effects of Redox Reagents on ESR Line Shape of Synthetic Melanins
Authors: Oniki Takayuki , Takahama Umeo 
Published: July 2006

Abstract
Melanins were synthesized from pyrogallol or β-(3,4-dihydroxyphenyl)alanine (dopa) and their electron spin resonance (ESR) spectra were measured. The pyrogallol melanin had four kinds of ESR signal; main and broad signals under anaerobic conditions, and inner and outer signals under aerobic conditions. The main, inner and outer signals disappeared by the reduction of the melanin by NaBH4 or ascorbic acid but the broad signal did not. By the oxidation of the melanin by hexacyanoferrate(III), the intensity of the signals decreased, and the inner and outer signals were not observed under aerobic conditions. Hydrogen peroxide decreased these signals especially under aerobic conditions at high pH. Superoxide gave the signals similar to that under aerobic conditions, but decreased the signals of the hexacyanoferrate(III)-oxidized melanin. ESR signals of dopa melanin showed similar behavior to that of pyrogallol melanin against redox reagents. The chemical structure around radicals in melanins were proposed from these results.
Single-Excitation Configuration Interaction Calculations of Hyperfine Coupling Constants of Small π and σ Radicals
Authors: Nakano Tatsuya , Morihashi Kenji , Kikuchi Osamu 
Published: July 2006

Abstract
Ab initio ROHF SCI calculations with Chipman’s [5s2p/3†s] and [5s2p1d/3†s1p] basis sets, in which all singly-excited configurations are included, give hyperfine coupling constants of α-protons which are in satisfactory agreement with the experiment values.
Crystal and Molecular Structure of the Asymmetric Cobaloxime, trans-Bis(2,3-butanedione dioximato(1−)-N,N′)iodopyridinecobalt(III): [Co(Hdmg)2I(py)]
Authors: Megnamisi-Belombe Michel , Nane Nlend Gaspard , Nuber Bernhard 
Published: July 2006

Abstract
The three-dimensional structure of the asymmetric cobaloxime, trans-bis(2,3-butanedione dioximato)iodopyridinecobalt(III), [Co(Hdmg)2I(py)] (Hdmg− = dimethylglyoximate; py = pyridine), has been determined by X-ray diffraction at ambient temperature. The monoclinic structure (P21⁄n) was refined by full matrix least-squares to a final Rw = 0.037 for 3233 observed independent reflections. The structure consists of interesting nautral cobaloxime molecules in which the coordination getmetry around CoIII resembles very closely that observed in cyanocobalamine or vitamin B12.
Choice of Manganese(III) Complexes for the Synthesis of 4,4′-Biphenyldiols and 4,4′-Diphenoquiones
Authors: Nishino Hiroshi , Itoh Nobuyuki , Nagashima Makiko , Kurosawa Kazu 
Published: July 2006

Abstract
2,6-Disubstituted phenols are oxidized with tris(2,4-pentanedionato)manganese(III), [Mn(acac)3], in glacial acetic acid to give the corresponding 4,4′-biphenyldiols in high yields, whereas similar reactions using manganese(III) acetate, [Mn(OAc)3], insted of [Mn(acac)3] quantitatively yield the corresponding 4,4′-diphenoquinones. Cross-coupling reactions of 2,6-di-t-butylphenol and other substituted phenols afford the corresponding cross-coupled 4,4′-biphenyldiols and 4,4′-diphenoquinones together with oxidation products derived from the starting phenols themselves. The advantageous use of [Mn(acac)3] and [Mn(OAc)3] in the ubiqitous phenol coupling reaction is discussed.
Spontaneous Color Development Encountered for Diquaternary Salts of 1,10-Phenanthrolines in Various Media
Authors: Kamogawa Hiroyoshi , Kato Atsushi , Mizuno Junichi 
Published: July 2006

Abstract
Diquaternary salts of 1,10-phenanthroline or, 2,9-dimethyl-1,10-phenenthroline (viologen), prepared according to the Menshutkin rection, developed intense colors spontaneously, presumably due to high reduction potentials. The extent and λmax of the colors developed were dependent upon both the kind of viologen and the media such as solvents and polymer matrices.
Sodium Tellurite as a Mild and Selective Oxidizing Agent for Thiols: Its Use in the One-Pot Synthesis of Unsymmetrical Disulfides
Authors: Suzuki Hitomi , Kawato Sei-ichi , Nasu Akira 
Published: July 2006

Abstract
Sodium tellurite acts as a mild and highly selective oxidizing agent for thiols under phase-transfer conditions at room temperature. Aromatic and benzylic thiols are rapidly converted to disulfides. Short-chain primary thiols undergo oxidation in preference to long-chain thiols. Secondary thiols are sluggish in oxidation and tertiary thiols remain intact. No overoxidation of the sulfur atom is observed. Similar results are also obtained with sodium tellurate.
Photochromism of Hemithioindigo Derivatives. I. Preparation and Photochromic Properties in Organic Solvents
Authors: Yamaguchi Takeo , Seki Takahiro , Tamaki Takashi , Ichimura Kunihiro 
Published: July 2006

Abstract
Thirteen hemithioindigo (HT) derivatives bearing alkyl chains are newly synthesized and their photochromism and emission properties are investigated. The Z/E photoisomerisms of these compounds in organic solvents are essentially in agreement with data reported by Mostoslavskii and Izmail’skii (J. Gen. Chem. USSR, Engl Transl.), 31, 21 (1961), and subsequent papers). At 77 K both the E and Z isomers of HT chromophore emit fluoresscences of comparable intensities, whereas at room temperature very weak fluorescence is observed only from the Z isomer. Examination of repeatable numbers of Z/E photoisomerization reveals that the HT chromophore possesses remarkable inherent photofatigue resistance.
Photochromism of Hemithioindigo Derivatives. II. Photochromic Behaviors in Bilayer Membranes and Related Systems
Authors: Seki Takahiro , Tamaki Takashi , Yamaguchi Takeo , Ichimura Kunihiro 
Published: July 2006

Abstract
Photochromic behaviors of hemithioindigo (HT) derivatives in bilayer membrane matrices and related aqueous system are investigated. HT derivatives were incorporated into bilayer membrane matrices at a molar ratio to bilayer amphiphiles of 0.01. Under these conditions, HT amphiphiles having an ammonio group disperse molecularly in the array bilayer membranes, and show the simple photochromism as in the organic solutions. For a HT derivative having no hydrophilic group, on the other hand, irreversible photobleaching proceeds in addition to the photochromic reaction possibly as a result of cluster formation in the bilayer membranes. E-Form conversion at the photostationary state and the E to Z thermal isomerization rate is largely influenced by the crystal to liquid crystal phase transition of the bilayer matrices.
Allylation of Aldehydes by Allyl- and Crotyltributyltin in the Presence of Catalytic Amounts of Bu2SnCl2 Complex
Authors: Yano Katsunori , Baba Akio , Matsuda Haruo 
Published: July 2006

Abstract
In nearly neutral media, the reaction of allylic tributyltin with aldehydes is effectively catalyzed by Bu2SnCl2 complexes. The addition of coordinative reagents and benzoyl chloride as a quencher is required of the catalytic allylation, furnishing homoallyl benzoates in good to excellent yields, where a regioreversed coupling to conventional methods using crotyltributyltin is exclusively observed.
Reaction of 1,3-Oxathiolium Salts with Three Types of Ring Expansion Reagents on a Nitrogen Atom
Authors: Yonemoto Katsumi , Honda Kazumasa , Shibuya Isao , Taguchi Yoichi , Tsuchiya Tohru , Yasumoto Masahiko 
Published: July 2006

Abstract
The ring expansion reactions of 1,3-oxathiolium salts (1) using NaN3 and an I2–aq NH3 system resulted exclusively in the formation of 1,4,2-oxathiazines (3) by incorporation of a nitrogen atom into the C–O bond in 1. On the other hand, the reaction of 1 with dialkylamino(thioxo)methanesulfenamides, another type of N-expansion reagent, gave di-5-thiazolyl sulfide derivatives (4) in addition to 3. The structure of 4 was confirmed by X-ray crystallographic analysis. It was speculated that the formation of 4 goes via initially-formed 3. Furthermore, 1 reacted with another N-unsubstituted sulfenamides having a heterocyclic substituent such as a 2-pyridyl and 2-benzothiazolyl group to afford 2-pyridyl 5-thiazolyl sulfide and 2-benzothiazolyl 5-thiazolyl sulfide derivatives, respectively, together with 3. The stability and reactivity of oxathiazines 3, which comprise an electron-rich π-system, were also examined.
The Hydroboration of 3-Chloro-1-trimethylsilyl-1-propyne with Dialkylboranes and Its Application to the Syntheses of (E)-3-Trimethylsilyl-2-alkenes and 3-Trimethylsilyl-1-alkenes
Authors: Hoshi Masayuki , Masuda Yuzuru , Arase Akira 
Published: July 2006

Abstract
The reaction of 3-chloro-1-trimethylsilyl-1-propyne with a stoichiometric amount of dialkylborane proceeds to the monohydroboration stage, giving a mixture of regioisomers, (Z)-dialkyl(3-chloro-1-trimethylsilyl-1-propenyl)borane and (Z)-dialkyl[1-chloromethyl-2-(trimethylsilyl)vinyl]borane. The hydroboration mixture is protonolyzed with acetic acid to give (Z)-3-chloro-1-trimethylsilyl-1-propene in a quantitative yield. Treatment of the hydroboration mixture with aqueous sodium hydroxide gives a good yield of highly pure (E)-3-trimethylsilyl-2-alkene whose alkyl group migrates from the boron atom. On the other hand, successive treatment of the hydroboration mixture with methyllithium and acetic acid gives a good yield of 3-trimethylsilyl-1-alkene whose alkyl group migrates from the boron atom. The above procedures provide convenient syntheses of (E)-3-trimethylsilyl-2-alkenes and 3-trimethylsilyl-1-alkenes. It is proposed that both products are afforded through the corresponding allylboranes derived from (Z)-dialkyl(3-chloro-1-trimethylsilyl-1-propenyl)borane, respectively. Thus, the former is formed by hydrolysis of alkyl[1-alkyl-1-(trimethylsilyl)allyl]hydroxyborane, while the latter is formed by protonolysis of alkylmethyl[3-alkyl-3-(trimethylsilyl)allyl]borane.
Dimer Formation of 9-Cyanoanthracene in a Nonpolar Medium at Low Temperatures
Authors: Hoshi Toshihiko , Okubo Jun , Imaizumi Fumitoshi , Ono Isao , Kobayashi Michio , Inoue Hiroyasu 
Published: July 2006

Abstract
The polarized electronic absorption spectrum of 9-cyanoanthracene has been measured in a stretched poly(vinyl alcohol) (PVA) film at 101 K, and the polarizations of the electronic transitions determined. It was found that the longer-molecular-axis polarized bands are at 364.4, 262. 1, and 229 nm, and that the shorter-molecular-axis polarized ones are at 411.2 and 223 nm. The absorption spectra of 9-cyanoanthracene were measured in MP (a 1:1 mixed solvent of methylcyclohexane and isopentane) at room and lower temperatures. It was found that additional bands appear at the lower energy sides of the corresponding monomer bands at lower temperatures. These spectral changes may be interpreted as being due to dimer formation. The dimer may be stabilized mainly through dipole-dipole interactions between the two cyano groups taking on a C2h symmetry. The 412.5, 363.5 and 281.5 nm bands of the dimer are assigned to the calculated S1←S0 (Bu←Ag), S4←S0 (Au←Ag) and S8←S0 (Au←Ag) transitions, respectively; these transitions correspond to the S1←S0 (A1←A1), S2←S0 (B2←A1) and S3←S0 (B2←A1) transitions of the monomer.
Oxidation of Alcohols with Peracetic Acid in Ethyl Acetate in the Presence of Sodium Bromide
Authors: Morimoto Takashi , Hirano Masao , Hamaguchi Takayoshi , Shimoyama Masahide , Zhuang Xiumin 
Published: July 2006

Abstract
Aliphatic primary alcohols and 1,ω-diols were oxidized to the dimeric esters and lactones, respectively, by peracetic acid in ethyl acetate in the presence of sodium bromide under mild conditions. Aliphatic secondary and benzylic alcohols were converted smoothly to the corresponding carbonyl compounds by the same system.
Synthesis and Characterization of Mono-, Bis-, and Trissubstituted Pyridinium and Pyrylium Dyes
Authors: Matsui Masaki , Kawamura Shigeo , Shibata Katsuyoshi , Muramatsu Hiroshige 
Published: July 2006

Abstract
A series of mono-, bis-, and trissubstituted pyridinium and pyrylium dyes have been synthesized by the condensation of methylpyridinium and methylpyrylium salts with aldehydes or nitroso compound. Large bathochromic shifts were observed in the following order, both in substituted azomethine pyridinium and pyrylium dyes, mono &lt; bis &lt; tris. The magnitude of the shift appeared in the order of multiple bonds, –CH=CH– &lt; –CH=CH–CH=CH– &lt; –CH=N–.
Electron-Transfer Reactions from Hydroquinone Dianions to 10-Methylacridinium Ion and a Cobalt(III) Porphyrin
Authors: Fukuzumi Shunichi , Yorisue Tomohiro 
Published: July 2006

Abstract
Electron transfer from various hydroquinone dianions (X-Q2−) to 10-methylacridinium ion (AcrH+) and [Co(tpp)]+ (H2tpp = tetraphenylporphyrin) occurs efficiently in deaerated MeCN to yield 10,10′-dimethyl-9,9′-biacridine [(AcrH)2] and [Co(tpp)], respectively. The electron transfer results in the one-electron or two-electron oxidation of X-Q2−, depending on the one-electron oxidation potentials of X-Q2− and X-Q−.
Effect of γ-Ray Irradiation on the Recoil Tritium Reaction in Xenon–Hydrogen Mixtures at 77 and 4.2 K. Competition of the Tunneling Reaction with the Combination Reaction
Authors: Miyazaki Tetsuo , Fujitani Yoshiteru , Shibata Masao , Fueki Kenji , Masaki Nobuyuki M , Aratono Yasuyuki , Saeki Masakatsu , Tachikawa Enzo 
Published: July 2006

Abstract
Recoil T-atom reactions have been studied in Xe–H2–D2 mixtures at 77 and 4.2 K. When T atom reactions were caused at 77 K by neutron irradiation at an extremely low dose rate of γ-rays, a large isotope effect (kHT/kDT≈7) on the formation of HT and DT was observed. When T-atom reactions were caused at 77 K by neutron irradiation at a high dose rate of γ-rays, there was no isotope effect (kHT/kDT≈1) on the formation of HT and DT. The production of H and D atoms by γ-irradiation of the Xe–H2–D2 mixtures was studied by ESR spectroscopy at 4.2 K. The significant effect of the dose rate of γ-rays on the HT and DT formation was interpreted in terms of competition between a tunneling reaction of thermal T atoms with H2(D2) and a combination reaction of thermal T atoms with H(D) atoms produced by γ-radiolysis.
Crystallization of Silica Gel in Alkaline Solutions. Characterization of SiO2–X2 and Other Crystalline Silicates by Comparing with Kenyaite
Authors: Muraishi Haruto 
Published: July 2006

Abstract
Several hydrated alkali silicates, SiO2–Y, SiO2–X2, and another silicate, form as intermediate products of the transformation of amorphous silica to quartz in alkaline solutions containing sodium and/or potassium salts at a temperature below 170 °C. SiO2–X2 (M2Si20O41·xH2O, M = K, Na, x = 8–10) usually appears after the formation of SiO2–Y (Na2Si14O29·xH2O, x = 9–11), and can also be prepared directly from a solution with the pH adjusted to about 9.5 or from a solution containing potassium ion alone. The resulting SiO2–X2 materials are compounds of hydrated sodium-, potassium- and (sodium, potassium)-form silicates. Another silicate precipitates directly from the solutions with the pH adjusted to below 9.5 by use of sodium carbonate and sodium hydrogencarbonate, and the product is a hydrated sodium silicate, Na2Si22O45·xH2O (x = 7–11). The structure and properties of this silicate are the same as that of natural kenyaite which is supposed to be a precursor of chert forming in evaporative alkaline lakes. These synthesized silicates have a layered structure and the interlayer alkali metal ions are exchanged by protons.
Kinetic Studies of the Incorporation of the Zinc(II) Ion into Water-Soluble N-Phenyl-Substituted Porphyrins. Deformation Effect on the Metallation Rate
Authors: Shimizu Yasuko , Taniguchi Keiko , Inada Yasuhiro , Funahashi Shigenobu , Tsuda Yasuyuki , Ito Yoshio , Inamo Masahiko , Tanaka Motoharu 
Published: July 2006

Abstract
Kinetics of zinc(II) ion incorporation into water-soluble N-phenylporphyrins (N-phenyl-5,10,20-tris(4-sulfonatophenyl)-15-phenylporphine: N-PhTPPS3 and N-phenyl-5,10,15,20-tetrakis(4-sulfonatophenyl)porphine:N-PhTPPS4) have been studied spectrophotometrically. The reaction proceeded through two parallel paths; one involving Zn2+ with a rate constant, k, and the other involving ZnOH+ with a rate constant, kOH. The rate constants (25 °C) and activation parameters at I = 0.10 M (NaNO3) were as follows (1 M = 1 mol dm−3): for N-PhTPPS3 k = (2.8 ± 0.1) × 103 M−1 s−1, kOH = (2.1 ± 0.1) × 106 M−1 s−1, ΔH≠ = 54 ± 3 kJ mol−1, ΔHOH≠ = 26 ± 2 kJ mol−1, ΔS≠ = 1 ± 10 J K−1 mol−1, ΔSOH≠ = −37 ± 8 J K−1 mol−1; for N-PhTPPS4 k = (5.3 ± 0.3) × 103 M−1 s−1, kOH = (2.0 ± 0.2) × 106 M−1 s−1, ΔH≠ = 62 ± 4 kJ mol−1, ΔHOH≠ = 34 ± 8 kJ mol−1, ΔS≠ = 35 ± 14 J K−1 mol−1, ΔSOH≠ = −11 ± 28 J K−1 mol−1. The rate of complexation for N-phenyl-substituted porphyrin was slower than that for the open-chain ligands, but much faster than that for the non-N-substituted homologues. This was due to the steric deformation of the porphyrin ring because of the presence of the bulky phenyl group. The ZnOH+ species was much more reactive in comparison to the Zn2+ species. Such a bound-ligand effect could be partly attributed to the labilization of the coordinated water molecules by electron donation from the bound hydroxide.
Effect of Water Vapor on the Thermal Behavior of Manganese cyclo-Tetraphosphate
Authors: Nariai Hiroyuki , Motooka Itaru , Tsuhako Mitsutomo 
Published: July 2006

Abstract
As a part of an investigation on the effect of water vapor on the thermal behavior of cyclo-phosphates, Mn3H2(P4O12)2·9.5H2O Mn3H2(P4m)2·9.5H2O was examined by means of DTA-TG, X-ray analysis, and HPLC-FIA. Mn3H2(P4m)2·9.5H2O lost the water of crystallization at about 145 °C. In a temperature range 165–265 °C, Mn3H2(P4m)2 anhydride decomposed to form oligophosphates(Poligo). At temperatures below 200 °C, the amounts of Poligo were more abundant under humid conditions than under dry conditions. At 265–450 °C, Poligo changed partially into polyphosphates (Ppoly) and insoluble highpolyphosphates(Phigh poly). The dehydration and condensation reactions proceeded faster under dry conditions than under humid conditions, where gradual water evolution was noted over the temperature range of 265 to 450 °C. The stable crystalline Phigh poly, Mn(PO3)2, was produced at temperatures above 450 °C, where the product was not affected by the water vapor.
Synthesis and Characterization of Vanadium-Substituted Heteropoly Molybdosulfate(VI) Complexes
Authors: Himeno Sadayuki , Osakai Toshiyuki , Saito Atsuyoshi , Hori Toshitaka 
Published: July 2006

Abstract
Monovanadium derivatives of 12-molybdosulfate(VI) and 18-molybdodisulfate(VI), [S(VMo11)O40]3− and [S2(VMo17)O62]5−, have been prepared as tetrabutylammonium (n-Bu4N+) salts from a Mo(VI)–V(V)–H2SO4–CH3CN system. Both mixed molybdosulfate(VI) comlexes were characterized by their IR and UV spectra and their voltammetric behaviors. These mixed complexes are stable in nonaqueous solutions. In a 90% (v/v) CH3CN–0.1 M (M = mol dm−3) HClO4 system, the [S(VMo11)O40]3− anion transforms spontaneously into 12-molybdovanadate(V), whereas the [S2(VMo17)O62]5− anion is stable. In a 90% (v/v) CH3CN–0.5 M HClO4 system, on the other hand, both mixed complexes change into 18-molybdodisulfate(VI), [S2Mo18O62]4−.
Exchange-Storage of a Guest Molecule in an Inclusion Crystal of 2,11,20,29-Tetramethyl-2,11,20,29-tetraaza [3.3.3.3]paracyclophane
Authors: Nonoguchi Hiroshi , Yamamura Kazuo , Tabushi Iwao , Higuchi Tai-ichi , Hirotsu Ken 
Published: July 2006

Abstract
The CHCl3 guest molecules of the 2,11,20,29-Tetramethyl-2,11,20,29-tetraaza[3.3.3.3]paracyclophane (1) inclusion complex were completely replaced by CH2BrCl when [1·CHCl3] powder simply made contact with gaseous CH2BrCl molecules. This guest exchange in the crystalline phase was confirmed by 1H NMR, GLPC, and X-ray analysis. The guest exchange was found to proceed in a biphasic manner, viz., (a) a “slow” exchange approaching a guest composition of 65% CHCl3 / 35% CH2BrCl followed by (b) a “rapid” exchange. The latter abrupt increase of the exchange rate was most reasonably attributed to a change of in crystal structure, based on the X-ray diffraction pattern of a fully guest-exchanged crystal (Type I) which was found to be very similar to that of a Type II crystal of [1·CH2BrCl].
[8+2] Cycloadditions of 2,4,6-Cycloheptatriene-1-imines with Chloroketenes: Facile and High-Yield One-Pot Synthesis of 1-Azaazulen-2(1H)-ones
Authors: Ito Kazuaki , Saito Katsuhiro , Takahashi Kensuke 
Published: July 2006

Abstract
Simple heating of mixtures of N-arylcycloheptatriene-1-imines and acyl chlorides in the presence of an excess amount of triethylamine afforded 1-azaazulen-2(1H)-ones in high yields. The intermediacy of the [8+2] cycloadducts between the 2,4,6-cycloheptatriene-1-imines and ketenes were confirmed by their isolations. Analogous results were obtained with tropone hydrazones.