bluuebunny/crossref_metadata_2025 huggingface dataset:
EXPLICIT BRAUER INDUCTION AND THE GLAUBERMAN CORRESPONDENCE
Authors: CASE ADAM , SNAITH VICTOR
Published: March 2003

We give a new proof of the Glauberman correspondence using the Explicit Brauer Induction technique developed by Boltje–Snaith–Symonds.
Expeditious and Stereoselective Synthesis of Chiral trans-β-Hydroxy-δ-lactone Systems
Authors: Miyazawa Masahiro , Matsuoka Erika , Sasaki Shinobu , Oonuma Satoshi , Maruyama Kimiyuki , Miyashita Masaaki
Published: March 2003

Expeditious and stereoselective synthesis of chiral trans-β-hydroxy-δ-lactone systems starting from γ,δ-epoxy acrylates is described which involves the regioselective ring opening of an epoxide and the intramolecular conjugate addition of a hemiacetal alkoxide anion of δ-hydroxy-α,β-unsaturated esters as key steps.
Total Synthesis of Sollasin a and Sollasin d via Photocycloaddition of Methyl 2,4-Dioxopentanoate to Methyl E-2-Methyl-2-butenoate
Authors: Hatsui Toshihide , Taga Masashi , Mori Akira , Takeshita Hitoshi
Published: March 2003

Starting from photocycloaddition of methyl 2,4-dioxopentanoate to methyl tiglate, an electron-deficient olefin, methyl-migrated monocyclofarnesyl sesquiterpenoids, d,l-sollasin a and d, anti-bacterial compounds, were synthesized.
Recognition of Helicity by Native Cyclodextrins. Highly Enantioselective Complexation of Tetrahelicene Dicarboxylic Acid with β-Cyclodextrin
Authors: Kano Koji , Negi Shigeru , Kamo Hisanobu , Kitae Takashi , Yamaguchi Masahiko , Okubo Hitoshi , Hirama Masahiro
Published: March 2003

Recognition of the helicity of 1,12-dimethylbenzo[c]-phenanthrene-5,8-dicarboxylic acid (1) by cyclodextrins (CDxs) has been studied by means of 1H NMR spectroscopy. The binding constant (K) for the (M)-1-β-CDx complex is 18700±1700 dm3 mol−1 which is much larger than that of the (P)-1-β-CDx complex (2200±100 dm3 mol−1). The results sugget the formation of the hydrogen bonds between the CO2− groups of 1 and the OH groups of twisted β-CDx in water.
Rhodium-Catalyzed Si-F Exchange Reaction between Fluorobenzenes and a Disilane. Catalytic Reaction Involving Cleavage of C-F Bonds
Authors: Ishii Yutaka , Chatani Naoto , Yorimitsu Shuhei , Murai Shinji
Published: March 2003

The reaction of functionalized fluorobenzenes, such as fluoroacetophenones and (fluorophenyl)oxazolines, with Me3SiSiMe3 in the presence of a catalytic amount of a rhodium complex results in a site-selective Si-F exchange to give ortho-(trimethylsilyl)fluorobenzenes. The reaction involves cleavage of C-F bonds.
Crown Ether-half-capped Sodium Ions as Bridges in the Formation of Complex Polymer, Structure of [{(Benzo-15-crown-5)Na}2Pd(i-mnt)2]n {i-mnt = [S2C = C(CN)2]2−}
Authors: Long De-Liang , Chen Jiu-Tong , Cui Yong , Huang Jin-Shun
Published: March 2003

The reaction of Na2Pd(i-mnt)2 and benzo-15-crown-5 leads to an unprecedented infinite chain-like [{(benzo-15-crown-5)Na}2 Pd(i-mnt)2]n, in which the conjugated species Pd(i-mnt)2 are linked by crown ether-half-capped sodium ions via Na-NC bonds.
A Supramolecule Composed of Two Phthalocyanine Dimer Radicals Linked by a Pivot Joint: Synthesis of Mono-15-Crown-5-Substituted Bis(phthalocyaninato)lutetium
Authors: Ishikawa Naoto , Kaizu Youkoh
Published: March 2003

Mono-15-crown-5-substituted bis(phthalocyaninato)lutetium was synthesized. By addition of potassium cation in solution, the phthalocyanine dimer radical formed a supramolecular structure which preserves two unpaired electrons and shows a ESR signal of a triplet state. From observed zero field splitting constant, the structure is likely to be bent rather than straightly linked.
Synthesis and Structures of (Porphinato)(thiolato)gallium(III) Complexes
Authors: Okamura Taka-aki , Nishikawa Nami , Ueyama Norikazu , Nakamura Akira
Published: March 2003

Gallium(III)-substituted P-450 models, [Ga(OEP)(SAr)] (OEP=octaethylporphinato; SAr=S-2-CF3CONHC6H4, SPh), were synthesized and the structures were determined by X-ray analysis. The gallium(III) complexes were found to be excellent structural analogues having a diamagnetic metal center.
A New Type of Cyclic Alkylacrylamide Polymer Langmuir-Blodgett Film
Authors: Feng Fei , Aoki Atsushi , Miyashita Tokuji
Published: March 2003

A high quality polymer LB film was newly prepared from adamantylacrylamide polymer without usual long alkyl chain. The measurements with XRD and cyclic voltammetry suggest that the polymer LB film with a thickness of 1.1nm and well defined molecular orientation is fabricated.
Sorption of CO2 in the Photocrosslinked PVCA Film
Authors: Matsuguchi Masanobu , Miura Jun-Ichi , Sakai Yoshiro
Published: March 2003

Sorption behavior of CO2 in the photocrosslinked poly(vinyl cinnamate) film was examined. The amount of sorbed CO2 was enhanced with the degree of crosslinking, while the amount decreased beyond ca.95% crosslinking.
Synthesis and Structural Characterization of Octanuclear Indium-Tungsten Mixed-metal Carboxylate Cluster, Na2[W3InO4(O2CEt)8]2
Authors: Xu Li , Cui Yong , Huang Jinshun
Published: March 2003

The insoluble indium-tungsten chain cluster, Na2[W3InO4(O2CEt)8]2, has been prepared from the self-assembly reaction of W(CO)6, Na2WO4·2H2O and InCl3 in propionic anhydride at 120 °C. The octametallic dianion, [W3InO4(O2CEt)8]22−, consists of the two incomplete cuboidal units [W3O4(O2CEt)8]4− which are centro-symmetrically bridged by two In3+. The In3+ ions dissociate from the trinuclear units in aqueous acidic solution.
Effects of the π and π* Orbitals of the 5-Unsaturated Substituents on the π-Facial Selectivities in the Diels-Alder Reactions of Cyclopentadienes
Authors: Ishida Masaru , Kobayashi Hiroki , Tomohiro Shingo , Wasada Hiroaki , Inagaki Satoshi
Published: March 2003

The exclusive anti-π-facial selectivity in the Diels-Alder reaction of 5-formylpentamethylcyclopentadine, Cp*-CHO, was proposed to come from the π-HOMO distortion of the diene due to the perturbation by low-lying π*orbital on the substituent. The role of the π* orbital was experimentally substantiated by a considerable amount of syn-attack products in the reactions of Cp*-CH=NOH and Cp*-CH=CH2 having high-lying substituent π* orbitals.
Reaction of Aromatic Aldehydes with (Dialkylamino)magnesium Reagents. Formation of 1,2-Diaryl-1,2-ethenediamines
Authors: Kobayashi Kazuhiro , Uneda Tomokazu , Uchida Masaharu , Furuta Yoshihisa , Tanmatsu Miyuki
Published: March 2003

(Dialkylamino)magnesium reagents, derived from secondary amines and ethylmagnesium bromide, have been found to react with aromatic aldehydes to give 1,2-diaryl-1,2-bis(dialkylamino)ethenes in moderate to good isolated yields.
New Route for Preparation of Layered Manganese Oxides with Multivalent Metals in the Interlayer
Authors: Yang Xiaojing , Kanoh Hirofumi , Tang Weiping , Liu Zong-huai , Ooi Kenta
Published: March 2003

Fe(III)-, Cr(III)-, Al(III)- and La(III)-buserite type manganese oxides were synthesized from a hydrothermally treated, well-crystallized Na+-birnessite through a two-step ion-exchange route, M/Mg2+ ion exchange subsequent to Mg2+/Na+exchange. The ion-exchange reactions progressed smoothly and the layered manganese oxides with multivalent metal ions in the interlayer could be obtained at room temperature.
Extraordinarily Low Cycloreversion Quantum Yields of Photochromic Diarylethenes with Methoxy Substituents
Authors: Shibata Katsunori , Kobatake Seiya , Irie Masahiro
Published: March 2003

Diarylperfluorocyclopentenes having 2-methoxy-5-phenylthiophene as the aryl groups were synthesized. Introduction of two methoxy substituents instead of methyl groups at the reactive carbons of 1,2-bis(5-phenyl-3-thienyl)perfluorocyclopentene decreased the photocycloreversion quantum yield by a factor of 103, while the cyclization quantum yield was similar.
MMA Modified Inorganic/Organic Hybrid Membranes by Sol–Gel Technology
Authors: Zhang Guochang , Chen Yunfa , Wu Zhenjiang , Xie Yusheng
Published: March 2003

The inorganic/organic hybrid membranes modified by MMA were deposited on the porous α-Al2O3 substrates (pore size, 2 µm) by the sol–gel technology. It was found that the introduction of MMA can not only improve the membrane formation properties, but also increase the selectivity of O2/N2 and O2/CO2. On the other hand, the modified hybrid membranes have more dense structure.
New Synthesis of Pinacols By Oxidative Coupling Mediated by 1,2-Disulfides as Dehydrogenating Reagents under Irradiation
Authors: Fujisawa Hidehiko , Hayakawa Yuichiro , Sasaki Yasuhiro , Mukaiyama Teruaki
Published: March 2003

A new procedure for the synthesis of pinacols is established by way of oxidative coupling reaction of benzylethers with a thiyl radical, a hydrogen acceptor, generated from disulfide under UV irradiation.
Improvement of the Hydrothermal Stability of Siliceous MCM-48 by Fluorination
Authors: Xia Q-H , Hidajat K , Kawi S
Published: March 2003

The siliceous MCM-48 molecular sieve, a member of the M41s family, is prepared for the first time in the presence of fluoride ions, and the hydrothermal stability of fluorinated MCM-48 framework is found to be remarkably improved as compared with those synthesized in other media.
Reaction of 1-Disilagermirene with Benzaldehyde: An Unexpected Combination of Cycloaddition and Insertion Pathways
Authors: Lee Vladimir Ya , Ichinohe Masaaki , Sekiguchi Akira
Published: March 2003

New strained bicyclic compounds were formed by the reaction of tetrakis[di-tert-butyl(methyl)silyl]-1-disilagermirene 1 with benzaldehyde, involving cycloaddition following the rearrangement and insertion pathways. Reaction of 1 with PhCHO gave three different products: two mono-adducts 2, 3 and one bis-adduct 4, depending on the ratio of the reagents and the reaction conditions.
Asymmetric Aldol Polymerization of Bis(trimethylsilylketene thioacetal) and Dialdehyde
Authors: Komura Kenichi , Itsuno Shinichi
Published: March 2003

Asymmetric repetitive Mukaiyama aldol reaction between bis(trimethylsilylketene thioacetal) and dialdehydes proceeded in the presence of chiral oxazaborolidinone to afford optically active poly(β-hydroxy thioester)s. Degree of asymmetric induction during polymerization was evaluated both by a model reaction and chiral HPLC analysis of degradation products of the chiral polymers.
Formation of an Optically Active Helical Polyisocyanide Langmuir–Blodgett Film
Authors: Feng Fei , Miyashita Tokuji , Takei Fumie , Onitsuka Kiyotaka , Takahashi Shigetoshi
Published: March 2003

An optically active helical polyisocyanide synthesized with a screw-sense-selective living polymerization formed a condensed monolayer on the water surface and was transferred onto a solid support as Y-type LB film with an ordered orientation.
Photocyanation of Pyrene in an Oil-in-Water Emulsion System
Authors: Kitagawa Fumihiko , Murase Masato , Kitamura Noboru
Published: March 2003

Photoirradiation of pyrene in the presence of 1,4-dicyanobenzene and NaCN in a benzonitrile/water mixture (1/100, vol/vol%) under vigorous stirring gave 1-cyanopyrene (PyCN) in an 83% yield, while an analogous reaction in acetonitrile/water (9/1, vol/vol%) yielded PyCN in a 61% yield.
Synthesis Conditions and Catalytic Properties of Highly Acidic Zeolite, UTM-1
Authors: Yamamoto Katsutoshi , Uneme Motonori , Plévert Jacque , Tatsumi Takashi
Published: March 2003

Preferable synthesis conditions for zeolite UTM-1 are studied; UTM-1 is crystallized under similar conditions to those of MCM-22, although it prefers high SiO2/Al2O3 ratio in mother gel. UTM-1, composed of the same basic building unit as ZSM-5, shows strong acidity comparable to that of ZSM-5. Although small aperture of UTM-1 actually restricts the catalytic activities, its large outer surface area enables the high catalytic activity in reactions occurring at the outer surface of catalyst.
A Novel Lithium Salt with a Chelate Compound of Phosphorus for Lithium Battery Electrolytes
Authors: Nanbu Noritoshi , Shibazaki Takatsugu , Sasaki Yukio
Published: March 2003

We have synthesized a novel Li salt with a chelate compound of phosphorus, lithium tris[4-methyl-1,2-benzenediolato(2–)-O,O′]phosphate (4-MLTBP). The thermal stability and electrolytic properties of 4-MLTBP, and the charge–discharge characteristics of a lithium electrode are investigated. The thermal decomposition temperature of 4-MLTBB is higher than those of a common lithium salt with phosphorus, LiPF6, and lithium tris[1,2-benzenediolato(2–)-O,O′]phosphate, which we previously synthesized. The specific conductivities and the cycling efficiencies become higher in an ethylene carbonate– and a propylene carbonate–dimethyl carbonate equimolar binary solutions containing a mixture of 4-MLTPB with LiPF6.
Photocatalytic Activity for Water Decomposition of RuO2-Loaded SrIn2O4 with d10 Configuration
Authors: Sato Junya , Saito Nobuo , Nishiyama Hiroshi , Inoue Yasunobu
Published: March 2003

A p-block metal oxide of SrIn2O4 with d10 configuration was found to be a new photocatalyst for the overall splitting of water when combined with RuO2.
Synthesis, Structure, and Optical Characterization of Sandwich-type (2,3-Naphthalocyaninato)(octaethylporphyrinato)europium(III)
Authors: Furuya Fumio , Kobayashi Nagao , Bian Yongzhong , Jiang Jianzhuang
Published: March 2003

The heteroleptic sandwich dimer of the title {Eu(OEP)(2,3-Nc)} has been synthesized, and its crystal structure, electronic absorption, and magnetic circular dichroism are discussed.
Cover Picture: Large Parity‐Violation Effects in Heavy‐Metal‐Containing Chiral Compounds (Angew. Chem. Int. Ed. 11/2003)
Authors: Schwerdtfeger Peter , Gierlich Johannes , Bollwein Tobias
Published: March 2003

What you see is not always what you get. The cover picture shows Lake Matheson in New Zealand, famous for its reflections of Mt. Cook and Mt. Tasman, where the still waters can make it difficult to tell the mountains from their reflection. Mirror‐image symmetry can break down in the microscopic world (parity violation), and high‐resolution spectroscopy cannot distinguish between molecular enantiomers. The [(C5H5)Re(CO)(NO)I] molecule gives very large parity‐violation energy differences that bring us closer to detecting such tiny effects. More details of this study are given in the Communication by P. Schwerdtfeger et al. on page 1293ff.
Crystallographic report: Bis[bis(N,N‐diethyldithiocarbamato)zinc(II)] (trans‐1,2‐bis(4‐pyridyl)ethylene)trans‐1, 2‐bis(4‐pyridyl)ethylene lattice adduct
Authors: Lai Chian Sing , Tiekink Edward R. T.
Published: March 2003

The dimeric and centrosymmetric structure of [Zn(S2CNEt2)2(trans‐NC5H4C(H)C(H)C5H4N)]2 shows bidentate coordination by the dithiocarbamate ligands and a distorted square pyramidal geometry for zinc, defined by a NS4 donor set with the N atom in the apical position. The compound co‐crystallises with a centrosymmetric molecule of trans‐NC5H4C(H)C(H)C5H4N that does not form a significant interaction to the Zn atom. Copyright © 2003 John Wiley & Sons, Ltd.
Crystallographic report: (4,4′‐Bipyridine)bis[bis(N,N‐diethyldithiocarbamato)zinc(II)]
Authors: Lai Chian Sing , Tiekink Edward R. T.
Published: March 2003

The structure of [Zn(S2CNEt2)2]2(4,4′‐bipy) shows two independent dimeric molecules, one located about a centre of inversion, the other lying on a two fold axis containing the zinc atoms. Bidentate coordination by the dithiocarbamate ligands and a distorted square pyramidal geometry are found for two of zinc atoms whereas for the third zinc atom, the geometry is intermediate between square pyramidal and trigonal bipyramidal, a result that underscores the flexibility of coordination in these systems. Copyright © 2003 John Wiley & Sons, Ltd.
Synthesis, structure characterization and insecticidal activity of some triorganotin dithiocarbamates
Authors: Eng George , Song Xueqing , Duong Quyen , Strickman Daniel , Glass Jacqulin , May Leopold
Published: March 2003

A series of triorganotin dithiocarbamates

has been synthesized using a low‐temperature method. Their structures have been characterized by IR, Mössbauer and NMR spectroscopies. In the solid state, an unsymmetrical chelation of the dithiocarbamate ligand was found in all the compounds synthesized. The observation of two SnS distances in the compounds was confirmed in the crystal structure of tricyclohexyltin N‐n‐butyldithiocarbamate. In solution, the compounds were found to exhibit distorted tetrahedral structures. The insecticidal activities of the title compounds were screened against the second larval instar of the Anopheles stephensi Liston and Aedes aegypti (L.) mosquitoes. Results from the screening studies indicated that the triorganotin dithiocarbamates were effective larvicides against both species of larvae. However, there were no significant activity differences between the triphenyltin and tricyclohexyltin derivatives. A quantitative structure–activity relationship was also developed for the An. stephensi. Copyright © 2003 John Wiley & Sons, Ltd.
Multisite Catalysis: A Mechanistic Study of β‐Lactone Synthesis from Epoxides and CO—Insights into a Difficult Case of Homogeneous Catalysis
Authors: Molnar Ferenc , Luinstra Gerrit A. , Allmendinger Markus , Rieger Bernhard
Published: March 2003

Carbonylation of epoxides with a combination of Lewis acids and cobalt carbonyls was studied by both theoretical and experimental methods. Only multisite catalysis opens a low‐energy pathway for trans opening of oxirane rings. This ring‐opening reaction is not easily achieved with a single‐site metal catalyst due to structural and thermodynamic constraints. The overall reaction pathway includes epoxide ring opening, which requires both a Lewis acid and a tetracarbonylcobaltate nucleophile, yielding a cobalt alkyl—alkoxy–Lewis acid moiety. After CO insertion into the CoCalkyl bond, lactone formation results from a nucleophilic attack of the alkoxy Lewis acid entity on the acylium carbon atom. A theoretical study indicates a marked influence of the Lewis acid on both ring‐opening and lactone‐formation steps, but not on carbonylation. Strong Lewis acids induce fast ring opening, but slow lactone formation, and visa versa: a good balance of Lewis acidity would give the fastest catalytic cycle as all steps have low barriers. Experimentally, carbonylation of propylene oxide to β‐butyrolactone was monitored by online ATR‐IR techniques with a mixture of tetracarbonylcobaltate and Lewis acids, namely BF3, Me3Al, Et2Al+⋅diglyme, and a combination of Me3Al/dicobaltoctacarbonyl. We found that the last two mixtures are extremely active in lactone formation.
Tetra‐ and Octalactam Macrocycles and Catenanes with Exocyclic Metal Coordination Sites: Versatile Building Blocks for Supramolecular Chemistry
Authors: Li Xi‐you , Illigen Jens , Nieger Martin , Michel Steffen , Schalley Christoph A.
Published: March 2003

The synthesis of a new tetralactam macrocycle and the simultaneous formation of catenanes and larger octalactam macrocycles is reported. These species bear 2,2′‐biquinoline moieties suitably positioned to bind a metal center at the outer periphery of the macrocycles. 1H NMR chemical shifts permit the unambiguous distinction of transoid and cisoid conformations of the biquinoline moiety, thereby allowing an unequivocal identification of the catenane and octalactam structures, despite the fact that both have the same elemental composition and bear identical structural subunits. With the aid of an anion template effect, rotaxanes can be prepared from the smaller tetralactam macrocycle. These reveal significantly altered requirements in terms of the stopper size as compared to previously reported tetralactam wheels. Several copper(I)‐mediated dimers and a (bpy)2RuII complex (bpy=2,2′‐bipyridine) have been synthesized from the tetralactam macrocycle and the rotaxanes. The anion binding abilities of the tetralactam macrocycle and its (bpy)2RuII complex in DMSO have been compared by 1H NMR titration experiments, which revealed significantly enhanced binding by the metal complex. Mass spectrometry has been used to study the potential formation of larger assemblies of copper(I) and the catenane built‐up from two tetralactam macrocycles. Indeed, a 2:2 complex was identified. In contrast, the octalactam macrocycle of the same elemental composition yields only 1:1 complexes, with the CuI ion connecting its two biquinoline moieties in the center of a figure‐eight‐shaped molecule. Molecular modeling studies support the structural assignments made.
Structural Investigation of High‐Valent Manganese–Salen Complexes by UV/Vis, Raman, XANES, and EXAFS Spectroscopy
Authors: Feth Martin P. , Bolm Carsten , Hildebrand Jens P. , Köhler Manuela , Beckmann Oliver , Bauer Matthias , Ramamonjisoa Rivo , Bertagnolli Helmut
Published: March 2003

XANES and EXAFS spectroscopic studies at the Mn–K‐ and Br–K‐edge of reaction products of (S,S)‐(+)‐N,N′‐bis(3,5‐di‐tert‐butylsalicylidene)‐1,2‐cyclohexanediaminomanganese(III) chloride ([(salen)MnIIICl], 1) and (S,S)‐(+)‐N,N′‐bis(3,5‐di‐tert‐butylsalicylidene)‐1,2‐cyclohexanediaminomanganese(III) bromide ([(salen)MnIIIBr], 2) with 4‐phenylpyridine N‐oxide (4‐PPNO) and 3‐chloroperoxybenzoic acid (MCPBA) are reported. The reaction of the MnIII complexes with two equivalents of 4‐PPNO leads to a hexacoordinated compound, in which the manganese atom is octahedrally coordinated by four oxygen/nitrogen atoms of the salen ligand at an average distance of ≈1.90 Å and two additional, axially bonded oxygen atoms of the 4‐PPNO at 2.25 Å. The oxidation state of this complex was determined as ≈+IV by a comparative study of MnIII and MnV reference compounds. The green intermediate obtained in reactions of MCPBA and solutions of 1 or 2 in acetonitrile was investigated with XANES, EXAFS, UV/Vis, and Raman spectroscopy, and an increase of the coordination number of the manganese atoms from 4 to 5 and the complete abstraction of the halide was observed. A formal oxidation state of IV was deduced from the relative position of the pre‐edge 1s→3d feature of the X‐ray absorption spectrum of the complex. The broad UV/Vis band of this complex in acetonitrile with λmax=648 nm was consistent with a radical cation structure, in which a MCPBA molecule was bound to the MnIV central atom. An oxomanganese(V) or a dimeric manganese(IV) species was not detected.
Time‐Resolved Resonance Raman and Density Functional Study of an Azirine Intermediate in the 2‐Fluorenylnitrene Ring‐Expansion Reaction To Form a Dehydroazepine Product
Authors: Ong Shing Yau , Zhu Peizhi , Leung King Hung , Phillips David Lee
Published: March 2003

We report time‐resolved resonance Raman spectra for the azirine intermediate produced in the 2‐fluorenylnitrene ring‐expansion reaction to form a dehydroazepine product. The Raman bands obtained with a 252.7 nm probe wavelength and 500 ns delay time exhibit reasonable agreement with predicted vibrational frequencies from density functional calculations for two isomers of azirine intermediates that may be formed from a 2‐fluorenylnitrene precursor. The Raman bands observed for delay times of 15 ns and 10 μs were consistent with predicted vibrational frequencies from density functional calculations for the 2‐fluorenylnitrene and dehydroazepine product species as well as previously reported 416 nm time‐resolved Raman spectra obtained on the ns and μs time scales. Our results demonstrate that the 2‐fluorenylnitrene ring‐expansion reaction to produce dehydroazepine products proceeds via relatively long‐lived 2‐fluorenylnitrene and azirine intermediates. Substitution of a phenyl ring para to the nitrene group of phenylnitrene appears to lead to significant changes in the ring‐expansion reaction so that longer lived arylnitrene and azirine intermediates can be observed. This should enable the chemical reactivity of azirine intermediates formed from arylnitrenes to be examined more readily.
Asymmetric Synthesis with 6‐tert‐Butyl‐5‐methoxy‐6‐methyl‐3,6‐dihydro‐2H‐1,4‐oxazin‐2‐one as a New Chiral Glycine Equivalent: Preparation of Enantiomerically Pure α‐Tertiary and α‐Quaternary α‐Amino Acids
Authors: Koch Claus‐Jürgen , Šimonyiová Soňa , Pabel Jörg , Kärtner Annerose , Polborn Kurt , Wanner Klaus Theodor
Published: March 2003

The chiral oxazinone 2 has been developed as a new chiral glycine equivalent for the asymmetric synthesis of mono‐ and disubstituted α‐amino acids. It is derived from the α‐hydroxycarboxylic acid 1, which serves as a chiral auxiliary, and is easily accessible in enantiomerically pure form by optical resolution of the racemic compound (RS)‐1. For alkylation reactions, 2 was deprotonated with sBuLi or phosphazenic base. Subsequent treatment with alkyl halides yielded the monosubstituted compounds 13/14a−c, e, f, (ent)‐13d, (ent)‐14d, while a second alkylation step, via the corresponding enolates, provided the disubstituted compounds 17/18a−d. Both alkylation steps proceeded with good yields and excellent diastereoselectivities (up to 99% de) and even less reactive electrophiles such as isopropyl iodide could be used. The results obtained in this reaction supported the assumption that the enolate of 2, as well as those of the monosubstituted derivatives of 2, have less tendency to form the aggregates that hamper alkylation reactions with other systems with higher oxygen content. From the major diastereomers of both the mono‐ and the disubstituted derivatives of 2 the corresponding α‐amino acids 33a−c and 34a−d were obtained in high enantiomeric purity by hydrolytic cleavage of the oxazinone ring, accomplished either in two steps with aqueous TFA and aqueous NaOH or in one with either aqueous NaOH or 3 N HBr. Alkylation of the enolate ions of (S)‐2 or (R)‐2 with epichlorohydrins as bifunctional electrophiles provided the hydroxymethylenecyclopropyl derivatives 21 and 22. Hydrolysis of 21 and 22 afforded the free amino acids 35 and (ent)‐35. Reductive amination with aniline after oxidation of 21 and 22 to the corresponding aldehydes 24 and 26 provided the compounds 25 and 27, whereas Mitsunobu treatment of 21 and 22 with 1‐phenyl‐3‐(trifluoroacetyl)urea (28) afforded the urea derivatives 29 and 31. Hydrolysis of these compounds yielded the corresponding 1‐aminocylopropanecarboxylic acid derivatives 36/(ent)‐36 and (ent)‐37. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Mono and double polar [4 + 2+] Diels–Alder cycloaddition of acylium ions with O‐heterodienes
Authors: Meurer Eduardo C. , Eberlin Marcos N.
Published: March 2003

Gas‐phase reactions of acylium ions with α,β‐unsaturated carbonyl compounds were investigated using pentaquadrupole multiple‐stage mass spectrometry. With acrolein and metacrolein, CH3—C+O, CH2CH—C+O, C6H5—C+O, and (CH3)2N—C+O react to variable extents by mono and double polar [4 + 2+] Diels–Alder cycloaddition. With ethyl vinyl ketone, CH3—C+O reacts exclusively by proton transfer and C6H5—C+O forms only the mono cycloadduct whereas CH2CH—C+O and (CH3)2N—C+O reacts to great extents by mono and double cycloaddition. The positively charged acylium ions are activated O‐heterodienophiles, and mono cycloaddition occurs readily across their C+O bonds to form resonance‐stabilized 1,3‐dioxinylium ions which, upon collisional activation, dissociate predominantly by retro‐addition. The mono cycloadducts are also dienophiles activated by resonance‐stabilized and chemically inert 1,3‐dioxonium ion groups, hence they undergo a second cycloaddition across their polarized CC ring double bonds. 18O labeling and characteristic dissociations displayed by the double cycloadducts indicate the site and regioselectivity of double cycloaddition, which are corroborated by Becke3LYP/6–311++G(d,p) calculations. Most double cycloadducts dissociate by the loss of a RCO2COR1 molecule and by a pathway that reforms the acylium ion directly. The double cycloadduct of the thioacylium ion (CH3)2N—C+S with acrolein dissociates to (CH3)2N—C+O in a sulfur‐by‐oxygen replacement process intermediated by the cyclic monoadduct. The double cycloaddition can be viewed as a charge‐remote type of polar [4 + 2+] Diels–Alder cycloaddition reaction. Copyright © 2001 John Wiley & Sons, Ltd.
Comparative proteomics based on stable isotope labeling and affinity selection
Authors: Regnier Fred E. , Riggs Larry , Zhang Roujian , Xiong Li , Liu Peiran , Chakraborty Asish , Seeley Erin , Sioma Cathy , Thompson Robert A.
Published: March 2003

Disease, external stimuli (such as drugs and toxins), and mutations cause changes in the rate of protein synthesis, post‐translational modification, inter‐compartmental transport, and degradation of proteins in living systems. Recognizing and identifying the small number of proteins involved is complicated by the complexity of biological extracts and the fact that post‐translational alterations of proteins can occur at many sites in multiple ways. It is shown here that a variety of new tools and methods based on internal standard technology are now being developed to code globally all peptides in control and experimental samples for quantification. The great advantage of these stable isotope‐labeling strategies is that mass spectrometers can rapidly target those proteins that have changed in concentration for further analysis. When coupled to stable isotope quantification, targeting can be further focused through chromatographic selection of peptide classes on the basis of specific structural features. Targeting structural features is particularly useful when they are unique to types of regulation or disease. Differential displays of targeted peptides show that stimulus‐specific markers are relatively easy to identify and will probably be diagnostically valuable tools. Copyright © 2002 John Wiley & Sons, Ltd.
Tandem mass spectrometry of Cu(II) complexes: the effects of ligand donor group on dissociation
Authors: Chaparro Amanda L. , Vachet Richard W.
Published: March 2003

A quadrupole ion trap mass spectrometer was used to study the dissociation patterns of Cu(II) complexes with various linear podand ligands. Cu(II) complexes having different combinations of nitrogen‐, oxygen‐ and sulfur‐containing terminal functionality attached to a diethylenetriamine (DIEN) framework were ionized by electrospray and collision‐induced dissociation (CID) was used to generate product ions. Regardless of the particular functional groups present, the complexes undergo predominantly heterolytic cleavages of carbon–carbon bonds along the DIEN backbone with Cu remaining coordinated to one of the two terminal functional groups. Upon dissociation, Cu's preference to remain coordinated to a particular functional group follows the trend thioether > amine > imidazole > pyridine > ether. A simple evaluation of this trend based upon metal‐functional group binding affinity appears not to be adequate for fully explaining these observations. The tendency of Cu(II) to be reduced upon dissociation helps explain the observed trend, as does the flexibility of the functional group, which affects its ability to orient its dipole effectively toward the metal. Copyright © 2003 John Wiley & Sons, Ltd.
Charge state dependent collision‐induced dissociation of native and reduced porcine elastase
Authors: Hogan Jason M. , McLuckey Scott A.
Published: March 2003

The [M + 20H]20+–[M + 12H]12+ charge states of native and reduced porcine elastase, a 25.9 kDa serine protease, were subjected to collisional activation in a quadrupole ion trap. For most charge states, ion parking was used to increase the number of parent ions over that yielded directly by electrospray. Ion–ion proton transfer reactions were used to reduce product ion charge states largely to +1 to simplify spectral interpretation. Both forms of the protein show charge state dependent fragmentation behavior. The native protein, which contains four disulfide linkages, shows almost no evidence for fragmentation within the regions of the protein linked by disulfide bonds. However, at the lowest charge states studied, evidence for cleavage of a least one of the disulfide bonds was evident in the appearance of a c‐type ion. The highest charge states of native elastase showed several prominent cleavages C‐terminal to valine residues. As the charge state decreased, however, preferential cleavages at acidic amino acid residues became important. The reduced form of the protein did not show particularly prominent cleavages at valine residues. However, many of the same preferential cleavages at acidic amino acid residues noted for the native protein were also observed in the same charge states of the reduced protein. The reduced protein also showed additional cleavages from regions of the protein that are ordinarily protected by disulfide linkages in the native form. Copyright © 2003 John Wiley & Sons, Ltd.
Interactions among nitric oxide and Bcl‐family proteins after MPP+ exposure of SH‐SY5Y neural cells I: MPP+ increases mitochondrial NO and Bax protein
Authors: Dennis Jameel , Bennett James P.
Published: March 2003

We studied effects of methylpyridinium ion (MPP+) on apoptosis, cell death and regulation of Bcl‐2‐family proteins in SH‐SY5Y neuroblastoma cells. MPP+ increased intracellular accumulation of DNA‐histone complexes as a measure of apoptosis and decreased intracellular calcein fluorescence as a measure of cell death. If ATP synthesis was supported, MPP+ caused apoptosis in ρ0 cells devoid of electron transport function. Caspase inhibition blocked apoptosis but not cell death caused by MPP+. MPP+ increased levels of Bax, Bcl‐2 and Bcl‐XL proteins ∼2‐fold over 24 hr, with Bax increases occurring first; Bax did not increase in ρ0 cells. The Bax increase, but not that of Bcl‐2 or Bcl‐XL, was dependent on nitric oxide (NO) and seemed post‐transcriptional. DAF‐FM imaging revealed increased mitochondrial NO within hours of exposure to MPP+. Western blots showed a constitutive ∼130 kD protein that stained for NOS‐2, consistent with reports of mitochondrial nitric oxide synthase (mtNOS). MPP+ caused a NO‐dependent release of cytochrome C into cytoplasm. MPP+ increases mitochondrial NO levels and causes a NO‐dependent increase in Bax protein, providing a mechanism for NOS‐and Bax‐dependency of MPTP neurotoxicity in vivo and implicating locally produced NO as a signaling molecule used by mitochondria to manipulate cell death cascades. © 2003 Wiley‐Liss, Inc.
Nanoscopic aspects of radiobiological damage: Fragmentation induced by secondary low‐energy electrons
Authors: Sanche Léon
Published: March 2003

I.
Introduction
349

II.
Experimental Methods
352

A. Thin‐Film Preparation
352

B. Electron‐Stimulated Desorption (ESD) of Ions and Neutral Species
353

C. Analysis by Electrophoresis
354

III.
Interpretation of the Dependence of Ion and Neutral Yields on Incident Electron Energy
354

IV.
Results and Discussion
356

A. Desorption of Ions and Neutral Species from Water‐Ice Films Induced by Low‐Energy Electrons (LEEs)
356

B. Anion ESD from Thin Films of Deoxyribose Analogs
358

C. Anion ESD from Thin Films of DNA Bases
359

D. Neutral‐Species Desorption from Short Single‐DNA Strands Induced by LEEs
360

E. Sequence‐Specific Damage Induced by LEE Impact on Oligonucleotides
362

F. Anion ESD from the Peptide and Disulfide Bridges of Proteins
364

G. LEE Damage to Plasmid DNA
365

V.
Summary and Conclusions
366

Acknowledgments
367

References
367

Low‐energy electrons (LEEs) are produced in large quantities in any type of material irradiated by high‐energy particles. In biological media, these electrons can fragment molecules and lead to the formation of highly reactive radicals and ions. The results of recent experiments performed on biomolecular films bombarded with LEEs under ultra‐high vacuum conditions are reviewed in the present article. The major type of experiments, which measure fragments produced in such films as a function of incident electron energy (0.1–45 eV), are briefly described. Examples of the results obtained from DNA films are summarized along with those obtained from the fragmentation of elementary components of the DNA molecule (i.e., thin solid films of H2O, DNA bases, sugar analogs, and oligonucleotides) and proteins. By comparing the results of these different experiments, it is possible to determine fundamental mechanisms that are involved in the dissociation of biomolecules and the production of single‐ and double‐strand breaks in DNA, and to show that base damage is dependent on the nature of the bases and on their sequence context. Below 15 eV, electron resonances (i.e., the formation of transient anions) play a dominant role in the fragmentation of all biomolecules investigated. These transient anions fragment molecules by decaying into dissociative electronically excited states or by dissociating into a stable anion and a neutral radical. These fragments usually initiate other reactions with nearby molecules, causing further chemical damage. The damage caused by transient anions is dependent on the molecular environment. © 2003 Wiley Periodicals, Inc., Mass Spec Rev 21:349–369, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mas.10034
Local a posteriori error estimates and adaptive control of pollution effects
Authors: Liao Xiaohai , Nochetto Ricardo H.
Published: March 2003

Local a posteriori error estimators are derived for linear elliptic problems over general polygonal domains in 2d. The estimators lead to a sharp upper bound for the energy error in a local region of interest. This upper bound consists of H1‐type local error indicators in a slightly larger subdomain, plus weighted L2‐type local error indicators outside this subdomain, which account for the pollution effects. This constitutes the basis of a local adaptive refinement procedure. Numerical experiments show a superior performance than the standard global procedure as well as the generation of locally quasi‐optimal meshes. © 2003 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 19: 421–442, 2003
Diffusion in glassy polymers
Authors: Vrentas J. S. , Vrentas C. M.
Published: March 2003

Two versions of the free‐volume theory of diffusion are compared by considering differences in the predictions for the activation energy for the diffusion process. A number of data‐theory comparisons for free‐volume theory are discussed and evaluated. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 785–788, 2003
Effects of anti‐ecdysteroid quaternary derivatives of azole analogues of metyrapone on the post‐embryonic development of the red cotton bug (Dysdercus cingulatus F)
Authors: Bélai Iván , Fekete Gábor
Published: March 2003

In order to improve the larvicidal activity of the azole analogues of metyrapone, previously found to have a strong inhibitory activity on ecdysone 20‐monooxygenase (E‐20‐M) from the fleshfly Neobellieria bullata Parker, soft‐alkylated compounds (3‐(1,1‐dimethyl‐2‐oxo‐2‐phenylethyl)‐1‐dodecanoyloxymethyl‐1H‐imidazolium chloride, sPIM) and (1‐(1,1‐dimethyl‐2‐oxo‐2‐phenylethyl)‐4‐dodecanoyloxymethyl‐1H‐1,2,4‐triazolium chloride, sPTM), derivatives of phenyl‐imidazolyl‐metyrapone (PIM) and phenyl‐1,2,4‐triazolyl‐metyrapone (PTM), respectively, were synthesized. Both sPIM and sPTM, designed as propesticides, inhibited E‐20‐M in vitro at 10−4 M concentration, which was unexpected since they had been expected to be inactive in vitro and to gain activity only within the organism. sPTM significantly delayed the pupariation of N bullata larvae and this effect could be reversed by the simultaneous application of 20‐hydroxyecdysone (20E), supporting the hypothesis that sPTM can act by interfering with the moulting hormone system. Due to this in vitro activity, sPTM and sPIM cannot be considered to be simple drug precursors, and their structure should contain structural elements (pharmacophores) responsible for the observed biological effects. In order to examine this hypothesis, derivatives of sPTM and sPIM were synthesised in which the hydrolytically labile N+—CH2O(CO)— moiety was changed to the more stable N+—CH2CH2(CO)—group. In three new stable derivatives, a dodecylamino or a phenyl group, respectively, is attached to the carbonyl group to obtain PTM and PIM derivatives quaternised with a 2‐dodecylcarbamoylethyl or a 3‐oxo‐3‐phenylpropyl group. In one derivative, the 2‐oxo‐2‐phenylethyl quaternising group has one fewer carbon atom. In addition to their moderate activity (LC50 = 10−6–10−5 M) against the red cotton bug Dysdercus cingulatus F, they delayed development and caused developmental abnormalities, including mortality in the pharate phase, mortality during moulting and wing deformations. These symptoms and the delay in development are characteristic of known compounds inhibiting the synthesis of 20E or interfering in the moulting processes. The facts that the frequent appearance of insects with developmental abnormalities and the delay in development could be reversed by co‐application of 20E indicate that the moulting system might be the site of action. We presume that the quaternary azole derivatives of PIM and PTM can themselves also interact with the moulting system.

© 2003 Society of Chemical Industry
Actions of the sodium channel inhibitor 202W92 on rat midbrain dopaminergic neurons
Authors: Caputi Luigi , Hainsworth Atticus , Guatteo Ezia , Tozzi Alessandro , Stefani Alessandro , Spadoni Francesca , Leach Michael , Bernardi Giorgio , Mercuri Nicola B.
Published: March 2003

Excessive glutamatergic activity is implicated in Parkinson's disease (PD) and sodium channel blockade, resulting in inhibition of glutamate release, is a potential therapeutic approach to PD therapy. Beneficial effects of riluzole and lamotrigine have been reported in animal models of PD, but these compounds have relatively low potency as sodium channel inhibitors and also inhibit N and P/Q‐type calcium channels. 202W92, a structural analog of lamotrigine, is a potent sodium channel inhibitor, with no effect on N, P/Q‐type channels. Here we present the effects of 202W92 on single patch‐clamped dopaminergic neurons. 202W92 (≥10 μM) inhibited spontaneous action potential firing and reduced amplitude and frequency of evoked action potentials. It also inhibited the frequency of 4‐aminopyridine (4‐AP)‐ and electrically evoked excitatory postsynaptic currents (EPSCs) and GABAergic inhibitory postsynaptic currents (IPSCs), with >80% inhibition at 10 μM (IC50 1.5 μM). EPSC and IPSC amplitudes were partially inhibited. 202W92 did not affect postsynaptic responses to locally applied glutamate and GABA, nor spontaneously occurring mini‐IPSCs. These actions of 202W92 are compatible with sodium channel inhibition and depression of transmitter release. Synapse 48:123–130, 2003. © 2003 Wiley‐Liss, Inc.
Biosynthesis of hepoxilins: evidence for the presence of a hepoxilin synthase activity in rat insulinoma cells
Authors: Shankaranarayanan Pattabhiraman , Ciccoli Roberto , Nigam Santosh
Published: March 2003

The 12(S)‐lipoxygenase (12‐LOX) pathway of arachidonic acid (AA) metabolism after dioxygenation to 12(S)‐hydroperoxy‐eicosatetraenoic acid is bifurcated in a reduction route to formation of 12(S)‐hydroxy‐eicosatetraenoic acid (12‐HpETE) and an isomerization route to formation of hepoxilins. Interestingly, we found that the rat insulinoma RINm5F cells, which are devoid of cytoplasmic glutathione peroxidase (cGPx)/phospholipid hydroperoxide glutathione peroxidase (PHGPx), produce solely hepoxilin A3 (HXA3). Since HXA3 synthesis was abolished in heat‐denatured or cGPx‐ or PHGPx‐transfected cells, it was tempting to speculate that a HXA3 synthase activity regulated by cGPx/PHGPx is present. To confirm this assumption we incubated AA with HeLa cells overexpressing the rat leukocyte‐type 12‐LOX. Neither HXA3 nor 12(S)‐HETE were detected due to abundance of cGPx/PHGPx. But, pretreatment of transfected cells with diethyl maleate, an inhibitor of glutathione and PHGPx, restored HXA3 synthase and 12‐LOX activities. Thus, we conclude, that cells containing rat leukocyte‐type 12‐LOX also possess an intrinsic HXA3 synthase activity, which is activated by inhibition of cGPx/PHGPx. In normal cells HXA3 is down‐regulated by cGPx/PHGPx, but, it is persistently activated in oxidatively stressed cells deficient in cGPx/PHGPx, such as RINm5F.
Amine‐randomised poly(2‐ethylhexyl acrylate) as impact and adhesive modifier for epoxy resin
Authors: Kar S. , Banthia A.K.
Published: March 2003

The adhesive and impact properties of cured epoxy resins, modified with amine‐randomised poly(2‐ethylhexyl acrylate) (ARPEHA) liquid rubber, as a function of the concentration of the liquid rubber, have been investigated. ARPEHA was synthesised by the reaction of the carboxyl‐randomised poly(2‐ethylhexyl acrylate) (CRPEHA) liquid rubber with 4,4′‐diaminodiphenyl sulphone. CRPEHA was synthesised by solution co‐polymerisation of 2‐ethylhexyl acrylate and acrylic acid. ARPEHA modified cured epoxy resins were formed by curing with an ambient temperature‐curing agent, triethylene tetramine. The modified epoxy resins were evaluated with respect to their adhesive and impact properties. The optimum properties were obtained at around 12.5 phr (parts per hundred parts of epoxy resin) of modifier. Analysis of the fracture surface using scanning electron microscopy indicated the presence of two‐phase microstructures.
Long-Term Administration of Polygonum multiflorum Thunb: Reduces Cerebral Ischemia-induced Infarct Volume in Gerbils
Authors: Chan Yin-Ching , Wang Ming-Fu , Chen Ya-Ching , Yang Dar-Yu , Lee Ming-Shih , Cheng Fu-Chou
Published: March 2003

Focal cerebral ischemia was produced by an occlusion of the middle cerebral artery for 1, 3 and 24 hours in gerbils. Infarct volumes were determined by 2,3,5-triphenyltetrazolium chloride (TTC) transcardiac perfusion 24 hours after cerebral ischemia. Significant and consistent infarct sizes were produced in gerbils subjected to 24-hour occlusion of the middle cerebral arterey when compared to the 1 and 3-hour occlusion groups. Long term pretreatment of the 50% ethanol extract of Polygonum multiflorum Thunb. for 2 weeks significantly reduced the infarct volume by 50% as compared to that of the 24-hour occlusion group. The results revealed that long term pretreatment of Polygonum multiflorum Thunb. may protect the brain against focal cerebral ischemia.
Effects of Goshajinkigan on Corneal Sensitivity, Superficial Punctate Keratopathy and Tear Secretion in Patients with Insulin-dependent Diabetes Mellitus
Authors: Nagaki Yasunori , Hayasaka Seiji , Hayasaka Yoriko , Kadoi Chiharu , Sekiya Nobuyasu , Terasawa Katsutoshi , Sakakibara Iwao
Published: March 2003

Goshajinkigan (Niu-che-shen-qi-wan in Chinese), a traditional herbal medicine, has been used in Japan to treat clinical symptoms of diabetic neuropathy. A double-masked study was performed to evaluate its effects on corneal sensitivity, superficial punctate keratopathy and tear production in patients with insulin-dependent diabetes mellitus. Fifty diabetic patients were randomized into two groups: Group A, in which 25 patients received Goshajinkigan orally, 7.5 g/day for 3 months; Group B, in which 25 patients were orally administered placebo, 6.0 g/day for 3 months; and in Group C, 25 non-diabetic subjects were orally administered Goshajinkigan, 7.5 g/day for 3 months. Corneal sensitivity was measured with an aesthesiometer. The area of superficial punctate keratopathy was expressed as a fluorescein staining score. Reflex tearing was determined with a Schirmer test without anesthesia. Goshajinkigan was analyzed by high-performance liquid chromatography. Corneal thresholds after treatment with Goshajinkigan (2.03 g/mm2) in Group A were significantly lower than those before treatment (2.47 g/mm2). Those in Groups B and C did not change after treatment.

Fluorescein staining scores after administration of Goshajinkigan (0.64) in Group A were significantly lower than those before treatment (1.32). Those in Groups B and C did not change after treatment. Schirmer test results after Goshajinkigan administration (11.0 mm/5 min) in Group A were significantly higher than those before treatment (9.3 mm/5 min). Those in Groups B and C did not change after treatment. Hemoglobin A1c levels in Groups A, B,and C did not change after treatment. Several components in Goshajinkigan were found on high performance liquid chromatography. In conclusion, Goshajinkigan improved ocular surface disorders in patients with insulin-dependent diabetes mellitus.