bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tandem Catalysis: A Ring‐Closing Metathesis Followed by Dehydrogenative Oxidation to Afford Substituted Indenones.
Authors: van Otterlo Willem A. L. , Coyanis E. Mabel , Panayides Jenny‐Lee , de Koning Charles B. , Fernandes Manuel A. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
The Indium‐Mediated Selective Introduction of Allenyl and Propargyl Groups at the C4‐Position of 2‐Azetidinones and the AuCl3‐Catalyzed Cyclization of 4‐Allenyl‐2‐azetidinones.
Authors: Lee Phil Ho , Kim Heechul , Lee Kooyeon , Kim Misook , Noh Kwanghyun , Kim Hyunseok , Seomoon Dong 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Homotryptamines as Potent and Selective Serotonin Reuptake Inhibitors (SSRIs).
Authors: Schmitz William D. , Denhart Derek J. , Brenner Allison B. , Ditta Jonathan L. , Mattson Ronald J. , Mattson Gail K. , Molski Thaddeus F. , Macor John E. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
New Intra—Intermolecular Criss‐Cross Cycloaddition of Unsymmetrical Allenylazines with Alkynes Leading to Three Fused Five‐Membered Heterocycles.
Authors: Man Stanislav , Necas Marek , Bouillon Jean‐Philippe , Baillia Henri , Harakat Dominique , Potacek Milan 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
ZrCl4‐Mediated Cross‐Cyclization Between Epoxides and Homoallylic Alcohols: Synthesis of 4‐Chlorotetrahydropyran Derivatives.
Authors: Yadav J. S. , Rajasekhar K. , Murty M. S. R. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Synthesis of Thienothiopyranthiones by a New Molecular Rearrangement.
Authors: Ogurtsov Vladimir A. , Rakitin Oleg A. , Rees Charles W. , Smolentsev Alexey A. , Belyakov Pavel A. , Golovanov Denis G. , Lyssenko Konstantin A. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Synthesis with Improved Yield and Study on the Analgesic Effect of 2‐Hydroxyphencyclidine.
Authors: Ahmadi Abbas , Shafiezadeh Mahshid , Fathollahi Yaghoob , Darvich Mohammad Raouf , Mahmoudi Ali , Bahmani Manouchehr , Rahmati Batol 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Nonpeptide αvβ3 Antagonists: Identification of Potent, Chain‐Shortened 7‐Oxo RGD Mimetics.
Authors: Zartman Amy E. , Duong Le T. , Fernandez‐Metzler Carmen , Hartman George D. , Leu Chih‐Tai , Prueksaritanont Thomayant , Rodan Gideon A. , Rodan Sevgi B. , Duggan Mark E. , Meissner Robert S. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Design, Synthesis and Structure—Activity Relationship Studies of Hexahydropyrazinoquinolines as a Novel Class of Potent and Selective Dopamine Receptor 3 (D3) Ligands.
Authors: Ji Min , Chen Jianyong , Ding Ke , Wu Xihan , Varady Judith , Levant Beth , Wang Shaomeng 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
New Four‐Component Ugi‐Type Reaction. Synthesis of Heterocyclic Structures Containing a Pyrrolo[1,2‐a][1,4]diazepine Fragment.
Authors: Ilyn Alexey P. , Trifilenkov Andrey S. , Kuzovkova Julia A. , Kutepov Sergey A. , Nikitin Alexandre V. , Ivachtchenko Alexandre V. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
The Methoxyallene Approach to Oxacycles. Part 2. Stereoselective Synthesis of 2,3‐Disubstituted Oxepanes.
Authors: Perez Manuel , Canoa Pilar , Gomez Generosa , Teijeira Marta , Fall Yagamare 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
YM‐216391, a Novel Cytotoxic Cyclic Peptide from Streptomyces nobilis. Part 1. Fermentation, Isolation and Biological Activities.
Authors: Sohda Kin‐ya , Nagai Koji , Yamori Takao , Suzuki Ken‐ichi , Tanaka Akihiro 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
6‐O‐Silyl‐N‐acetyl‐2‐amino‐2‐N,3‐O‐carbonyl‐2‐deoxyglucosides: Effective Glycosyl Acceptors in the Glucosamine 4‐OH Series. Effect of Anomeric Stereochemistry on the Removal of the Oxazolidinone Group.
Authors: Crich David , Vinod A. U. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
A New Antibiotic, Antimycin A9, Produced by Streptomyces sp. K01‐0031.
Authors: Shiomi Kazuro , Hatae Kenji , Hatano Hiroko , Matsumoto Atsuko , Takahashi Yoko , Jiang Cheng‐Lin , Tomoda Hiroshi , Kobayashi Susumu , Tanaka Haruo , Omura Satoshi 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Microwave‐Assisted Michael Addition of Some Pyrimidine and Purine Nucleobases with α,β‐Unsaturated Esters: A Rapid Entry into Carboacyclic Nucleoside Synthesis.
Authors: Khalafi‐Nezhad A. , Zarea A. , Soltani Rad M. N. , Mokhtari B. , Parhami A. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Total Synthesis and Biological Activities of (+)‐Sulfamisterin (AB5366) and Its Analogues.
Authors: Sato Hideyuki , Maeba Takaki , Yanase Ryota , Yamaji‐Hasegawa Akiko , Kobayashi Toshihide , Chida Noritaka 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Discovery of an Exceptionally Potent and Selective Class of Fatty Acid Amide Hydrolase Inhibitors Enlisting Proteome‐Wide Selectivity Screening: Concurrent Optimization of Enzyme Inhibitor Potency and Selectivity.
Authors: Leung Donmienne , Du Wu , Hardouin Christophe , Cheng Heng , Hwang Inkyu , Cravatt Benjamin F. , Boger Dale L. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
The Studies on the Structure—Activity Relationship of Allyl Substituted Oxopyrimidines Searching for the Novel Antagonist or Agonist of Barbiturates to the Sleep Mechanism Based on Uridine Receptor Theory — Barbituric Acid to Uridine. Part 1.
Authors: Yamamoto Ikuo 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
The Influence of Halogens on the Electronic System of Biologically Important Ligands: Spectroscopic Study of Halogenobenzoic Acids, Halogenobenzoates and 5‐Halogenouracils
Authors: Lewandowski W. , Kalinowska M. , Lewandowska H. 
Published: June 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Br2(X) Microsolvation in Helium Clusters: Effect of the Interaction on the Quantum Solvent Density Distribution
Authors: Di Paola Cono , Gianturco Franco A. , López‐Durán David , de Lara‐Castells Maria Pilar , Delgado‐Barrio Gerardo , Villarreal Pablo , Jellinek Julius 
Published: June 2005

AbstractThe Born–Oppenheimer potential energy surface for the Br2(X) molecule interacting with a varying number of 4He bosons is constructed following two different schemes which employ either a full ab initio evaluation of the Br2–He interaction forces or an estimate of the latter through an empirical model. Both descriptions are employed by carrying out diffusion Monte Carlo (DMC) calculations of the ground‐state energies and quantum wavefunctions for Br2–(He)n clusters with n up to 24. The results clearly indicate, for both interactions, the occurrence of the full solvation of the molecular dopant within the quantum bosonic “solvent” but also show differences between the two models in terms of the expected density distributions of the surrounding particles within the shorter‐range region that makes up the clusters with smaller n values. Our calculations also show that such differences become insignificant for the larger 4He clusters surrounding the Br2 molecule, where density profiles and bulk behaviour are chiefly driven by the solvent structure, once n values reach the region of 15–20 adatoms.
Assessment of Density Functionals for the High‐Spin/Low‐Spin Energy Difference in the Low‐Spin Iron(II) Tris(2,2′‐bipyridine) Complex
Authors: Lawson Daku Latévi Max , Vargas Alfredo , Hauser Andreas , Fouqueau Antony , Casida Mark Earl 
Published: June 2005

AbstractIn the iron(II) low‐spin complex [Fe(bpy)3]2+, the zero‐point energy difference between the 5T2g(t${{{4\hfill \atop 2g\hfill}}}$${e{{2\hfill \atop g\hfill}}}$) high‐spin and the 1A1g(t${{{6\hfill \atop 2g\hfill}}}$) low‐spin states, ΔE${{{0\hfill \atop HL\hfill}}}$, is estimated to lie in the range of 2500–5000 cm−1. This estimate is based on the low‐temperature dynamics of the high‐spin→low‐spin relaxation following the light‐induced population of the high‐spin state and on the assumption that the bond‐length difference between the two states ΔrHL is equal to the average value of ≈0.2 Å, as found experimentally for the spin‐crossover system. Calculations based on density functional theory (DFT) validate the structural assumption insofar as the low‐spin‐state optimised geometries are found to be in very good agreement with the experimental X‐ray structure of the complex and the predicted high‐spin geometries are all very close to one another for a whole series of common GGA (PB86, PW91, PBE, RPBE) and hybrid (B3LYP, B3LYP*, PBE1PBE) functionals. This confirmation of the structural assumption underlying the estimation of ΔE${{{0\hfill \atop HL\hfill}}}$ from experimental relaxation rate constants permits us to use this value to assess the ability of the density functionals for the calculation of the energy difference between the HS and LS states. Since the different functionals give values from −1000 to 12000 cm−1, the comparison of the calculated values with the experimental estimate thus provides a stringent criterion for the performance of a given functional. Based on this comparison the RPBE and B3LYP* functionals give the best agreement with experiment.
Synthesis, Structure and Luminescence Properties of Four Novel Terbium2‐Fluorobenzoate Complexes
Authors: Li Xia , Zhang Zhuo‐Yong , Zou Ying‐Quan 
Published: June 2005

AbstractFour new complexes [Tb(2‐FBA)3·(2‐HFBA)·H2O]2 (1), {[Tb(2‐FBA)3·(4,4'‐bpy)·H2O]3}n (2), [Tb(2‐FBA)3·(2,2'‐bpy)]2 (3), and [Tb(2‐FBA)3·phen·CH3CH2OH]2·[Tb(2‐FBA)3·phen]2 (4) (2‐HFBA: 2‐fluorobenzoic acid; 4,4'‐bpy: 4,4'‐bipyridine; 2,2'‐bpy: 2,2'‐bipyridine; phen: 1,10‐phenanthroline) have been synthesized and characterized by X‐ray diffraction analysis. Complex 1 is a dimeric molecule with a one‐dimensional supramolecular structure formed by hydrogen bonds. Complex 2 is an infinite one‐dimensional polymer chain formed by bridging carboxylato groups; its 2D framework structure is formed by hydrogen bonds. The structure of complex 3 contains three independent binuclear molecules in the asymmetric unit. In two of them, two Tb3+ ions are held together by four 2‐FBA groups, with two of them in a bidentate‐bridging mode and the other two in a chelating‐bridging mode. In the third, two Tb3+ ions are held together by four 2‐FBA groups, all of which are in the bidentate‐bridging mode. One 2‐FBA group and one 2,2'‐bpy chelate to one Tb3+ ion, resulting in coordination numbers of the central terbium ion of nine and eight, respectively. The structure of complex 4 contains two nonequivalent binuclear molecules in the asymmetric unit — [Tb(2‐FBA)3·phen·CH3CH2OH]2 and [Tb(2‐FBA)3·phen]2. In the former, the Tb3+ ion is surrounded by eight atoms, five O atoms from five 2‐FBA groups, one O atom from one ethanol molecule and two N atoms from phen, and the 2‐FBA groups act in monodentate and bridging coordination modes. In the latter, the Tb3+ ion is coordinated by nine atoms, seven O atoms from five 2‐FBA groups and two N atoms of phen, and the 2‐FBA groups link the Tb3+ ion in chelating, bridging, and chelating‐bridging coordination modes. Complexes 1, 3, and 4 emit a bright green light under UV light in the solid state. There are four emission peaks in the luminescence spectra at 488, 543, 584, and 618 nm, corresponding to the 5D4→7F6, 5D4→7F5, 5D4→7F4, and 5D4→7F3 transitions, respectively, of the Tb3+ ion. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Novel Analogues of 5‐Fluorouracil – Synthesis, X‐ray Crystallography, and Cytotoxic Effects in Normal Human Peripheral Blood Lymphocytes and Colon Adenocarcinoma HT 29
Authors: Matlawska Ksenia , Kalinowska Urszula , Erxleben Andrea , Osiecka Regina , Ochocki Justyn 
Published: June 2005

AbstractThe aim of many studies is to discover new chemicals as potential antitumor agents. We have prepared novel analogues of 5‐fluorouracil (5‐Fu): 5‐uracilmethylphosphonic acid (5‐umpa), dimethyl 5‐uracilmethylphosphonate (5‐umpm), diethyl 5‐uracilmethylphosphonate (5‐umpe) and a K+ (K+/5‐umpa, 1) and Na+ (Na+/5‐umpa, 2) complex of 5‐umpa. Complexes 1 and 2 have infinite chain structures built up by H‐bonded pairs of 5‐umpa– and {(H2O)K(μ‐OH2)3K(OH2)}2+ and {(H2O)2Na(μ‐OH2)2Na(OH2)2}2+ entities. The alkali metal ions bind directly to the exocyclic oxygen atoms O(2) and O(4) of the nucleobase moiety and indirectly, i.e. through hydrogen‐bond interactions involving metal‐coordinated water molecules, to the phosphonate group. The new derivatives were tested for their antiproliferative and cytotoxic effects on normal human peripheral blood lymphocytes and HT 29 cancer lines in vitro using the tetrazolium salt (MTT) assay. The IC50 values were evaluated (the drug concentration inhibiting 50 % of the cell growth after 72 h exposure of cells to the drug). The results indicate that 5‐umpa, 5‐umpm, 5‐umpe, and the K+ and Na+ complexes of 5‐umpa do not exert toxic effects on regular lymphocytes and on the colon adenocarcinoma HT 29 cell line (IC50 > 1 mM), in comparison with 5‐Fu. However, an atypical course of survival curves was observed after treatment of HT 29 cells with 5‐umpa,5‐umpm and the Na+ complex of 5‐umpa. These observations suggest that it is very important to continue the studies in different biological systems in vitro and in vivo using various experimental protocols. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Fragmentation of Alkoxo(catecholato)vanadium(V) Complexes[(C6H4O2)V(OR1)(OR2)]+ in the Gas Phase
Authors: Kaczorowska Malgorzata , Schröder Detlef , Schwarz Helmut 
Published: June 2005

AbstractElectrospray ionization (ESI) mass spectrometry is used to investigate the gas‐phase dissociation behavior of vanadium(V) complexes [(C6H4O2)V(OR1)(OR2)]+ containing two identical or different alkoxy groups (R1, R2 = CH3, C2H5, n‐C3H7, i‐C3H7 and t‐C4H9) and a catecholato ligand (C6H4O2). The fragmentation reactions of the complexes are studied by collision‐induced dissociation (CID) and labeling experiments. For [(C6H4O2)V(OR1)(OR2)]+ cations with alkoxo groups larger than methyl, a trend for preferential evaporation of hydrocarbon fragments is observed, followed by expulsion of neutral alcohols. Further, the CID spectra of all complexes show a signal which can be assigned to the complex [(C6H4O2)VO]+. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Novel Indenylzirconium Complexes as Supported Catalysts in the Polymerization of Ethylene
Authors: Alonso‐Moreno Carlos , Antiñolo Antonio , Carrillo‐Hermosilla Fernando , Carrión Pedro , López‐Solera Isabel , Otero Antonio , Prashar Sanjiv , Sancho José 
Published: June 2005

AbstractA series of substituted indene {C9H7R‐3 [R = CH2CH2CH2OSiMe3 (1), CH2CH2CH2OCH2C6H5 (2), CH2CH2CH2OSiMe2tBu (3)]}, and ansa‐indene compounds {Me2Si(C9H6R‐3)2‐1[R = CH2CH2CH2OSiMe3 (4)], Me2Si(C9H6R‐3)‐1(C5HMe4) [R = CH2CH2CH2OSiMe3 (5), CH2CH2CH2OCH2C6H5 (6), CH2CH=CH2 (7), CH2CH2CH2OSiMe2tBu (8)]} have been prepared. The lithium derivatives of 1–8 were employed in the synthesis of the indenylzirconium complexes [Zr(η5‐C9H6R‐1)2Cl2] [R = CH2CH2CH2OSiMe3 (17), CH2CH2CH2OCH2C6H5 (18), CH2CH2CH2OSiMe2tBu (19)], rac‐[Zr{Me2Si(η5‐C9H5R‐3)2‐1}Cl2] [R = CH2CH2CH2OSiMe3 (20)], [Zr{Me2Si(η5‐C9H5R‐3)‐1(η5‐C5Me4)}Cl2] [R = CH2CH2CH2OSiMe3 (21), CH2CH2CH2OCH2C6H5 (22), CH2CH=CH2 (23), CH2CH2CH2OSiMe2tBu (24)] and [Zr(Me2Si{η5‐C9H5(CH2CH2CH2O)‐3}‐1{η5‐C5Me4})Cl] (21a). The alkyl complexes [Zr(Me2Si{η5‐C9H5(CH2CH2CH2O)‐3}‐1{η5‐C5Me4})Me] (25) and [Zr{Me2Si(η5‐C9H5R‐3)‐1(η5‐C5Me4)}Me2] [R = CH2CH2CH2OSiMe2tBu (26)] have been synthesized by the reaction of the corresponding ansa‐zirconocene derivative with the alkyl Grignard reagent. The molecular structure of [(Zr{C9H6(CH2CH2CH2O)‐1}Cl2)2(Zr–O)] (17a), a subproduct in the formation of 17 has been determined by single‐crystal X‐ray diffraction studies. The indenylzirconium complexes 17–24 have been immobilized on partially dehydroxylated SiO2, and these supported systems used to polymerize ethylene in the presence of methylaluminoxane. The catalytic activity of these compounds in both homogeneous and heterogeneous polymerization is reported. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Enrichment of low‐abundant serum proteins by albumin/immunoglobulin G immunoaffinity depletion under partly denaturing conditions
Authors: Huang Hong‐Lei , Stasyk Taras , Morandell Sandra , Mogg Maurice , Schreiber Martin , Feuerstein Isabel , Huck Christian W. , Stecher Guenther , Bonn Guenther K. , Huber Lukas A. 
Published: June 2005

AbstractWe present a simple protocol for affinity depletion to remove the two most abundant serum proteins, albumin and immunoglobulin G (IgG). Under native conditions, albumin/IgG were efficiently removed and several proteins were enriched as shown by two‐dimensional electrophoresis (2‐DE). Besides that, partly denaturing conditions were established by adding 5 or 20% acetonitrile (ACN) in order to disrupt the binding of low‐molecular‐weight (LMW) proteins to the carrier proteins albumin/IgG. 2‐DE results showed that the total number of detected LMW proteins increased under denaturing conditions when compared to native conditions. Interestingly, the presence of 5% ACN in serum revealed better enrichment of LMW proteins when compared to 20% ACN condition. Seven randomly distributed spots in albumin/IgG depleted serum samples under 5% ACN condition were picked from the 2‐DE gels and identified by mass spectrometry (MS). The intensity of five LMW protein spots increased under denaturing conditions when compared to native conditions. Three of the seven identified spots (serum amyloid P, vitamin D‐binding protein, and transthyretin) belong to a group of relatively low‐abundant proteins, which make up only 1% of all serum proteins. The method presented here improves the resolution of the serum proteome by increasing the number of visualized spots on 2‐D gels and allowing the detection and MS identification of LMW proteins and proteins of lower abundance.
Rolf Huisgen: A Gentleman Scholar with Energy and Passion
Authors: Seeman Jeffrey I. 
Published: June 2005

AbstractA brief personal tribute to Professor and Mrs. Rolf Huisgen is presented. The essay describes Rolf Huisgen's energy and passion for science and art. Quotations from Huisgen's autobiography ‘The Adventure Playground of Mechanisms and Novel Reactions’ as well as many quotes from his correspondence with the author are presented. The essence and personality of this gentleman scholar are further highlighted by a number of photographs of him and of Trudl and other friends and colleagues.
Synthesis of the Cyclopentyl Nucleoside (−)‐Neplanocin A from D‐Glucose via Zirconocene‐Mediated Ring Contraction
Authors: Paquette Leo A. , Tian Zhenjiao , Seekamp Christopher K. , Wang Tony 
Published: June 2005

AbstractTwo approaches for the conversion of d‐glucose to (−)‐neplanocin A (2), both based on the zirconocene‐promoted ring contraction of a vinyl‐substituted pyranoside, are herein evaluated (Scheme 1). In the first pathway (Scheme 2), the substrate possesses the α‐d‐allo configuration (see 6) such that ultimate introduction of the nucleobase would require only an inversion of configuration. However, this precursor proved unresponsive to Cp2Zr (=[ZrCl2(Cp)2]), an end result believed to be a consequence of substantive nonbonded steric effects operating in a key intermediate (Scheme 5). In contrast, the C(2) epimer (see 7) experienced the desired metal‐promoted conversion to an enantiomerically pure polyfunctional cyclopentane (see 5 in Scheme 3). The substituents in this product are arrayed in a manner such that conversion to the target nucleoside can be conveniently achieved by a double‐inversion sequence (Scheme 4). Recourse to palladium(0)‐catalyzed allylic alkylation did not provide an alternate means of generating 2.
Use of Tröger's Base as a Scaffold for New Chiral Molecular Tweezers: Synthesis of Trimeric, Fused Tröger's Bases
Authors: Mas Thierry , Pardo Carmen , Elguero José 
Published: June 2005

AbstractFour novel molecular tweezers, 6–9, have been synthesized having, for the first time, three fused Tröger's bases. The compounds differ in the relative configuration of the three fused methylene bridges and have been unambiguously characterized by NMR.
Catalytic Decomposition of Diazo Compounds as a Method for Generating Carbonyl‐Ylide Dipoles
Authors: Padwa Albert 
Published: June 2005

AbstractThe transition metal catalyzed reaction of α‐diazo carbonyl compounds has found numerous applications in organic synthesis, and its use in either heterocyclic or carbocyclic ring formation is well‐precedented. In contrast to other catalysts that are suitable for carbenoid reactions of diazo compounds, those constructed with the dirhodium(II) framework are most amenable to ligand modification that, in turn, can influence reaction selectivity. The reaction of rhodium carbenoids with carbonyl groups represents a very efficient method for generating carbonyl ylide dipoles. Rhodium‐mediated carbenoid–carbonyl cyclization reactions have been extensively utilized as a powerful method for the construction of a variety of novel polycyclic ring systems. This article will emphasize some of the more recent synthetic applications of the tandem cyclization/cycloaddition cascade for natural product synthesis. Discussion centers on the chemical behavior of the rhodium metal–carbenoid complex that is often affected by the nature of the ligand groups attached to the metal center.
The Effect of Ring Size on Reactivity: The Diagnostic Value of ‘Rate Profiles’
Authors: Masson Eric , Leroux Frédéric 
Published: June 2005

AbstractThe rates of cycloalkyl phenyl sulfide formation of a series of homologous bromocycloalkanes upon treatment with sodium benzenethiolate have been determined to ascertain the effect of ring size on reactivity. The ‘rate profile’, i.e., reaction rate vs. ring size, for these nucleophilic substitutions (SN2) was determined. A linear free‐energy relationship could be derived from computed hydride affinities of cycloalkanes and rates of typical SN1 reactions, whereas rates of SN2 reactions exhibited a strong discrepancy from the seven‐ up to the twelve‐membered rings. This discrepancy was rationalized by a careful examination of the geometry of the intermediates and transition states involved in these reactions.
Stereoselective Synthesis of Tetrahydrofuran Spiro‐β‐Lactams by Ru‐Catalyzed Metathesis of 7‐Oxabicyclo[2.2.1]heptenes
Authors: Csákÿ Aurelio G. , Medel Rocío , Murcia M. Carmen , Plumet Joaquín 
Published: June 2005

AbstractA new method for the synthesis of spiro‐β‐lactams tethered to tetrahydrofuran rings is described. The procedure is based on Ru‐catalyzed metathesis sequences with oxanorbornene precursors easily obtained by the Staudinger [2+2] cycloaddition of related imines.
Cycloadditions of Bifunctional Vinyl Ethers with Electrophilic Alkenes through Tetramethylene Zwitterion Intermediates
Authors: May Eric J. , Padias Anne Buyle , Bates Robert B. , Hall Henry K. 
Published: June 2005

AbstractBifunctional vinyl ethers react with electron‐poor alkenes to cyclobutanes in good yields. The second CC bond reacted with neither the cyclobutane nor its zwitterion intermediate, even on heating. Cyclobutanes formed from ‘tetracyanoethylene’ (8) were transformed into tetrahydropyridines by reaction of the corresponding zwitterion with MeCN as the solvent. In contrast, cyclobutanes formed from dimethyl (dicyanomethylidene)propanedioate (9) did not react with MeCN, which is ascribed to diminished stabilization of the zwitterion intermediate, and increased steric effects. These results extend the classical studies of Huisgen and his co‐workers.