bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recent Developments in the Chemistry of Beryllocenes
Authors: Fernández Rafael , Carmona Ernesto 
Published: July 2005

AbstractSynthetic studies on substituted beryllocenes have provided new representatives of this family of compounds. Knowledge of their structures gives a better understanding of the long‐standing problem of the structure of the parent beryllocene, Be(C5H5)2. Theoretical calculations offer a clear picture of their bonding properties, while spectroscopic and reactivity investigations have clarified their dynamic behaviour. Beryllocenes of the type BeCp'2 (Cp' = methyl‐substituted cyclopentadienyl group) and half‐sandwich cyclopentadienylberyllium compounds are considered. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Unimolecular Fragmentation of CH3NH2: Towards a Mechanistic Description of HCN Formation
Authors: Roithová Jana , Schröder Detlef , Schwarz Helmut 
Published: July 2005

AbstractThe mechanism of the consecutive fragmentation of methylamine, CH3NH2, is studied by means of neutralization‐reionization mass spectrometry (NRMS), labeling experiments, and calculations employing density functional theory. It is shown that under the conditions of NRMS the fragmentations proceed by a radical mechanism that involves four distinct X–H bond cleavages (X = C, N). In the first step, a hydrogen atom is eliminated from the methyl group; next, homolytic cleavage of an N–H bond occurs. The so‐formed CH2NH intermediate then, in competition, releases a hydrogen atom either from the nitrogen or the carbon part, resulting in the formation of the radicals H2CN· and HCNH·, respectively. The reaction sequence is terminated by yet another homolytic bond cleavage to produce HCN. An alternative pathway proceeding by an initial 1,1‐elimination of H2 from the methyl group of CH3NH2, followed by a 1,1‐elimination of H2 from the amino function, is also considered, but found to be more energy‐demanding. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Preparation of Intact Hexahydrobenzofuran Subunits of Ivermectin by Selective Ozonolysis of the Δ3,4‐Intermediate Secoester
Authors: Rouge dos Santos Anderson , Garcia Ferreira Maria de Lourdes , Kaiser Carlos R. , Férézou Jean‐Pierre 
Published: July 2005

AbstractAvermectins, and especially their semi‐synthetic partial hydrogenation adduct Ivermectin, constitute a potent endectocide family of worldwide veterinary use that has been known for more than twenty years and has also demonstrated a great efficacy in the treatment of various human filariasis diseases. In a program to design new access to cost‐effective analogues with a new or optimised medical profile, we decided to develop a practical synthetic strategy starting from southern subunits cut from commercial Ivermectin, which is now easily available at a reasonable price. We describe here the first process for preparing intact hexahydrobenzofuran subunits by controlled degradation of Ivermectin in a basically three‐step process that totally preserves the integrity of the Δ3 unsaturated pattern of the unit, which is a requisite feature for the biological activity of this family of molecules. The two crucial steps of the sequence, developed here on a gram scale, involve a transesterification reaction in the presence of titanium(IV) alkoxide that allows the macrolactone opening without isomerisation in 55–70 % yields, followed by the selective ozonolysis of the C10–C11 double bond in the presence of different reducting agents to afford the expected southern unit in reasonable yields. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Facile Regio‐ and Diastereoselective Syntheses of Hydroxylated2‐Aminocyclohexanecarboxylic Acids
Authors: Fülöp Ferenc , Palkó Márta , Forró Enikő , Dervarics Máté , Martinek Tamás A. , Sillanpää Reijo 
Published: July 2005

AbstractBy means of total regio‐ and diastereoselective functionalizations of cis‐ and trans‐2‐amino‐4‐cyclohexenecarboxylic acid derivatives 1, 9, 12 and 16, isomers of 2‐amino‐4‐hydroxycyclohexanecarboxylic acid 8 and 11, and 2‐amino‐5‐hydroxycyclohexanecarboxylic acid 15 and 19 were prepared in good yields, via 1,3‐oxazine or γ‐lactone intermediates. The enantiomers of 8 and 15 were also prepared by the same pathway, resulting in products with ee > 99 %. The structures, stereochemistry and relative configurations of the synthesized compounds were proved by NMR, using some key vicinal couplings and characteristic NOEs. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Efficient Heterogeneous Asymmetric Transfer Hydrogenation Catalyzed by Recyclable Silica‐Supported Ruthenium Complexes
Authors: Liu Pei‐Nian , Gu Pei‐Ming , Deng Jin‐Gen , Tu Yong‐Qiang , Ma Ya‐Ping 
Published: July 2005

AbstractEasily accessible N‐(p‐tolylsulfonyl)‐1,2‐diphenylethylenediamine‐(TsDPEN‐)derived organic–inorganic hybrid ligands were prepared and applied to the heterogeneous asymmetric transfer hydrogenation in traditional HCO2H/NEt3 and in water with HCO2Na as the hydrogen source and sodium dodecyl sulfate (SDS) as the phase‐transfer catalyst. The reactions demonstrated high catalytic activities and excellent enantioselectivities for most aromatic ketones and the imine tested, with results similar to those in homogeneous catalysis.In particular, this heterogeneous catalyst can be readily recovered and used in multiple consecutive catalytic runs with the high enantioselectivity maintained both in HCO2H/NEt3 and in water. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
From Vetiver to Patchouli: Discovery of a NewHigh‐Impact Spirocyclic Patchouli Odorant
Authors: Kraft Philip , Eichenberger Walter , Frech David 
Published: July 2005

AbstractIn the course of synthetic work on new vetiver odorants, a new, potent patchouli odorant was discovered. Its structure was elucidated as 1‐hydroxy‐1,4,7,7,9‐pentamethylspiro[4.5]decan‐2‐one (15/16), and both diastereoisomers were synthesized from the previously reported 4,7,7,9‐tetramethyl‐1‐methylenespiro[4.5]decan‐2‐one by epoxidation with m‐chloroperoxybenzoic acid, reduction with lithium aluminum hydride, and subsequent oxidation with pyridinium chlorochromate or Dess–Martin periodinane. The 1,4‐unlike‐isomer 15 was found to be the diastereoisomer with the most powerful odor, and its excellent odor threshold of 0.067 ng/L air triggered the synthesis of the derivatives 19, 22, 23, and 26 possessing a different methyl substitution pattern or ring size. Glycol cleavage in the oxidation step was circumvented by Swern oxidation. Three further 4‐demethylated derivatives, 32, 33, and 34, were prepared by a short sequence consisting of Diels–Alder reaction with 4‐methylene‐5‐oxohexanenitrile (28), reductive radical cyclization mediated by the titanocene(III) complex Cp2Ti(Ph)(iPr), and standard hydrogenation. Finally, the enantiomers of 15 were separated by forming their SAMP hydrazones, which were subsequently cleaved by ozonolysis. The odor of the racemate 15 was shown to be exclusively due to the (+)‐(1S,4R,5R,9S)‐configured enantiomer 38, the stereocenters of which superimpose well with those of (–)‐patchoulol (3), the odorous principle of patchouli oil. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Syntheses of New Chiral Phosphane Ligands by Diastereoselective Conjugate Addition of Phosphides to Enantiomerically Pure Acceptor‐Substituted Olefins from the Chiral Pool
Authors: Wiese Burkhard , Knühl Guido , Flubacher Dietmar , Prieß Jan W. , Ulriksen (nee Laursen) Bolette , Brödner Kerstin , Helmchen Günter 
Published: July 2005

AbstractA variety of new chiral phosphanes were prepared by highly diastereoselective additions of phosphanes to α,β‐unsaturated carbonyl compounds and related acceptor‐substituted olefins derived from myrtenal as ex chiral pool source. Monophosphanes with astereogenic as well as stereogenic phosphorus are described. In addition diphosphanes were prepared by a highly diastereoselective double conjugate addition of a secondary diphosphane. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Synthesis of a αMan(1→3)αMan(1→2)αMan Glycocluster Presented on aβ‐Cyclodextrin Scaffold
Authors: Carpenter Clare , Nepogodiev Sergey A. 
Published: July 2005

AbstractApplication of 6‐thio‐α‐ and β‐cyclodextrins as the core component for the construction of multivalent carbohydrate structures is described. The method employed for the attachment of monomeric glycosides to a cyclodextrin core is based on the efficient nucleophilic displacement of bromide from an N‐bromoacetamido functionality. The N‐bromoacetyl group was positioned at the end of a spacer arm of glycosides and reacted with thiol groups present on the primary face of thiolated cyclodextrins. This coupling reaction led to perfunctionalised cyclodextrins which were thiother‐linked to appended saccharides through a short spacer arm. Both components of the key conjugation step — 6‐thiocyclodextrins and monomeric glycosides — were used without protecting groups, thus facilitating isolation and purification of target compounds. Glycoclusters incorporating six and seven α‐D‐mannopyranose or β‐D‐glucopyranose residues linked to cyclodexrin cores were synthesized in 57–75 % yield. Using the same technique, 3‐(2‐bromoacetamido)propyl trioside, incorporating a synthetic Man‐α‐(1→3)‐Man‐α‐(1→2)‐Man fragment of antigenic yeast mannan, was attached to per‐6‐thio‐β‐cyclodextrin to afford a heptavalent glycocluster. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Palladium‐Catalyzed Suzuki Coupling with Terminal Alkynes – Application to the Synthesis of 2,3‐Disubstituted Benzo[b]furans
Authors: Colobert Françoise , Castanet Anne‐Sophie , Abillard Olivier 
Published: July 2005

AbstractThe Suzuki coupling reaction between alkynylboronic esters (generated in situ from acetylenic derivatives) and aryl bromides, pyridyl bromides or vinyl bromides is reported. 5‐endo‐dig‐iodocyclisation of o‐alkynylanisoles, generated by this palladium‐catalyzed Suzuki coupling reaction, was performed with N‐iodosuccinimide (NIS) in the presence of BCl3. 2‐Substituted 3‐iodobenzo[b]furans were synthesized and transformed into 2,3‐disubstituted benzo[b]furans by Suzuki coupling reactions in high yields. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
One‐Pot Synthesis of Novel Enantiomerically Pure and Racemic 4‐Ferrocenyl‐β‐lactams and Their Reactivity in Acidic Media
Authors: Bernardi Luca , Bonini Bianca F. , Comes‐Franchini Mauro , Dessole Gabriella , Fochi Mariafrancesca , Ricci Alfredo 
Published: July 2005

AbstractA series of 4‐ferrocenyl‐ and 4‐[(SFc)‐2‐(p‐tolylsulfanyl)ferrocenyl]‐β‐lactams has been synthesized in good yields by a one‐pot reaction of achiral and planar‐chiral ferrocenylimines with substituted acetic acids. The acid‐induced stereoconvergent transformation of cis‐ and trans‐4‐ferrocenyl‐β‐lactams into (Z)‐α,β‐unsaturated amides by protonation, N–C‐4 cleavage and subsequent exo‐H elimination and the lack of reaction of the ortho‐S‐tolylsulfanyl analogs are discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Methods for the Cleavage of Allylic and Propargylic C–N Bonds in Amines and Amides – Selected Alternative Applications of the 1,3‐Hydrogen Shift
Authors: Escoubet Stéphanie , Gastaldi Stéphane , Bertrand Michèle 
Published: July 2005

AbstractThe aim of this article is to provide an updated review on the various methodologies that allow allylic C–N bonds (and by extension propargylic C–N bonds) to be cleaved. Since selectivity is crucial for synthetic planning, as far as possible, the relative reactivity of the various allylic groups is examined, and the discrimination between O‐allyl and N‐allyl derivatives is discussed. A special development is devoted to reactions leading to enamines through a 1,3‐hydrogen shift, even though some of these reactions were not originally performed for the purpose of cleaving the N‐allyl bond. Some selected applications are discussed. In addition to preparative deprotection methods, reactions such as the enzyme‐mediated cleavage of allylic C–N bonds are also mentioned, although these reactions may not have any practical synthetic interest at the moment. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Cycloadditions with Cyclic Seven‐Membered Ketene Imines
Authors: Giera Henry , Huisgen Rolf , Polborn Kurt 
Published: July 2005

AbstractThe cyclic seven‐membered ketene imines 8 – isolable despite ring strain – are available by reactions of thiocarbonyl ylides 3 with 2,3‐bis(trifluoromethyl)fumaronitrile (4). In contrast to open‐chain ketene imines, 8A–8C underwent (2+2) cycloadditions with ethyl vinyl ether at the C=N double bond; the diastereomeric cycloadducts 10 and 11 were characterized by their spectra, and 10A by X‐ray analysis. The corresponding adduct 12 from 8A and 2‐methoxypropene easily hydrolyzed to give 14. When 8A–8C were treated with diazomethane, (2+3) cycloadditions took place side by side to the C=C and C=N bond of 8. A supposed adduct at the C=C bond, 18A, lost N2, and 19A was formed which contained a cyclopropylideneamine group; at 50 °C, cheletropic elimination produced the isocyanide 22A. Diazomethane addition to the C=N bond of 8 gave rise to condensed 1,2,3‐triazoles 21; the HF elimination from the pyrazolines 20 as primary adducts was probably induced by the excess of diazomethane. The structure of 21B was confirmed by X‐ray. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Cover Picture: Divergent and Linear Solid‐Phase Synthesis of PNA Containing Thiazole Orange as Artificial Base (Eur. J. Org. Chem. 15/2005)
Authors: Jarikote Dilip V. , Köhler Olaf , Socher Elke , Seitz Oliver 
Published: July 2005

AbstractThe cover picture shows the divergent synthesis of peptide nucleic acid based probes in which the DNA intercalator dye thiazole orange serves as a base surrogate. The so‐called FIT (Forced Intercalation of Thiazole orange) PNA probes can provide information about the hybridization to complementary DNA by enhancement of fluorescence. The graphical representation depicted in the bottom left corner gives an idea of the structure of FIT PNA complexed by DNA. In this model, FIT PNA has been hybridized to DNA that contains an abasic site opposite to thiazole orange. The article by O. Seitz et al. on p. 3187 ff. describes the details of linear and divergent solid‐phase syntheses of FIT PNAs. Both methods provide very rapid access and should be applicable to the synthesis of any type of base‐modified PNA molecule.
Optimal design of an induction motor for an electric vehicle
Authors: Faiz Jawad , Sharifian M. B. B. 
Published: July 2005

AbstractIn this paper a squirrel‐cage three‐phase induction motor, selected as the driving power of an electric vehicle (EV), is designed optimally using a modified‐Hooke–Jeeves optimization technique. The optimal designs are analyzed and compared with varying pole number, rated base speed and slot shapes. This optimization technique has the same advantages such as simple programming, non‐gradient, short convergence time and independent variation of each parameter. Variation of design parameters of optimally designed motors versus rated base speed for 2‐ and 4‐pole motors are presented and discussed. The results show that a 2‐pole motor with parallel‐sided stator and rotor slots and rated speed 1800 rpm has the best performance. Copyright © 2005 John Wiley & Sons, Ltd.
Fast computation evolutionary programming algorithm for the economic dispatch problem
Authors: Somasundaram P. , Kuppusamy K. , Kumudini Devi R. P. 
Published: July 2005

AbstractThis paper essentially aims to propose a new EP based algorithm for solving the ED problem. The ED problem is solved using EP with system lambda as decision variable and power mismatch as fitness function. The algorithm is made fast through judicious modifications in initialization of the parent population, offspring generation and selection of the normal distribution curve. The proposed modifications reduce the search region progressively and generate only effective offsprings. The proposed algorithm is tested on a number of sample systems with quadratic cost function and also on a 10‐unit system with piecewise quadratic cost function. The computational results reveal that the proposed algorithm has an excellent convergence characteristic and is superior to other EP based methods in many respects. Copyright © 2005 John Wiley & Sons, Ltd.
A systematic approach to nuclear microscopy of water trees for a large number of field‐aged HV cable samples
Authors: Ahmed M. , Al‐Ohali M. , Garwan M. , Al‐Hamouz Z. , Al‐Soufi K. , Minqin R. , Rajta I. , Watt F. 
Published: July 2005

AbstractIn order to perform micro‐PIXE measurements on water trees in underground HV cables when a large number of cable samples are involved, a sequence of tests has been devised to minimize time and effort for sample preparation, water tree detection and analysis. These tests include electrical diagnostic tests to predict the possible presence of water trees, optical microscopy on cable insulation to detect water trees in the samples screened by the electrical tests, scanning electron microscopy for detailed surface topography of water trees, and nuclear microscopy for elemental composition and distribution maps of water trees. Correlations among the results of the four types of measurements are discussed to evaluate the usefulness of the methodology. Copyright © 2005 John Wiley & Sons, Ltd.
Unstructured lattice Boltzmann method in three dimensions
Authors: Rossi N. , Ubertini S. , Bella G. , Succi S. 
Published: July 2005

AbstractOver the last decade, the lattice Boltzmann method (LBM) has evolved into a valuable alternative to continuum computational fluid dynamics (CFD) methods for the numerical simulation of several complex fluid‐dynamic problems. Recent advances in lattice Boltzmann research have considerably extended the capability of LBM to handle complex geometries. Among these, a particularly remarkable option is represented by cell‐vertex finite‐volume formulations which permit LBM to operate on fully unstructured grids. The two‐dimensional implementation of unstructured LBM, based on the use of triangular elements, has shown capability of tolerating significant grid distortions without suffering any appreciable numerical viscosity effects, to second‐order in the mesh size. In this work, we present the first three‐dimensional generalization of the unstructured lattice Boltzmann technique (ULBE as unstructured lattice Boltzmann equation), in which geometrical flexibility is achieved by coarse‐graining the lattice Boltzmann equation in differential form, using tetrahedrical grids. This 3D extension is demonstrated for the case of 3D pipe flow and moderate Reynolds numbers flow past a sphere. The results provide evidence that the ULBE has significant potential for the accurate calculation of flows in complex 3D geometries. Copyright © 2005 John Wiley & Sons, Ltd.
2‐Halogeno‐1,3,2‐diazaarsolenes and 2‐halogeno‐1,3,2‐diazastibolenes: Examples for spontaneous EX bond heterolysis or not?
Authors: Gans‐Eichler Timo , Gudat Dietrich , Nieger Martin 
Published: July 2005

Abstract2‐X‐1,3,2‐diazaarsolenes and 2‐X‐1,3,2‐ stibolenes (X = Cl, Br) were prepared from appropriate α‐amino‐aldimine precursors via transamination with ClSb(NMe2)2or via base‐induced dehydrohalogenation with EX3(E = As, Sb). The products were further converted into 2‐iodo‐derivatives via halide exchange with Me3SiI, or into 1,3,2‐diazaarsolenium or 1,3,2‐stibolenium salts via halide abstraction using E′X3(E′ = Al, Ga, Sb) or Me3SiOTf. All compounds synthesized were characterized by spectroscopic data and several of them by single‐crystal X‐ray diffraction studies. The results of these investigations confirmed that diazaarsolenium or stibolenium cations are stabilized by similar π‐delocalization effects as the corresponding diazaphospholenium cations. 2‐Halogeno‐1,3,2‐diazaarsolenes and 2‐halogeno‐132‐stibolenes are best addressed as molecular species whose covalent EX bonds are as in 2‐chloro‐diazaphospholenes weakened by intramolecular π(C2N2) → σ*(EX) and, in the case of the Sb‐containing heterocycles, inter‐ molecular n(X′) → σ*(EX) hyperconjugation between the σ* (EX) orbital and a lone‐pair of electrons on the halogen atom of a neighboring molecule. Correlation of structural and spectroscopic data and the evaluation of halide transfer reactions allowed to conclude that the extent of EX bond weakening in the 2‐X‐substituted heterocycles decreases and thus the Lewis acidity of the cations increases, with increasing atomic number of the pnicogen atom. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:327–338, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20098
Crystal structures of dibenzo[ce]‐1,2‐dithiine and its related oxides
Authors: Aucott Stephen M. , Milton Heather L. , Robertson Stuart D. , Slawin Alexandra M. Z. , Woollins J. Derek 
Published: July 2005

AbstractThe X‐ray structures of dibenzo[ce]‐1,2‐dithiine, dibenzo[ce]‐1,2‐dithiine‐5,5‐dioxide, diben‐ zo[ce]‐1,2‐dithiine‐5,5,6‐trioxide, and dibenzo[ce]‐1, 2‐dithiine‐5,5,6,6‐tetraoxide are reported and compared with the related “constrained'' naphthalene deri‐ vatives. The S‐S distances vary upon oxidation of the S centers in the order S‐S < SO‐S > SO2‐S < SO2‐SO > SO2‐SO2 i.e. the most oxidized sulfur atoms do not lead to the longest bond lengths. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:346–351, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20101
Synthesis and structure of the scandium‐rich indides Sc5Ni2In4 and Sc5Rh2In4
Authors: Lukachuk Mar'yana , Heying Birgit , Rodewald Ute Ch. , Pöttgen Rainer 
Published: July 2005

AbstractThe ternary indides Sc5 Ni2 In4 and Sc5 Rh2 In4 were synthesized by arc‐melting of the elements and subsequent annealing. A structural investigation by X‐ray powder and single crystal diffraction revealed: Lu5 Ni2 In4 type, Pbam, a = 1716.3(2), b = 755.1(1), c = 335.22(5) pm, wR2 = 0.0721, 844 F2 values for Sc5 Ni2 In4, and a = 1754.3(3), b = 765.0(1), c = 332.97(6) pm, wR2 = 0.0363, 1107 F2 values for Sc5 Rh2 In4 with 36 variables per refinement. Both structures can be described as intergrowths of distorted AlB2‐ and CsCl‐related slabs, where the transition metal (T) atoms have a trigonal prismatic and the indium atoms a distorted square prismatic coordination. The shortest interatomic distances occur for ScT and TIn. The crystal chemistry and chemical bonding in these intermetallics are briefly discussed. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:364–368, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20106
On the electronic structure and bonding of the intriguing mixed Fe2+/Fe3+ [{Cp(CO)2Fe}tBuPO2FeCl2]2‐Complex
Authors: Lorenz Ingo‐Peter , Maier Markus , Schulz Axel 
Published: July 2005

AbstractThe structure and bonding of [{Cp(CO)2Fe}tBuPO2FeCl2]2(2) have been investigated theoretically and experimentally. The molecular orbitals of 2 have been calculated to investigate the question why this type of complex forms a planar ring system. The electronic configuration of different electronic states, spin polarization, and bonding of 2 are discussed. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:398–405, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20109