bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and preliminary pharmacology* of the rigid dehydroxylated etorphine analogue 4,5α‐epoxy‐α,α,17‐trimethyl‐6α,14α‐etheno‐isomorphinan‐7α‐methanol (chemistry of opium alkaloids, part XXVI**)
Authors: Linders J. T. M. , Lie T. S. , Maat L. 
Published: September 2010

AbstractThe synthesis of 4, 5α‐epoxy‐α, α, 17‐trimethyl‐6α, 14α‐ethenoisomorphinan‐7α‐methanol (6) via hydrogenolysis of the corresponding 3‐(1‐phenyltetrazol‐5‐yl) ether (5) is described. The etheno bridge was retained under the conditions used. Preliminary pharmacology of the title compound showed strong analgesic potency.
Hydrogenolysis Mechanism of Five Membered Heteroatom Rings Over MoS2‐Based Catalysts
Authors: Delmon B. , Dallons J.‐L. 
Published: September 2010

AbstractThis paper describes a concerted mechanism for the hydrogenolysis of the carbon‐heteroatom bond of thiophene, pyrrole and furan (and homologs) on molybdenum or tungsten sulfided catalysts (promoted by Co, Ni or Fe). The five‐membered rings would adsorb by a π bond on a coordinatively unsaturated Mo (or W), with their heteroatom (S, N or O) interacting, as electron acceptors, with the sulfur atoms of two vicinal sulfhydryl groups. After a 2,3 semi‐hydrogenation, a concerted mechanism would bind the hydrogen atoms of the sulfhydryl groups to the carbon atoms in the 1 and 4 positions, while the hydrogen atoms initially attached to these 1 and 4 carbon atoms would form H2S with the thiophenic sulfur (or NH3 or H2O). The mechanism explains most published features of the reactions and explains the special selectivity of sulphide catalysts, especially with furan.
Simple and efficient deoxygenation of heteroaromatic n‐oxides using TiCl4/SnCl2
Authors: Kaczmarek Lukasz , Malinowski Marek , Balicki Roman 
Published: September 2010

AbstractVarious unfunctionalized heteroaromatic N‐oxides are efficiently deoxygenated to the corresponding bases under mild conditions by treatment with the novel reagent TiCl4/SnCl2.
Fundamental questions about entropy I. Definitions: Clausius or Boltzmann?
Authors: Huyskens P. L. , Siegel G. G. 
Published: September 2010

AbstractThe expression of Boltzmann S = k In W differs in principle from the entropy as defined by Clausius because it is not strictly extensive. It becomes strictly extensive when the number W of all possible molecular arrangements is replaced by a normalized value <W> ‐ <WoneA>N A <WoneB>N B… where 1) the standardized probability <WoneA> that characterizes one particle A is the same for all the NA particles; 2) the possibilities for the particles of a given kind are considered separately from the possibilities of the particles of another kind. In contrast to W that characterizes the whole system, <W> is a product of as many factors as there are particles of different kinds in the different phases. Examples are given for the entropy of mixing of mixed crystals and the entropy of expansion of real gases.
Fragmentation et Isomérisation de Pyrazolides en Pyrolyse‐Éclair Sous Vide
Authors: Maquestiau A. , Bienfait I. , Ben Abdelouahab F. B. , Flammang R. 
Published: September 2010

AbstractFlash‐vacuum pyrolysis of 1‐benzoylpyrazole 1 at ca 800° under low pressure conditions affords mainly 2‐phenylfuran 2 and phenylallene 3 as indicated by a real‐time analysis using tandem mass spectrometry and by preparative scale experiments. Although 1‐acetylpyrazole [8] loses quasi exclusively ketene, isomerization into (a) C‐acylated isomer(s) is also detected by mass spectrometry.
Application de la Technique RMN de Transfert de Saturation Pour Mesurer L'Activité Enzymatique dans des Muscles Lisses de Mytilus Edulis
Authors: Schanck A. , Baguet F. 
Published: September 2010

AbstractThe unidirectional fluxes between phosphoarginine and ATP were determined by 31P NMR saturation transfer on in vitro preparation of anterior byssus retractor muscles of Mytilus edulis. The forward and reverse fluxes are comparable and it is deduced that the arginine kinase reaction is near equilibrium for these resting muscles.
Reaction du fluoroborate du benzoyl‐2 dihydro‐1,2 isoquinaldonitrile avec les esters α,β‐ethyleniques cas des esters acrylique, fumarique et maleique. Competition entre les reactions de cycloaddition [3+2] et [4+2]
Authors: Schmitt Gérard , Laude Bernard , Vebrel Joël , Rodier Noël , Theobald François 
Published: September 2010

AbstractIn all reactions studied up to the present time with olefinic esters, the Reissert salts have given only the Diels‐Alder adducts. By adding triethylamine to the reaction medium, we have found evidence for competing 1,3‐dipolar cycloaddition and Diels‐Alder reactions in three cases: acrylic, fumaric and maleic esters. The regiochemistry of the 1,3‐dipolar cycloadducts was determined chemically and from spectroscopic (IR, NMR) data. The stereochemistry of the cycloadducts was specified by radiocrystallographic studies. The reaction is assumed to proceed by a concerted mechanism.
Diels‐Alder Adducts From 4‐O‐Acetyl‐6‐Demethoxy‐N‐Formyl‐β‐Dihydro‐N‐Northebaine With Methyl Vinyl Ketone and Nitroethene (Chemistry of Opium Alkaloids, Part XXIX)
Authors: Linders J. T. M. , Lipman P. J. L. , Saly E. , Lie T. S. , Maat L. 
Published: September 2010

AbstractReductive epoxy ring scission of 6‐demethoxy‐N‐northebaine (5) with zinc and potassium hydroxide gave a 85:15 mixture of 6a and its non‐conjugated isomer. Formylation with triethyl orthoformate, followed by acetylation with acetic anhydride in the presence of 4‐(dimethylamino)pyridine gave a 4:1 mixture of the title compound 6c and its non‐conjugated isomer in 80% overall yield.Diels‐Alder reaction of 6c with methyl vinyl ketone afforded a 2:1 mixture of 7β‐acetyl‐and 8β‐acetyl‐6β, 14β‐ethenomorphinan 7 and 8a. Cycloaddition of nitroethene yielded the 8β‐nitro‐6β, 14β‐ethenomorphinan 8b as major product.N‐Demethylation of 2b, the 4‐O‐phenyl ether of 6‐demethoxy‐β‐dihydrothebaine (2a), with diethyl azodicarboxylate failed to give the N‐norcompound.
Extraction‐Spectrophotometric Determination of Cadmium With 2‐(5′‐Ethyl‐1′,3′,4′‐Thiadiazolyl‐2′‐Azo)‐4‐Methoxyphenol
Authors: Reyes J. P. , Trujillo J. P.Pérez , Sosa Z. , Arias J. J. 
Published: September 2010

AbstractA new extraction‐spectrophotometric method for the determination of cadmium, based on the formation of the complex Cd(II): 2‐(5′‐ethyl‐1′,3′,4′‐thiadiazolyl‐2′‐azo)‐4‐methoxyphenol into benzene is developed (ϵ=37,800 l. mol−1. cm−1 at 610 nm).
A Conformational Study of Some Secondary 2‐Furanecarbothioamides
Authors: Jagodzinski Tadeusz S. , Dziembowska Teresa M. , Szczodrowska Barbara 
Published: September 2010

AbstractAnalysis of the UV, IR and 1H‐NMR spectra and of the dipole moments indicated nonplanarity of the secondary thioamides derived from 2‐furanecarboxylic acid and a free rotation of the thioamide group around the C‐C bond. Quantum‐mechanical calculations of the s‐cis ⇆ s‐trans conformational equilibrium and of the dipole moments were carried out by the CNDO/2 method for the N‐methylthioamides of 2‐furane‐ and 2‐thiophenecarboxylic acid.
FVP Interconversion of 1‐, 2‐and 3‐Tritylindazoles
Authors: Pérez Jorge D. , Yranzo Gloria I. , Elguero José , Claramunt Rosa María , Garcerán Rafael 
Published: September 2010

AbstractFVP of 1‐1, 2‐2 and 3‐tritylindazole 3 was carried out at 300 and 400°C. The experimental results show that 3 isomerizes to 1 and 2; 2 isomerizes to 1 at 300°C and 1 remains unchanged at 300 and at 400°C gives 2 and by‐products. These transformations represent novel isomerizations in heterocyclic chemistry.
Protonation Behaviour of Diphenylamine in Water‐Dimethyl‐Formamide (Dmf) Mixtures
Authors: Murali Rao D. Mohan , Kalidas C. 
Published: September 2010

AbstractThe thermodynamic dissociation constant (pK) of diphenylamine (DPA) ion in Water‐DMF mixtures of various compositions at 25°C has been determined by a spectrophotometric method. The pK is found to decrease and passes through a minimum around 60 wt % DMF. The variation of pK has been examined in terms of the variation of Gibbs transfer energies of various species involved in the equilibrium.
Synthèse Dans La Série Des Phenanthridines I. Recherches Des Conditions Éxperimentales Optimales Dans La Préparation D'Alkyl‐6 Phenanthridines Et De Leur Sel
Authors: Lion C. , Boukou‐Poba J. P. , Charvy C. 
Published: September 2010

AbstractThe synthesis of 6‐alkylphenanthridines and their corresponding salts has been developed. The well known “biphenyl method” has been studied. Acylation of o‐aminobiphenyl is achieved by an acid or the corresponding anhydride or acyl chloride. Cyclization of the intermediate o‐acylamidobiphenyl has been studied in various conditions (solvents, temperature…). Quaternization has also been accomplished: new 6‐alkylphenanthridinium salts have been prepared in good yields.
Les Membranes De Permeation Gazeuse: Caractéristiques Et Principales Applications Industrielles
Authors: Deschamps A. , Avrillon R. , Mileo J.‐C. 
Published: September 2010

AbstractThis paper is an introduction, for membranes non specialists, to the different aspects of gas separation by membranes.It summarizes the fundamentals of gas permeation, the problems of polymer selection and membrane manufacture. Then the main industrial applications are reviewed.
Oxidation of Aldehydes to α,β‐Unsaturated Aldehydes via α‐Chloroaldimines
Authors: Kimpe Norbert De , Stevens Christian 
Published: September 2010

AbstractThe oxidation of aldehydes to α,β‐unsaturated aldehydes has been performed by a sequence of reactions involving conversion into aldimines, chlorination at the α‐position to form α‐chloroaldimines, base‐induced dehydrochlorination and hydrolysis. The four‐step transformation can be executed without isolation of the intermediates. This method has been applied to the synthesis of an artificial flavor, i.e. 2‐butyl‐3‐phenylpropenal.
A Serendipitous Synthesis of Bis(α‐Cyano‐4‐Nitrostyrene‐β‐yl) Ether
Authors: Roose B. , Anteunis M. J. O. , Tavernier D. 
Published: September 2010

AbstractThe title compound is obtained by reacting α‐cyano‐4‐nitrostyrene‐β‐ol with dicyclohexylcarbodiimide (molar ratio 2:1) at room temperature in tetrahydrofuran solvent.
The Active Ester α‐Cyano‐4‐Nitrostyrene‐β‐yl Acetate is also the Captodative Olefin 2‐Acetoxy‐1‐Cyano‐1‐(4‐Nitrophenyl)Ethene. Synthesis of 2,4‐bis(4‐Nitrophenyl)Pent‐2‐Enedinitrile
Authors: Roose B. , Anteunis M. J. O. , Tavernier D. 
Published: September 2010

AbstractThe new compounds (α‐cyano‐4‐nitrostyrene‐β‐yl) phenyl sulfide and Z‐2,4‐bis(4‐nitrophenyl)pentenedinitrile (BPD) were synthesized by reacting α‐cyano‐4‐nitrostyrene‐β‐yl acetate with benzenethiolate and 4‐nitrobenzyl cyanide anion respectively. BPD is a carbon acid, pKa = 3.5 in MeOH/H2O (2:1); solutions of BPD anion have an intense blue colour (VIS absorption in methanol: λm = 582nm, ε = 60000 L mol−1cm−1). −1H and −13C NMR spectra of BPD and BPD anion are discussed. The formation of minute amounts of BPD, observed during the N‐acylation of α‐amino acid hydrochlorides/Et3N with α‐cyano‐4‐nitrostyrene‐β‐yl esters, could be traced to the presence, in the α‐cyano‐4‐nitrostyrene‐β‐ol used to prepare the active ester, of ca 1% 4‐nitrobenzyl cyanide, which is partially deprotonatable by Et3N. The possibility that the α‐cyano‐4‐nitrostyrene‐β‐ol ejected in the acylation step would generate 4‐nitrobenzyl cyanide, and hence BPD, by deformylation, with e.g. water or amines as acceptor of the formyl group, could be disproved. The formation of BPD is avoided by replacing Et3N by the weaker base N‐methylmorpholine.
Étude de la coupure des liaisons o‐si d'éthers siliciés du type en présence d'agent nucléophile et/ou d'acide
Authors: Giral L. , Madit N. , Montginoul C. , Sagnes R. , Schué F. 
Published: September 2010

AbstractWe report a study on the hydrolytic instability of the oxygen‐silicon bond of the following compounds: p‐tert‐butyldimethylsilyloxytoluène, p‐triméthylsilyloxytoluène and poly(p‐triméthylsilyloxystyrène). The instability occurs in an acidic media: HCl, H−2SO4, CF3CO0H, BF3 or in presence of a salt: KPF6, KAsF6, KSbF6, NaBF4, [CH3(CH2)3]4NF, [CH3(CH2)3]4NBF4, [CH3(CH2)3]4NPF6, [CH3(CH2)3]4N AsF6, [CH3(CH2)3]4NSbF6. A mixture containing both an acid and a salt from those previously discussed can also be used.A number of representative examples is presented. The tert‐butyldimethylsilylether derivatives are much more stable than the trimethylsilylethers. It is shown that the rate of reaction is dependent on the nucleophilicity of anion used in these salts. This simple procedure undoubtedly extends the scope for a preparation of organosilicon resists.
−1H and −13C NMR Study of C‐16 OYL and C‐17 Acyl Vinblastine Derivatives at 300 MHz Using 2‐D NMR Experiments
Authors: Bhushana Rao Kandukuri S. P. , Cornet Jeanine , Bruyn André De 
Published: September 2010

AbstractIn the present study we describe: (1) the −13C NMR study of two compounds resulting from the amidation of the ester at C‐16 of 17‐deacetyl‐vinblastine and (2) the −1H and −13C NMR study of one compound resulting from the acylation (or esterification) at C‐17 of vinblastine. For the assignment of the −13C NMR resonances, DEPT and −13C, −1H‐heteronuclear shift correlated experiments were performed.
Some Simple Conjugates of Virginiamycin and their Bioactivity
Authors: Di Giambattista M. , Sharma N. K. , Anteunis M. J. O. 
Published: September 2010

AbstractDerivatives of the native antibioticum Viginiamycin S1 (3) conjugated at the pipecolic acid oxo position (5–12) have been prepared and their bioactivity tested together with some earlier prepared congeners (4, 13–16). Some of these show promising activities (e.g. 9, 15 and 16).
Intramolecular Diels‐alder Reaction with Furan‐Diene and Allene‐Dienophile. Application in Steroid Synthesis
Authors: Missiaen Patrick , De Clercq Pierre J. 
Published: September 2010

AbstractIn connection with the synthesis of corticosteroids the potential of adducts 4a and 4b, which are obtained in the intramolecular Diels‐Alder reaction of furan‐allene 3, is studied. The hydrogenation of 4a, followed by double bond isomerization, results in enone 9a, which was found to be a useful substrate both for 1,4‐addition and for dissolving metal reduction.
Étude expérimentale de la structure d'une flamme NH3/NO/AR
Authors: Bian J. , Vandooren J. , Tiggelen P. J. Van 
Published: September 2010

AbstractAn ammonia‐nitric oxide‐argon flat flame has been stabilized at low pressure (54 torr) and analyzed by using the molecular beam sampling technique coupled with the mass spectrometric analysis (MBMS).The signal intensities of stable (NH3, NO, N2, H2O, H2, N2O et Ar) as well as of unstable (NH2 et H) species have been recorded throughout all the flame. The temperature profile was measured by using a PtRh6%‐PtRh30% coated thermocouple. The absolute mole fraction profiles of the measured species have been established by an appropriate calibration.A preliminary examination of the flame structure shows the ammonia oxidation leads to the formation of NH2 radicals and to the occurrence of H, O and OH radicals concentrations much lower than those observed in an NH3/O2/Ar flame. The reaction of NH2 with NO is the key process for the formation of N2 as well as for the increase of the total radical concentration in the flame.
Contribution of GC‐MS Analyses to the Determination of the Self‐Ignition Mechanism of 1,4‐Dioxane in Chlorine
Authors: Battin F. , Dzierzynski M. , Marquaire P. M. , Côme G. M. , Baronnet F. 
Published: September 2010

AbstractAn experimental investigation in a conventional static apparatus of gas phase reactions between 1,4 dioxane and chlorine has permitted to observe auto‐ignitions above 100°C at subatmospheric pressure and to map out the limits of reaction zones in a pressure‐temperature diagram. To achieve a better understanding of the reaction mechanism leading to these auto‐ignitions, we have performed an experimental investigation of the slow reaction in a flow system; GC‐MS analyses were used to identify the reaction products. Our results show that at high conversion, 1,4‐dioxene is the dominant reaction product; we also obtain smaller amounts of chlorinated by‐products of 1,4‐dioxane. The results of this investigation are used to build a tentative reaction scheme accounting for the experimental features of the reaction.
Étude expérimental et modèlisation de flammes de prémélangé
Authors: Pauwels J.‐F. , Sochet L.‐R. 
Published: September 2010

AbstractThe aim of flame structure analysis is to set up a chemical mechanism which describes the flame chemistry satisfactorily.Two ways can be used. The first one compares the experimental and modelled mole fraction profiles. In the second one, the experimental net rates are compared with the balance of formation and destruction rates obtained from the postulated mechanism.These methods are applied to study different methanol‐air flames (0.82<ø<1.50). A reaction path analysis is used to interpret a reduced model which gives a good description of the experimental phenomena.
The Influence of Data Truncation Upon Signal, Noise and Resolving Power in Residual Controlled Translation Searches
Authors: Petit G. A. , Lenstra A. T. H. 
Published: September 2010

AbstractFor structures in the space group P1 first and second moments are derived of the density distribution function P(R2) of the residual R2 corresponding to the one correct (signal) and to all the completely incorrect translations (noise) of the search fragment in function of the size of the fragment and the intensity moments of the structure at hand. This allows us to investigate the resolving power of R2‐controlled translation searches based on the property that R2 values related to incorrect translations are Gaussian distributed.The results are made structure independent by averaging over all observable structures. It could be concluded that any data truncation reduces the resolving power, but that the elimination of small E2obs values is least detrimental. A method is given to estimate ”a priori“ the minimum size of the search fragment which allows a successful translation search.
Localization of Mn2+ Ions in Zeolites Y Derived from Computer Simulation of Experimental EPR Spectra
Authors: Zawacki M. , Gutsze A. , Kornatowski J. 
Published: September 2010

AbstractA correlation between the shape of electron paramagnetic resonance spectra and the localization of Mn2+ ions in zeolite Y partially exchanged with Mg2+ and Ca2+ ions has been studied.The spectra have been interpreted based on computer simulation of EPR powder spectra of paramagnetic ions of electron spin S = 5/2 and nuclear spin I = 5/2. This interpretation resulted in differentiation of the experimental EPR spectra into 4 types corresponding with localization of Mn2+ ions in the structure of zeolite Y.
Macroheterocycles: Synthesis and applications as complexing agents, enzyme mimics and catalysts
Authors: Kellogg Richard M. , Kaptein Bernard , Buter J. 
Published: September 2010

AbstractTwo types of systems are discussed. The first one is derived from lutidine, which either is condensed with two equivalents of a ketone or ketone equivalent or is subjected to nucleophilic substitution by stabilized carbanions via lutidine‐2,6‐dibromide. The resulting non‐macrocyclic systems (podands) on further conversion form derivatives that wrap themselves selectively about metal ions. The Zn2+ complexes mimic the active site zinc of liver alcohol dehydrogenase. The other type of compound is a thiamacrocycle. Excellent synthetic routes to these sulfur analogs of crown ethers have been devised and the chemistry ‐ complexations of metal ions, reaction with BH3 ‐ has been explored.
Nucleoside Analogues with a 1,4‐Dioxane, 1,4‐Oxathiane or 1,4‐Oxazine Ring Structure as the Carbohydrate Fragment
Authors: van Aerschot Arthur , Janssen Gerard , Herdewijn Piet 
Published: September 2010

AbstractPyrimidine and purine nucleoside analogues with a 1,4‐dioxane, 1,4‐oxathiane or 1,4‐oxazine ring structure have been prepared from the corresponding dimesylated seconucleosides by treatment with either sodium hydroxide, sodium sulfide or primary alkylamines.
Hydrogen Bonds in Ethenoisomorphinan‐7α‐Carboxamides Studied by Molecular Modelling (Chemistry of Opium Alkaloids, Part XXXIV
Authors: Cappon J. J. , Linders J. T. M. , Maat L. 
Published: September 2010

AbstractWithin the scope of the study of structure‐activity relationships of opioids, we examined some conformational aspects of the rotation of the 7α‐substituent in ethenoisomorphinan peptides. Using molecular mechanics (MMX88) we have determined the relative contribution of two possible intramolecular hydrogen bonds to the orientation of the 7α‐substituent in a model compound (7). The minimum conformation found shows great resemblance in the morphinan skeleton with an X‐ray structure of a morphinan peptide studied previously. The results indicate that the orientation of the 7α‐substituent will be largely defined by hydrogen bonding. The hydrogen bond between the amide hydrogen and the 6‐hydroxyl oxygen (B) causes a greater stabilization than the competing bond between the 6‐hydroxyl hydrogen and the 7α‐carbonyl oxygen (A) in case of the model compound.
Haloaldehyde polymers XLVIII., Optical activity of diastereomeric bornyloxy terminated aldehyde unimers
Authors: Hatada Koichi , Ute Koichi , Nishimura Tohru , Xi Fu , Vogl Otto 
Published: September 2010

AbstractBornyl oxide initiated, acetate endcapped unimers of trifluoroacetaldehyde, trichloroacetaldehyde and tribromoacetaldehyde were prepared and their optical rotations were determined. The value of the optical rotations of the unimers was correlated to the bulk size of the trihalomethyl group and they were compared to those of the unimer of formaldehyde and bornyl acetate. The bornyloxy terminated trihaloacetaldehydes consist of 2 diastereomeric unimers. In the cases of the chloral and bromal unimers they have been isolated. One diastereomer of the trichloroacetaldehyde unimers was crystallized and its absolute configuration was established by x‐ray spectroscopy.
Chemical Modification of Polymers Intended to Increase Blood Compatibility
Authors: Bamford C. H. , Al‐Lamee K. G. , Middleton I. P. , Paprotny J. , Carr R. 
Published: September 2010

AbstractSynthetic methods available for improving the haemocompatibility of polymer surfaces are outlined. The present paper is concerned mainly with ”passivation“ techniques and some of the chemical routes by which they may be effected.Uses of isocyanatoethyl methacrylate as a functionalising reagent and for grafting to polymers are discussed with examples of its applications in the syntheses of (a) monomers from α‐amino acids and peptides, and the amino‐sugars D‐glucamine and D‐glucosamine, and (b) macromers from poly(ether urethanes) and from the hydroxylic macromolecules poly(ethylene glycol), poly(tetrahydrofuran), poly (vinyl alcohol) and dextran.Grafting of monomers and macromers to functionalised polymers is considered. A series of grafts to polyurethane elastomers have been synthesised and tested for blood‐platelet adhesion (a measure of passivation) by a simple procedure which is outlined. All the graft copolymers tested show significantly reduced platelet adhesion compared to the base polyurethane. In particular, a Pellethane‐poly D‐glucamine graft is probably the most inert material towards platelets which we have examined.
Calorimetric Investigation of the Phase Behaviour of the System Poly(2,6‐Dimethyl‐1,4‐Phenyleneoxide)‐Antracene
Authors: Aerts L. , Berghmans H. 
Published: September 2010

AbstractThe phase behaviour of the system poly(2,6‐dimethyl‐1,4‐phenyleneoxide) (PPO) ‐ antracene was investigated. An eutectic behaviour was deduced from calorimetric observations. In samples prepared by evaporation of a benzene solution, the melting point depression of both components and the eutectic melting was observed. When the samples are prepared by freeze‐drying from a benzene solution, only the melting point depression of antracene and the eutectic melting was observed. The presence of PPO crystallites could only be revealed by X‐ray scattering observations.