bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immunological Reactions Carried out at a Liquid‐Solid Interface
Authors: Rothen A. , Mathot C. 
Published: December 2004

AbstractDes γ‐globulines humaines et des polysccharides de pneumocoques de types III et VIII («antigènes») adsorbés en couches minces de 5 à 30 Å d'épaisseur sur des plaques métallisées par du chrome, sont capables d'adsorber spécifiquement des couches d'anticorps pouvant aller jusqu'à plusieurs centaines d'Å d'épaisseur. Les vitesses d'adsorption d'anticorps homologues par les couches de globulines ou de polysaccharides déposées sur les plaques furent mesurées avec un ellipsomètre enregistreur. Avec des plaques non recouvertes préalablement d'antigène, les couches adsorbées après immersion des plaques dans l'antisérum étaient extrêmement minces, d'environ 12 Å, ce qui montre bien que les adsorptions observées en présence d'antigène ont un caractère spécifique. De très grandes différences dans les vitesses d'adsorption sont observées selon que les plaques sont respectivement sèches ou mouillées au moment de l'immersion. Les plaques mouillées adsorbent les anticorps plus rapidement et en une couche plus épaisse que les plaques sèches pourvu que la densité d'antigène présent sur la plaque soit suffisamment élevée. Cette condition était réalisée par l'emploi de solutions d'antigène de 10−3 g/ml pour revêtir les plaques d'une couche d'antigène. Cette différence dans la vitesse d'adsorption peut s'expliquer si l'on formule l'hypothèse qu'il y a coopération entre les molécules d'antigène lorsqu'elles sont suffisamment voisines, ce qui permet une interaction à grande distance favorisant la diffusion des molécules d'anticorps à travers le film d'eau adhérant à la plaque, au détriment des globulines non spécifiques du sérum.Lorsqu'un faible courant électrique (300 μA) est utilisé pour l'adsorption des antigènes et des anticorps, de très faibles concentrations d'antigène descendant jusqu'à 10−14 g/ml et parfois jusqu'à 10−15 g/ml peuvent être décelées.Ces resultats ne sont obtenus qu'avec des plaques révélant par diffraction d'électrons la présence de cristallites de chrome partiellement orientés, d'au moins 50 Å de diamètre, ce qui confirme l'hypothèse que des phénomènes de coopération entrent en jeu dans ces réactions immunologiques à une interphase liquide‐solide.
Optical Rotatory Dispersion and Circular Dichroism Part LXXV: Circular dichroism of some aryl‐amino acids [1]
Authors: Klyne W. , Scopes P. M. , Thomas R. N. , Dahn H. 
Published: December 2004

AbstractCD. curves have been recorded for α‐aryl‐α‐amino acids, esters and amides related to α‐phenylglycine, α‐phenyl‐alanine and their N‐dimethyl derivatives, and for the corresponding α‐cyclohexyl‐α‐amino acids and esters. Compounds with the (S)‐configuration at the single asymmetric carbon atom give strong positive Cotton effects near 220 nm. The conformations of the acids are discussed and compared with those of other α‐amino acids.
14N‐kernresonanzspektroskopische Untersuchungen an o‐substituierten N‐Äthylpyridiniumkationen
Authors: Giger W. , Schauwecker P. , Simon W. 
Published: December 2004

AbstractIn a series of 17 o‐substituted N‐ethylpyridinium salts the pyridinium nitrogen‐14 chemical shifts were determined by heteronuclear double resonance. A shift range of about 30 ppm was observed. No shift correlation was obtained with total electron densities calculated by the Extended Hückel Theory. By comparison with carbon‐13 shifts in analogously substituted aromatic systems a similar substituent dependence of 14N and 13C shifts could be established.
Etude des composés d'addition d'acides de Lewis, XXXVII [1] composés d'addition de quelques quinones avec TiCl4, et relation entre les fréquences carbonyle et diverses grandeurs physicochimiques
Authors: Giallonardo R. 
Published: December 2004

Abstract1:1 or 1:2 solid stoichiometric adducts of TiCl4 with anthraquinone‐1,4, anthraquinone‐1,2, naphtacenequinone‐5,12, pentacenequinone‐6,13 have been prepared. The very important lowering Δω(CO) of the respective IR. carbonyl frequencies, ranging from −160 to −100 cm−1, shows that the acceptor is linked by a dative bond to the carbonyl oxygen atom acting as donor. On the basis of calculations and various considerations, the reduction of the CO double bond character is confirmed. Linear relations are found to exist between the oxydo‐reduction or the polarographic reduction potential of the quinones, and their antisymetric ωa(CO) frequencies, the values of Δω, and the O → Ti vibrations, respectively.
Studies of Oriented Monolayers on Solid Surfaces by Ellipsometry
Authors: Steiger R. 
Published: December 2004

AbstractZusammenfassung. Anhand ellipsometrischer Messungen an orientierten Monoschichten von Cd‐Arachidat, Perylen, Tripalmitin und Cyaninen auf aufgedampftem Gold oder auf reinen Silberbromideinkristallen wird gezeigt, dass damit Dicke und optische Konstanten solcher Monoschichten sehr genau bestimmt sowie Rückschlüsse über deren Stabilität (Kristallisation, Assoziationsverhalten, Reorientierung usw.) gezogen werden können.Das abnormale Verhalten des komplexen Refraktionsindexes der ersten paar Monoschichten lässt auf die Gegenwart von absorbierenden Bereichen an der Grenze zwischen Substrat und Schichtsystem schliessen.
Transketolase from Human Erythrocytes Purification and Properties
Authors: Heinrich Peter C. , Wiss Oswald 
Published: December 2004

AbstractHuman erythrocyte transketolase (sedoheptulose‐7‐phosphate: D‐glyceraldehyde‐3‐phosphate glycolaldehyde‐transferase) was purified 8200‐fold by adsorption onto hydroxylapatite, DEAE‐cellulose treatment, acetone fractionation, and chromatography on Sephadex G‐100. The purified transketolase could not be separated from glyceraldehyde‐3‐phosphate dehydrogenase, whereas the latter enzyme could be isolated in a pure state. Its homogeneity is suggested by sedimentation velocity, sedimentation equilibrium, and acrylamide electrophoresis. A molecular weight of 136000 was found. The physicochemical properties of glyceraldehyde‐3‐phosphate dehydrogenase and transketolase are very similar. A molecular weight of 136000 is suggested for transketolase, although gel filtration with Sephadex G‐100 gave only 104000 ± 10%. This discrepancy is a reflection of an interaction of transketolase with the gel filtration medium. The isoelectric point for transketolase as well as for glyceraldehyde‐3‐phosphate dehydrogenase, as determined by isoelectric focussing, was found to be around 8.5. The activity of the enzyme is close to the maximum for pH 7.5 to pH 8.6. Additions of thiamine pyrophosphate or other cofactors do not influence the activity. Several divalent cations were tested. Sulfate and phosphate inhibit transketolase approximately to 50% between 50 and 100 mM concentration. Thiamine was present in transketolase, as shown by a microbiological assay and by the thiochrome reaction. The activation energy for the formation of sedoheptulose‐7‐phosphate from xylulose‐5‐phosphate was estimated from rate measurements to be 11.2 kcal/mole in the temperature range from 5° to 55°.
Microcalorimetric Determination of ΔH0, ΔG0 and ΔS0 for the Interaction of the Carrier Antibiotics Nigericin and monensin with sodium and potassium ions
Authors: Lutz W. K. , Früh P. U. , Simon W. 
Published: December 2004

AbstractThe thermodynamic parameters ΔH0, ΔG0 and ΔS0 – and thereby the equilibrium constants – for the complexation of the carrier antibiotics nigericin and monensin with sodium and potassium ions in methanol at 25°C have been determined by microcalorimetry. The results are discussed in terms of the nature of the interaction between ligands and cations.
Tris‐hexafluoropropyl‐2‐ates de terres rares
Authors: Merbach A. , Carrard J.‐P. 
Published: December 2004

AbstractTris‐hexafluoro‐2‐propoxides of yttrium, lanthanum, neodymium and erbium have been prepared, by the ammonia method, directly from the hydrated rare earth chlorides, dehydrated in situ by trimethyl orthoformate. The compounds are not volatile.
α, β‐Epoxyketon → Alkinon‐Fragmentierung I: Synthese von exalton und rac ‐ muscon aus cyclododecanon über synthetische methoden, 3. Mitteilung
Authors: Felix Dorothee , Schreiber J. , Ohloff G. , Eschenmoser A. 
Published: December 2004

AbstractExperimental details concerning some examples of the tosylhydrazone version of the α, β‐epoxyketone → alkynone fragmentation as well as a discussion of this process are given.
Elektrocyclischer Ringschluss als Nebenreaktion bei einer Wolff‐Kishner‐Reduktion. Über Steroide, 227. Mitteilung
Authors: Kaufmann H. , Wieland P. , Kalvoda J. 
Published: December 2004

AbstractA side reaction occurring in the Wolff‐Kishner reduction of certain acetylenic aldehydes (as e.g. 2 or 10) is shown to be a synchronous thermal process. The mechanism of this reaction is discussed in terms of the rules of the conservation of orbital symmetry.
Acidity Constants of the Thienyl‐ and Phenyl‐Pyridines and Stability Constants of the Corresponding Copper (II) 1:1 Complexes
Authors: Sigel Helmut , Wynberg Hans , van Bergen T. J. , Kahmann Klaus 
Published: December 2004

AbstractThe acidity constants of the six thienyl‐ and the three phenyl‐pyridines, and the stability constants of the corresponding Cu2+ 1:1 complexes were determined in aqueous solution (I = 0.1, NaCIO4; 25°). The basicity of the pyridyl group is increased by a shift of a thienyl or phenyl group in the order 2 < 3 < 4 and the influence of the 2′‐thienyl group is greater than that of the 3′‐thienyl group. The stability of the Cu2+ 1:1 complexes formed with 3‐ and 4‐substituted pyridines is only dependent on their basicity, as is commonly observed for structurally related ligands and their complexes. Due to steric hindrance the complexes of the 2‐substituted derivatives are less stable by about 1.5 log units. There is no evidence that the aromatic bonded sulfur of 2‐(2′‐thienyl)‐pyridine participates in complex formation with Cu2+, in opposition to an earlier claim [1].
Formation and dissociation mechanism of amide complexes III. Water substitution as the rate limiting factor for the interconversion of Cu2+ complexes with neutral and deprotonated amide groups
Authors: Zuberbühler A. , Kaden Th. 
Published: December 2004

AbstractThe protonation and deprotonation rates of the coordinated amide group in the Cu2+ complexes with Nα‐(2‐pyridyl‐methyl)‐glycinamide (I) and Nα‐(2‐pyridyl‐methyl)‐glycineethylamide (II) have been studied by stopped flow techniques. It is shown that the rate determining step of the formation of the complex with the deprotonated amide group is given by the rate of water dissociation from Cu2+. Weaker bases than OH− or stronger acids than water can react by a different path, in which the proton transfer and/or the rotation from the O‐co‐ordinated into the N‐co‐ordinated form and vice versa is rate determining.
Über die Indolalkaloide von Pleiocarpa talbotii Wernham. 145. Mitteilung über Alkaloide
Authors: Naranjo J. , Pinar M. , Hesse M. , Schmid H. 
Published: December 2004

AbstractBesides talbotine (1) three new indole alkaloids, talpinine (2), talcarpine (3) and 16‐epi‐affinine (4) were isolated from the stem bark of Pleiocarpa talbotii Wernham. The structure of 2 was deduced by chemical degradation and by analyses of the spectra of the alkaloid and its derivatives. One of these derivatives is identical with talcarpine (3).The structures 2 and 3 are similar to that of macroline (14), a splitting product of the bisindole alkaloid villalstonine from Alstonia species. 16‐epi‐Affinine (4) was chemically correlated with the known alkaloid vobasine (19).Talpinine (2) and 16‐epi‐affinine (4) were also isolated from the root bark of Pleiocarpa talbotii.
Catalytic deoxygenation of organic compounds by carbon monoxide: III. The reaction under pressure of aromatic nitro compounds in the presence of o‐phthalaldehyde
Authors: Iqbal Abul F. M. 
Published: December 2004

AbstractThe reaction of o‐phthalaldehyde with several aromatic nitro compounds in the presence of carbon monoxide and catalytic quantities of hexarhodium‐hexadecacarbonyl eventuated in the formation of the corresponding N‐substituted isoindolinone as the major product. A reaction mechanism has been suggested incorporating deoxygenation of the nitro compound by carbon monoxide to a nitrene intermediate and the subsequent interception of the latter by o‐phthalaldehyde.
A Chiral Cystine Disulfide Group without Inherent Optical Activity in the Long‐Wavelength Region. (1H‐ and 13C‐NMR., UV., CD., and ORD. Studies with cyclo‐L‐cystine)
Authors: Donzel B. , Kamber B. , Wüthrich K. , Schwyzer R. 
Published: December 2004

AbstractKonformation und Konfiguration von cyclo‐L‐Cystin wurden mit spektroskopischen Methoden untersucht. Nach 1H‐ und 13C‐NMR. besitzt die Molekel einen wannenförmigen Diketopiperazin‐Ring (CαH—NH‐Diederwinkel ⋍ 40°) und eine chirale Ausbildung der Disulfidbrücke. In Molekelmodellen mit diesen Spezifikationen beträgt der C‐S‐S‐C‐Diederwinkel φ ⋍ 90°. Im CD. war aber kein langwelliger Cotton‐Effekt zu beobachten, welcher auf eine inhärente optische Aktivität des asymmetrischen Disulfid‐Chromophors hinwiese. Dieses Verhalten stützt die Theorie von Linderberg & Michl [3 b], wonach bei Disulfiden mit φ = ±90°, infolge der Entartung der beiden Elektronenübergange niederer Energie und der irreduziblen Darstellung A bzw. B, die sonst getrennten Absorptionsbanden bei 250 nm zusammenfallen und ihre entgegengesetzten Rotationasstärken sich aufheben.Den starken, negativen Cotton‐Effekt bei 228 nm (CD., in Äthanol) ordnen wir dem n,π*Übergang der Peptid‐Carbonylgruppe zu. Vorzeichen und Rotationsstärke (R = −45,4×10−40 erg · cm3) dieser Bande deuten wir als starke Indizien für das Vorliegen des cyclo‐L‐Cystins als P‐helikales Diastereomeres.
L‐Leucyl‐sarkosyl‐L‐phenylalanin, Synthese und Wirkung auf die Aminopeptidasen I und II von Bacillus stearothermophilus
Authors: Jost Rolf , Tun‐Kyi Aung , Stoll Erwin , Zuber Herbert 
Published: December 2004

AbstractThe synthesis of L‐leucyl‐sarcosyl‐L‐phenylalanine is described. This tripeptide resists hydrolysis by the aminopeptidases AP I and AP II from Bacillus stearothermophilus. The peptide is a reversible inhibitor of both enzymes. The inhibition constant for AP I is 5 × 10−3 mol/l and 1.5 × 10−3 mol/l for AP II.In the hydrolysis of leucine p‐nitroanilide we observed noncompetitive inhibition by leucylsarcosyl‐phenylalanine with both enzymes.With dipeptide substrates however, the inhibitory effect of leucyl‐sarcosyl‐phenylalanine was drastically reduced by saturating substrate concentrations.
Über eine neue Synthese von Uracilderivaten
Authors: Meindl H. , Ackermann H. 
Published: December 2004

AbstractWhen N,N‐dialkylamide dimethylsulfate adducts are reacted with cyanoacetyl urea or carbethoxy acetyl urea, the corresponding dialkylamino alkylidene derivatives are formed which cyclize to substituted uracils in the presence of a strong base. When the adducts of cyclic amides are used, the lactam ring is opened simultaneously on cyclisation.
Synthesis of 9‐epi‐Quinine and 9‐epi‐Quinidine. Preliminary communication
Authors: Grethe G. , Gutzwiller J. , Lee H. L. , Uskoković M. R. 
Published: December 2004

AbstractDie stereoselektive Synthese der beiden Cinchona‐Nebenalkaloide 9‐epiChinin (14) und 9‐epi‐Chinidin (15) wird beschrieben.
Synthesen mit Nitrilen. 33. Mitteilung. Phenylhydrazone des Dicyanmethylenindandions: Struktur und Farbe
Authors: Junek H. , Fischer‐Colbrie H. , Aigner H. , Braun A. M. 
Published: December 2004

AbstractDie Darstellung von 2‐Dicyanmethylen‐indandion‐1,3‐monophenylhydrazonen wird beschrieben und die intensive, blaugrün bis violette Farbe der Verbindungen 2a–d diskutiert. Durch Vergleich mit dem gelb gefärbten 2‐Isopropyliden‐indandion‐1,3‐monophenylhydrazon (3c) wird der spezifische Einfluss der Dicyanmethylengruppe auf den Farbcharakter nachgewiesen. 2 a und b sind thermisch und lösungsmittelabhängig instabil und cyclisieren zu substituierten Indenopyridazinen 4a–b, deren chemische Reaktivität beschrieben wird.
Die Synthese von asymmetrisch substituierten o‐Hydroxyphenyl‐s‐triazinen
Authors: Brunetti H. , Lüthi C. E. 
Published: December 2004

AbstractMono‐ and bis‐(2‐hydroxyphenyl)‐s‐triazines 4, 14, 18, 22, 28, 29 can be prepared by (a) reaction of salicylic acid esters 2 with amidines 3; (b) reaction of 4H‐1, 3‐benzoxazin‐4‐ones 10 with amidines 3; and (c) Friedel‐Crafts‐reaction of chloro‐s‐triazines 26, 27 with resorcinol 24.In case (b) the path of reaction is determined by the character of substituent R4 in 10. Scope and limitations of these reactions and accessibility of starting materials are discussed.
Synthèse d'une série de spiropyrannes benzothiazoliniques photochromes substitués en position 3
Authors: Samat André , Guglielmetti Robert , Metzger Jacques 
Published: December 2004

AbstractLa synthèse de spiropyrannes photochromes substitués en position 3 montre que la méthode de cyclisation classique est limitée dans certains cas, notamment pour les composés multifonctionnels ou lorsque les anhydrobases intermeAdiaires sont peu réactives; elle constitue en mêmo temps une généralisation de la synthèse en série benzothiazolinique. Les nouveaux substrats obtenus sont intéressants pour étudier l'influence des paramètres structuraux sur le photochro misme (cinétiques de décoloration thermique, sensibilité spectrale). Nous donnons enfin les caractéristiques spectroscopiques des composés synthétisés.
Notiz über die Kernresonanzspektren von trifluormethyl‐substituierten Naphthalinderivaten
Authors: Huber H. , Pascual C. , Wirz J. 
Published: December 2004

AbstractThe proton and fluorine NMR. spectra of 25 trifluoromethyl substituted naphthalene derivatives have been analysed. The proton chemical shifts of the trifluoromethyl naphthylamines and naphthols have been correlated with calculated π‐electron charge densities (PPP SCF).
Heterotricyclodecane VIII. (−)‐(1S, 3R, 6R, 8R)‐2, 7‐Dioxaisotwistan und (−)‐(1R, 3R, 6R, 8R)‐2, 7‐Dioxa‐twistan; Synthese und Bestimmung der absoluten Konfiguration
Authors: Ackermann P. , Tobler H. , Ganter C. 
Published: December 2004

AbstractA synthesis and the determination of the absolute configuration of (−)‐(1S, 3R′ 6R, 8R)‐2, 7‐dioxa‐isotwistane (13) and (−)‐(1R, 3R, 6R, 8R)‐2, 7‐dioxa‐twistane (14) is described. The results for 14 are compared with those for carboeyclic (+)‐twistane (2) of known chirality.
Heterotricyclodecane IX. 2, 7‐Dioxa‐isotwistan, 2, 7‐Dioxatwistan und 2, 8‐Dioxa‐homotwistbrendan sowie Derivate
Authors: Wicker K. , Ackermann P. , Ganter C. 
Published: December 2004

AbstractThe synthesis of 2, 7‐dioxa‐isotwistane (10), 2, 7‐dioxa‐twistane (17), and 2, 8‐dioxa‐homotwistbrendane (36) and several of their derivatives is described starting from endo‐2‐hydroxy‐9‐oxabicyclo[3.3.1]non‐6‐ene (1).The 10O(7)‐isotwistane iodide 7 and the corresponding tosylate 15 as well as the 10O(2)‐iodide 9 were treated under reaction conditions suitable for molecular rearrangements involving oxonium ions g and i, respectively, by neighbouring group participation leading to 2, 7‐dioxa‐twistanes and 2, 8‐dioxa‐homotwistbrendanes, respectively.
Dárivás C‐glycosyliques. IX. Syntháse de spiro‐Δ2‐isoxazolines et de spiro‐Δ1‐pyrazolines à partir du dásoxy‐3‐di‐O‐isopropylidène 1, 2: 5, 6‐máthylène‐3‐α‐D‐ribo‐hexofurannose. Communication práliminaire
Authors: Tronchet J. M. J. , Bourgeois J. M. , Suard Mlle Y. 
Published: December 2004

AbstractTreatment of 3‐deoxy‐1, 2:5, 6‐di‐O‐isopropylidène‐3C‐méthylene‐α‐D‐ribo‐hexofuranose with aromatic nitrile oxides led to spiro‐Δ2‐isoxazolines, whereas a Δ1‐pyrazoline was obtained by reacting the same C‐methylenic sugar with diazomethane. Properties of these compounds, a new class of carbohydrates, and 5, 6‐di‐O‐acetyl derivatives thereof are described.
Dérivés C‐glycosyliques X. C‐Nucléosides oxadiazoliques inversés. Communication préliminaire
Authors: Tronchet J. M. J. , Moskalyk R. E. 
Published: December 2004

AbstractThe synthesis of «reversed» 1, 3, 4‐oxadiazolyl C‐nucleosides by treatment of alduronic chlorides with N‐benzoylamino‐triphenylphosphinimine or by oxidation of aldehydodialdose benzoylphenylhydrazones is described. One of these compounds is the first example of an «reversed» C‐amino‐nucleoside having a β‐heteroaryl‐ethylamino grouping, a structural unit whose introduction into a sugar molecule is interesting from a pharmacological standpoint.
Studies on the Primary Structure of Cow χ‐Casein.‐Structural Features of para‐χ‐Casein; N‐terminal sequence of χ‐caseinoglycopeptide studied with a sequencer
Authors: Jollès Jacqueline , Schoentgen Françoise , Alais Charles , Fiat Anne‐Marie , Jollès Pierre 
Published: December 2004

AbstractSeveral long tryptic peptides obtained from reduced maleylated χ‐casein were sequenced: they belonged to the N‐ and C‐terminal (37 residues) moieties of para‐χ‐casein. Several tryptic peptides could then be joined by chymotryptic overlap peptides. 102 amino acid residues of para‐χ‐casein were thus placed into two long and four shorter sequences. Some structural results were established with a Sequencer which was also employed for a verification of the N‐terminal sequence of the χ‐caseinoglycopeptide; a previously described short glycopeptide was found again and was reinvestigated.
Bemerkungen zur Überführung von Resibufogenin in Bufalin. Über Krötengifte, 41. Mitteilung
Authors: Hauser Emil , Linde Hort H. A. , Spengel Sigrid 
Published: December 2004

AbstractBei der Reduktion von Resibufogenin 1 mit LiAlH4 bei tiefer Temperatur entsteht nicht wie von Kondo [11], Pettit [7], [8] und Sondheimer [5] beschrieben Bufalin 2 sondern das Hemiacetal 7.
Antibiotic X‐5108. II. Structure of goldinono‐1, 4‐lactone‐3, 7‐hemiketal, a degradation product of the antibiotic. Preliminary communication
Authors: Maehr Hubert , Blount John F. , Evans Ralph H. , Leach Michael , Westley John W. , Williams Thomas H. , Stempel Arthur , Büchi George 
Published: December 2004

AbstractAntibioticum X‐5108 ist ein Naturprodukt mit neuartiger Struktur. Behandlung des Antibioticums mit Essigsäure führte zu einem kristallinen Abbauprodukt, das als 3(S)‐Äthyl‐3, 3a, 5(S), 6, 7, 7 a(R)‐hexahydro‐3a(R), 7(R)‐dihydroxy‐6, 6‐dimethyl‐5‐[1(cis), 3(trans)‐pentadienyl]‐2H‐furo[3, 2‐b]pyran‐2‐on (5) identifiziert wurde.
Konfigurationen und Konformationen von zwei 2,4,6,8‐Tetrabrom‐cyclooctan‐1, 5‐dionen
Authors: Heller Jürg E. , Dreiding André S. 
Published: December 2004

AbstractThe two isomeric tetrabromides, α‐isomer mp. 198° and β‐isomer mp. 226° described in [1], are identified as cis, cis, trans‐2, 4, 6, 8‐tetrabromo‐cyclooctane‐1, 5‐dione (2) and cis, trans, cis‐2, 4, 6, 8‐tetrabromo‐cyclooctane‐1, 5‐dione (3) by an analysis of their NMR.‐spectra which also allows a derivation of their preferred conformations. Both exist in solution as boat‐chair conformers, the geometries of which correlate well with the IR.‐ and UV.‐spectra.
Über die stereoisomeren α‐Phenyläthylamide der Biphenyl‐2,2′,6,6′‐tetracarbonsäure, Molekeln der Punktsymmetrie D2, S4, C2 und C1
Authors: Helmchen Günter , Haas Georges , Prelog Vladimir 
Published: December 2004

AbstractAll four possible diastereomeric α‐phenylethylamides of biphenyl‐2,2′, 6,6′‐tetra‐carboxylic acid (point symmetries D2, S4, C2 and C1) have been prepared and their properties investigated. Both enantiomers of the C2‐diastereomer have been synthetized along stereospecific routes which determine their absolute configurations.Specification of molecular chirality and pseudoasymmetry of compounds with axial chirality in two and three dimensional space is discussed.
Zur Kenntnis von Rifamycin‐S.‐Reaktionen des Ansaringes. Modifikationen von Antibiotica, 8. Mitteilung [1]
Authors: Kump Wilhelm , Bickel Hans 
Published: December 2004

AbstractThe reactivity of rifamycin‐S with respect to acids, bases, and oxydizing or reducing agents has been studied. A number of compounds resulting from these experiments as well as derivatives of rifamycin‐S resulting from acylation and ketalisation reactions are described.