bluuebunny/crossref_metadata_2025_split huggingface dataset:
Über Pyrrolizidinchemie 6. Mitteilung. Konfiguration der HARINGTON'schen(±)‐β‐Hydroxyglutaminsäure und der daraus hergestellten (±)‐3‐Hydroxypyrrolidon‐2‐carbonsäure
Authors: Viscontini M. , Odasso G. , Freitag W. 
Published: December 2004

AbstractFür den von HARINGTON synthetisierten (±)‐β‐Hydroxy‐glutaminsäure‐äthylester wird die erythro‐Konfiguration bewiesen. Der daraus gewonnene (±)‐3‐Hydroxy‐prolin‐äthylester ist dementsprechend ein trans‐Derivat.
Die Strukturen der mittleren Ringverbindungen. X. 1, 6‐trans‐Diaminocyclodecan‐dihydrochlorid, monokline Modifikation
Authors: Huber‐Buser Effi , Dunitz J. D. 
Published: December 2004

AbstractThe structure of the monoclinic modification of 1,6‐trans‐diaminocyclodecanedihydrochloride has been determined, and refined by full‐matrix least‐squares analysis of three‐dimensional X‐ray data. The cyclodecane skeleton is very similar to that found previously in the triclinic modification, but the substituents are attached to different types of carbon atoms. The two crystal modifications thus correspond to different conformational isomers.
Nigrescigenin, Identifizierung mit Sarmentosigenin A Glykoside und Aglykone, 281. Mitteilung
Authors: Brandt R. , Kaufmann H. , Reichstein T. 
Published: December 2004

Abstract“Sarmentosigenin A” has been identified with nigrescigenin. The latter is the older and thus valid name for this 3β, 5β, 11α, 14β‐tetrahydroxy‐19‐oxo‐card‐20:22‐enolide.
Die Isolierung zweier neuartiger Indol‐Derivate aus dem Mycel von Claviceps paspali STEVENSet HALL
Authors: Fehr Th. , Acklin W. 
Published: December 2004

AbstractInvestigation of the dried mycelium of Claviceps paspali STEVENS et HALL has led to the isolation of two new neutral metabolites, paspalin, C28H39O2N, and paspalicin, C31H35O4N, both of which contain a 2,3‐disubstituted indole nucleus.
Über Pterinchemie. 17. Mitteilung. Neuer Beitrag zum Studium eines von Tetrahydropterinen aktivierten Enzymmodelles der Hydroxylierung
Authors: Viscontini M. , Leidner H. , Mattern G. , Okada T. 
Published: December 2004

AbstractAnhand neuer experimenteller Ergebnisse wird für den Mechanismus der von Tetrahydropterin und Fe2+ bzw. Fe3+ katalysierten Hydroxylierung des Phenylalanins zum o‐, m‐ und p‐Tyrosin eine neue Hypothese formuliert, wobei zwei wichtige Punkte hervorgehoben werden: 1. Diese Hydroxylierung ist keine «gemischte» Oxydation, wie wir sie selbst früher postulierten; 2. N‐Oxide sowie Tetrahydropterin‐und HO‐Radikale treten vermutlich als Zwischenprodukte der chemischen bzw. enzymatischen Hydroxylierung auf.
Zum Mechanismus der Autoxydation von Vanadium (IV)‐Komplexen
Authors: Kaden Th. 
Published: December 2004

AbstractThe stoichiometry and the kinetics of the autoxidation of vanadium(IV)‐picolinic acid complexes are studied. Oxygen is reduced to H2O2, a stable peroxovanadate being formed as end product.
Über eine neuartige Substitutionsreaktion am Chinoxalinsystem: nucleofuge Carbonamid‐ und Carbonester‐ Gruppen
Authors: Dahn H. , Moll H. 
Published: December 2004

AbstractThe oximes or arylhydrazones of quinoxaline‐2‐carboxylic acid and its esters or amides substituted in position 3 by an aromatic acyl group are easily cyclized to form condensed isoxazole or pyrazole derivatives, respectively. In the reaction, the oxime oxygen or hydrazone nitrogen acts as a nucleophile; the eliminated carboxyl, carboxylic ester or carboxamide group is partly found as formic acid and CO. The reaction may proceed by an addition‐elimination mechanism.
Über Pyrrolizidinchemie. 7 Mitteilung. Herstellung von L‐Prolin und trans‐3‐Hydroxy‐DL‐prolin durch elektrochemische Reduktion der entsprechenden Pyrrolidon 2‐carbonsäuren
Authors: Viscontini M. , Bühler H. 
Published: December 2004

AbstractDie Darstellung von (teilweise racemisiertem) L‐Prolin und von trans‐3‐Hydroxy‐DL‐prolin durch elektrochemische Reduktion von 5‐Oxo‐L‐pyrrolidin‐2‐carbonsäure (oder deren Äthylester) bzw. von trans‐3‐Acetoxy‐5‐oxo‐DL‐pyrrolidin‐2‐carbonsäure‐äthylester wird beschrieben.
Die Konstitution von Roridin D. Verrucarine und Roridine, 12. Mitteilung
Authors: Böhner B. , Tamm Ch. 
Published: December 2004

AbstractThe antibiotic roridin D (C29H38O9), a companion of roridin A, yields on base catalysed hydrolysis verrucarol (3) and the hitherto unknown 2, 3‐epoxy‐2‐anhydrororidinic acid (4) (C14H18O7). Roridin D is a macrocyclic diester to which structure 1 is assigned. In roridin D an epoxy group replaces the hydroxyl group of roridin A.
Katalytische Effekte bei den Reaktionen von 2,4‐Dinitrofluorbenzol und 2,4‐Dinitrochlorbenzol mit p‐Anisidin in Benzol. 5. Mitteilung über nucleophile aromatische Substitutionsreaktionen
Authors: Bernasconi C. F. , Zollinger Hch. 
Published: December 2004

Abstract(1) The rates of the reactions of 2.4‐dinitrofluorobenzene and 2.4‐dinitrochlorobenzene with p‐anisidine have been measured in benzene solution, with and without the addition of pyridine and 1.4‐diaza‐[2.2.2]‐bicyclooctane (DABCO) as catalysts.
Resorption, Retention, Ausscheidung und Verteilung von PhyllochinonMenachinon‐4 und α‐Tocopherolchinon im Vergleich zum α‐Tocopherol bei der Ratte
Authors: Gloor U. , Wiss O. 
Published: December 2004

Abstract(1) Phylloquinone (K), menaquinone‐4 (MK‐4) and α‐tocopherolquinone (α‐TQ) were compared with d,l‐α‐tocopherol as regards absorption, retention and distribution in various organs.
Katalytische Effekte bei den Reaktionen von 2, 4‐Dinitrofluorbenzol mit Benzylamin und N‐Methylbenzylamin in Benzol. 6. Mitteilung über nucleophile aromatische Substitutionsreaktionen
Authors: Bernasconi C. F. , Zollinger Hch. 
Published: December 2004

Abstract
The rates of reaction of 2,4‐dinitrofluorobenzene with benzylamine and with N‐methylbenzylamine have been measured in benzene solution, with and without the addition of pyridine or 1, 4‐diaza‐bicyclo[2.2.2]octane (DABCO) as catalyst.
Both reactions are catalyzed by the reacting amine, by pyridine and by 1, 4‐diaza‐bicyclo[2.2.2]octane.
Whereas the dependence on base concentration is linear in the case of N‐methyl‐benzylamine, the rate constants are curvilinearly related to base concentration in the reaction with benzylamine. Steric effects are shown to be responsible for this different behaviour, which is easily understood in terms of the two‐step intermediate mechanism (eq.1) for nucleophilic aromatic substitutions.
Part of the pyridine catalysis has to be attributed to a medium effect, as can be shown directly in the reaction involving benzylamine.
The sensitivity of both reactions to base catalysis is much greater than that of the reaction of piperidine with 2, 4‐dinitrofluorobenzene, but is found to be considerably smaller than in the reaction of p‐anisidine with the same substrate, thus suggesting a correlation between the basicity of the reacting amine and the sensitivity of the reaction to base catalysis.
Zur Frage der Koordinationsweise von Chromkomplexen aus dem Azofarbstoff 1‐Amino‐2‐hydroxy‐naphtalin‐4‐sulfonsäurepiperidid →→ 1‐Phenyl‐3‐methyl‐5‐pyrazolon
Authors: Schetty G. , Beffa F. 
Published: December 2004

AbstractOn chroming the dyestuff 1‐amino‐2‐hydroxy‐naphthalene‐4‐sulfonic acid piperidide → 1‐phenyl‐3‐methyl‐5‐pyrazolone, only one 1:2 chromium complex is formed. This fact as well as the absorption spectra and the great stability of the complex indicate that the complex must be coordinated in the Drew‐Pfitzner arrangement, and that the sandwich arrangement must be excluded. Since the steric structure of the 1:2‐complex is already preformed in the adequate 1:1‐complex, our results disprove the conclusions presented by IDELSONet al. [1] [3].
Fluoreszierende Stoffe aus Roten Waldameisen der Gattung Formica (Ins. Hym.). 5. Mitteilung. Isolierung von Lumazin‐Derivaten aus Ameisenmännchen
Authors: Schmidt G. H. , Viscontini M. 
Published: December 2004

AbstractAus Männchen der Ameisenart Formica polyctena FOERST. wurden mit Hilfe chromatographischer Verfahren an Cellulosesäulen Lumazin, Lumazin‐6‐carbonsäure, Isoxantholumazin, 6‐Methyl‐8‐ribityl‐isoxantholumazin sowie zwei weitere, noch nicht identifizierte Isoxantholumazinderivate isoliert. Die ersten vier Lumazine wurden durch Vergleich mit authentischen synthetischen Produkten identifiziert.
Dipolmomente 1, 6‐überbrückter [10]‐ Annulene
Authors: Bremser W. , Grunder H. T. , Heibronner E. , Vogel E. 
Published: December 2004

AbstractThe dipole moments of 1, 6‐bridged [10]‐annulenes of type I (X = CH2, O, NH) and of bromo derivatives with X = CH2, O
magnified image
are in agreement with the previously established structure of these compounds if a partial moment of approximately 0,8 D is assigned to the non‐planar π‐electron system.
Weitere Alkaloide aus Aspidosperma limae Woods
Authors: Pinar M. , Schmid H. 
Published: December 2004

AbstractAus der Stammrinde von Aspidosperma limae Woods. wurden die drei neuen, einander sehr nahe verwandten Alkaloide 11‐Methoxylimatin (5), Limatinin (3) und 11‐Methoxylimatinin (7) kristallisiert abgetrennt. Die Struktur und die Chiralität dieser Alkaloide wurden bestimmt; sie entsprechen dem Aspidospermatidin‐Typus.
Optische Rotationsdispersion von Indolalkaloiden der Yohimban‐, Corynanthean‐ und Quebrachamin‐Gruppe
Authors: Klyne W. , Swan R. J. , Dastoor N. J. , Gorman A. A. , Schmid H. 
Published: December 2004

AbstractIt has been shown that optical rotatory dispersion curves can be used to determin‐ the absolute stereochemistry at C(3) of indole alkaloids of the yohimban and corynane thean types. This is dependent on the absence of strong chromophores other than that of the aromatic system.
Exposition et développement simultanés de plaques cristallines de bromure d'argent. II
Authors: Fernandez‐Garcia J. G. , Steiger R. , Guillemin M. , Boissonnas C. G. 
Published: December 2004

AbstractThin monocristalline sheets of silver bromide have been developed at the contact of a platinum wire connected with a battery. It is shown by electron diffraction that the developed silver grains are composed of silver crystals with a diameter of approximately 150 Å. Autoradiography proves that most of the reduced silver ions are located in a thin superficial layer of the crystalline sheet of silver bromide.
Synthese von 7α‐Methylöstron. Über Steroide, 210. Mitteilung
Authors: Wieland P. , Anner G. 
Published: December 2004

AbstractVarious ways of converting testosterone and dehydroisoandrosterone into 7α‐methylestrone are described. The best method starts from dehydroisoandrosterone and gives 7α‐methylestrone in a total yield of about 24% by weight.
Synthese von geminal methylierten 4‐Chlorbutylaminen
Authors: Currell D. , Grob C. A. , Tam S. W. 
Published: December 2004

AbstractThe syntheses of 4‐chloro‐1‐dimethylamino‐4‐methyl‐pentane (1) and 4‐chloro‐1‐dimethylamino‐2,2,4‐trimethyl‐pentane (2a) are described.
Stabile Dihydroflavine und quartäre Flaviniumsalze Studien in der Flavinreihe, 12, Mitteilung
Authors: Dudley K. H. , Hemmerich P. 
Published: December 2004

AbstractFlavohydroquinones (leucoflavins) protected by acetylation at N(5) have been alkylated to give derivatives substituted at oxygen and/or nitrogen functions in the pyrimidine part of the nucleus. Removal of the protecting group under oxidizing conditions gave N(1),N(3)‐, O(2),N(3)‐ or O(2), O(4)‐dialkyl‐flavoquinonium salts. The N(1)‐substituted type could be reduced to give free flavohydroquinones stable in air, which in turn could be further alkylated at N(5). On oxidation the N(5)‐alkyl groups are readily removed through the radical intermediate. The N(10)‐alkyl groups may be split from the flavoquinonium salt if they are activated (e. g. ‐CH2COOR). The O‐alkyl groups are readily hydrolysed under neutral or slightly acid conditions whereas a basic medium provokes deprotonation at the 8‐CH3 group and concomitant irreversible dimerization. The potential importance of these models for elucidating the mechanism of flavin‐dependent biological dehydrogenation is mentioned.
Die sterischen Bedingungen der Fragmentierungsreaktion III. Teil. Stereoisomere 4‐, 5‐ und 7‐Decahydrochinolyl‐toluolsulfonate Fragmentierungsreaktionen, 16. Mitteilung
Authors: Grob C. A. , Kiefer H. R. , Lutz H. J. , Wilkens H. J. 
Published: December 2004

AbstractIn a heterolytic fragmentation reaction of the type a‐b‐c‐d‐X → a‐b + c=d + :X the geometry of the d‐X bond and that of the electron‐donating group a relative to the b‐c bond are critical. This follows from a study of solvolysis rates and products of stereoisomeric 1‐methyl‐4‐, ‐5‐ and ‐7‐decahydroquinolyl p‐toluenesulphonates in 80 Vol.% ethanol.
Die Cardenolide der Samen von Mansonia altissima, A. CHEV. Glykoside und Aglykone, 286. Mitt.
Authors: Allgeier H. , Weiss Ek. , Reichstein T. 
Published: December 2004

AbstractThe seeds of Mansonia altissima A. Chev. were found to contain ca. 1% cardiac glycosides. A total of 30 substances has been traced by paper chromatography, of which only 8 (E, K, O, P, Q, R, S, and T) were present in amounts large enough to be traced without prior enrichment of the extracts. These substances could be isolated either in pure form or as enriched mixtures. Substances E, K, O, and S were obtained in crystalline form. Apart from these substances a large amount of a mixture (N) was obtained comprising 7 components. The substances E (mansonin) and O (strophallosid) could be identified with known cardenolides. The structure of O was known; the structures of E and K (strophothevosid) are reported in the following publication. The structures of the other isolated and enriched substances (P, Q, R, S, and T) were only partially elucidated.
Gymnemasäure, das antisaccharine Prinzip von Gymnema sylvestre R. Br. Isolierungen und Identifizierungen Glykoside und Aglykone 288. Mitteilung
Authors: Stöklin W. , Weiss E. , Reichstein T. 
Published: December 2004

AbstractThe isolation, characterisation, purity control and probable structure of gymnemic acid, the antisaccharine principle of Gymnema sylvestre R. Br. (Asclepiadaceae) has been reported. According to the results, gymnemic acid is the D‐glucuronide of a probably new hexahydroxy‐δ12‐oleanene which has been named gymnemagenin and which is esterified with various combinations of the following five acids: formic, acetic, n‐butyric, isovaleric, and tiglic acid. Gymnemic acid is not an absolutely pure substance. It is composed predominantly of gymnemic acid A1, which is accompanied by components having similar properties, especially the gymnemic acids A2, A3 and A4. The difference between these components probably lies in the absence or presence of one of the five named acids.
Präbetanin, ein Schwefelsäure‐halbester des Betanins. Ein Beitrag zur Kenntnis der Betacyane
Authors: Wyler H. , Rösler H. , Mercier M. , Dreiding André S. 
Published: December 2004

AbstractPrebetanin, a minor companion of betanin in the red beet, was isolated and found to be the 6′‐sulfuric acid half‐ester of betanin. The arguments are based on elemental analyses, partial hydrolysis and methanolysis, and on comparison of the NMR‐spectra of prebetanin and betanin, and of their derivatives.
Thermische Umlagerungen der Caryophyllene
Authors: Ohloff G. , Uhde G. , Schulte‐Elte K. H. 
Published: December 2004

Abstract(‐)‐Caryophyllen (1) lagert sich oberhalb 240° in (4S)‐(+)‐4,8,8‐Trimethyl‐4‐vinyl‐bicyclo[5.2.0]non‐2‐en (3) um, das sich über (‐)‐iso‐Caryophyllen (2) mit seinem Diastereomeren 4 ins Gleichgewicht setzt. Die Isomerisierungen erfolgen nach dem Prinzip einer Cope‐Umlagerung.
Über die Struktur der Phenazin‐N‐oxide
Authors: Siǵǵ H. P. , Toth A. 
Published: December 2004

AbstractFür das Antibioticum Myxin wird die Struktur des 1‐Hydroxy‐6‐methoxy‐phenazin‐5,10‐dioxids (IV) bewiesen(2).
Die Reaktion von halogenierten s‐Triazinen mit Cyclopentadienylnatrium
Authors: Neuenschwander M. , Schaltegger H. , Stuber F. 
Published: December 2004

AbstractBeim Umsatz von 2‐Chlor‐4,6‐dimethoxy‐s triazin mit Cyclopentadienylnatrium entstehen zwei isomere Dimere, für die auf Grund der NMR.‐Spektren die Strukturen 3(oder 4),8‐Bis‐(4,6‐dimethoxy‐2‐s‐triazinyl)‐tricyclo[5.2.1.02,6]deca‐3, 8‐dien (IIIa) und 1,3(oder 4)‐Bis‐(4,6‐dimethoxy‐2‐s‐triazinyl‐tricyclo[5.2.1.02,6]deca‐3, 8‐dien (IVa)) vorgeschlagen werden. Unter den gleichen Bedingungen erhält man aus 2,4‐Dichlor‐6‐methoxy‐s‐triazin und Cyclopentadienylnatrium neben einem höher‐molekularen Produkt in beträchtlichem Ausmass 3(oder 4), 8‐Bis‐(4‐chlor‐6‐methoxy‐2‐s‐triazinyl)‐tricyclo[5.2.1.02,6]deca‐3, 8‐dien (IIIb).
Über eine neue Synthese zur darstellung heterocyclisch substituierter Stilbenverbindungen, die Anil‐Sythese
Authors: Siegrist A. E. 
Published: December 2004

AbstractHeterocyclische Ringsysteme aromatischen Charakters mit mindestens einem Ring‐Stickstoffatom, die eine oder mehrere p‐Tolylgruppen oder in einem an den Heterocyclus ankondensierten Benzolring eine Methylgruppe in p‐Stellung zu einer CN‐oder NC‐Gruppe des Heterocyclus enthalten, können in Dimethylformamid in Gegenwart von Kaliumhydroxid oder Kalium‐t‐butylat mit aromatischen Aldehydanilen zu heterocyclisch substituierten Stilbenverbindungen umgesetzt werden.
La configuration du «carquéjol» (Isopropényl‐2‐méthylène‐3‐cyclohexène‐4‐ol) et la conformation privilégiée de l' ortho‐néo‐isomenthol
Authors: Thomas Alan F. 
Published: December 2004

AbstractThe complete stereochemistry of carquejol (= cis‐(2S)‐isopropenyl‐3‐methylene‐cyclohex‐4‐en‐1‐ol) is described. The absolute configuration was obtained from the circular dichroism of the corresponding 0‐menthones. Carquejol and its reduction products, having the all‐cis configuration, appear from NMR. measurements to prefer a conformation having the hydroxyl (or acetoxyl) group axial and the isopropenyl (or isopropyl) group equatorial, even when the exo‐methylene group is reduced to methyl. The mass spectra of the compounds are briefly described.
Steroide und Sexualhormone 232. Mitteilung [1] die synthese von 1β, 4β‐oxido‐3‐aza‐17β‐hydroxy‐a‐homo‐5α‐androstan vorläufige mitteilung
Authors: Eggart Fr L. G. , Pascual C. , Wehrli H. 
Published: December 2004

AbstractA sterically controlled transformation of 3‐oxo‐17β‐acetoxy‐Δ1−‐α‐androstene (2) into 1β,4β‐oxido‐3‐aza‐17β‐hydroxy‐A‐homo‐5α‐androstane (16) is described. With the exception of two conversions [14→15 (60%); 15 →16 (50%)], the yields of the remaining seven steps are higher than 75% each. The reaction sequence will serve as a model for an analogous partial synthesis of samandarine (1).
Catalyse acide de certaines réactions nucléophiliques en série phosphoranique. ‐ Action de l'anhydride chloracétique sur les alcoxycarbonylméthylène‐phosphoranes
Authors: Chopard P. A. 
Published: December 2004

Abstract(Alkoxycarbonyl‐chloroacetyl‐methylene)‐phosphoranes dealkylate in the presence of acids and give the very stable lactone‐betaine IV. The mechanism of this reaction is tentatively compared to other known dealkylations catalysed by protons or quaternary phosphonium compounds.
Die Kristall‐ und Molekelstruktur des Naphtalin‐chromtricarbonyl C10H8Cr(CO)3
Authors: Kunz V. , Nowacki W. 
Published: December 2004

AbstractNaphtalin‐chromtricarbonyl kristallisiert in 2 Modifikationen: (a) als Schindeln mit a=12,37, b=6,58, c=7,36 Å, α=107°22′, β=96°44′, γ=92°50′, P1 oder P\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop 1\limits^ - $\end{document}, Z=2, und (b) als Nadeln mit a=13,98, b=11,71, c=6,87 α, P212121, Z=4. Von letzterer wurde mittels einer 3d‐Patterson‐Synthese, gefolgt von mehreren 3d‐Fourier‐und ‐Differenz‐Fourier‐Synthesen und Kleinste‐Quadrate‐Verfeinerungen die vollständige Struktur bestimmt (R=8,5%). Die C‐C‐Abstände im ebenen Naphtalinring von 1,375‐1,447 α weisen gegenüber denjenigen im Naphtalin selber (1,364‐1,427 Å) keine wesentliche, durch den Cr(CO)3‐Komplex bedingte Auflockerung auf. Keine Carbonylgruppe liegt in der «langen» Spiegelebene der Naphtalinmolekel, sondern jede ist aus ihr herausgedreht. Die zwischenmolekularen Abstände von 3,34‐3,71 Å fallen in den Bereich schwacher (CH…O)‐Wechselwirkungen.
N‐Terminale Sequenzanalyse von Peptiden mittels EDMAN‐Abbaus: Kombinierte Anwendung der direkten und der subtraktiven methode
Authors: Pataki György 
Published: December 2004

AbstractA particularly reliable N‐terminal sequence analysis of peptides can be achieved by the following combined application of Edman's phenylisothiocyanate technique, and thin‐layer chromatography. The N‐terminal amino acids acids split off are identified as phenylthiohydantoin‐ and dimethylaminonaphthalensulfonyl‐derivatives; additionally, quantitative analysis of amino acids using thin‐layer chromatography is carried out before and after each degradation step. The applicability of this combined procedure is demonstrated in the case of a nonapeptide.
Etudes sur les composés organométalliques I action du chlorure de benzylmagnésium et du bromure de phénylmagnésium sur le tétrachlorure de titane
Authors: Boustany Kamel S. , Bernauer Klaus , Jacot‐Guillarmod André 
Published: December 2004

AbstractThe reactions between phenylmagnesium bromide or benzylmagnesium chloride and titanium tetrachloride have been studied. The influence of the introduction order of the reagents is mentioned. Decomposition of the (non‐isolated) compounds RnTiX4‐n is shown to be essentially intermolecular, and rarely intramolecular.
Etudes sur les composés organométalliques II [1] Etude spectrophotométrique IR. de quelques complexes de TiCl4 avec la pyridine et des pyridines substituées
Authors: Boustany Kamel S. , Bernauer Klaus , Jacot‐Guillarmod André 
Published: December 2004

AbstractThe preparation of some complexes of titanium tetrachloride with pyridine and substituted pyridines is described. The IR. spectra of the complexes compared with those of the pure ligands (L) indicate the presence of L→Ti dative bonds in the complexes.
Über die Chemie des Vitamins E 7. Mitteilung [1] die stereospezifische Cyclisierung von (3′R, 7′R, 11′R)‐α‐Tocopherolchinon
Authors: Mayer H. , Vetter W. , Metzger J. , Rüegg R. , Isler O. 
Published: December 2004

AbstractStereospecific cyclizations of (3′R, 7′R, 11′R)‐α‐tocopherolquinone (2) are reported:Treatment with conc. sulfuric acid in methanol at 0‐5° gave (2R, 4′R, 8′R)‐α‐tocopherol (1a) with complete retention of configuration at C‐3′.
Zur Taktizität anionisch hergestellter Poly‐α‐methylstyrole
Authors: Lüssi H. , Barman J. 
Published: December 2004

Abstractα‐Methylstyrene has been polymerized with lithium, sodium and potassium naphthalene in tetrahydropyran, tetrahydrofuran and 1.2‐dimethoxyethane at −30°. The tacticity of the polymers was determined by NMR. spectroscopy. Within the limits of reliability no influence of the cation on the tacticity was observed. With growing polarity of the solvent a slight but definite trend towards higher stereospecifity was noticed. The distribution of isotactic and syndiotactic links is purely statistical. The considerable dependence of tacticity upon the polymerization mechanism is ascribed to differences in the steric configuration of carbanions and carbonium ions due to different hybridization.
«α»‐, «β»‐ und «δ»‐Anhydrodigitoxigenin. Glykoside und Aglykone, 293. Mitteilung
Authors: Janiak P. St. , Weiss Ek. , Rechstein T. 
Published: December 2004

AbstractThe syntheses of 3β‐hydroxy‐5β‐carda‐14, 20:22‐dienolide (= «β»‐anhydro‐), 3β‐hydroxy‐5β‐carda‐8:14, 20:22‐dienolide (= «α»‐anhydro‐) and «δ»‐anhydro‐digitoxigenin (= probably 3β‐hydroxy‐5β, 14β‐carda‐8, 20:22‐dienolide) by the best ways known to date, have been described. «δ»‐Anhydro‐digitoxigenin represents the thermodynamically most stable isomer. In this isomer the double bond in position 8 is unaffected by hydrogenation with Pt in acetic acid; with perbenzoic acid an epoxide results from which, on hydrogenation, the double bond can be regenerated in its original position. Analogous reactions are known to occur in the 8:14‐epoxides.