bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthèses dans la série des bis‐indéno‐fluorènes V [1]. Dihydro‐13, 15–11 H‐bis‐indéno[2, 1‐b; 1′, 2′‐h]fluorène et dihydro‐13, 15–5H‐bis‐indéno[1, 2‐a; 1′, 2′‐h]fluorène
Authors: Chardonnens Louis , Stauner Thomas
Published: December 2004

Starting from cyclohexene and 2, 2′, 4, 4′‐tetramethylbiphenyl the linear bis‐indenofluorene 13, 15‐dihydro‐11 H‐diindeno [2, 1‐b; 1′, 2′‐h] fluorene (X) has been synthetised in 5 steps (overall yield 30%). As an intermediate product the 11, 13, 15‐trioxo‐derivative IX was obtained. By a side way the 13‐oxo‐derivative of X and the already known monoangular bis‐indenofluorene 13, 15‐dihydro‐5 H‐diindeno [1, 2‐a; 1′, 2′‐h] fluorene (XIX) were also obtained.
Fluorénacènes et fluorénaphènes Synthèses dans la série des indéno‐fluorènes XIV [1] Nouvelle synthèse du trans‐fluorénacène
Authors: Chardonnens Louis , Avar Lajos
Published: December 2004

A new synthesis of 6, 12‐dihydro‐indeno [1,2‐b] fluorene (trans‐fluorenacene) in 9 steps starting from fluorene (overall yield 24,5%) is recorded. By partial oxidation of the hydrocarbon its 6‐oxo derivative is also obtained.
Dérivés propargyliques IX [1] Propargyl‐pyrrolidinols et propargyl‐perhydro‐azépinols et leurs esters
Authors: Prost M. , Urbain M. , Charlier R.
Published: December 2004

The authors describe the synthesis of 3‐propargyl‐pyrrolidin‐3‐ols and 4‐propargylperhydro‐azepin‐4‐ols, and their esters. The antitussive, analgetic, and local anesthetic activities as well as the respiration stimulative effect of these compounds are related.
Optisch aktive 9,9′‐Spirobifluoren‐Derivate
Authors: Haas G. , Prelog V.
Published: December 2004

The optically active compounds XXIII, XXIV, and XXV, named vespirenes, have been synthetized as first examples of compounds containing a single chirality centre of the type X(A4). The analogous optically active 9,9′‐spirobifluorene derivatives XXI, XXVI, and XXVIII have been prepared for comparison of their chiroptic properties with those of vespirenes.
Beitrag zur Deutung der Lichtechtheit bei den Chinophtalon‐Farbstoffen
Authors: Manukian B. K. , Niklaus P. , Ehrsam H.
Published: December 2004

1. Mit Hilfe von IR.‐ und NMR.‐spektroskopischen Untersuchungen wird das Vorliegen von intramolekularen Wasserstoffbrücken bei 3′‐Hydroxychinophtalon wahrscheinlich gemacht. Die bei 3′‐Hydroxychinophtalonfarbstoffen stets gefundene hohe Lichtechtheit scheint demnach durch die H‐Brücke zwischen dem OH in 3′‐Stellung und dem CO des Anhydrid‐Fünfrings bedingt zu sein.

2. Umsetzungen von Pyromellitsäure‐dianhydrid (V) mit Chinaldin bzw. 3‐Hydroxychinaldin lieferte eine Anzahl neuerer Chinophtalon‐Abkömmlinge. Die beiden hydroxyhaltigen «Dichinophtalon»‐Pigmente XXII & XXIII zeigten in Weich‐PVC gute Licht‐ und Migrierechtheit.
Anil‐Synthese. 2. Mitteilung [1]. Über die Darstellung von Stilben‐ und Styryl‐Derivaten stickstoffreier Sauerstoff‐ und Schwefel‐Heterocyclen aromatischen Charakters
Authors: Siegrist A. E. , Meyer H. R.
Published: December 2004

Phenyl‐substituierte Furane, Benzo [b]furane, Naphto‐[1,2‐b]‐und‐[2,1‐b]‐furane, Thiophene, Benzo [b] thiophene, Naphto [2,1‐b]thiophene, ferner Dibenzofurane, Dibenzothiophene, Phenoxathiine und Thianthrene, die im Phenylrest und/oder in einem an den Heterocyclus ankondensierten Benzolring eine oder mehrere Methylgruppen tragen, können in Dimethylformamid in Gegenwart von Kaliumhydroxid oder Kalium‐t‐butylat mit aromatischen Aldehydanilen zu den entsprechenden Stilben‐ bzw. Styryl‐Derivaten umgesetzt werden.
Über Metaboliten von Thiocarlid
Authors: Balsiger R. W. , Leuenberger Th. , Michaelis W. , Schindler O.
Published: December 2004

Nach oraler Verabreichung des Tuberkulostatikums Thiocarlid (I) wurden im menschlichen Urin die beiden in den Seitenketten hydroxylierten Derivate VI und XI nachgewiesen; unverändertes Thiocarlid konnte nicht aufgefunden werden. Die durch Abbaureaktionen an amorphen Präparaten von VI und XI ermittelten Konstitutionen wurden durch Synthese sichergestellt. Im Verhältnis zur verabreichten Dosis von I sind die ausgeschiedenen Mengen von VI und XI nur gering.
Organische Phosphorverbindungen 39. Methoden zur Herstellung von Chloräthylphosphonsäuredichlorid, ClCH2CH2P(O)Cl2 und CH3CHClP(O)Cl2 [1]
Authors: Maier Ludwig
Published: December 2004

It is shown that the KINNEAR‐PERREN reaction with ClCH2CH2Cl, PCl3, and AlCl3 produces the two possible isomers ClCH2CH2P(O)Cl2 and CH3CHClP(O)Cl2. Methods for the preparation of pure ClCH2CH2P(O)Cl2 and pure CH3CHClP(O)Cl2 are described. The physical properties of a number of chloroethyl groups containing phosphorus compounds are listed.
Die Aminoalkylierung von Phtalazinen und Phtalazonen mit Hilfe der GRIGNARD‐Reaktion. 4. Mitteilung über GRIGNARD‐Reaktionen mit Halogenalkylaminen [1]
Authors: Marxer A. , Hofer F. , Salzmann U.
Published: December 2004

Phtalazines and 4(3H)‐phthalazones are aminoalkylated in high yield by 3‐dimethylaminopropyl‐magnesiumchloride. Phthalazines add only one molecule of the GRIGNARD reagent at the CN‐double bond, giving mono‐aminoalkylated 1,2‐dihydrophthalazines which undergo no further reaction without previous oxydation. Phthalazones react with the carbonyl and the CN‐group yielding in one step di‐aminoalkylated dihydrophthalazines. The dihydrophthalazines are easily oxydized with K3Fe(CN)6 to the corresponding phthalazines.
Synthese und Eigenschaften von 1‐Aminoalkyl‐dibenzo[b, e]bicyclo[2.2.2]octadienen
Authors: Wilhelm M. , Schmidt P.
Published: December 2004

The syntheses of dibenzo [b, e] bicyclo [2.2.2] octadienes substituted at the bridgehead by aminomethyl, aminoethyl or aminopropyl groups are described. The influence of this substitution on the fragmentation upon electron impact and on the nmr spectra of the new compounds is discussed.
Über die Synthese von 2‐(p‐Biphenylyl)‐isopropyloxycarbonyl‐(Bpoc)‐Aminosäuren und den Zerfall von Aralkyl‐phenyl‐carbonaten
Authors: Sieber P. , Iselin B.
Published: December 2004

The syntheses of a number of new Bpoc‐amino acids and the preparation of some activated esters of Bpoc‐amino acids are described. In recent work on the total synthesis of calcitonin hormones the Bpoc residue has been found to be very useful for the selective protection of α‐amino groups of complicated intermediate peptide fragments.

The reagent preferentially used for the introduction of the Bpoc group into amino acids, [2‐(p‐biphenylyl)‐isopropyl]‐phenyl‐carbonate (I), is stable at 0°, but undergoes at higher temperatures a decomposition which is a accelerated by phenol. Based on the reaction products formed — [2‐(p‐biphenylyl)‐isopropyl]‐phenyl‐ether (II), 2‐(p‐biphenylyl)‐propene (III), and phenol — a scheme is proposed for this thermal decomposition, and the possibility of a correlation between the stability of carbonates R3C—O—CO—OC6H5 and the rate of the acidolytic cleavage of urethanes R3C—O—CO—NHR′ depending on the substituents R is discussed.
Struktur und Reaktionen von Coleon B. 2. Mitteilung über Coleon B
Authors: Ribi M. , Sin‐Ren A. Chang , Küng H. P. , Eugster C. H.
Published: December 2004

Für Coleon B, C19H20O6, den gelben Farbstoff aus Blattdrüsen von Coleus igniarius Schweinf. (Labiatae) wird Struktur 1 bewiesen. Die absolute Konfiguration wurde durch Überführung in 19‐Nor‐dihydro‐royleanon‐trimethyläther und Vergleich mit dem konfigurativ verknüpften Dihydro‐royleanon‐trimethyläther bestimmt. Für die besondere chemische Reaktivität von Coleon B ist einerseits der Hydrochinonring C und andererseits das die Ringe A und B umfassende konjugierte Hexadiendion‐System verantwortlich. Sie wurde durch zahlreiche Reaktionen belegt.

Die früher [5] erwähnte (—)‐Coleus‐Substanz C hat sich als Gemisch aus Spinasterin und Dihydrospinasterin, die (+)‐Substanz D als α‐Amyrin erwiesen.
Bestimmung der Chiralität der enantiomeren α‐Cyclogeraniumsäuren, α‐Cyclogeraniale, α‐Jonone, γ‐Jonone, α‐Carotine, ε‐Carotine und verwandter Verbindungen durch chemische Verknüpfungsreaktionen. Vorläufige Mitteilung
Authors: Eugster C. H. , Buchecker R. , Tscharner Ch. , Uhde G. , Ohloff G.
Published: December 2004

Die im Titel genannten enantiomeren Verbindungen sind durch chemische Reaktionen mit Ambrein und Manool verknüpft worden, so dass ihre Chiralität festgelegt ist. Damit ist zum erstenmal die Konfiguration eines chiralen Carotinoidkohlenwasserstoffes bestimmt. Das natürlich vorkommende (+)‐α‐Jonon hat R‐Konfiguration, ebenso das natürliche (+)‐α‐Carotin.
Derivate des 5, 6‐Dihydro‐p‐dithiin‐2, 3‐dicarbonsäure‐anhydrids, I: Imide
Authors: Schweizer H. R.
Published: December 2004

5. 6‐Dihydro‐p‐dithiin‐2. 3‐dicarboxylic anhydride reacts with primary amines quite readily to form the substituted imides. The imide formation occurs much more easily than with maleic or phthalic anhydride. The imide and all N‐substituted imides have a fairly strong, bright yellow colour. Their absorption spectra differ considerably from those of the anhydride, ester and dinitrile. Electron‐attracting substituents on the imide nitrogen increase the absorption maximum somewhat, while strongly electron‐releasing groups decrease it, and may even shift it to a shorter wave‐length. It is therefore concluded that the imide nitrogen is part of the election acceptor group of the chromorphoric system.
Die Ermittlung der Oberflächenkonzentration von Ionenadsorbaten mit Hilfe einer Zwei‐Elektroden‐Dünnschichtmethode
Authors: Schmidt E. , Siegenthaler H.
Published: December 2004

Es wird ein Verfahren zur Untersuchung von Ionenadsorbaten an ideal polarisierbaren Elektroden beschrieben, bei dem eine zusätzliche, bezüglich der adsorbierbaren Spezies reversibel arbeitende Generatorelektrode im Kontakt mit der Elektrolytphase steht und in dieser eine konstante Aktivität der betreffenden Komponenten aufrecht erhält. Änderungen der Oberflächenkonzentration setzen sich dann in FARADAY'sche Ströme an der Generatorelektrode um, die leicht gemessen und zur Ermittlung von Γ‐Isothermen herangezogen werden können. Zur praktischen Durchführung derartiger Versuche empfiehlt sich die Anwendung einer Dünnschichtmethode.

Mit Hilfe dieses Verfahrens wurde die Oberflächenkonzentration von Pb an Ag‐Elektroden in Perchloratlösung bestimmt. Die erhaltenen Γ‐Werte lassen sich als eindeutige Funktion der Differenz zwischen den Potentialen der adsorbatbildenden und der Generator‐Elektrode darstellen und entsprechen damit dem bekannten Metallmonoschichtmodell.
Beiträge zur Chemie der Si‐N Bindung, XXI. [1] Über die Strukturisomerisierung N‐silylierter Cyclosilazane
Authors: Fink Walter
Published: December 2004

When 6‐ and 8‐membered silazane rings are silylated after previous metalation with n‐butyllithium isomerizations to cyclodisilazane structures take place by ring contraction. Structures of the various isomers are assigned by 1H‐nmr.‐ and infrared spectra. The anionic rearrangements which were studied by proton nmr. spectroscopy and vapor‐phase chromatography occur with catalytic amounts of base and proceed partly to equilibria following first‐order‐kinetics.
Sur la séparation des terres rares XIII. Systèmes de solubilité comprenant des chlorures de terres cériques [1]
Authors: Brunisholz G. , Nozari M.
Published: December 2004

In aqueous solution, the chlorides of lanthanum, cerium and praseodymium cristallize as heptahydrates, those of the other rare earth elements as hexahydrates. Therefore, a miscibility gap exists in the solid phases in all systems comprising the two types of chlorides. Five ternary systems and a quaternary one with this behaviour have been studied.
Untersuchungen über das Verhalten organischer Mischphasen 8. Mitteilung. Dampfdrücke, Dichten, thermodynamische Mischungsfunktionen und Brechungsindices der binären Systeme Wasser‐Tetrahydrofuran und Wasser‐Diäthyläther bei 25°
Authors: Signer R. , Arm H. , Daeniker H.
Published: December 2004

The total vapor pressures and the heats of mixing of the water‐tetrahydrofuran and water‐diethyl ether systems were measured at 25°. Density, index of refraction, and KARL‐FISCHER‐titration were used to determine concentrations for the total pressure measurements. The partial pressures, activity coefficients, excess free energies, entropy functions, and excess volumes were calculated.
Die Aminoalkylierung von Chinazolinen und Chinazolonen mit Hilfe der GRIGNARD‐Reaktion. 5. Mitteilung über GRIGNARD‐Reaktionen mit Halogenalkyliminen [2]
Authors: Marxer A. , Salzmann U. , Hofer F.
Published: December 2004

Quinazoline is aminoalkylated at C(4) by 3‐dimethylaminopropyl‐magnesium‐chloride in preparative yield to give 3, and by oxidation 5, just as aryl and alkyl‐magnesiumbromide give 15, 19, and 22. These 4‐substituted quinazolines yield by further treatment with the same GRIGNARD compound by 3, 4 or 1, 2‐addition 3, 4‐di‐hydro‐quinazolines (12, 16) and 1, 2‐dihydro‐quinazolines (13, 17, 20, 23), the latter being formed exclusively when the 4‐position in the quinazoline is occupied by bulky residues; only the later can be oxidised to give 2,4‐disubstituted aromates (cf 14, 18, 21, 24). The spectroscopic and physicochemical behaviour of the dihydro compounds and the aromatic and the aromatic compounds are discussed.
Über einige Eigenschaften von 6‐Keto‐δ7‐Steroiden
Authors: Scherrer H.
Published: December 2004

Some aspects of the ORD.‐, UV.‐, and NMR.‐spectra of 6‐keto‐δ7‐steroids are discussed. It is shown that there exists a correlation between the configuration of rings A/B and the position of the maxima of the ORD. curves. On treatment with bases the 6‐keto‐δ7 group is unstable and undergoes deconjugation to δ8(14)‐steroids.
Photochemische Reaktionen. 56. Mitteilung [1]. Die Photoisomerisierung des α,β‐ungesättigten δ‐Diketons 3, 7‐Dioxo‐4, 4‐dimethyl‐17 β‐acetoxy‐δ5‐androsten und dessen 3‐Ketalderivates
Authors: Domb S. , Bozzato G. , Saboz J. A. , Schaffner K.
Published: December 2004

On irradiation with light of wavelengths 2537 or > 3400 Å 4,4‐dimethyl‐17β‐acetoxy‐androst‐5‐ene‐3, 7‐dione (8) rearranges to the two diastereoisomeric products 9 and 10. This isomerization is the only detectable photochemical reaction of 8 in a variety of solvents, including p‐dioxane. Complete quenching with 0.5M naphthalene (on irradiation with > 3400 Å) indicates a triplet reaction.

The photochemistry of the 3‐ethylene ketal derivative 29 differs completely. Irradiation in p‐dioxane solution leads exclusively to photoreduction and formation of the four diastereoisomeric dioxanyl allyl tert.‐carbinols 30a–d.
14‐Epi‐Digitoxigenin und 3‐Desoxydigitoxigenin. 19. Mitteilung über Reaktionen mit Mikroorganismen [1]
Authors: Zürcher W. , Weiss‐Berg E. , Tamm Ch.
Published: December 2004

The synthesis of the hitherto unknown 14‐epi‐digitoxigenin (8) and of 3‐deoxy‐digitoxigenin (16) is described. The 15,15‐propylene‐thio‐sulfoxides 6 and 7 proved to be valuable intermediates. The results of the cardiotonic activity (ATPase test) of the cardenolides 8 and 16 are reported.
Intramolekulare Beweglichkeit eines Dibenzo‐[b, f]‐1,4‐thiazepin‐5‐oxids. 13. Mitteilung über siebengliedrige Heterocyclen
Authors: Michaelis W. , Gauch R.
Published: December 2004

The kinetics of the equilibrium in aqueous solution between the diasteromers of 2‐Chloro‐11‐(4‐methyl‐1‐piperazinyl‐4‐oxide)‐dibenzo‐[b, f]‐1,4‐thiazepine‐5‐oxide (V) have been investigated. Both isomers differ in the position of the oxygen atom of the sulphoxide group. The sulphoxide group. The isomer with a pseudo‐equatorial oxygen atom is 0.75 kcal/mol more stable than the isomer with the pseudo‐axial oxygen atom. The calculated free energies of activation δG≠ are 24.6 kcal/mol and 23.9 kcal/mol.
Induktion von Circulardichroismus in einer optisch inaktiven Verbindung durch zwischenmolekulare Wechselwirkung mit einem optisch aktiven Lösungsmittel
Authors: Noack K.
Published: December 2004

l‐menthol induces a circular dichroism in the n,π* transition of saturated, optically inactive ketones. Its magnitude is strongly dependent on the total concentration and the menthol‐Ketone ratio. It increases with increasing excess of menthol and with increasing total concentration of the components. An analysis shows that the reciprocal of the induced CD. (1/δε,) is proportional to the reciprocal of the menthol concentration, and from this follows, that probably optically active 1:1 complexes are formed. This complexing is due to hydrogen bonding. It is strongly temperature dependent. Sterical hindrance of the ketone has also a strong influence. It was also possible to induce with l‐menthol a CD. in aliphatic nitro compounds.
Anil‐Synthese. 3. Mitteilung [1] Über die Darstellung von Styryl‐Derivaten aus methyl‐substituierten carbocyclischen Aromaten
Authors: Siegrist A. E. , Liechti P. , Meyer H. R. , Weber K.
Published: December 2004

Methyl‐substituierte carbocyclische Aromaten der Benzol‐, Diphenyl‐, Terphenyl‐, Stilben‐, 1,4‐Diphenylbutadien‐, Tolan‐, 1,4‐Diphenylbutadiin‐, Naphtalin‐, Anthracen‐und Phenanthren‐Reihe werden mit Anilen aromatischer Aldehyde in Dimethylformamid in Gegenwart von Kaliumhydroxid oder Kalium‐t‐butylat zu Styryl‐Derivaten umgesetzt.
Cardenolide und Pregnanderivate aus den Wurzeln von Trachycalymma fimbriatum (WEIMARCK) BULLOCK Glykoside und Aglykone, 322. Mitteilung
Authors: Elber R. , Weiss Ek. , Reichstein T.
Published: December 2004

The roots of Trachycalymma fimbriatum (WEIMARCK) BULLOCK contain both cardenolide and pregnaneglycosides. Elimination of 2‐deoxysugars by mild acid hydrolysis gave a mixture from which some anhydroderivatives and the following compounds could be isolated: uzarigenin (l), ascleposide = 3‐O‐(6‐deoxy‐β‐D‐allopyranosyl)‐uzarigenin (4), coroglaucigenin (6) and two pregnane derivatives (H and J). Compound H could be identified as 3β,14β‐dihydroxy5α, 17α‐pregnan‐20‐one (10). Compound J is probably a new substance, for which we tentatively assign structure 18, i.e. 3β8β,14β‐trihydroxy‐5α,17α‐pregnan‐20‐one. We suspect H and J to be artefacts produced from the corresponding 17b‐derivatives during acid hydrolysis. 17‐iso‐H is probably a precursor in the biosynthesis of uzarigenin. The cardenolides of Trachycalymma fimbriatum are the same as found in Asclepias glaucophylla, a closely related species, while the pregnane derivatives of the latter are distinctly higher hydroxylated.
Acetylene mit Elektronendonator und Elektronenakzeptorgruppen
Authors: Gais H.‐J. , Hafner K. , Neuenschwander M.
Published: December 2004

Acetylenes having both electrondonating and electronaccepting groups (1) may be obtained in good yield from the correspondingly substituted olefinesviabromination and elimination of HBr. The reaction of the acetylene aldehyde1awith proton acids yields, after rearrangement of the primary adducts, the β‐substituted acrylamides. Addition of nucleophiles leads to the β‐disubstituted α.β‐unsaturated carbonyl compounds. With hydrazines one obtains pyrazoles and pyrazolones. The acetylenes1undergo [2+2]‐, [2+3]‐ and [2+4]‐cycloaddition reactions.
La structure chimique primaire du lysozyme du lait de Femme: établissement d'une formule développée provisoire
Authors: Jollés Jacqueline , Jollès Pierre
Published: December 2004

The detailed primary sequences of the N‐terminal moiety (72 amino acid residues) and of the C‐terminal end (23 amino acid residues) of human milk lysozyme (129 residues) are reported. A tentative complete structure of the enzyme is compared to hen and duck egg‐white lysozymes which are very near related proteins despite many amino acid replacements (around 50), the insertion of an additional residue in the N‐terminal and a deletion in the C‐terminal moiety.
S,S'‐Bis‐cyclo‐gylcyl‐L‐hemicystyl‐glycyl‐glycyl‐L‐prolyl, ein künstliches, bicyclisches Peptid mit Kationenspezifität.15. Mitteilung über homodet cyclische Polypeptide
Authors: Schwyzer R. , Tun‐Kyi Aung , Caviezel M. , Moser (z.T.) P.
Published: December 2004

Using only amino acids occurring in proteins it should, in principle, be possible to synthetize peptide molecules capable of complexing metal cations. The approach described in this contribution is to build cages of oxygen atoms that could contain A‐cations of specific diameter (in a manner similar to nigericin, nonactin, valinomycin, and other antibiotics) by binding together face‐to‐face and in the correct distance from one another two homodetic cyclic peptide rings. Using a link that may be formed and broken in a reversible manner (for example oxidativeformationon the outside of the cell membrane and reductive cleavage on the inside), one should even be in a position to construct a model for active, energy‐coupled transport of cations across the cell membrane.

An example of this type of synthetic products is the bicyclic peptide S, S′‐bis‐cyclo‐glycyl‐L‐hemicystyl‐glycyl‐glycyl‐L‐prolyl. This compound, the first to contain two homodetic peptide rings bound together, was prepared by stepwise synthesis from the C‐terminal of the S‐protected pentapeptide active ester, glycyl‐(S‐diphenylmethyl)‐L‐cysteyl‐glycyl‐glycyl‐L‐proline‐p‐nitro‐phenyl ester, using active esters of protected amino acids, followed by cyclization of this inter‐mediate, cleavage of the diphenylmethyl protecting group, and final oxidation of the thiol group to the disulfide function. EMF.‐Measurements on membranes by Simon and Pioda according to the method of Stefanac & Simon [4] revealed cation specificity in the order: K+ > Na+ > Li+ > Ca++. Optical rotatory dispersion shows that there is a conformational transition during complexation. Circular dichroism points to a 75–90° dihedral angle and right‐handed helicity of the disulfide bond. On this basis the models shown in Fig. 6 were constructed as hypothetical representations of the potassium complexes with cages of eight or of ten oxygen atoms.
Allgemeine Basenkatalyse der Azokupplung von o‐Diazophenolen. 19. Mitteilung zur Kenntnis der Azokupplungsreaktion
Authors: Jermini C. , Koller S. , Zollinger H.
Published: December 2004

1. The kinetics and the mechanism of the diazo coupling reaction of 2‐diazophenol‐4‐sulphonic acid with 1‐naphthol‐2‐sulphonic acid have been investigated at 0° and ionic strength I=0.45.

2. The pKa‐value of the hydroxyl group in 2‐diazophenol‐4‐sulphonic acid has been determined: pKa=‐ 0.04 ± 0.10. It is the diazonium‐phenolate anion which actually enters into the diazo coupling reaction.

3. The reaction is subject to general base catalysis. It is shown that no intermediate is enriched during the reaction at pH 11.3–11.6 which proceeds by a two‐step mechanism with a steady state intermediate.
Elektronendonator‐Akzeptor‐Komplexe von Diazonium‐Ionen und die Struktur von stabilisierten Diazonium‐Salzen. 20. Mitteilung zur Kenntnis der Azokupplungsreaktion
Authors: Koller S. , Zollinger H.
Published: December 2004

1. In 0.1N HCl/H2O, o‐ and p‐nitrobenzenediazonium ions rapidly form a complex with 2‐naphthol‐6, 8‐disulphonic acid anions. Visible and NMR, spectra show that it has the structure of a charge‐transfer complex (π‐complex). The latter is probably an intermediate in the electrophilic aromatic substitution (diazo coupling reaction).

2. Diazonium ions form charge‐transfer complexes with naphthalene, 1‐methylnaphthalene, naphthalene‐1‐sulphonic acid, 1‐naphthyl‐methanesulphonic acid and also 2‐naphthol‐1‐sulphonic acid. The equilibrium constants of all these complexes have been determined.

3. The stabilisation of diazonium salts by arylsulphonic acids with regard to decomposition is due to charge‐transfer complex formation and not to formation of diazosulphonates as assumed by former investigators. The sulphonic group is not essential for the stabilisation.

4. Charge‐transfer complex formation decreases the electrophilicity of the diazonium ion (rate of diazo coupling reaction) only slightly.
ESR.‐Untersuchungen an Radikal‐Anionen des 1, 6‐Imino‐[10]annulens und seines N‐Methyl‐Derivats
Authors: Gerson F. , Heinzer J. , Vogel E.
Published: December 2004

The ESR.‐spectrum of the radical anion of 1,6‐imino‐[10]annulene (II) has been recorded. Its hyperfine structure reflects the reduced symmetry (Cs) of the molecule, as compared with that (C2v) of 1,6‐methano‐ and 1,6‐oxido‐[10]annulenes (I and III, resp.). The coupling constants of the ring protons in II⊖ are intermediate between the corresponding values of I⊖ and III⊖. The ESR.‐spectrum of the radical anion of 1,6‐methylimino‐[10]annulene (IV) has also been obtained, but not analysed in detail. The relative stabilities of the radical anions of the four bridged [10]annulenes are: I⊖≫II⊖ > III⊖ > IV⊖. The main secondary product identified by ESR.‐spectroscopy after the decay of II⊖, III⊖ and IV⊖ is the naphthalene radical anion. A remarkable exception is IV, when reduced with sodium in 1,2‐dimethoxyethane: in this case the ESR.‐spectrum of the azulene radical anion is observed.
ESR.‐Spektren des Radikal‐Anions des syn‐1, 6; 8, 13‐Bis‐oxido‐[14]annulens
Authors: Gerson F. , Heinzer J. , Vogel E.
Published: December 2004

The ESR.‐spectra of the radical anion of syn‐1, 6; 8, 13‐bis‐oxido‐[14]annulene have been recorded. The hyperfine structure of the electrolytically generated anion (solvent: N, N‐dimethylformamide; gegenion: Et4N⊕) is that of an unassociated species; on the other hand, evidence of strong ion‐pairing can be derived from the spectra of chemically prepared anions (solvent: 1,2‐dimethoxyethane; gegenion: K⊕ or Na⊕). The distribution of the n‐spin population confirms the conclusion previously drawn for the radical anion of 1,6‐oxido‐[70]annulene that the overall effect of the oxygen bridging is electron repelling.
Herstellung von 3‐Oxo‐17β‐hydroxy‐1,19‐cyclo‐5α‐androstan. Über Steroide, 219. Mitteilung
Authors: Wieland P. , Anner G.
Published: December 2004

Under the influence of radical anions generated from lithium and biphenyl, 3‐oxo‐17β‐acetoxy‐19‐mesyloxy‐Δ1‐5α‐androstane was converted into 3‐oxo‐17β‐acetoxy‐1, 19‐cyclo‐5α‐androstane.
2α, 3β, 19‐Triacetoxy‐14α‐hydroxy‐5α‐card‐20:22‐enolid: Teilsynthese. Zusätzlicher Beweis für die Struktur des Calotropagenins. Glykoside und Aglykone, 324. Mitteilung
Authors: Lardon A. , Stöckel K. , Reichstein T.
Published: December 2004

Coroglaucigenin, which is known to be a 3β, 14β, 19‐trihydroxy‐5α‐card‐20: 22‐enolid, was transformed into 2α, 3β, 19‐triacetoxy‐14β‐hydroxy‐5α‐card‐20 : 22‐enolid. The latter was identical with the known tri‐O‐acetyl‐19‐dihydro‐calotropagenin. The structure of calotropagenin (1) is thus established through an independent way.
L'action de l'ammoniac sur l'oxyde cuivrique. et les hydroxo‐complexes de cuivre (II)
Authors: Gübeli A. O. , Hébert J. , Cǒté P. A. , Taillon R.
Published: December 2004

Using a new mathematical treatment, the nature and stability constants of the simple and mixed complex‐species of copper(II) with hydroxyde and ammonia as ligands have been determined. The solubility curves of CuO in heterogeneous equilibrium have been identified in function of pH only and in function of pH and pNH3tot at 25° and unit ionic strength (NaClO4).

The predominent species in the relatively dilute system limited by the ionic strength are [Cu2+], [Cu(OH)2], [Cu(OH)], [Cu(OH)], [Cu(NH3)], [Cu(NH3)], [Cu(NH3)], [Cu(NH3) (OH)+], [Cu(NH3)3(OH)+] and [Cu(NH3)2(OH)2].
Thermische Umwandlung von Penta‐2, 4‐dienyl‐phenyläthern in 4‐(Penta‐2, 4‐dienyl)‐phenole; [5s, 5s]‐sigmatropische Umlagerungen
Authors: Fráter Gy. , Schmid H.
Published: December 2004

trans‐Penta‐2, 4‐dienyl phenyl ether (trans‐1), on heating at 186° in a five‐fold excess of N, N‐diethylaniline, gave via a [3s, 3s] rearrangement 23% of 2‐(1‐vinyl‐allyl)‐phenol (2) and via a [5s, 5s] rearrangement 37% of trans‐4‐(penta‐2, 4‐dienyl)‐phenol (trans‐3). The dimeric residue was formed from trans‐1 by diene synthesis. By working at high dilution, the formation of dimeric products was kept to a minimum. The inversion of the migrating pentadienyl residue during the rearrangement of trans‐1 to trans‐3 was proved by rearrangement of the methyl labelled ether trans, trans‐4 to the p‐dienyl‐phenol 8 (93%) (accompanied by only 7% of 9). trans‐5 gave the p‐phenol 9 quantitatively.

cis‐Penta‐2, 4‐dienyl phenyl ether (cis‐1) was converted to 10 on heating, by a fast [1, 5s] H‐migration.

The above mentioned reactions of the type trans‐1 → trans‐3 show first order kinetics and are the first examples of [5s, 5s] sigmatropic rearrangements shown to go through a ten‐membered transition state. The conformation of the activated complex is discussed in the light of the stereochemistry of the migrating penta‐2, 4‐dienyl group.
Die Photoelektron‐Spektren der Dihalogen‐acetylene
Authors: Heilbronner E. , Hornung V. , Kloster‐Jensen Else
Published: December 2004

The photoelectron‐spectra of the six dihaloacetylenes XCCY with X, Y  Cl, Br, I have been recorded. The first five bands of these spectra can be assigned (in order of increasing ionization potentials) to the states 2∏(u)(1), 2∏(g)(2), 2∏(u)(3), 2∑(g)+(4), 2∑(u)+(5) where the lower indices g, u are valid only for the centro‐symmetric molecules I(X, X). The first three states correspond to π‐ionization, the last two to σ‐ionization of the axially symmetrical lone pairs. The 2∏‐states split under the influence of spin‐orbit‐coupling into components 2∏3/2 and 2∏1/2, the former having the lower energy. The assignment of states and components to the individual bands is confirmed by the size of the split due to spin‐orbit‐coupling, the vibrational fine structure of the bands and by a simple parametrization of the ZDO. molecular orbital model assumed as a basis for the qualitative discussion.
Contribution à l'étude de la Mésomérie, VII [1] Système formé d'un atome à deux électrons et de n atomes à un électron chacun
Authors: Klement O. , Portmann J.
Published: December 2004

On indique une méthode graphique simplifiant considérablement, dans le cadre de la méthode de mésomérie, le calcul de l'énergie et de la répartition des électrons. Les règles de calcul présentées sont valables pour un système formé d'un atome à deux électrons et d'un nombre quelconque d'atomes à un électron chacun.
Réarrangements d'acétonides de sucres carbonylés. Communication préliminaire
Authors: Tronchet J. M. J. , Bourgeois J. M. , Baehler Br.
Published: December 2004

Isopropylidene derivatives of keto‐ or aldehydo‐sugars are susceptible to rearrangements involving participation of the dioxolane ring.
Stereochemische Aspekte der Addition von Ketenen an Cyclopentadien
Authors: Rey M. , Roberts S. , Dieffenbacher A. , Dreiding A. S.
Published: December 2004

Earlier work has shown that the cyclo‐addition of a ketene to a conjugated diene is always (a) 2 + 2, (b) polarily directed, and (c) suprafacial with respect to the diene CC. The adducts of ketenes and cyclopentadiene are thus always 7‐substituted bicyclo [3.2.0] hept‐2‐ene‐6‐ones. New evidence is presented to show that unsymmetrically substituted ketenes add to cyclopentadiene in such a manner that the larger substituent has a greater tendency to take up the endo‐ position in the adduct. This is interpreted to mean that a ketene participates in such reactions antarafacially. Thus the ketene approaches cyclopentadiene (a) with its functional plane perpendicular to that of the ring, (b) with the carbonyl carbon over the middle of the ring, and (c) with the larger of the two substituents oriented preferentially away from the ring (transition state 11).

This endo‐specificity for the larger ketene substituent is demonstrated by the indicated endo/exo ratios observed in the cyclo‐adducts from ketenes with the following substituent pairs: C6H5/H = >95/<5, CH3/H = 98/2, Cl/H = 97/3, CH3O/H = >95/<5, C6H5/CI = >95/<5, C6H5/CH3 = >95/<5, CH3/Cl = 80/20, CH3/CHCH2 = ∼65/35, C2H5/CH3 = ∼60/40, n‐C3H7/CH3 = ∼60/40, CH3/Br = 56/44.

These ratios enable a list to be compiled indicating the endo‐specificity of the ketene substituents. The order closely parallels the space filling capacity as derived by other methods.

The establishment of such ratios required reliable configurational assignments at carbon 7. These were derived by five methods based upon the following effects: (1) Both HC7 and CH3C7 cause nmr. signals at higher field in endo‐position (compared with exo). (2) The CH3C7 group in exo‐position gives rise to a nuclear Overhauser effect with the vicinal HC1, and in one case also with the trans‐annular HC5. (3) The nmr.‐coupling constants of HC7‐exo (observed at HC7) with HC1 is always larger than of HC7‐endo. (4) The coupling constant of HC7‐exo with HC6 (known to be exo‐) of the LiAlH4 reduction products of the cyclo‐adducts (observed at HC6) is always larger than that of HC7‐endo. (5) The nmr. signals of most protons in the cyclo‐adducts are at higher field in benzene than in chloroform solution; this “benzene shift” is larger for HC7 or for CH3C7 when in exo‐ than when in endo‐position.
Totalsynthese eines Neobetanidin‐Derivates und des Neobetenamins
Authors: Badgett B. , Parikh I. , Dreiding André S.
Published: December 2004

The total synthesis of a neobetanidine derivative (3b) is described.

Preliminary experiments led to the synthesis of neobetenamine (4), which presents the ring system of neobetanidine (3). A general method for the synthesis of several compounds containing the essential neobetanidine chromophore (a 1, 7‐diazaheptamethine system incorporating a pyridine ring) consisted of Vilsmeier‐Haack condensations involving the active (enolizable) methyl group of γ‐picoline. Neobetenamine (4) resulted from this reaction with N‐formyl‐indoline, and also by an amine exchange between indoline and the Vilsmeier‐Haack product from γ‐picoline and N‐methyl‐formanilide.

The methyl group of γ‐picoline‐2, 6‐dicarboxylic ester 9, however, was resistant to the Vilsmeier‐Haack condensation, but could be activated by introduction of a carboxyl into it: 4‐chloropyridine‐2, 6‐dicarboxylic ester (11a) (from chelidamic ester) was used to alkylate malonic ester. The product (12a) lost only one carboxyl group when saponified. The resulting 2, 6‐dicarboxy‐pyridine‐4‐acetic acid (13a) readily underwent a novel decarboxylative condensation with the Meerwein acetal of dimethyl formamide to 4‐(2‐dimethylamino‐vinyl)‐2, 6‐dimethoxycarbonyl‐pyridine (14b), the first synthetic derivative of a neobetalaine. The enamine 14b was subjected to amine exchange reactions with indoline to 2‐decarboxy‐5, 6‐dideoxy‐neobetanidine dimethyl ester (15), and with (S)‐cyclodopa (16) 5, 6‐di‐O‐methyl‐neobetanidine trimethyl ester (3b). The latter was identical with the diazomethane transformation product of betanidine (1), the aglucone of the pigment of the red beet, betanine.

A few proton resonance and electron spectral properties, as well as the basicities of several of the synthesized compounds, are tabulated and discussed as far as they express special structural and electronic features of the common 1, 7‐diazaheptamethine chromophore.
Autoxydation von CuI‐Komplexen III. Das System CuI/CH3CN in Wasser mit und ohne Zusatz. von Dicarbonsäuren
Authors: Zuberbühler A.
Published: December 2004

The autoxidation of cuprous copper in aqueous CH3CN is studied spectrophotometrically and by following O2‐as well as H+‐consumption. The rate of the reaction is greatly enhanced by the addition of chelating dicarboxylic acid anions such as oxalate and malonate, at low pH it increases proportional to H+‐concentration. This is explained by proton attack on the coordinated O2‐group in an oxygen adduct. The reaction is of first order with respect to [CuI] and [O2] and proceeds via one‐electron steps.
Valenzisomerisierung von cis‐Dienonen I. 2‐Vinyl‐3,4,5,6‐tetrahydrobenzaldehyd; Pyrolyse. von 6‐Oxabicyclo [3,1,0] hex‐2‐en [1]
Authors: Schiess P. , Chia H. L.
Published: December 2004

The synthesis of 2‐vinyl‐3,4,5,6‐tetrahydrobenzaldehyde (10) is described. This compound equilibrates above 70° with its valence isomer 4,5‐tetramethylene‐2H‐pyran (11) as can be shown by cis‐trans‐isomerization of the double bond in selectively deuterated 10. The unstable 2H‐pyran 11 can be trapped as tetracyanoethylene adduct 12.

Gas phase pyrolysis of 6‐oxabicyclo [3.1.0] hex‐2‐ene (18) at 400°C leads to cis‐penta‐2, 4‐dienal (19) in fair yield.
Menschliches Calcitonin. V). Aufbau und Charakterisierung des geschützten Synthese‐Zwischenprodukts Calcitonin M‐(1‐10)‐decapeptid
Authors: Kamber B. , Brückner H. , Riniker B. , Sieber P. , Rittel W.
Published: December 2004

The present report describes in detail the synthesis and characterisation of the protected Calcitonin M decapeptide 1–10, , a key intermediate in the synthesis of Calcitonin M. I. was obtained from the openchain precursor Boc‐Cys (Trt)‐Gly‐Asn‐Leu‐Ser (But)‐Thr (But)‐Cys (Trt)‐Met‐Leu‐Gly‐OH (II) by oxidation with iodine in a yield of 70%, after purification by counter‐current distribution.

II was prepared by fragment coupling of the sequences 1–4 and 5–10.

The free calcitonin M (1–10)‐decapeptide, obtained from I by removal of the protecting groups by acidolysis, has no hypocalcaemic activity and does not inhibit specific binding of calcitonin M to its antibodies in rabbit serum.
Dünnschichtchromatographie als Hilfsmittel in der Radiochemie. 4. Mitteilung Trennung von 113Sn und 113mIn
Authors: Seiler H. , Seiler M.
Published: December 2004

Thin‐layer chromatography is applied to the separation of 113mIn from 113Sn. Different factors influencing migration and separation of the ions are investigated. The method can be used for the examination of the purity of isolated 113mIn solutions.
Über die Heterogenität der Aldolasen. Vorläufige Mitteilung. 17. Mitteilung über Aldolasen [1]
Authors: Gürtler B. , Leuthardt F.
Published: December 2004

Aldolase A (rabbit muscle) and aldolase B (human liver) have been resolved by isoelectric focusing into five distinct enzymatically active compounds. Each single component, if refocused under the same conditions, yields one single peak at the same isoelectric position as in the previous run. If component I or III are rehybridized (method of Penhoet et al.) component I yields one single peak, whereas component III yields the complete five membered set.

Apparently the aldolases A and B are both tetrameres of two heterogeneous types of subunits α/α′ and β/β′ respectively. Analogous to the five membered set produced by hybridization of the aldolases A, B and C, the subunits α/α′ or β/β′, respectively, combine randomly to tetrameres forming five membered sets of the type α4, α3α′, α2α2′, α1α3′, α4′, etc.
Über das Alkaloid Lonicerin aus Callichilia barteri. 137. Mitteilung über Alkaloide
Authors: Naranjo J. , Hesse M. , Schmid H.
Published: December 2004

The alkaloid lonicerine was isolated from Callichilia barteri (Apocynaceae). By chemical and spectroscopic evidence it could be shown to be 16‐epi‐aspidodasycarpine (1).
Über die Stereochemie von Zwischenprodukten (Aldolbasen) der Doebner‐von Miller‐Chinolin‐Synthese
Authors: Schindler O. , Michaelis W.
Published: December 2004

In the Doebner‐von Miller quinoline synthesis with acetaldehyde or crotonaldehyde two stereoisomeric 4‐hydroxy‐1, 2, 3, 4‐tetrahydroquinaldines are formed as intermediates. The stereochemistry of these compounds differing in the relative positions of the hydroxygroups to the methyl‐group can be ascertained by NMR.‐spectroscopy. The pKa‐values of stereoisomers are not identical due to the different spacial positions of the HO‐groups.
Über Pterinchemie 30. Mitteilung [1] Die Oxydation der hydrierten Lumazine durch Luftsauerstoff und das unerwartete Verhalten der 6, 7‐Diphenyl‐5, 6‐dihydro‐pteridine in sauren Lösungen
Authors: Viscontini M. , Leidner H.
Published: December 2004

Die hydrierten 6, 7‐Diphenyllumazine sind gegen Luftsauerstoff beständiger als die entsprechenden 6, 7‐Diphenylpteridine, werden jedoch nach einem gleichen Mechanismus oxydiert. Während die tetrahydrierten Pteridine unter intermediärer Bildung eines trihydrierten Radikals und anschliessend eines dihydrierten chinoiden Pteridins zu 7, 8‐Dihydropteridinen oxydiert werden, verläuft die Oxydation der 5, 6‐Dihydropteridine anders, In neutralen sowie in alkalischen Lösungen wird ein monohydriertes Radikal gebildet, welches dem Sauerstoff ein zweites Elektron und Proton abgibt, unter Bildung der entsprechenden Pteridine. In sauren Lösungen addiert die 7, 8‐Doppelbindung eine Molekel Wasser. Die so entstandenen hydratisierten Pteridine werden – wie die Tetrahydropteridine – viel rascher oxydiert, so dass die Oxydation der 5, 6‐Dihydropterine leichter in sauren als in neutralen Lösungen erfolgt. Das intermediäre 7‐Hydroxy‐6, 7‐diphenyl‐5, 6, 7, 8‐tetrahydrolumazin wurde als Hydrochlorid rein isoliert.
Ringschlussreaktionen von 1‐(2‐Aminophenyl)‐1‐phenyl‐äthylenen durch Kondensation mit Phosgen
Authors: Künzle F. , Schmutz J.
Published: December 2004

Cyclization of 1‐(2‐aminophenyl)‐1‐phenyl‐ethylenes or 1‐(2‐aminophenyl)‐1‐phenyl‐propenes (II) by condensation with phosgene led to 4‐phenyl‐carbostyrils (III) or 2‐chloro‐4‐phenyl‐quinolines (IV). Similarly, thiophosgene afforded 4‐phenyl‐thiocarbostyril.

Treatment of 1‐(2‐aminophenyl)‐2‐methyl‐1‐p‐tolyl‐propene (VII) with phosgene led to the corresponding isocyanate IX, which cyclized in the presence of aluminum chloride with loss of a methyl group to 3‐methyl‐4‐p‐tolyl‐carbostyril (III‐6). However, 1‐(2‐aminophenyl)‐2‐methyl‐1‐phenyl‐propene (VIII) treated with phosgene gave the isocyanate XI and 3‐phenyl‐3‐isopropenyloxindole (X). Cyclization of the isocyanate XI with aluminium chloride led simultaneously to 3‐methyl‐4‐phenyl‐carbostyril (XIV), and with migration of a methyl group to 3‐methylene‐4‐methyl‐4‐phenyl‐3. 4‐dihydro‐carbostyril (XV).
ESR. Spectra of the Radical Ions of Indeno[1, 2, 3‐cd]fluoranthene
Authors: Elschenbroich Ch. , Gerson F.
Published: December 2004

The ESR. spectra of the radical anion and the radical cation of indeno [1, 2, 3‐cd]‐fluoranthene have been recorded. Their hyperfine structures are consistent with those expected on the basis of simple MO models.
Cycloaddition an das Tetracyclo[4.2.0.02, 8.05, 7]octan‐System [1]. Vorläufige Mitteilung
Authors: Prinzbach H. , Philippossian G. , Scheidegger U.
Published: December 2004

The tetracyclo [4.2.0.02, 8.05, 7]octane derivative 2 adds dienophiles (tetracyanoethylene, dimethylacetylenedicarboxylate) stereospecifically to its bishomocyclobutadiene system, yielding the adducts 5 and 6, resp.
Eine neue Synthese von Petalin
Authors: Grethe G. , Lee H. L. , Uskoković M. R. , Brossi A.
Published: December 2004

A new synthesis of the alkaloid petaline (14), which includes a Stevens rearrangement (5→6) and the preferential O‐demethylation of 6, is described.

The structures of the by‐products in the demethylation were determined by the use of nmr. and mass spectroscopy.
Alkylation des «malonyl‐α‐aminopyridines»
Authors: Urban René , Grosjean Mireille , Arnold Wolf
Published: December 2004

The alkylation of the ‘malonyl‐α‐aminopyridines’ (4) gives mixtures of substitution products, mainly the N1‐and O2‐alkyl derivatives. The IR., UV. and NMR. spectra are discussed.
Die Tropfzeitabhängigkeit der polarographischen Halbstufen‐potentiale von 2‐Phenylchinoxalin
Authors: Schellenberg M.
Published: December 2004

Reversible redox reactions which are followed by irreversible steps give often polarographic waves with drop life dependent shapes. A mathematical model is proposed which is capable to describe the change of the polarographic waves of quinoxalines, even at short drop lives and slow reactions of the irreversible step.
Chimie et pharmacologie de l'apiose III. Synthèse et propriétés de l'hydrate de l'O‐isopropylidène‐1, 2‐tétrosulo‐3‐furannose
Authors: Tronchet J. M. J. , Tronchet Mme J.
Published: December 2004

Ruthenium tetroxide oxidation of 1, 2‐O‐isopropylidene‐β‐D‐threofuranose affords, besides the known 1, 2‐O‐isopropylidene‐α‐L‐glycero‐tetros‐3‐ulofuranose, a lactone. The tetrosulose is easily hydrated to the corresponding gem‐diol whose dehydration on molecular sieves leads to a branched‐chain dimer. Lead tetraacetate oxidation of 1, 2‐O‐isopropylidene‐α‐L‐glycero‐tetros‐3‐ulofuranose p‐nitrophenylhydrazone leads quantitatively, to a gem‐azoacetate, a new synthetic intermediate in carbohydrate chemistry. The 3‐O‐acetyl‐1, 2‐O‐isopropylidene‐α‐L‐glycero‐tetr‐3‐enofuranose is easily obtained from the gem‐diol. A highly stereoselective procedure is described to prepare the 3‐O‐acetyl‐1, 2‐O‐isopropylidene‐α‐L‐3, 4‐exo‐D2‐erythrofuranose.
Flexional Effects in Bridged Bicyclic Molecules Progressive Flattening of Chair Cyclohexane
Authors: Jefford C. W. , Baretta A. , Fournier J. , Waegell B.
Published: December 2004

Measures of the progressive flattening of the chair conformation in a series of constrained cyclohexanols are obtained and compared by proton NMR. coupling constants and by molecular mechanics.
Fluorine NMR. Spectra of conformationally constrained Gem‐difluorocyclohexanes
Authors: Jefford C. W. , Hill D. T. , Ramey K. C.
Published: December 2004

The 19F chemical shifts and geminal coupling constants have been measured for 3,3‐dimethyl‐ (I), 3,3,5‐trimethyl‐ (II) and 3,3,5,5‐tetramethyl‐1, 1‐difluorocyclohexane (III) and 3,3‐difluorobicyclo [3.2.1]octane (IV). The Eyring parameters for the ring inversion were obtained for I and III. Representative values for the Arrhenius activation energy (Ea), ΔG‡, ΔH‡, and ΔS‡ are: 11.0, 9.4, 10.4 kcal/mole and 4.5 e.u. for I, and 10.0, 8.3, 9.7 kcal/mole and 8.3 e.u. for III. It appears that the syn‐axial methyl‐fluorine interaction has a negligible effect on the inversion process. However, the syn‐axial methyl‐methyl interaction, as found in III, significantly increases the rate of inversion. Substituent effects on the 19F shifts are marked. Introduction of methyl at C‐3 in an equatorial position leads to shielding of the equatorial and axial fluorines (+1.8 and + 1.3 ppm). Substitution in the axial C‐3 position causes deshielding of the equatorial and axial fluorines (−5.9 and −4.9 ppm).
Über Pterinchemie. 32. Mitteilung [1]. Synthese des natürlichen D‐Neopterins und L‐Monapterins
Authors: Viscontini M. , Provenzale R. , Ohlgart S. , Mallevialle J.
Published: December 2004

Bei der Kondensation von 2, 4, 5‐Triamino‐6‐oxo‐1, 6‐dihydropyrimidin mit dem Phenylhydrazon der D‐Arabinose bzw. L‐Xylose im wässerigen Methanol unter N2 und anschliessender Oxydation der Kondensationsprodukte werden D‐Neopterin bzw. L‐Monapterin gebildet. Nach Reinigung und Umkristallisation aus Wasser werden beide Substanzen als farblose Kristalle in sehr hoher Ausbeute erhalten.
Pigmente von Nereiden (Annelida, Polychaeten). 1., Vorläufige Mitteilung. Isolierung von Pterindimeren aus den Augen von Platynereis dumerilii (Audouin & Milne Edwards) 1833
Authors: Viscontini M. , Hummel W. , Fischer A.
Published: December 2004

Aus den Augen von Platynereis dumerilii wurden Neopterin und die in ihrer Struktur noch nicht vollständig aufgeklärten neuen Pterine Platynerepterin und Nerepterin isoliert. Diese zwei dunkelgelb und dunkel‐blauviolett gefärbten Pterine besitzen UV.‐Spektren, die demjenigen des Pterorhodins ähnlich sind. Ihren Eigenschaften nach sind sie sehr wahrscheinlich hydroxylierte Pterindimere. Somit wird bestätigt, dass Pterindimere in der Natur viel weiter verbreitet sind, als man hätte annehmen können. Beide Pigmente kommen ebenfalls bei anderen Nereiden als Augenpigmente vor.
Thermisches Verhalten von Mesitylallenen; Beispiel einer aromatischen [1, 5s]‐sigmatropischen H‐Verschiebung. Vorläufige Mitteilung
Authors: Heimgartner H. , Zsindely J. , Hansen H.‐J. , Schmid H.
Published: December 2004

Mesitylallene (6a), 1‐mesityl‐3‐methyl‐allene (6b) and 1‐mesityl‐3, 3‐dimethylallene (6c) were prepared via dienol‐benzene‐rearrangements. At 170° 6a isomerises to give 5, 7‐dimethyl‐1, 2‐dihydronaphthalene (8). Under the same conditions 6b rearranges to give 2, 5, 7‐trimethyl‐1, 2‐dihydronaphthalene (10; 60%) and cis‐1‐mesitylbuta‐1, 3‐diene (11; 40%) while 6c gives only cis‐1‐mesityl‐3‐methyl‐buta‐1, 3‐diene (13). The allenes undergo first an aromatic [1, 5 s]‐sigmatropic H‐shift to the o‐xylylene derivatives 7, 9 and 12, which then exhibit disrotatory ring closure to the dihydronaphthalenes or aromatic [1, 7 a]‐sigmatropic H‐shift to the 1‐mesitylbuta‐1, 3‐dienes.