bluuebunny/crossref_metadata_2025 huggingface dataset:
The Gas‐Solid Interface Heats of Adsorption of Simple Molecules on Microporous Carbons and on Graphitized Carbon Blacks, at Low Surface Coverage
Authors: Stoeckli Fritz
Published: December 2004

The heats of adsorption of nitrogen, argon, xenon, pentane, cyclohexane and benzene on a typical microporous carbon have been measured by gas‐solid chromatography. An overall comparison of the limiting heats of adsorption on active carbons and on graphitized carbon blacks shows a ratio of 1.6 between them. This is also the value of the ratio of the minima of the adsorption potentials. This result is discussed in terms of simple models for the shape of the micropores. Slot‐like pores give a better agreement.
Alkalische Spaltung und Benzilsäureumlagerung von 1,2,3‐Triketonen. 29. Mitt. über Reduktone und Tricarbonylverbindungen [1]
Authors: Dao Huu Lé , Dayer Francis , Duc Laurent , Rodé‐Gowal Heike , Dahn Hans
Published: December 2004

Under the conditions of the benzilic acid rearrangement diaryl und dialkyl 1,2,3‐triketones RCOCOCOR′ show two reactions: (1) Migration of RCO towards the more electronegative or less hindered CO group, yielding an α‐hydroxy‐β‐ketoacid which can undergo secondary reactions, and (2) direct cleavage between adjacent carbonyl groups forming RCOOH and R′CHOHCOOH, RCO being more electronegative or less hindered than R′CO. The balance between these reactions depends upon the steric and electronic properties of R and R′.
Reversible Photochemistry, Absorption‐ and 1H‐NMR.‐spectra, and oxidation of the [2,2]metacyclophane‐1‐ene ⇄ 4,5,15,16‐tetrahydropyrene system
Authors: Naef R. , Fischer Ernst
Published: December 2004

The reversible photointerconversion in the above system was investigated in a wide range of temperatures and wavelengths of irradiation. The tetrahydropyrenes are obtainable only photochemically. The unmethylated and the mono‐methylated compound are oxidized with iodine quantitatively to 4,5‐dihydropyrene, even at −30°. This makes it possible to estimate the absolute concentration of the tetrahydropyrenes, and thereby their molar extinction coefficients and complete electronic absorption spectra. The quantum yields in both directions do not vary appreciably with the temperature, down to −190°. This is the first case in which the photocyclization yield of a cis‐stilbenelike compound is not attenuated on cooling, and reflects the special character of highly constrained structures. No emission was observed in solution. 1H‐NMR.‐spectra of both modifications of the dimethylated compound were taken. They support the structures assumed for both modifications, and also allow an estimate of their relative concentrations.
Reaction of Singlet Oxygen with 2‐Methylnorborn‐2‐ene, 2‐Methylidenenorbornane, and their 7,7‐Dimethyl Derivatives. The transition state geometry for hydroperoxidation
Authors: Jefford Charles W. , Boschung André F.
Published: December 2004

The dye‐sensitized photo‐oxygenation of 2‐methylnorbonr‐2‐ene (3), 2‐methylidene‐norbornane (4) and their 7,7‐dimethyl derivatives (5 and 6) has been studied. In all cases allylically rearranged hydroperoxides were formed, except that 4 also gave a little norbornanone (presumably from the dioxetane) and 5 gave some endo‐3,7,7‐trimethylnorbornan‐2‐one as a secondary photo‐product. It was found that the exo/endo attack ratios by singlet oxygen on 3 and 5 are 66 and 0.19. By exploiting the C (3) monodeuteriated derivatives, 4 and 6 showed ratios of 28 and 0.67.

Rates of reactivity of the olefins 3 and 4 were compared to methylidenecyclopentane, 1‐methylcyclopentene and 1‐methylcyclohexene as monocyclic standards. Additionally, comparative rates between the 7,7‐dimethyl olefins and their parents were measured. When further comparison was made of the rate ratios partitioned for exo and endo attack, it was seen that oxygen experienced a 500‐ to 1000‐fold rate retardation on approach to the endo side of 3 compared to that for its monocyclic analogue. Exo rates between the parent norbornene 3 and its 7,7‐dimethyl derivative 5 showed a 250‐fold decrease. Although four times smaller than the difference reported for epoxidation, the evidence clearly pointed to a one‐step cyclic process as the rate determining step for photo‐oxygenation. The steric evidence, taken with the low values found for the intermolecular isotope effects of 1.14 ± 0.01 and 1.02 ± 0.01 observed for exo and endo‐3‐deuterio‐2‐methylidene‐norbornanes, permits the deduction that the transition state is largely dipolar. In the early stages of the addition bonding between one end of the oxygen molecule and the terminal vinyl carbon is advanced. At the same time positive charge is dispersed by hyperconjugation between the central carbon atom and the allylic carbon‐hydrogen bond. At a later stage the anionic oxygen atom abstracts the loosened allylic hydrogen atom to create the hydroperoxide. No evidence for the formation of a discrete perepoxide intermediate was obtained.
Synthese von Pyrimido[1,2‐a]benzimidazolen durch Umsetzung von 2‐Aminobenzimidazol mit Acetylendicarbonsäure‐dimethylester und ihre Überführung in Imidazo[1,2‐a]benzimidazole
Authors: Troxler Franz , Weber Hans Peter
Published: December 2004

The main product of the reaction between 2‐aminobenzimidazole and dimethyl acetylenedicarboxylate is shown to be methyl 1, 2‐dihydro‐2‐oxo‐pyrimido[1, 2‐a]benzimidazole‐4‐carboxylate (6), which can be methylated at position 1 to give 7. Catalytic hydrogenation of 7 leads to the 1,2,3,4‐tetrahydro derivative 8, whereas NaBH4 reduces the ester and, to some extent, the double bond to yield a mixture of 9 and 10. When a 1‐substituted 1, 2‐dihydro‐4‐hydroxymethyl‐pyrimido[1, 2‐a]benzimidazol‐2‐one (for example 11) is catalytically hydrogenated, the double bond is unaffected, but hydrogenolysis of the alcohol group occurs instead to give 13. The lactam group is less stable in the tetrahydro series than in the dihydro compounds. For example, the lactam is cleaved when 8 is treated with amines containing a small amount of water, and the monoamides 16 and 17 are formed. Similarly, sodium hydroxyde cleaves the lactam under mild conditions to the dicarboxylic acid 19, which can be converted to 2, 3‐dihydro‐1‐methyl‐2‐oxo [1H]imidazo[1, 2‐a]benzimidazole‐3‐acetic acid (4‐methyl)piperazide (20) with thionyl chloride and N‐methylpiperazine. However, when 7 is treated with methylamine at low temperature, the amide 22 is formed, whilst at room temperature the amine attacks both the ester and the double bond to give 23. The structure of 8 was confirmed by X‐ray analysis.
Die Kristallstruktur von 1,2,3,4‐Tetrahydro‐1‐methyl‐2‐oxopyrimido[1,2‐a]benzimidazol‐4‐carbonsäuremethylester
Authors: Weber Hans Peter , Troxler Franz
Published: December 2004

The crystal structure of 1,2,3,4‐Tetrahydro‐1‐methyl‐2‐oxopyrimido[1,2‐a]benzimidazol‐4‐carboxylicacid‐methylester was investigated by an X‐ray analysis in order to determine unequivocally the positions of the substituents. The triclinic structure was solved by the multisolution method and refined to an R = 0.0302 with 1486 structure factors for 222 structural parameters.
Recherches sur la biochimie des champignons inférieurs IX. Synthèse de précurseurs marqués et biosynthèse de la phoenicine et de l'oosporéine
Authors: Steiner Eric , Kalamar Julius , Charollais Etienne , Posternak Théodore
Published: December 2004

The biosynthesis of phoenicine and of oosporeine by intact cells of Penicillium phoeniceum VAN BEYMA and of Chaetomium aureum CHIVERS respectively, has been investigated. Starting from acetic acid, biosynthetic sequences have been proposed; they are based on the incorporation of radioactivity into the two pigments of labelled, biochemically probable precursors. Orsellinic acid appears as a common intermediate, which is converted by multistep processes to 2,3,5‐trihydroxytoluene or to 2,3,5,6‐tetrahydroxytoluene. Oxidative coupling of two molecules of the triphenol furnishes the reduced form of phoenicine. Similarly, coupling of two molecules of the tetraphenol gives leuco‐oosporeine. Both leuco‐derivatives are easily dehydrogenated, under physiological conditions, with formation of the diquinones. Coupling occurs when the monophenyl derivatives contain the required number of OH groups in suitable positions.
Über die säurekatalysierte Umlagerung von β‐Jonon‐5,6‐epoxid
Authors: Skorianetz Werner , Ohloff Günther
Published: December 2004

β‐Ionone‐5,6‐epoxide (1) undergoes acid‐catalyzed ring contraction and enlargement, concurrently, by [1, 2]‐alkyl shifts, to give the isomeric cyclopentane derivative 6 and the cycloheptafurane derivative 7. Spectroscopic and chemical evidence for the structures of 6 and 7 is presented.
Stoffwechselprodukte von Mikroorganismen 143. Mitteilung. Echinocandin B, ein neuartiges Polypeptid‐Antibioticum aus Aspergillus nidulans var. echinulatus: Isolierung und Bausteine
Authors: Benz Fritz , Knüsel Fritz , Nüesch Jakob , Treichler Hansjörg , Voser Walter , Nyfeler Robert , Keller‐Schierlein Walter
Published: December 2004

From a strain of Aspergillus nidulans var. echinulatus, A 32204, echinocandin, a novel polypeptide antibiotic complex with high and specific anti‐yeast activity was isolated. The main component, echinocandin B, was separated by counter‐current distribution. A tentative molecular formula C52H81N7O18 is discussed. The antibiotic is characterized by its IR. and NMR. spectra and by its characteristic hydrolytic degradation products: linoilic acid, L‐4‐hydroxyproline, L‐4‐oxoproline, (2S, 3S, 4S)‐4‐methyl‐3‐hydroxy‐proline, L‐threonine (2 mols), and 1‐(p‐hydroxyphenyl)‐3‐amino‐propan‐2‐one.
Extraction liquide‐liquide par des esters alkylphosphoriques. III. Séparation de la paire yttrium – gadolinium par l'acide di‐(2‐éthylhexyl)phosphorique
Authors: Brunisholz G. , Hirsbrunner W.
Published: December 2004

The separation of yttrium and gadolinium by solvent extraction with di‐(2‐ethylhexyl)phosphoric acid (H(DEHP)) from solutions in HNO3 has been studied. The extraction takes place by the same mechanism for both elements. The extraction by the ion‐exchange reaction is more selective than the extraction by the solvatation reaction. Methyl isobutyl ketone, compared to kerosene as diluent for H(DEHP), reduces more the extraction of Y than that of Gd, without affecting the mechanisms.
Eine einfache Synthese von 2,2‐Dimethyl‐thietan
Authors: Mayer Carl
Published: December 2004

A simple two step procedure for the synthesis of the naturally occurring 2,2‐Dimethyl‐thietan is given. Yield about 90%.
Organic Phosphorus Compounds 67. The exchange Cleavage of dialkylaminomethylphosphines with aryl and diarylphosphines [1]
Authors: Kaska William C. , Maier Ludwig
Published: December 2004

Interaction of dialkylaminomethyl‐substituted tertiary phosphines with primary or secondary phosphines results often in the cleavage of a PC bond and the formation of PP bonds. Thus treatment of Ph2PCH2NEt2 with Ph2PH at 180° yields Ph2PPPh2 and HNEt2, and interaction of PhP(CH2NEt2)2 and PhPH2 at 150° results in the formation of (PhP)5, (PhP)4 CH2, HNEt2 and CH3NEt2.
Intramolecular Thermal 2 + 2‐Cycloadditions of Styrene‐Derivatives
Authors: Oppolzer Wolfgang , Loosli Hans‐Rudolf
Published: December 2004

Beim Erhitzen des Bis‐styryl Derivates 1 in siedendem o‐Dichlorbenzol entstehen überraschenderweise in hoher Ausbeute die Aza[3.1.1]bicycloheptane 2 und 3, deren Struktur durch 1H‐ und 13CNMR.‐Spektren unter Verwendung eines Computerprogrammes eindeutig bestimmt wurde. Auf analoge intramolekulare 2 + 2‐Additionen 8 → 9 wird hingewiesen.
The Thermal 2 + 2‐Addition of N‐(2‐Phenylallyl), N‐(3‐phenylally)‐toluenesulfonamide: Stereochemical and kinetic evidence for a diradical intermediate
Authors: Oppolzer Wolfgang
Published: December 2004

Durch Thermolyse der trans‐ und cis‐Bis‐styryl Derivate 1a und 1b erhält man unabhängig von der Konfiguration des Ausgangsmaterials die Produkte 2 und 3 im gleichen Verhältnis. Die Verbindungen 1a, 2 und 3 lassen sich unter den Reaktionsbedingungen ineinander überführen. Diese Resultate sprechen für einen reversiblen Cycloadditionsprozess unter Beteiligung des diradikalischen Zwischenproduktes 4. Eine der Addukt‐Bildung vorgelagerte rasche cis/trans‐Isomerisierung 1b → 1a verläuft offensichtlich über das gleiche Diradikal. Übereinstimmungsgemäss erfolgt die cis/trans‐Isomerisierung des Mono‐styryl Derivates 5 zu 6 wesentlich langsamer als die Isomerisierung 1b → 1a.
Synthesis of New Xanthones, I
Authors: Pinto Madalena M. , Polónia Joaquim
Published: December 2004

Condensation of salicylic acid and C‐methylphloroglucinol gave the already known 1,3‐dihydroxy‐2‐methylxanthone (1) along with two new compounds: 1,3‐dihydroxy‐4‐methylxanthone (2) and a second one tentatively presented as being 1,3‐dihydroxy‐2‐methyl‐4‐(2‐hydroxybenzoyl)xanthone (3). The UV., IR., NMR, and mass spectra for the two first compounds are reported and their structures discussed on the basis of δ‐values for H(2), H(4), CH3(4) and CH3(2). The UV. and IR. spectra for the third compound are reported too.
Etude par RMN. de polyaminocarboxylates de terres rares, III. Hydroxyéthyliminodiacétates de praséodyme
Authors: Chastellain François , Merbach André E.
Published: December 2004

1H—NMR. has been used to study the chemistry of the hydroxyethyliminodiacetate complexes of praseodymium in aqueous solution. The ligand exchanges by spontaneous dissociation of the metal‐bis‐hydroxyethyliminodiacetate (1:2 complex) and of the metal‐bis‐hydroxyethyliminodiacetate hydroxocomplex, by acid catalysed dissociation of the 1:2 complex, and by a bimolecular process involving the free ligand and the 1:2 complex or the ternary hydroxo‐complex. The ligand exchange rate constants are given and the mechanisms discussed.
The Synthesis of Spiro[tetrahydroisoquinoline‐piperidines] and related compounds
Authors: Berney Daniel , Jauner Theodor
Published: December 2004

The reaction of 3,4‐dimethoxyphenethylamine with some cyclic aminoketones in the presence of polyphosphoric acid afforded 1‐spiro‐tetrahydroisoquinolines. A two‐step procedure starting from veratrylamine and amino‐ketones gave 3‐spiro‐tetrahydroisoquinolin‐4‐ones. The Schmidt rearrangement of 5,6‐dimethoxy‐3‐spiro‐indan‐1‐ones yielded 4‐spiro‐tetrahydroisoquinolin‐1‐ones.
Varianten im Zuckerteil des Streptozotocins
Authors: Gassmann Niklaus , Stoos Fred , Meier Arthur , Eldin Helali Salah , Hardegger Emil
Published: December 2004

Wir beschreiben die Synthese von krist. Analogen des Streptozotocins, welche sich von 6‐Amino‐D‐glucose, D‐Glucosaminol, D‐Glucamin, D‐Galactosamin, D‐Arabinamin, D‐Mannamin und D‐Galactamin ableiten. Die meisten der krist. Präparate wurden als Acetylderivate charakterisiert.
Isolement et identification de composés phénoliques et monoterpéniques de la mousse de chêne (Evernia prunastri (L.) Ach.)
Authors: Gavin José , Tabacchi Raffaele
Published: December 2004

The composition of different oakmoss extracts was investigated by combined gas chromatography/mass spectrometry. A series of 38 compounds – especially phenol derivatives and monoterpenes – was identified, 22 of which have not yet been reported as constituents of oakmoss.
Synthetische Juvenilhormone 3. Mitteilung. p‐Substituierte 4‐Phenyl‐buten(1)‐carbonsäurederivate
Authors: Franke Albrecht , Mattern Günter , Traber Walter
Published: December 2004

The syntheses of p‐substituted 2‐methyl‐4‐phenylbuten(1)‐carboxylic acid derivatives are described, using Blanc's chloromethylation reaction, the Friedel‐Crafts alkylation of unsaturated ketones or the Meerwein arylation; the formed intermediates react in subsequent steps to the title compounds.
Conformation of Some Anomeric O‐Benzylated D‐gluco‐, L‐Ido‐, and Hex‐4‐enopyranoside derivatives
Authors: Kiss Joseph , Arnold Wolf
Published: December 2004

By use of 1H‐NMR. spectroscopy it is shown that in the anomeric tri‐O‐benzyl derivatives of D‐gluco‐ and L‐idopyranosides the C(5) (aliphatic) substituent has a strong tendency to assume an equatorial position. The conformer (4C1 or 1C4) with C(6) in equatorial position is favoured, even if other bulky substituents are forced to occupy an axial position; the same effect is observed in some anomeric O‐benzylated 6‐deoxy‐L‐idopyranoside derivatives.

If, however, the tetragonal configuration of the saturated C(5) is changed into a trigonal (sp2) configuration, e.g. in the anomers of 1,2,3‐tri‐O‐benzylated L‐threo‐hex‐4‐enopyranosiduronates, the C(5)–C(6) bond no longer determines the equilibrium of (distorted) pyranoid conformations; the anomeric (‘Eduard‐Lemieux’) effect then becomes important in the stabilization of the corresponding half‐chair (1H2 or 2H1) conformations.
Notiz zur Synthese von 1‐Aryl‐ und 1‐Alkyl‐2, 3‐dimethyl‐chinoxaliniumperchloraten
Authors: Schelz Dieter , Priester Martin
Published: December 2004

Some 1‐substituted 2, 3‐dimethyl‐quinoxalinium‐perchlorates were synthesized by reaction of butane‐2, 3‐dion with N‐monosubstituted 1,2‐diamino‐benzenes in strongly acidic solution. 2, 3‐dimethyl‐4‐cyclohexyl‐pyrido[2,3‐b]pyraziniumperchlorate was obtained from an analogous reaction.
Synthèse de sucres aminés ramifiés III. Synthèse et réactions de 1′α‐amino‐nitrile dérivé du di‐O‐isopropylidène‐1,2:5,6‐α‐D‐ribo‐hexofurannosul‐3‐ose
Authors: Bourgeois Jean‐Marc
Published: December 2004

The addition of cyanohydric acid to 1,2:5,6‐di‐O‐isopropylidene‐α‐D‐ribo‐hexofurannos‐3‐ulose can be sterically controlled. Under kinetic conditions, the allo cyanohydrine epimer is formed, under thermodynamic conditions, the gluco epimer is formed. The configuration of these two products is proved by their chemical reactions. Hydration followed by hydrolysis of the nitrile group of the allo epimer (O‐acetyl derivative) gives the 3‐C‐carboxy‐1,2‐O‐isopropyloidene compound.

This product forms the corresponding γ or δ‐lactone with hydroxyl (5) or (6). On the other hand, after hydrolysis of 5,6‐isopropylidene, the 3‐O‐acetyl derivative of the gluco epimer gives an acetyl migration from position 3 to position 5 and finally to position 6. By reaction of the allo epimer with NH3 and CN−, an aminonitrile is formed. The allo configuration is deduced from the above mentioned reaction and from IR. and NMR. data. Several acetylated and trifluoracetylated derivatives of these products are described. The oxidation of the nitrile group to the amide group is possible with both epimeric cyanohydrines and the amino‐nitrile.
Biosynthese der Verrucarine und Roridine. Teil 3. Der Einbau von (3R)‐[5‐14C]‐, [2‐14C]‐ und an C(2) stereospezifisch tritiiertem Mevalonat in Verrucarol Verrucarine und Roridine, 29. Mitteilung
Authors: Müller Beat , Achini Roland , Tamm Christoph
Published: December 2004

Separate experiments, involving incorporation of either (3R)‐[5‐14C]‐mevalonate or each enantiomer of [2‐3H]‐mevalonate into verrucartin A and roridin A, indicate that hydroxylation at C(4) of the tricothecane skeleton, to yield verrucarol (4), proceeds with an overall retention of configuration; they confirm that C(8) and not C(10) is derived specifically from C(2) or mevalonate.
Biosynthesis of the Verrucarins and Roridins. Part 4. The mode of incorporation of (3R)‐[(5R)‐5‐3H]‐mevalonate into verrucarol. Evidence for the identity of the C(11)‐hydrogen atom of the trichothecane skeleton with the (5R)‐hydrogen atom of (3R)‐mevalonic acid
Authors: Müller Beat , Tamm Christoph
Published: December 2004

Incorporation of (3R)‐[(5R)‐5‐3H]‐mevalonate into verrucarin followed by hydrolyses to verrucarol (2) and transformation of the latter to the spirolactol 5 and the spirolactone 6 successively, demonstrate the identity of the C(11)‐hydrogen of the trichothecane skeleton with the 5‐‘pro‐R’ hydrogen atom of (3R)‐mevalonate.
Hydrazide as a Carboxyl Protecting Group deprotection by acidolysis
Authors: Schnyder Jörg , Rottenberg Max
Published: December 2004

Elimination of the hydrazide group was studied with the model compounds N‐benzoyl‐glycine hydrazide and N‐benzoyl‐L‐phenylalanine hydrazide, using phosphorus oxychloride, hydrogen bromide or hydrogen chloride in acetic acid, or 60% perchloric acid. It was found that treatment of N‐benzoyl‐L‐phenylalanine hydrazide with perchloric acid gave N‐benzoyl‐L‐phenylalanine in 100% yield and without racemisation.
The Preparation of trans‐N‐Acyl, N‐alkyl‐1‐amino‐1,3‐butadienes. Preliminary communication
Authors: Oppolzer Wolfgang , Fröstl Wolfgang
Published: December 2004

In der vorliegenden Mitteilung wird erstmals ein Zugang zu trans‐N‐Acyl,N‐alkyl‐1‐amino‐1,3‐butadienen 4, sowie zu trans‐N‐Acyl, N‐aryl‐1‐amino‐1,3‐butadienen 4 beschrieben. Deprotonierung von N‐substituierten 1‐Imino‐2‐butenen 2 führt vermutlich zu den nicht isolierten delokalisierten Anionen 3, die anschliessend regioselektiv am Stickstoffatom acyliert werden.
A stereoselective approach to cis‐ and trans‐1,2,3,4,4,4a,5,6,8a‐octahydroquinolines by intramolecular Diels‐alder reactions preliminary communication
Authors: Oppolzer Wolfgang , Fröstl Wolfgang
Published: December 2004

N‐Acyl‐N‐(4‐penten‐1‐yl)‐1‐amino‐1, 3‐butadiene (1) isomerisieren sich bei 190–215° über eine intramolekulare Diels‐Alder‐Reaktion stereoselektiv zu cis‐ verknüpften Octahydro‐chinolinen 2. Unter den gleichen Bedingungen erhält man aus dem N(Pent‐4‐enoyl)‐N‐propyl‐1‐amino−1, 3‐butadien (4) überwiegend das trans‐verknüpfte Octahydrochinolin‐2‐on 5 neben dem cis‐Isomeren 6. Diese Selektivität wird auf eine bevorzugte koplanare Anordnung von Amid‐ und Dien‐System im Übergangszustand zurückgeführt.
The Total Synthesis of (±)‐Pumiliotoxin‐C preliminary communication
Authors: Oppolzer Wolfgang , Fröstl Wolfgang , Weber Hans Peter
Published: December 2004

Die erste Totalsynthese des racemischen Alkaloids Pumiliotoxin‐C (9) ausgehend von trans‐1‐Brom‐3‐penten (1) wird beschrieben. Die Schlüsselstufe 6 → 7 verläuft über eine intramolekulare Diels‐Alder‐Reaktion unter weitgehender sterischer Kontrolle von vier Chiralitätszentren. Die Struktur des synthetischen Produkte 9 wurde durch eine Röntgenstrukturanalyse des kristallinen Hydrogenmaleinates bestätigt.
Réctivité de dérivés des acides acétoacétique et γ‐chloroacétoacétique envers l'ion cyanure Réarrangement conduisant à de nouvelles iminopyrrolinones
Authors: Adam Jean‐Marie
Published: December 2004

Lors d'essais de substitution de l'atome de chlore du chloro‐4‐acétoacétate d'éthyle 5 et du chloro‐4‐acétoacétanilide 6 par l'ion cyanure, il a été montré que dans les conditions expérimentals décrites la substitution n'intervient en aucun cas. 5 conduit par dimérisation à la bis(éthoxycarbonyl)‐2,5‐cyclohexanedione‐1,4, 7, et 6 conduit intermédiairement à la cyanhydrine 8 qui se réarrange en Oxo‐2‐hydroxymethyl‐4‐mino‐5‐Δ3‐N‐phénylpyrroline 13 puis en Oxo‐2‐hydroxy‐méthyl‐4‐phénylimino‐5‐Δ3‐pyrroline 10. Ce réarrangement n'a pas été n' constaté dans le cas de l'acétoacétanilide 14 qui conduit, dans les mêmes conditions, intermédiairement à la cyanhydrine 15 puis à ses dérivés d'hydrolyse. Les structures chimiques ont été établies par les méthodes physiques habituelles, en particulier par 13C‐RMN., et confirmées, dans le cas des composés 13 et 10 par analyse aux rayons X.
Welkstoffe und Antibiotika. 43. Mitteilung. [1]. Fusarinonsäure und die enantiomeren Fusarinolsäuren
Authors: Büyük Füurol , Hardegger Emil
Published: December 2004

Aus 2‐Carboxy‐5‐methylpyridin (1a) wurde über das 5‐Brommethyl‐2‐methoxycarbonylpyridin (2) mit Acetessigester der Ketodicarbonsäureester 3 und daraus die Fusarinonsäure (8) hergestellt. Ein anderer Weg führte von 1a über 5‐Dibrommethyl‐2‐methoxycarbonylpyridin (5) zum 5‐Formyl‐2‐methoxycarbonylpyridin (6), welches ebenfalls zur Gewinnung der Fusarinonsäure geeignet ist. Die schon früher aus natürlicher Dehydrofusarinsäure und nun auch aus Fusarinonsäure (8) hergestellte rac. Fusarinolsäure (10a) wurde mit (+)‐und (–)‐1‐Phenyläthylamin erstmals in die optisch reinen Enantiomeren 11 & 12 zerlegt, deren absolute Konfiguration gesichert ist.
The Optical Activity of the Amide Chromophore, I. MO‐Theoretical calculation of the long‐wavelength optical activity of γ‐lactams and of related isoelectronic molecules
Authors: Geiger Rudolf E. , Wagnière Georges H.
Published: December 2004

The rotational strength of the longest‐wavelength electronic transition in some simple γ‐lactams and some related isoelectronic molecules is calculated using the CNDO‐CI method. Qualitative agreement with experimental values is obtained. In all investigated systems the long‐wavelength transition corresponds to the nπ* transition. A quadrant rule seems to hold for this transition.
Stereoselectivity in Reactions of Metal Complexes IV. Asymmetric Synthesis of (2R, 7S, 10R)‐ and (2R, 7R, 10R)‐2, 10‐diamino‐5, 5, 7‐trimethyl‐4, 8‐diazaundecanenickel (II) by Stereoselective Hydrogenation of (2R, 10R)‐2, 10‐diamino‐5, 5, 7‐trimethyl‐4, 8‐diaza‐7‐undecenenickel(II)
Authors: Güntert Bruno , Claude Saturnin , Bernauer Klaus
Published: December 2004

The catalytic hydrogenation of (2R, 10R)‐2, 10‐diamino‐5, 5, 7‐trimethyl‐4, 8‐diaza‐7‐undecenenickel(II) yields two products when the reaction is performed in the presence of ethylenediamine, but only one, when ethylenediamine is absent. The stereochemistry of the reaction is discussed and a proposal for the absolute configuration of the two diastereomeric complexes and the free ligands is given on the base of CD.‐ and NMR.‐spectra.
Alkaloide im menschlichen Gewebe 5. Mitteilung [1]. Basenkatalysierte Epimerisierung von Derivaten aus Kondensationsprodukten von L‐ und D‐Dopa mit Acetaldehyd
Authors: Bruderer Hans , Brossi Arnold , Focella Antonino , Teitel Sidney
Published: December 2004

Base catalysed equilibration studies of optically active 2‐acetyl‐tetrahydro‐6,7‐dimethoxy‐1‐methyl‐isoquinoline carboxylic esters have been carried out, showing in all cases that the equilibrium mixtures mainly contain the trans‐isomer.
Reaktionen von Tetracyanoäthylen mit Polyenen
Authors: Pfoertner Karl‐Heinz
Published: December 2004

Reactions of tetracyanoethylene with polyenes have been studied. With vitamin A derivatives 7,10‐ and 11,14‐cycloadducts were formed. Starting with the unsaturated dihydroxy compound 13 tetracyanoethylene first catalyzed the ring closure to give the dihydrofuran 14 which then was dehydrogenated to the corresponding furan 15.
Die Phloroglucide von drei Dryopteris‐Arten von den Azoren sowie zwei Arten von Madeira und den Kanarischen Inseln zum Vergleich
Authors: Widén Carl‐Johan , Lounasmaa Mauri , Vida Gabor , Reichstein Tadeus
Published: December 2004

The phloroglucinols of Dryopteris aemula from the Azores and from Brittany (France), D. azorica and D. crispifolia, a new tetraploid species endemic to the Azores [8], have been investigated. The following two species recently analysed with insufficient amounts of material have been reinvestigated using improved methods: D. maderensis and ‘D. dilatata’ from Tenerife, a new species endemic to the Canary islands and described by Gibby et al. [8] as D. guanchica Gibby & Jermy. We have now found that both these species also contain much albaspidin, particularly the homologue BA. Former results for these and other species differing in some details were corrected (see Table 1) after careful re‐examination of the old chromatograms.

D. aemula from all origins contains relatively large amounts of two new compounds: aemulin (1) and trisaemulin (20), the structures of which were proved by degradation, NMR.‐ and mass‐spectroscopy. Trisaemulin was present as a mixture of two homologues BBB and BAB. The latter is the first three‐ring phloroglucinol found in nature which carries an acetyl group in the middle ring. So far only butyryl‐groups were found in this position.

D. azorica is diploid like D. maderensis and D. intermedia and all 3 taxa contain practically the same range of phloroglucinols. These facts are in agreement with conclusions based on morphology and cytology, which suggest that these three taxa are essentially conspecific.

D. crispifolia contains the same phloroglucinols as D. dilatata s. str.; ths is a further example showing at occasionally different species produce te same compounds.

‘D. dilatata’ from Tenerife differs from D. dilatata s. str. chemically not only by the absence of para‐aspidin, but also by the presence of the albaspidins‐2 and ‐3. In the same way it differs of course from D. crispifolia. This is a welcome confirmation of the morphological results [8], showing that D. crispifolia is really different from ‘D. dilatata’ from Tenerife, although it is difficult to differentiate pressed fronds of these two species.

Chemical results (see Table 1) are best compatible with the assumption that D. dilatata s. str. may have had its origin from a hybrid of D. assimilis x D. maderensis (= D. azorica = D. intermedia) with subsequent doubling of its chromosomes. They also would be compatible with the possibility that D. crispifolia has arisen from D. aemula and D. azorica in a similar way, provided the latter had suppressed formation of margaspidin and aemulin present in D. aemula but absent in D. azorica and D. crispifolia. No simple rationalisation is yet possible to explain the chemical results for ‘D. dilatata’ from Tenerife with the phloroglucinols present in its putative ancestors.
Rationelle Synthese von α‐L‐Homoprolin und einiger Derivate. Herstellung von 7‐α‐L‐Homoprolin‐bradykinin
Authors: Baláspiri L. , Penke B. , Papp Gy. , Dombi Gy. , Kov´cs K.
Published: December 2004

Optically pure α‐L‐homoproline can be prepared with good yield from N‐bnezyloxycarbonyl‐L‐proline through its diazoketone‐derivative. Preparation of derivatives of α‐L‐homoproline used in peptide chemistry, and of 7‐α‐L‐homoproline‐bradykinin, as well as biological investigation of the latter are described.
Synthese und Isolierung von Heptafulven und Sesquifulvalen
Authors: Schenk Walter Karl , Kyburz Rolf , Neuenschwander Markus
Published: December 2004

The synthesis and isolation of heptafulvene (1) and sesquifulvalene (2) is reported: Acetoxy‐tropylium‐fluoroborate (10) may be prepared by addition of tropone to acetyl‐fluoroborate at low temperatures. The tropylium salt reacts easily with methyllithium and sodium cyclopentadienide to give the acetoxy‐methyl‐cycloheptatrienes 11 and the acetoxy‐cyclopentadienyl‐cycloheptatrienes 12 respectively. Gas‐phase pyrolysis of 11 and 12 affords in remarkably good yields heptafulvene (1) and sesquifulvalene (2), which are isolated in cristalline form at low temperatures. Spectroscopic as well as chemical evidence of the title compounds is presented.
Gasphasenkomplexe zwischen Kobaltchlorid und Aluminiumchlorid
Authors: Dell'Anna A. , Emmenegger F. P.
Published: December 2004

CoCl2 forms two gaseous complexes in the presence of gaseous Aluminiumchlorid:
equation image

The equilibria were investigated by dynamic vapour pressure measurements (transpiration and chemical transport), by optical spectroscopy and by quenching the equilibrium gasphase followed by analysis of the condensates. The chromophor in the gaseous complexes appears to be tetrahedral CoCl4.
Dérivés C‐glycosyliques XXIII. Radicaux libres stables dérivés de sucre Communication préliminaire
Authors: Tronchet Jean M. J. , Mihaly Eva , Geoffroy Michel
Published: December 2004

Treated with 2,3‐dimethyl‐2,3‐bis‐(hydroxylamino)‐butane, aldehydo‐dialdofuranoses (1) gave a mixture of two compounds: a 1,3‐dihydroxyimidazolidine (2) and a 1‐hydroxyimidazoline (3). Oxidation (PbO2) of compounds 3 gave stable free radicals having the structure of 2‐C‐Glycosyl‐4,4,5,5‐tetramethylimidazolines 1‐oxyl (4), whereas 2‐C‐Glycosyl‐4,4,5,5‐tetramethylimidazolines 3‐oxide 1‐oxyl (5) were formed by oxidation of 2. The ESR. spectra of compounds 4 and 5 establish the structure of the imidazoline part of these radicals and provide informations on the sugar moiety.
Neuartige Merocyanine vom Typ des «Bindons»
Authors: Schelz Dieter
Published: December 2004

The title compounds (new type of merocyanines) were obtained from the reaction of heterocyclic enamines with indan‐1,3‐dione, biindantrione, 2‐(3‐methoxy‐inden‐1‐yliden)‐indan‐1, 3‐dione, or 2‐(3‐chloro‐inden‐1‐yliden)‐indan‐1, 3‐dione respectively. The enamines were obtained from the corresponding quaternary salts and reacted in situ.
Thermodynamik der Metallkomplexbildung mit Polyoxadiazamacrocyclen
Authors: Anderegg Giorgio
Published: December 2004

Ligands of the type H3‐nN(CH2CH2OCH2CH2OCH2CH2)nNH3−n with n values from 1 to 3 have been investigated. The stability constants and the heat evolved by formation of the 1:1 complexes of Na+, K+, Rb+, Tl+, Ca2+, Sr2+, Ba2+, Cd2+, Ag+, Hg2+ and Pb2+ have been determined. The complex formation is discussed in terms of ΔH and ΔS taking into consideration the radii of the cations. In contrast with the normal trend, for the A cations, complex formation is exothermic and almost exclusively favoured by the reaction enthalpy.
Cheletrope Reaktion vinyloger Enollactone
Authors: Skorianetz Werner , Ohloff Günther
Published: December 2004

Gasphase thermolysis above 220° of 2(3H)‐oxepinones 2 and 2(3H)‐furanones 5 gives carbon monoxide and the corresponding unsaturated carbonyl compounds 3, 4 and 6. The preparative value of these cheletropic processes is demonstrated.
«Nα/Nβ‐Isomerie» bei äquatorial koordinierten 1:2‐Co(III)‐Komplexen aus 2‐Hydroxy‐6‐methylphenyl‐1,1′‐azonaphtolen‐(2′)
Authors: Steiner Eginhard , Schetty Guido
Published: December 2004

An o, o′‐Dihydroxyphenylazomethin und‐azofarbstoffen, welche im Phenylrest eine zur Azomethin‐ bzw. Azogruppe o‐ständige Methylgruppe besitzen, wurden die Unterschiede der CH3‐Protonensignale im 1H‐NMR.‐Spektrum beim Übergang der Liganden zu den 1:2‐Co(III)‐Komplexen untersucht. Die beobachteten Regelmässigkeiten unterstützen und ergänzen die in [1] gemachten Feststellungen.

Ausserdem wird durch die Einführung der CH3‐Gruppe in die genannte Stellung bei «Phenylazo‐2‐naphthol‐Komplexen» eine «Nα/Nβ‐Isomerie» induziert, die bei Abwesenheit dieser CH3‐Gruppe nicht auftritt.

Dieses Ergebnis ist ein Hinweis dafür, dass grundsätzlich jedem o, o′‐Dihydroxyazofarbstoff diese Isomeriefähigkeit inhärent ist.
Réactivité des silyl‐ et germylphosphines vis‐à‐vis de divers composés à insaturation CN: imines, α‐diimines, N‐acylimines et cétènimines
Authors: Couret Claude , Couret Françoise , Satgé Jacques , Escudié Jean
Published: December 2004

Silylphosphines R3SiPR′2 add on the CN group of aldimines yielding phosphinylated silylamines of the structure . Hydrolysis of these adducts leads to the corresponding substituted aminomethyl‐phosphines.

In the reaction between α‐diimines and silylphosphines or silyldiphosphines R2Si(PR′2)2 the acyclic 1/1 and ½ addition compounds have been characterized. The adduct 1/1 obtained by the action of diethyl‐hydrodimethylsilyl‐phosphine on di‐tert‐butylimino‐ethane undergoes in the presence of Wilkinson's catalyst, (Ph3P)3RhCl, an intramolecular Si‐H/CN cyclisation leading to a phosphinylated siladiazolidine.

Silylphosphines add to N‐acylimines in 1,4 position to form phosphinylated siloxyimines. The methanolysis of the latter derivatives is an novel method of preparation of phosphinylated amides.

Silyl‐ and germylphosphines react on the CN groupement of cetimines. The hydrolysis of the adducts (N‐metallated enamines) leads to C‐phosphinylated imines.
Heteronuklear überbrückte tricyclische Systeme. Oxa‐brexane‐ und ‐brendane
Authors: Fritz Hans , Weis Claus D. , Winkler Tammo
Published: December 2004

Unsaturated cyclic and bicyclic hydrocarbons react with chloral in presence of aluminium chloride to yield tricyclic oxabrexanes which undergo acid catalyzed rearrangements to oxabrendanes. 1,5‐cyclooctadiene gives the new oxa‐cyclo[c, d]octahydropentalen. Structural evaluations and stereochemical assignments are discussed on the basis of detailed 1H‐ and 13C‐NMR.‐spectra.
Beitrag zur Partialsynthese 18‐oxygenierter Cortexone I. Synthese von 18‐Hydroxy‐cortexon Über Steroide, 230. Mitteilung
Authors: Biollaz Michel , Kalvoda Jaroslav , Schmidlin Julius
Published: December 2004

Two improved procedures for the synthesis of 18‐hydroxycortexone and derivatives thereof are presented. One approach involved the development of an efficient method for preparing cyclic 20‐enol ethers as key intermediates for the oxygenation at position 21. In an alternative sequence, starting from a 21‐hydroxypregnene compound, 18‐functionalization has been achieved as the final step by hypoiodite reaction.
Beitrag zur Partialsynthese 18‐oxygenierter Cortexone II. Synthese von 18‐Oxo‐cortexon Über Steroide 231. Mitteilung
Authors: Biollaz Michel , Schmidlin Julius , Kalvoda Jaroslav
Published: December 2004

18‐Oxocortexone, a potential metabolite of 11‐deoxy‐corticosterone and precursor of aldosterone has been synthesized, starting from 3β‐hydroxy‐5‐pregnene‐20‐one acetate via subsequent functionalization at positions 18 and 21.
Herstellung von DL‐N‐Benzyloxycarbonyl‐γ‐carboxy‐glutamin‐säure‐γ,γ′‐di‐t‐butyl‐α‐methyl‐ester, einem für die Peptidsynthese geeigneten Derivat der neuen Aminotricarbonsäure aus Prothrombin
Authors: Märki Walter , Schwyzer Robert
Published: December 2004

The first synthesis of a selectively, fully protected derivative of the new aminotricarboxylic acid found in prothrombin and other homologous blood‐clotting factors, γ‐carboxy‐glutamic acid (Gla), is described. The compound DL‐N‐benzyloxycarbonyl‐γ‐carboxy‐glutamic acid γ,γ′‐di‐t‐butyl‐γ‐methyl‐ester is potentially useful for peptide synthesis. The free amino‐acid (DL‐Gla) and DL‐pyro‐γ‐carboxy‐glutamic acid dimethyl‐ester were also prepared.
2,3,5,6‐Tetramethylidene‐Bicyclo[2.2.1]Heptane (Preliminary Communication)
Authors: Florey André , Vogel Pierre
Published: December 2004

Preparation of the title compound 1 is described. An important transannular effect between the two unconjugated s‐cis‐butadiene chromophores is observed by comparison of the UV. spectra of the tetramethylidenenorbornane 1 and the dimethylidenenorbornane 3. The differences observed between the UV. spectra of 2,3,5,6‐tetramethylidene‐7‐oxanorbornane 2 and 1 are also discussed briefly.
Reactions with benzo[b]thiophene‐2,3‐diones I: Synthesis of 2,3‐dihydroxy‐2,3‐diaryl(aralkyl)benzo[b]thiophene derivatives
Authors: Sallam Mohamed Mohamed Mohamed , Elnagdi Mohamed Helmi , Abdel‐Hady Mohamed Husein
Published: December 2004

Benzo[b]thiophene‐2,3‐diones (1) react with Grignard reagents to yield 2,3‐dihydroxy‐2,3‐diaryl(aralkyl)benzo[b]‐thiophenes (2). The latter compounds yield 3,3‐diaryl(aralkyl)‐benzo[b]thiophene‐2‐ones (3) by pinacolone rearrangement. Treatment of 3 by hot ethanolic sodium hydroxide solution yields the corresponding carboxylic acids by hydrolytic heteroring opening.
Chemisch‐spezifische Kopplung von Adrenocorticotropin‐ und Angiotensin‐II‐Derivaten an Polymerträger für die Affinitätschromatographie
Authors: Fauchère Jean‐Luc , Pelican Giatgen‐Mario
Published: December 2004

Specific covalent attachment of adrenocorticotropin and angiotensin II derivatives to polymeric matrices for use in affinity chromatography

The purpose of this investigation was to prepare polymer‐supported forms of adrenocorticotropin and angiotensin II with unique points of covalent attachment and presumably low rates of hormone detachment, making them potentially useful for affinity chromatography. Conventional chemical synthesis provided the peptides cysteinyl‐ACTH (5–24) ([4‐cysteine]‐adrenocorticotropin‐(4‐24)‐heneikosipeptide) and cysteinyl‐angiotensin II amide ([I‐Nα‐cysteinyl‐asparagine,5‐valine]‐angiotensin II). Strategies were devised to bind these hormone derivatives either in the protected form to polyacrylamide or in the deprotected form to sepharose beads. The obtained high degree of matrix substitution suggests a general applicability of these methods.
The Crystal and Molecular Structures of Two Acid‐Catalysed Rearrangement Products of Taxochinon
Authors: Weber Hans Peter , Petcher Trevor J. , Hensch Marcel , Eugster Conrad Hans
Published: December 2004

Die Strukturen von zwei säurekatalysierten Umlagerungsprodukten von Taxochinon (1) wurden kristallographisch bestimmt: Die eine Verbindung stellte sich als ein 20 (10 → 9) abeo‐Abietan (2) heraus, die andere als ein achirales Phenalenon (3). Die Abietanverbindung, C20H26O3, kristallisiert in der Raumgruppe P212121 mit 4 Molekeln in der Zelle und wurde mit 879 signifikanten Reflexionen bis R = 0,032 verfeinort. Die Phenalenonvervindung, C20H22O2, KRISTALLISIERT IN DER rAUMGRUPPE p21/c mit 12 Molekeln in der Zelle und wurde mit 1823 signifikanten Reflektionen bis R = 0,058 verfeinert.
Aza‐2‐diènes‐1,3. 2. Synthèse et structure d'un ylure d'azométhine stable
Authors: Fleury Jean‐Pierre , Schoeni Jean‐Paul , Clerin Daniel , Fritz Hans
Published: December 2004

2‐Aza‐1,3‐dienes. 2. Synthesis and Structure of a Stable Azomethine‐ylid.

Thermal treatment of 2‐(2′‐cyano‐2′‐methoxycarbonyl)methylide‐amino‐1‐morpholino‐cyclohexene results in the formation of a stable isomere. Its azomethine‐ylid structure is demonstrated from the spectroscopic data (UV., IR., 1H‐ and 13C‐NMR.). 1,3‐dipolar cycloaddition reactions of this ylid leads to spiropyrrolines.
Piperaceae Alkaloids: Part III. Synthesis of N‐isobutyl‐11‐(3,4‐methylenedioxyphenyl)‐undeca‐2,4,6‐trans, trans, trans‐trienoic amide and N‐isobutyl‐11‐(3,4‐methylenedioxyphenyl)‐undeca‐2,8,10‐trans, trans, trans‐trienoic amide (piperstachine)
Authors: Viswanathan Narayanan , Balakrishnan Venkatachalam , Joshi Balawant S. , von Philipsborn Wolfgang
Published: December 2004

N‐Isobutyl‐11‐(3, 4‐methylenedioxyphenyl)‐undeca‐2,4,6‐trans, trans, trans‐trienoic amide (II) and N‐isobutyl‐11‐(3,4‐methylenedioxyphenyl)‐undeca‐2,8,10‐trans, trans, trans‐trienoic amide (III), two of the three possible structures of the alkaloid piperstachine, have been synthesized. Compound (III) has been found to be identical with piperstachine. The 1H‐ and 13C‐NMR. spectra of the compound (II) are discussed.
Photoelectron Spectra of Vicinal Tricarbonyls
Authors: Bischof Peter , Gleiter Rolf , Hofmann Peter
Published: December 2004

The He I photoelectron spectra of tetramethylcyclopentane‐1,2,3‐trione 1, 4,4,6,6‐tetramethylcyclohexane‐1,2,3‐trione 2, bicyclo[1.2.3]octane‐2,3,4‐trione 3, bicyclo[2.2.3]nonane‐2,3,4‐trione 4 and anhydrous ninhydrine 5 are presented. The assignment of the first two bands is discussed using semiempirical calculations together with a qualitative band shape analysis. It is shown that the first two bands in 1 to 4 are due to the ionization of an electron from lone pair combinations of the 2p‐oxygen orbitals.
Über einen neuen Zugang zu Imidazolen, sowie deren Verwendung zur Synthese von Purinen und 4,6‐Dihydro‐1,2‐dimethyl‐8‐phenylimidazo[4,5‐e]‐1,4‐diazepin‐5(1H)‐on
Authors: Edenhofer Albrecht
Published: December 2004

A novel route to imidazoles and their use for the synthesis of purines and 4,6‐dihydro‐1,2‐dimethyl‐8‐phenylimidazo[4,5‐e]‐1,4‐diazepin‐5(1H)‐on.

Recently it has been shown [2] that pyrimidines are available from Thorpe‐Ziegler cyclization of the appropriate dinitriles. As an extension of this work, a novel route to imidazoles has been developed. It has been demonstrated that these imidazole derivatives are valuable intermediates for the synthesis of purines by application of standard procedures. The use of these imidazoles has enabled the preparation of some derivatives not accessible by other methods.
Die Struktur einer stabilen dipolaren Verbindung aus 2,2‐Dimethyl‐3‐dimethylamino‐2H‐azirin und Benzoylisothiocyanat. Vorläufige Mitteilung
Authors: Schmid Ursula , Heimgartner Heinz , Schmid Hans , Schönholzer Peter , Link Helmut , Bernauer Karl
Published: December 2004

Structure of a Stable Dipolar Compound from 2,2‐Dimethyl‐3‐dimethylamino‐2H‐azirine and Benzoylisothiocyanate.

Benzoylisothiocyanate and 2,2‐dimethyl‐3‐dimethylamino‐2H‐azirine (1) react to given the dipolar compound 4,4‐dimethyl‐2‐thiazolin‐5‐dimethylimminium‐2‐benzcarboxamidate (2), whose structure has been proved by X‐ray analysis. Compound 2, upon addition of water, yields the thiourea derivative 3, whereas by acid catalyzed hydrolysis the thiazolinone derivative 4 is formed. The dipolar structure 2 is also existent in organic solvents like dimethylsulfoxide or chloroform.
Über Reaktionen oxygenierter Kobalt(II)‐Komplexe. V. Reaktivität diastereoisomerer μ‐Peroxo‐μ‐hydroxo‐dikobalt(III)‐Ionen
Authors: Zehnder Margareta , Mäcke Helmut , Fallab Silvio
Published: December 2004

On Reactions of oxygenated Cobalt(II) Complexes. V. Reactivity of diastereoisomeric μ‐peroxo‐μ‐hydroxo‐dicobalt(III) Ions

The kinetics of dissociation of μ‐peroxo‐μ‐hydroxo‐dicobalt(III) chelates have been reinvestigated using a stopped flow technique. The binuclear cations [(trien)Co(O2, OH) Co(trien)]3+, [(tren)Co(O2, OH)Co(tren)]3+ and [(en)2Co(O2, OH)Co(en)2]3+ dissociate on acidifying to Co2+ and the protonated ligand and up to 100% of the bound O2 is evolved. The dissociation is H+‐catalyzed and first order in complex. The observed rate constants at pH 2 are in the range of 10−3 to 10−1 s−1 (20°). They depend not only on the nature of the ligand and on ligand configuration but also on the diastereoisomeric structure of the binuclear cation.

In the case of trien there are 8 possible chemically different isomers. On oxygenation of Co(trien)2+ in dilute solution 3 of those isomers seem to be formed preferentially. Their rate constants are separated over a factor of 50. For [(en)2 Co(O2, OH)Co(en)2]3+ there exist a meso form and a chiral structure. On oxygenation of Co(en)22+ in dilute solution the meso form and the racemate are formed to about equal amounts. The racemate dissociates about 5 times slower. Of the 3 possible achiral isomers of [(tren)Co(O2, OH)Co(tren)]3+ one is formed stereoselectively by oxygenation in solution.
Anwendung von Ringerweiterungen zur Herstellung von rac‐Muscon und Exalton®
Authors: Karpf Martin , Dreiding André S.
Published: December 2004

Application of Ring Expansions for the Preparation of rac‐Muscone and Exaltone®

4,6‐Undecamethylene‐2‐pyrone (8), prepared from 1‐morpholino‐cyclododec‐1‐ene (7) according to Hünig et al., was saponified and decarboxylated to a mixture of the 3‐methyl‐cyclotetradecenones 11, 12, 13 and 14, which was hydrogenated to 3‐methyl‐cyclotetradecanone (3). Similarly, 4,6‐dodecamethylene‐2‐pyrone (16) was prepared from 1‐morpholino‐cyclotridec‐1‐ene (15) and ketene, saponified to a mixture of the 3‐methyl‐cyclopentadecenones 19, 20, 21 and 22 and the latter hydrogenated to rac‐muscone (6).

The ratios of the four regio‐ and stereoisomers in the above mentioned two mixtures of 3‐methyl‐cycloalkenones were derived from the 1H‐NMR.‐spectra.

From the reactions of the enamines 7 and 15 were also isolated small amounts of 4,5‐decamethylene‐ (9) and 4,5‐undecamethylene‐6‐methyl‐2‐pyrone (17) respectively. Saponification and partial decarboxylation of 9 lead to (2‐acetyl‐cyclododec‐1‐enyl)‐acetic acid (23) and methyl‐(2‐methyl‐cyclododec‐1‐enyl)‐ketone (24), the latter possessing an incense‐like odor.

The keton homologation method of Mock & Hartman (reaction of alkanones with diazoacetic ester in the presence of triethyl oxonium fluoroborate, followed by saponification and decarboxylation) was applied three times in succession, starting with cyclododecanone (1). This furnished, after the first stage, the cyclotridecanone (4) required for the above described synthesis of rac‐muscone (6) and, after the third stage, cyclopentadecanone (5 = exaltone®).

Application of this reaction to 2‐methyl‐cyclododecanone (28) resulted in a low yield of 2‐methyl‐ (30) and 3‐methyl‐cyclotridecanone (31) in the ratio of 2:1.
The Radical Anion of 2,7‐Diazapyrene, a Change in Orbital Sequence on Protonation
Authors: Bruhin Jürg , Gerson Fabian
Published: December 2004

ESR.‐spectra are reported for the radical anion I · Θ of 2,7‐diazapyrene (I), along with those for the radical cations I(2H) · ⊕ and I(2 CH3) · ⊕ of 2,7‐dihydro‐2,7‐diazapyrene and its 2,7‐dimethyl‐derivative, respectively. In contrast to the analogous radical ions of 4,4′‐bipyridyl (II) and other previously studied diazaaromatic compounds, there is a striking change in the 14N and proton coupling constants on going from the radical anion I · Θ to the radical cations I(2H) · ⊕ and I(2 CH3) · ⊕. This change can be rationalized in terms of the HMO model of the pyrene π‐system. A reversal in the energy sequence of the lowest antibonding orbitals is predicted upon an increase in the absolute value of the Coulomb integral for the azasubstituted π‐centres, such an increase simulating the enhanced electronegativity of the azanitrogen atoms 2 and 7 on protonation.