bluuebunny/crossref_metadata_2025 huggingface dataset:
Über Pterinchemie. 39. Mitteilung. Zur Frage des “aktiven Formaldehyds”. Wird durch Formaldehyd‐Anlagerung an Tetrahydrofolsäureanaloge ein Imidazolidinring gebildet?
Authors: Viscontini M. , Bieri J.
Published: December 2004

Es werden Versuche mit Tetrahydrofolsäure‐Modellsubstanzen unternommen, um die eigentliche Struktur des sogenannten «aktiven Formaldehyds» abzuklären. Alle Addukte der tetrahydrierten Substanzen mit Formaldehyd erweisen sich als Hydroxymethyl‐ und nicht als Imidazolidin‐Derivate. Ob das Additionsprodukt des Formaldehyds mit Tetrahydrofol‐säure ebenfalls ein Hydroxymethyl‐Derivat ist, bleibt noch abzuklären.
Composés d'addition des chlorures de terres rares avec le méthanol, l'éthanol et le propanol‐2. Préparations, solubilités et réactions de transsolvatation
Authors: Merbach A. , Pitteloud M.‐N. , Jaccard P.
Published: December 2004

By reaction of hydrated rare earths chlorides (M = La, Nd, Sm, Gd, Dy, Er, Yb, Y) with orthoformates, the following adducts have been prepared: MCl3· 4MeOH, MCl3 ·3EtOH (M = La, Nd, Sm, Gd, Yb), MCl4 · 4 EtOH (M = Dy, Er, Y); adducts MCl3 · 3iso‐PrOH have been prepared by successive action of methyl orthoformate and of 2‐propanol. The solubilities of these adducts in the corresponding alcohols at 25° (for the lanthanum adducts equally at 0 and 50°) are given. Two examples of the transsolvatation of these compounds, yielding adducts with weakligands, are described.
Metal Complexes of Free Radicals. Part II: Identification and structures of radical complexes of alkaline earth metals and zinc
Authors: Clopath P. , v. Zelewsky A.
Published: December 2004

The formation of chelate complexes between free radicals and closed‐shell metal ions is observed by ESR. spectroscopy. High resolution spectra of 1:1 complexes formed between the radical anion of glyoxal‐bis‐(N‐t‐butylimine) (GLIR) and Mg2+, Ca2+ and Zn2+ are completely analysed. The complexes formed in dimethoxyethane or tetrahydrofuran solutions are Ca(GLIR)+, Mg(GLIR)X, Zn (GLIR)X and Zn(GLIR)Y−2, where X = Cl−, Br−, I−, and Y = CN−, NCS−. The formation of the heterometallic, binuclear cyanide‐bridged complex Zn(GLIR)Fe(CN)63− is also described. Isotropic coupling constants are given for protons and 14N in GLIR as well as for the metal nuclei and magnetic nuclei in the groups X and Y. Stabilities, structures and ESR. parameters of these radical complexes are discussed.
The Stabilization of Bridged Structures of Ethanes
Authors: Hoffmann Roald , Williams J. E.
Published: December 2004

The source of the instability of D2h, bridged, diborane type geometries of ethanes is traced to a single molecular orbital, b2g or π* in symmetry. The energy of this orbital can be lowered, and the barrier to bridging accordingly decreased, by appropriately placed acceptor substituents. Low bridging barriers, relative to ethane, are predicted for cyclopentenyl cation, and cyano or nitro substituted ethanes.
Synthese der 2‐Methyl‐lysergsäure Eine neue Friedel‐Crafts‐Methode. 74. Mitteilung über Mutterkornalkaloide
Authors: Stütz P. , Stadler P. A.
Published: December 2004

The new reagent 2‐methoxy‐1,3‐dithiolane and cyclic ortho‐thioesters can be used in a new reaction of the Friedel‐Crafts type to introduce the corresponding aldehydic or ketonic thioacetal function directly into substrates containing an indole nucleus with free 2‐ or 3‐position.
Reaction of Tribenzylaluminium with Acetylene
Authors: Stefani A. , Consiglio G.
Published: December 2004

Acetylene reacts smoothly with tribenzylaluminium both by ‘normal’ addition to the AlC bond and by aromatic substitution in ortho position; further addition reactions can take place.
Darstellung und spektroskopische Untersuchungen von Platinkomplexen, I. Interpretation der Spektren inverser Elektronentransfer‐ und Ligandenfeldübergänge von Platin (II)‐Komplexen mit Halogenid und Stickstoffliganden
Authors: Textor M. , Ludwig W.
Published: December 2004

Das Auftreten von inversen Elektronentransfer‐Übergängen vom Typ d(M) → π* (L) in PtL2X2‐Komplexen mit Liganden, die ein L‐internes π‐Elektronensystem haben, wird nachgewiesen. Eine Unterscheidung von den normalen Elektronentransferübergängen aus dem Halogenidsystem X → M ist bei diesen Komplexen sowohl bei D2h‐ wie bei C2v‐Symmetrie ausnahmslos möglich. Insbesondere wird gezeigt, dass bei dieser Verbindungsreihe eine quantitative Korrelierung der Energien von Ligandenfeld‐ und inversen Elektronentransferübergängen möglich ist, die eine Zuordnung der einzelnen Banden mit hohem Wahrscheinlichkeitsgrad erlaubt. Die weitaus besten Resultate der Korrelation werden erhalten für eine Zufallsentartung der «d»‐ Orbitale xy, xz und yz bei D2h‐ bzw. 2z2‐x2‐y2, xz und xy bei C2v‐Symmetrie. Nur ein einziges der in den d8‐Systemen besetzten «d»‐Orbitale ist demnach deutlich stabiler, 2z2–x2–y2 in D2h und x2–y2 in C2v, so dass jeweils nur zwei spinerlaubte Ligandenfeldbanden beobachtet werden können.
Stoffwechselprodukte von Mikroorganismen. 101. Mitteilung. Synthese der trans‐5‐Hydroxy‐3‐methylpenten‐(2)‐säure (trans‐Δ2‐Anhydromevalonsäure)
Authors: Keller‐Schierlein W. , Widmer J. , Maurer B.
Published: December 2004

trans‐Δ2‐Anhydromevalonic acid (XVII) was prepared by a Wittig reaction, starting from (4‐tetrahydro‐2‐pyranyloxy)‐2‐butanone. On the other hand, the corresponding 4‐acetoxy‐2‐butanone gave, under similar conditions, the cyclohexene derivative V, explainable by a twofold Michael addition of the Wittig reagent to methyl vinyl ketone, followed by an intramolecular alcol condensation.
Lokalisierte intermolekulare Induktionswechselwirkung endlicher Dipole mit apolaren Lösungsmittelmolekeln: Die Deutung temperaturabhängiger Dipolmomente von Carbonyl‐ und Thionderivaten der 1,2‐Dithiacyclopentene
Authors: Eicke H.‐F. , Christen H.
Published: December 2004

Solute‐solvent interactions of the 1,2‐dithiacyclopentenones and the analogue dithiathiones with non‐polar solvent molecules as well as the formation of hetero‐association complexes of these compounds is attributed to localized electrostatic induction. The distribution of the electric field around the oxo and thiono groups, respectively, is of special importance in determining the strength of the association. The temperature dependent solute‐solvent interactions are correlated with changes in the observed dipole‐moments.

A plausible quantitative model based on finite dipole‐moments is proposed in order to interpret the fundamental process of association.
Photoelectron Spektra of Azabenzenes and Azanaphthalenes: II. A Reinvestigation of Azanaphthalenes by High‐Resolution Photoelectron Spectroscopy
Authors: Brogli F. , Heilbronner E. , Kobayashi T.
Published: December 2004

The bands with Iv < 13 eV in the photoelectron spectra of quinoline (IX), isoquinoline (X), cinnoline (XI), quinazoline (XII), and quinoxaline (XIII) have been reassigned in a way consistent with the assignment proposed for pyridine (II), the diazines (III, IV, V), s‐triazine (VI), and 1,2,4,5‐tetrazine (VII). The bands corresponding to the ejection of an electron from a π‐orbital have been identified by a regression calculation based on a HMO perturbation treatment. It has been found that the combined through‐space and through‐bond interaction of the lone pairs in III, IV, V and in their corresponding benzologues XI, XII, XIII are the same within experimental error ( ±, 0.2 eV). Our assignment is also supported by an empirical correlation of the pKa, 1− values and the mean lone‐pair ionization potentials of the azaderivatives I to XIII.
Über die Synthese der Pilocarpus‐Alkaloide Isopilosin und Pilocarpin, sowie die absolute Konfiguration des (+)‐Isopilosins
Authors: Link H. , Bernauer Karl
Published: December 2004

A novel synthesis for rac‐pilosinine (6 rac) and transformation of (+)‐pilosinine (6) into the pilocarpus alkaloids (+)‐isopilosine (9) and (+)‐pilocarpine (18) are described. By correlation via 5 with 18 the absolute configuration of (+)‐isopilosine (9) is established.
Zur Reaktionsweise von Enaminen mit Cyclopropenonen II
Authors: Bilinski V. , Steinfels M. A. , Dreiding A. S.
Published: December 2004

The addition of diphenylcyclopropenone 2 to several enamines 1 as described by Ciabattoni & Berchtold [1] [2] has been reinvestigated. The products which were previously postulated to be enamines of β‐dicarbonylcompounds 9 to 14 have now been shown to be ‘amides’ 16 to 20. The reaction does not take the course of a ‘C, C‐insertion’, which would have been useful for ring expansion, but rather of a ‘C, N‐insertion’, which attaches a C3 side chain to the α‐carbon of enamines. This conclusion was reached by new interpretations of spectral data and by chemical transformations of old and new products. In the course of this reinvestigation, a new class of products, the amino‐cyclopentenones 41, 45 and 47, were isolated from the enamine‐cyclopro‐penone‐reaction. Their structures were proven by spectroscopic considerations and by chemical degradation.

A systematic representation of these reactions is proposed in the reaction scheme.
The Synthesis and Some Reactions of N‐Alkyl‐4‐Quinolone‐3‐Carboxylic Acids
Authors: Markees D. G. , Schwab Linda S.
Published: December 2004

A modification of the Gould‐Jacobs reaction, particularly useful for the preparation of N‐alkyl‐4‐quinolone‐3‐carboxylic acids, is described. Decarboxylation of these acids leads to N‐alkyl‐4‐quinolones or, in the case of N‐ethyl‐benzo[h]‐4‐quinolone‐3‐carboxylic acid, to 4‐ethoxy‐benzo[h]quinoline. Evidence for the structure of the products is presented and the synthesis of relevant compounds is described.
A Chemical Study of Burley Tobacco Flavour (Nicotiana tabacum L.). I. Volatile to medium‐volatile constituents (b.p. ≦ 84°/0.001 Torr
Authors: Demole Edouard , Berthet Dominique
Published: December 2004

The fraction b.p. ≦ 84° (0.001 Torr) from Burley tobacco condensate was carefully investigated using fractional distillation and preparative column and gas liquid chromatography aided by GLC/MS coupling. Among the 193 compounds thus separated and characterized by their spectral data, 81 were newly identified tobacco constituents.

Most of the compounds isolated in the course of this work display flavouring properties which make them highly suitable for improving the flavour and aroma of tobacco and tobacco smoke.
Synthèses dans la série des‐indéno‐fluorénes, VII. Le trioxo‐5,12,13‐dihydro‐12,13‐5H‐bis‐indéno[2.1‐a; 2′.1′‐g] fluoréne
Authors: Chardonnens Louis , Chen Te Tseng
Published: December 2004

Starting from 9‐oxo‐fluorene‐1‐carbaldehyde, the title compound, XII, a trioxoderivative of a new biangular diindenofluorene system, has been synthesized in 5 steps (overall yield 37,5%). The corresponding hydrocarbon could not be obtained by reduction of XII. Attempts to synthesize the isomer XX of the trioxoderivative XII are described.
Arbeiten über Phosphorsäure‐ und Thiophosphorsäureester mit einem heterocyclischen Substituenten. 5. Mitteilung. 2‐Alkoxy‐ und 2‐Alkylthio‐5‐chlormethy1‐‐1, 3,4‐thiadiazole, 2‐Alkyl‐ 5‐chlormethy1‐1,3,4‐oxadiazole und daraus hergestellte Thio‐ und Dithiophosphorsäure‐O, O‐dialkyl‐S‐[(2‐alkoxy‐ und 2‐alkylthio‐1, 3, 4‐ thiadiazol‐5‐yl)‐methyl]‐ bzw. ‐S‐[(2‐alky1‐1, 3, 4‐oxadiazol‐5‐yl)‐methyl‐ester
Authors: Rüfenacht K.
Published: December 2004

2‐Alkoxy‐5‐chloromethy1‐1,3,4‐thiadiazoles are prepared by ring closure of 3‐chloroacetyl‐thiocarbazic acid O‐alkyl esters with concentrated sulfuric acid, 2‐alkylthio‐5‐chloro‐methy1‐1,3,4‐thiadiazoles directly from dithiocarbazic acid alkylesters with chloroacetylchloride in benzene in a one step synthesis omitting the 3‐chloroacetyl‐derivatives and 2‐alkyl‐5‐chloro‐methy1‐1,3,4‐oxadiazoles from 1‐chloroacetyl‐2‐acyl‐hydrazines with POCl3. These three types of chloromethyl heterocycles easily react with salts of thio‐ and dithiophosphoric acids to form the corresponding O,O‐dialkyl‐S‐[(2‐alkoxy‐ and 2‐alkylthio‐1,3,4‐thiadiazol‐5‐yl)‐methyl]‐ and ‐S‐[(2‐alky1‐1,3,4‐oxadiazol‐5‐yl)‐methyl]‐thio‐ and ‐dithiophosphates.
Surface chemistry of polymers Adsorption and absorption of gases by polyvinylchloride
Authors: Perret E. A. , Stoeckli H. F. , Jeanneret C.
Published: December 2004

Nitrogen and carbon monoxide are physically adsorbed on polyvinylchloride between 78 and 86 K, without hysteresis. At higher temperatures, carbon dioxide (195 K), sulfur dioxide (273 and 293 K) and chloroethane (293 K) are strongly absorbed by the solid, with hysteresis. The possibility of trapping CO inside the solid indicates that PVC has an open structure at higher temperatures. The effect of heating on the polymer was also investigated.
Struktur von Coleon E, einem neuen diterpenoiden Methylenchino aus der Coleus barbatus‐Gruppe (Labiatae)
Authors: Rüedi P. , Eugster C. H.
Published: December 2004

We have isolated from the glands on the leaves of Coleus barbatus (Benth.) Agnew C. Kilimandschari (Gürcke) Agnew and a C. species P. R.O. Bally No. 10431, all of East Africa origin, a new, very labile, deeply red coloured quinone methide, Coleon E, C20H22O5. Degradations and spectra (including 13C‐NMR.) have been interpreted in terms of the unusual irregular diterpenoid structure 1. Its fully conjugated unsaturated system extends over 3 rings. The CH3‐group at C(3) and n‐propyl side chain at C(13) instead of the usual isopropyl group are regarded as arising by modification of an abietane precursor. Coleon E, after reduction and methylation, has been found to undergo a skeletal rearrangement leading to a formal interchange of the alkyl side chain with a phenolic OH‐group.
Carbon Magnetic Resonance Spectra of α, β, γ, δ‐ and α, β, α′, β′‐ Unsaturated Ketones
Authors: Hollenstein R. , von Philipsborn W.
Published: December 2004

Carbon‐13 spectra of a series of 26 unsaturated ketones (ortho‐ and para‐cyclo‐hexadienones and corresponding open‐chain analogues) have been measured by Fourier‐transform. Pulse spectroscopy. A complete analysis has been achieved by means of double resonance experiments using noise‐modulated and coherent off‐resonance proton irradiation and with the aid of non‐decoupled spectra. Chemical shifts are interpreted in terms of charge distribution in the dienone system and of methyl substituent effects. Carbon chemical shifts were also obtained for O‐protonated ortho‐ and para‐cyclohexadienones. One‐bond and long‐range carbon‐proton and carbon‐fluorine spin coupling constants are reported for several compounds.
Über die Alkaloide von Anisocyclea grandidieri H. Bn. (Menispermaceae)
Authors: Schlittler Emil , Weber Nikolaus
Published: December 2004

Four alkaloids were isolated from Anisocyclea grandidieri (Fam. Menispermaceae). Trilobine and stebisimine have already been found in other menispermaceous plants, whereas (−)‐epistephanine and 12′‐O‐desmethyltrilobine have not been isolated before.
Electrophilic Aromatic Substitution of Groups other than Hydrogen. Part II: SN1‐Type Desulfonation of 2‐Naphthol‐1‐sulfonic Acid by Diazonium Ions in Aprotic Apolar Solvents. 27th communication on diazo coupling reactions
Authors: Fischer P. B. , Zollinger H.
Published: December 2004

The rates of formation of 1‐(4′‐chlorophenylazo‐)‐2‐naphthol by SO3 of release from the π‐complex [2‐naphthol‐1‐sulfonate anion …︁ p‐chlorobenzenediazonium cation] have been measured in chloroform and in methylene chloride; they are first‐order with respect to the complex. They are catalysed by pyridine and co‐catalysed by acetic acid. Acids alone, in stoichiometric or higher concentrations, inhibit the reaction. A mechanism is postulated involving proton transfer to the sulfonate group, followed by rearrangement to the σ‐complex which, in the catalysed reaction, first loses a proton to the base and then releases SO3, but in the uncatalysed reaction loses SO3H⊕. The function of the co‐catalyst (pyridinium ion) is explained (see text). This reaction is ‐ in contrast to electrophilic aromatic substitutions in which the leaving group is a protonan SN1‐type re‐aromatization of the σ‐complex to the product.
Magnetic Circular Dichroism Studies XXIII [1] Magnetic Circular Dichroism Spectra of Indole Alkaloids
Authors: Barth Günter , Linder Robert E. , Bunnenberg Edward , Djerassi Carl
Published: December 2004

The magnetic circular dichroism spectra of a number of indole alkaloids show two B‐terms of opposite sign in the 250–330 nm wavelength region associated with the 1Lb and 1La electronic transitions, the long wavelength, 1Lb, band being of positive sign, whereas both bands strongly overlap in absorption. Various substituents in different positions of the indole ring cause a red shift of both bands and a broadening of the long wavelength B‐term. The sign pattern, howver, remains unchanged in all examples thus far investigated. Dihydroindole and oxindole, on the other hand, exhibit MCD. bands with the opposite sign sequence as compared to the indole chromophore. This observation allows identification of the indole chromophore in alkaloids from the sign pattern of the MCD. bands.
α‐Chlor‐nitrone III: Ein Weg zur indirekten «carboxolytischen» Spaltung von Olefin‐Doppelbindungen. Über synthetische Methoden, 7. (vorläufige) Mitteilung
Authors: Gygax P. , Das Gupta T. K. , Eschenmoser A.
Published: December 2004

The enaminoid derivatives formed by deprotonation of the olefin‐α‐chloro‐nitrone cycloadducts (see preceding communications) undergo a beautifully clean cycloreversion at ambient or slightly elevated temperatures. The sequence (2+4)‐cycloaddition → deprotonation → (2′+4)‐cycloreversion constitutes a potentially useful method for the oxidative cleavage of olefinic double bonds with concomitant extension of the carbon chain at one of the double bond termini (indirect «carboxolytic» cleavage of double bonds; see schemes 1 and 3).
The Reaction of Bicyclo [3.2.1] octenyl Halides with Metal Hydrides
Authors: Jefford C. W. , Sweeney A. , Delay F.
Published: December 2004

Reduction of 2‐phenyl‐ and 2‐methyl‐exo‐3,4‐dichlorobicyclo[3.2.1]oct‐2‐enes with lithium aluminium hydride (LAH) or tributyltin hydride (TBTH) gave endo‐2‐phenyl‐3‐chlorobicyclo[3.2.1]oct‐3‐ene, 2‐phenyl‐3‐chlorobicyclo[3.2.1]oct‐2‐ene and their methyl analogues. The action of both reagents on 2‐phenyl‐exo‐3, 4‐dibromobicyclo[3.2.1]oct‐2‐ene similarly resulted in reductive monodebromination to give normal and allylically rearranged products. Additionally, further reduction occurred to give endo‐2‐phenylbicyclo[3.2.1]oct‐3‐ene and 2‐phenylbicyclo[3.2.1]‐oct‐2‐ene. In all cases, LAH gave mainly the allylic rearrangement product whereas TBTH gave mostly unrearranged product. The reason for these differences could have been due either to the intervention of allylic radicals in the TBTH reduction or to differences in nucleophilicity. The results also show that LAH is equally efficaceous as TBTH in the reduction of these allylic halides and equally selective in the reduction of the vinyl bromides. The stereochemistry of the allylic rearrangement was shown to be synfacial in that hydride replaced halide on the same face of the molecule.
Die Totalsynthese des Alkaloids Rhoeadin
Authors: Klwötzer W. , Teitel S. , Brossi A.
Published: December 2004

The conversion of the phthalideisoquinoline (−)‐bicuculline into the benzazepine alkaloid rhoeadine and its unnatural (−)‐isomer is described.
The Acid‐catalyzed Isomerization of an α‐Ketoester into β‐Ketoesters and the Unusual Fragmentation of an α‐Ketoester. Preliminary communication
Authors: Kagan Jacques , Agdeppa Dalmacio A.
Published: December 2004

The first example of an acid‐catalyzed isomerization of an α‐ketoester into β‐ketoesters is described. Ethyl 2‐keto‐3,3‐diphenylbutyrate rearranged in fluorosulfonic acid at 0° into ethyl 2‐benzoyl‐2‐phenylpropionate and ethyl 2,2‐diphenylacetoacetate. In contrast, fragmentation of ethyl 3,3‐diphenylpyruvate to benzophenone occurred in the same conditions.
Über das Lipoxygenase‐« Lipoperoxidase »‐System in Cerealien: III. Zur Kinetik des enzymatischen Abbaues von Linolsäurehydroperoxiden
Authors: Heimann W. , Reinartz F. , Schreier P.
Published: December 2004

Durch Untersuchung der Kinetik der Peroxidase‐katalysierten Linolsäure‐hydroperoxid (LHPO)‐Abbaureaktion mit einem Hafer‐Ammoniumsulfatpräparat wird gezeigt, dass es sich um eine bimolekulare Reaktion in zwei Ein‐Elektron‐Schritten des Peroxidase‐Hydroperoxid‐Komplexes mit dem Wasserstoffdonator handelt. Der Nachweis wird durch die Übereinstimmung der Versuchswerte mit einer aus der Theorie der binären Komplexbildung abgeleiteten mathematischen Funktion erbraeht.
Synthese der enantiomeren 1,6‐Spiro[4.4]nonadiene
Authors: Gerlach H. , Müller W.
Published: December 2004

Two new syntheses of spiro[4.4]nonane‐1, 6‐dione (I) are described: one by rearrangement of 1,6‐epoxy‐bicyclo[4.3.0]‐nonane‐2‐one (IV) with boron trifluoride, the other by an acid catalyzed, intramolecular Claisen condensation of 4‐(2‐oxocyclopentyl)‐butyric acid. Spiro[4.4]‐nonane‐1,6‐dione is converted into trans, trans‐spiro[4.4]nonane‐1,6‐diol which is resolved into enantiomers via the diastereomeric esters with (−)‐camphanic acid. (+)‐(5S)‐Spiro[4.4]nona‐1,6‐diene (III) is prepared from (1R, 6R)‐trans,trans‐spiro[4.4]nonane‐1,6‐diol (II) by pyrolysis of the corresponding bis‐4‐methylphenyl‐thionocarbonate. This modification of the Chugaev reaction is particularly useful with sterically hindered alcohols which cannot be converted into S‐me‐thylxanthates. The circular dichroism, UV.‐ and NMR.‐spectrum of optically active spiro[4.4]‐nonane‐1,6‐diene are discussed.
Stoffwechselprodukte von Mikroorganismen 102. Mitteilung. Über die Struktur der Venturicidine A und B
Authors: Brufani M. , Cellai L. , Musu C. , Keller‐Schierlein W.
Published: December 2004

Chemical degradations and spectroscopic investigations of the macrolide antibiotics venturicidin A and B are described. In combination with an X‐ray crystallographic analysis they lead to complete structures.
σ, π‐Isomerisierungen von Monohetero‐σ‐bishomobenzol‐Derivaten. Vorläufige Mitteilung
Authors: Stusche D. , Breuninger M. , Prinzbach H.
Published: December 2004

The cis‐oxa‐ (13a‐d) and ‐aza‐σ‐bishomobenzene (13 e) derivatives have been synthesized; they are sufficiently stable to be isolated in pure form. On heating, 13a‐e are easily isomerized into the π‐bishomobenzene analogues 14a‐e, the processes 13 a ⇄ 14 a, 13 b ⇄ 14b and 13d ⇄ 14d being reversible. Some kinetic and thermodynamic data for these σ, π,bishomobenzene transformations are presented.
Zur Kenntnis der sesquiterpenoiden C12‐Ketone des ätherischen Öls von Vetiveria zizanioides (L.) Nash
Authors: Maurer B. , Fracheboud M. , Grieder A. , Ohloff G.
Published: December 2004

Two new C12‐ketones, (+)‐(1S, 10R)‐1,10‐dimethylbicyclo[4.4.0]dec‐6‐en‐3‐one (5) and (+)‐(6S, 10S)‐6,10‐dimethylbicyclo[4.4.0]dec‐1‐en‐3‐one (6), have been isolated from Reunion vetiver oil (Vetiveria zizanioides (L.) Nash). Structure and absolute configuration of 5 were established by a four‐step synthesis from (+)‐isonootkatone ((+)‐α‐vetivone) (1). The structure of 6 followed from its spectroscopic properties and was confirmed by direct comparison with an authentic racemic sample. The absolute configuration of 6 was established by chemical correlation with (+)‐α‐eudesmol (13).
Eine verbesserte Synthese von Chinuclidin‐4‐carbonsäure. Chinuclidinreihe, 10. Mitteilung
Authors: Eckhardt W. , Grob C. A. , Treffert W. D.
Published: December 2004

An improved synthesis of 4‐carbethoxyquinuclidine from 1‐benzyl‐4‐piperidone is described.
Synthese und Eigenschaften von Spiro[1,3‐benzodioxol‐2,3′‐pyrrolidin]
Authors: Berthold R. , Gmünder J. , Troxler F.
Published: December 2004

Spiro[1,3‐benzodioxole‐2,3′‐pyrrolidine] was synthesized in several steps from ethyl 2‐ethoxycarbonyl‐1, 3‐benzodioxole‐2‐acetate, prepared by condensation of pyrocatechol with either diethyl meso‐dibromosuccinate, diethyl acetylenedicarboxylate or diethyl bromo maleate. The structural factors leading to the formation of the benzodioxole rather than the benzodioxan and some possible reaction mechanisms are discussed.
Parmon, eine Phantomverbindung im Veilchenblütenöl
Authors: Uhde G. , Ohloff G.
Published: December 2004

Das Blütenöl des Parma‐ sowie des Viktoria‐Veilchens geörte am Anfang unseres Jahrhunderts zu den kostbarsten Ingredienzien der feinen Parfümerie. Sein Wohlgeruch faszinierte jedoch nicht nur die Noblen der damaligen Haute‐Volée, sondern es regte ebenfalls in segensreiche Weise die Phantasie des Naturstoffchemikers jener Epoche an1). Der extrem hohen Herstellungskosten2) wegen ist das Veilchenblütenöl seit langem aus dem Handel verschwunden. Sicherlich liegt aus diesem Grund bis heute lediglich ein einziger Bericht über die chemische Zusammensetzung dieses ätherischen Öles vor [3].
Die übergangsmetall‐katalysierte reduktive Carbonylierung von Arylaziden zu 1,3‐Diarylharnstoffen
Authors: Iqbal Abul F. M.
Published: December 2004

Several group VIII metal carbonyls catalyze decomposition of aryl azides to yield in the presence of carbon monoxide and a low concentration of hydrogen the corresponding symmetrical disubstituted ureas. Based on the formation of nitrenoid intermediates, probable and alternative reaction mechanism pathways have been examined.
Steroid Total Synthesis, Part VIII; (+)‐estr‐4‐ene‐3,17‐dione
Authors: Rosenberger M. , Duggan A. J. , Borer R. , Müller R. , Saucy G.
Published: December 2004

A novel synthesis of the title compound, involving the resolution of a Mannichbase derived from racemic 11,11‐o‐phenylenedioxy‐7‐hydroxy‐1‐dodecen‐3‐one is described. In an alternate approach 2(S)‐acetamido‐6,6‐o‐phenylenedioxy‐heptanoic acid was used as the optically active starting material. This scheme features the preparation of a chiral 1,2‐epoxide and its regiospecific alkylation with lithio‐1, 1‐diethoxy‐2‐propyne.
Electron Spin Resonance Studies of Free Radicals Arising from α‐Hydrogen Abstraction from Thioethers
Authors: Lucken E. A. C. , Poncioni B.
Published: December 2004

On rapporte les spectres de résonance paramagnétique de radicaux libres du type RSCR1R2, créés par photolyse d'un mélange de t‐butylperoxyde et d'un thioéther. Pour les thioéthers cycliques, tétrahydrothiophène et thiopyranne, les spectres indiquent une interconversion rapide du cycle qui est empêchée dans le 4 t‐butyl‐thiopyranne, permettant ainsi l'attribution des couplages aux divers protons axiaux et équatoriaux.
Affinity Chromatography with ε‐Aminocaproyl‐choline Derivatives. (Preliminary Communication)
Authors: Schwyzer Robert , Frank Jörg
Published: December 2004

An Sepharose 2 B gebundene Derivate von ε‐Aminocaproylcholin vermögen Acetylcholinesterase und andere, vermutlich ebenfalls für Acetylcholin spezifische Proteine aus Elektroplax von Electyophorus electricus bevorzugt zu adsorbieren. Die Elution erfolgt mit Tetramethylammonium‐chlorid.
NMR.‐Investigation of the Formaldehyde Addition and Oligomerisation Equilibria in the System Formaldehyde/Water/Acetic Acid/Hydrochloric Acid
Authors: Gorrie T. M. , Raman S. Kalyana , Rouette H. K. , Zollinger Heinrich
Published: December 2004

An NMR. investigation of the state of formaldehyde in acidic solutions has been carried out. Solutions of DCl/D2O/CD3COOD containing two sources of formaldehyde, i.e. paraformaldehyde (I) and trioxane (II), were used for this purpose. In systems I and II the effect of various D2O/CD3COOD ratios, at a constant DCl concentration, was studied, while for II the effect of changing DCl concentration was also investigated. The results show that in aqueous solution, formaldehyde exists primarily as the monomeric and linear oligomeric forms of methylene glycol. Reducing the amount of D2O (at constant DCl concentration), while increasing the CD3COOD content, results in an increase in the polymeric species and in trioxane. In addition, substitution of water by acetic acid results in systems that are catalytically more active than aqueous solutions of the same hydrochloric acid concentration. Along with the usual polymer‐monomer equilibria which exist in such solutions, side reactions of methylene glycol with the hydrochloric acid present also occur to a small extent, e.g. acetylation, substitution of OH by Cl and the Cannizzaro reaction. It is suggested that these findings will result in a better understanding of the formaldehyde crosslinking reactions in cotton cellulose.
Lösungsmittelbedingte Temperaturabhängigkeit des Dipolmoments polarer Molekeln in apolaren Medien
Authors: Christen H. , Eicke H.‐F. , Jungen M.
Published: December 2004

Solute‐solvent interactions of polar molecules generally result in an apparent temperature dependence of dipole moments. Variations of the dielectric constants with temperature of solutions of mono‐ and 1,2‐dichlorobenzene in different apolar solvents confirm the repeatedly observed solvent‐influenced apparent temperature dependence of the dipole moments. An attempt has been made for the first time to interpret these temperature effects on the basis of a statistical (Monte‐Carlo‐Method) and a continuum model. Both models permit the description of the typical curve of the dipole moments as a function of temperature and in addition reproduce the observed effects as to the order of magnitude.
ESR. Spectra of Radical Anions in the Cyclazine Series
Authors: Gerson Fabian , Jachimowicz Joanna , Kowert B. , Leaver D.
Published: December 2004

The ESR. spectra of the radical anions of three cyclazines are described. Their π‐spin distributions are discussed in terms of simple MO theory and compared with those of structurally related species.
Sur l'acylation des méthylfluorènes VI. Formylation du méthyl‐2‐fluorène et du méthyl‐3‐fluorène selon Rieche
Authors: Chardonnens Louis , Noël François
Published: December 2004

The formylation of 2‐methylfluorene and of 3‐methylfluorene according Rieche yields 2‐methyl‐7‐fluorene‐carbaldehyde and 3‐methyl‐2‐fluorenecarbaldehyde respectively. The constitution of the obtained aldehydes is proved by their conversion into the known 2,7‐dimethyl‐fluorene and 2,7‐dimethyl‐9‐fluorenone, respectively into the known 2,3‐dimethylfluorene and 2,3‐dimethyl‐9‐fluorenone.
Synthetische Übergänge von der Jonon‐ in die Damasconreihe
Authors: Schulte‐Elte K. H. , Müller B. L. , Ohloff Günter
Published: December 2004

New preparative routes to the isomeric damascones (2, 4 and 9) and β‐damascenone (1) starting from the readily accessible ionone isoxazoles [11] are described. γ‐Damascone (9) was prepared from 10 following the Büchi‐Vederas transformation [11], while α‐ and β‐damascone (4 and 2) were obtained as the end products of the reaction sequence: β‐aminodamascones [11]→β‐ketodihydrodamascones (20 and 21) → β‐hydroxydihydrodamascones (24 and 25). β‐Damas cenone (1), however, is formed from the epoxides of β‐ionone isoxazole (14) by Birch reduction followed by treatment with acid.

The unusual behaviour towards metal hydrides of the crotonyl group in the damascones and damascenones is described.
Silylierte Polyphenyläther; ihre Darstellung und einige physikalische Eigenschaften
Authors: Fink Walter
Published: December 2004

Chemical modification of aromatic polyphenyl ethers by silylation (trimethylsilyl, dimethylphenylsilyl, methyldiphenylsilyl and siloxanyl groups), has been investigated and shown to give products with improved low‐temperature fluidity without change of thermal stability.
Isomeriefälle bei CrIII‐ und CoIII‐1:2‐Komplexen aus 8‐(2′‐Carboxyphenyl)‐amino‐chinolinen: Zur Frage der pyramidalen Struktur des koordinierten, dreibindigen Stickstoffatoms von Metallchelaten
Authors: Steiner E. , Schetty Guido
Published: December 2004

8‐(2′‐Carboxyphenyl)‐aminoquinolines are tridentate ligands. They form on complexation with CoIIIor CrIIIsingly negatively charged 1:2 complexes by loss of two protons. In these octahedral complexes the ligands are very probably coordinated equatorially. Nevertheless up to 3 isomeric 1:2 complexes are formed. According to the NMR.‐spectra two of them an symmetrical the third is asymmetrical. The basis of our assumption is that a trivalent N‐atom which is co‐ordinated to a metal ion and which is a link of two annelated rings can possess pyramidal valence structure. The ligand in the complex would thus be bent, which renders the possibility to form three conformers.
Kinetics of Photochemical Systems with Modulated Optical Excitation
Authors: Forster M. , Fringeli U. P. , Günthard Hs. H.
Published: December 2004

The kinetic equations of a photochemical system are discussed in which the transitions from the ground to the first excited state are produced by a sinusoidally modulated photon source. The system includes irreversible reactions starting from the first excited singlet state S1 and the first triplet state T1 (cf. Fig. 1). Explicit solutions are given for a linear approximation of the equations of motion for the parametrically modulated system. The solutions apply only when there is weak optical pumping, low quantum yields of the photochemical end‐products and for certain conditions, of the modulation frequency. The concentrations of all particles occurring are shown to consist of modulated and unmodulated components where the amplitudes of the modulated components are slowly decaying exponentials. Thc phases of the modulated components are shown to be non‐decreasing along a sequence of irreversible steps. Formulae are given which permit determination of the photochemical system rate constants and location of a particle in a sequence of irreversible reactions.
Complex Formation of Macrotetrolide Carrier Antibiotics with Cations Studied by Microcalorimetry and Vapour Pressure Osmometry
Authors: Züst Ch. U. , Früh P. U. , Simon W.
Published: December 2004

Complex formation parameters of macrotetrolide antibiotics with alkali and alkaline earth metal cations are given. The stability constants for the complexes in methanol and ethanol at 30°, as determined by vapour pressure osmometry, and ΔH0, ΔG0, and ΔS0 for some interactions in methanol and ethanol at 25°, measured by microcalorimetry, are compared and discussed.
Synthese von Haschisch‐Inhaltsstoffen. 6. Mitteilung
Authors: Petrzilka Th. , Demuth M. , Lusuardi W. G.
Published: December 2004

The synthesis of a new (−)‐Δ8‐6a,10a‐trans‐tetrahydrocannabinol analogue, containing a N‐methyl‐3‐propyl‐pyrrolidin‐3‐yl side‐chain, is reported.
Steric Effect in [6+4] Cycloaddition Reactions. Part I
Authors: Pfaendler H. R. , Tanida Hiroshi
Published: December 2004

Kinetics of cycloaddition of tropone to 6‐methylfulvene and 6,6‐dimethylfulvene were determined. It was concluded that steric effects play a role in [6+4] cycloadditions.
Steric Effect in [6+4] Cycloadditions. Part II
Authors: Pfaendler H. R. , Tanida Hiroshi
Published: December 2004

2‐Chlorotropone reacts with 6,6‐dimethylfulvene to form a 1:1 adduct only. From kinetic data as well as from structural evidence the conclusion was drawn that the [6+4] cycloidditions between tropones and cyclopentadiene or fulvenes are highly disfavoured by substituents at the reaction center.
Die Struktur von Ovalicin
Authors: Bollinger Pietro , Sigg Hans‐Peter , Weber Hans‐Peter
Published: December 2004

The structure of ovalicine, a metabolite of the fungus Pseudeurotium ovalis with immunosuppressive activity, has been determined to be 15.
Die Phloroglucide von Dryopteris caucasica (A. Br.) Fraser‐Jenkins et Corley
Authors: Widén C.‐J. , Fraser‐Jenkins C. R. , Lounasmaa M. , v. Euw J. , Reichstein T.
Published: December 2004

Rhizomes of the recently rediscovered diploid fern Dryopteris caucasica were shown to contain the following phloroglucides: much filixic acid and para‐aspidin, appreciable amounts of desaspidin and traces of flavaspidic acid, trisdesaspidin and aspidinol (artefact), i.e. exactly the same compounds as recently found in D. villarii ssp. villarii. These results are compatible with the hypothesis that either D. caucasica or a member of the D. villarii complex is the second, still unknown, ancestor of the allotetraploid D. filix‐mas (L.) Schott. They also demonstrate the limitations of the chemical method which is quicker but less informative than the classical hybridisation procedures.
Über eine neue Methode zur quantitativen Bestimmung, Reinheitsprüfung und Stabilitätsmessung von Calcium‐Leucovorin
Authors: Suter Hans , Conti Josef , Litmanowitsch Menasche , Grossmann Albert , Hedinger Alfred
Published: December 2004

Die Kombination der dünnschichtchromatographischen Auftrennung mit einer spektrophotometrischen Auswertung ergibt eine spezifische quantitative Methode zur Bestimmung von Ca‐Leucovorin. Diese Methode ergibt präzise Resultate auch bei Anwesenheit von weiteren Folinaten. Ein speziell gereinigtes Ca‐Leucovorin wird als neuer hochaktiver Standard vorgeschlagen.
Die Addition von Nucleophilen an Alkinderivate mit Push‐pull‐Gruppen
Authors: Niederhauser Andreas , Frey Alfred , Neuenschwander Markus
Published: December 2004

The preparative aspects of the addition of nucleophiles to alkyne‐derivatives having both push‐ and pull‐groups (1) are discussed: The addition of primary and secondary amines as well of aliphatic alcohols to the alkyne‐derivatives 1 in most cases predominantly yields the Michael‐adducts 2–10. The importance of a side‐reaction consisting in an addition of amines to C(2) of the alkyne‐derivatives 1 increases in the series 1c ≪ 1b < 1a and is controlled by stereoelectronic effects. The spectroscopic properties of the compounds 2–10 are given.
Desoxaphomin, das erste [13]Cytochalasan, ein möglicher biogenetischer Vorläufer der 24‐Oxa‐[14]cytochalasane
Authors: Binder Michael , Tamm Christoph
Published: December 2004

From cultures of a Phoma species (strain S 298) the hitherto unknown metabolite deoxaphomine has been isolated. On the basis of the spectral data, structure 1 of the (7S, 16R, 20R)‐7,20‐dihydroxy‐16‐methyl‐10‐phenyl‐[13]cytochalasa‐6(12),13t,21t‐triene‐1,23‐dione is assigned to deoxaphomine. This structure is confirmed by the chemical degradation of 1, yielding the products 4 and 6 which are identical with derivatives of phomine (2)((7S,16R,20R)‐7,20‐dihydroxy‐16‐methyl‐10‐phenyl‐24‐oxa‐[14]cytochalasa‐6(12), 13t,21t‐triene‐1,23‐dione) and cytohalasin D (8) ((7S,16S,18R,21R)‐21‐acetoxy‐7,18‐dihydroxy‐16,18‐dimethyl‐10‐phenyl‐[11]sytochalasa‐6(12),13t,19t‐triene‐1,17‐dione). Deoxaphomine (1) is a potential biogenetic precursor of the 24‐oxa‐[14]cytochalasans. Preliminary results of the biological activity of deoxaphomine are reported.
Die Cyclopropylcarbinyl‐Cyclobutyl‐Homoallyl‐Umlagerung II. Teil. Produkte und Geschwindigkeit der Umlagerung von Tricyclo[3.2.1.02,7]octan‐3‐ol‐, endo‐ und exo‐Tricyclo‐[3.2.1.03,6]octan‐4‐ol und exo‐Bicyclo[3.2.1.]oct‐2‐en‐7‐ol‐Derivaten
Authors: Geisel Manfred , Grob Cyril A. , Santi Werner , Tschudi Werner
Published: December 2004

Solvolyses of the 2,4‐dinitrobenzoates of the cyclopropylcarbinol 1a, the cyclo‐butanol 2a and the homoallylic alcohol 3a in buffered 70% aqueous dioxane lead to the same product mixture consisting of 78% cyclopropylcarbinol 1a and 22% homoallylic alcohol 3a. Approximately the same product mixture is optained when the homoallylic chloride 3b and the cyclopropylcarbinyl p‐nitrobenzoate 1c are solvolyzed. A common cationic intermediate is indicated in these kinetically controlled rearrangement reactions. Under conditions of thermodynamic control only homoallylic products are formed.

The 2,4‐dinitrobenzoates 1d and 2d react 7.2 × 103 and 7.7 times, respectively, as fast as the homoallylic isomer 3d. Since the homoallylic chloride 3b reacts ca. 105 times as fast as its saturated analogue, 7‐exo‐bicyclo[3.2.1]octyl chloride 4, all three esters react with the enhanced rates which are characteristic of these structural types.

The endo‐cyclobutyl dinitrobenzoate 2d reacts more than 60 times as fast as its exo‐isomer 6d. The rate difference is ascribed to a stereoelectronically more favorable orientation of the participating σ bonds in the puckered cyclobutane ring in the endo isomer 2d.
Selektive Reduktion von β‐Jonon und Dehydro‐β‐jonon mit Triphenylzinnhydrid
Authors: Wolf Hans Richard , Zink Markus Peter
Published: December 2004

The application of triphenyltinhydride and of triphenyltindeuteride in specific reduction of β‐jonone and dehydro‐β‐jonone has been investigated and the preparation of pure dihydro‐β‐jonone,dihydro‐β‐jonone‐d1, dihydro‐β‐jonone‐d2, and dihydro‐dehydro‐β‐jonone described.
Über Tris(siloxymethyl)‐, Tris(silylmercaptomethyl)‐ und Tris(silylmethyl)amine
Authors: Fink Walter
Published: December 2004

By the reaction of alkali salts of triorgano‐silanols, ‐silanethiols and trimethylsilylmethanol as well as of triorganosilyllithium compounds with tris(chloromethyl)amine, silyl derivatives of tris(hydroxymethyl)‐, tris(mercaptomethyl)‐ and tris(methyl)amine were prepared.
Absolute Konfiguration von Picrocrocin
Authors: Buchecker Richard , Eugster Conrad Hans
Published: December 2004

By correlation with (−)‐3‐methoxy‐β‐jonone picrocrocin has been shown to have R‐configuration.
Absolute Konfiguration von α‐Zeacarotin, α‐Apo‐8‐carotinal und α‐Apo‐8‐carotinol
Authors: Buchecker Richard , Eugster Conrad Hans
Published: December 2004

α‐Zeacarotene, isolated from corn gluten, has been shown to have the same absolute configuration at C(6) as natural (+)‐α‐carotene. Chiroptical comparison was made with the derived α‐apo‐8‐carotenole. The same chirality has been found with δ‐, ε‐carotene, lutein, semi‐α‐carotenone, zeinoxanthin, crocoxanthin and β,ε‐carotene‐2‐ol. Therefore, biological cyclisation of the acyclic precursor to the α‐ionone ring seems to be stereospecific and is probably different (enantiomeric) to that leading to β‐ionone derivatives.

Cotton effects of carotenoids have for the first time been measured in the visible region. All carotenoids examined with C(6)‐R‐chirality show a positive effect at their longest absorption band.
Massenspektren neuer Phloroglucide, insbesondere solcher mit Valerylseitenketten
Authors: Lounasmaa M. , Widén C.‐J. , Reichstein T.
Published: December 2004

Mass spectra of phloroglucinol derivatives recently isolated from African Dryopteris species are presented. Phloroglucides with n‐valeryl side chain were found in these ferns for the first time. In the mass spectra they show strong peaks corresponding to loss of propene (C3H6) produced by McLafferty rearrangement, as shown in model compounds. Aside of the rottleron change (discussed formerly) this must be considered in order to avoid wrong interpretation, particularly when mass spectra are used to analyse mixtures of homologues, as usually present in the plants. If valeryl side chains are present other methods must be used therefore to measure the amount or show the absence of lower homologues with acetyl side chains.
L'indice de rétention des alcanes isomères en chromatographie en phase gazeuse
Authors: Rappoport Serge , Gäumann Tino
Published: December 2004

A method, using the radiolysis of an alkane, for the obtention of a great number of branched hydrocarbons is given. The retention index at 100° as well as its variation with temperature is determined on Apiezon L for 200 alcanes containing between seven and twenty four carbons. It is shown that for branched hydrocarbons the decrease of the retention index is mainly due to the length of the substituent group but also to its position on the chain. Some rules between retention index and molecular structure are deduced that allow the determination of the index of higher branched hydrocarbons. It is also shown that the variation of the retention index with temperature is only a function of the length of the substituent group.
Substoichiometric Extraction of Mercury by Diethyldithiocarbamic Acid
Authors: Wyttenbach A. , Bajo S.
Published: December 2004

The substoichiometric extraction of Hg2+ using diethyldithiocarbamic acid and 203Hg tracer was studied. Chloroform was employed to remove the complexes from the aqueous media which were 0.5M H2SO4 or 1 M HClO4 and 0 to 5 M NaCL. ‐ Systems containing Cl− allowed extraction of Hg2+ for all DDC/Hg molar ratios, the extracted complexes being HgCl(DDC) and Hg(DDC)2. Their exchange constant was determined. ‐ In the absence of Cl−, no extraction could be effected in either system if the DDC/Hg molar ratio was < 1; the H2SO4 system remained clear, whereas a precipitate of HgClO4(DDC) formed in the HClO4 system. For molar ratios > 1, the extraction of Hg2+ increased linearly with the addition of DDC, the extracted complex being Hg(DDC)2.
Aspects of Formation of the D‐Penicillamine‐Antigenic Determinant from Penicilloyl Compounds
Authors: Schneider Conrad H. , Pfeuti Christiane , de Weck Alain L.
Published: December 2004

The formation of D‐penicillamine‐L‐cysteine mixed disulfide from benzylpenicilloic acid, benzylpenilloic acid and benzylpenicilloyl amide derivatives in L‐cysteine suspensions at pH 7,6 and 37° was studied. The reaction is faster than direct penicilloylation of proteins known to be a route to penicilloyl antigenic determinants. The production of S‐bound penicillamine on protein from penicilloyl compounds must therefore definitely be considered as a potential antigenforming step. The reaction may be partly if not fully blocked by acylation of the thiazolidine nitrogen of penicilloyl compounds. When formylation is applied a considerable reduction of the capacity of penicilloyl antigenic determinants to interact with anti‐penicilloyl antibody is noted. A D‐penicillamine‐specific test antigen was prepared by binding D‐penicillamine via thioether links to a partly succinylated poly‐L‐lysine. Clinical test reactions elicited with this conjugate and with penicilloic acid cannot be well correlated. Penicilloic acid probably detects reactions of undefined specificity in addition to D‐penicillamine‐specific ones.
Die Umlagerung substituierter Aminoacrylderivate. Präparative anwendungsbreite
Authors: Niederhauser Andreas , Neuenschwander Markus
Published: December 2004

The addition of carboxylic acids to dimethylamino‐propinal (1a) and 4‐dimethyl‐amino‐but‐3‐in‐2‐on (1b) gives, after rearrangement of the very instable primary adducts (2), Z‐3‐acetoxy‐N,N‐dimethylacrylamides and ‐crotonamides 3 to 8 in excellent yields and in a stereospecific manner. Similarly, the adducts of HCl and HBr to the alkynes 1a and 1b may be rearranged at low temperature by traces of acid to cis/trans equilibria of 3‐halo‐acrylamides and ‐crotonamides 9 and 10. ‐ On the other hand, treatment of 3‐alkoxy‐3‐dimethylaminoacrolein with traces of acid yields alkylesters of E‐3‐dimethylaminoacrylic acid (12, X = OR). ‐ The preparative aspects of the rearrangement are discussed, and a brief outline of the spectroscopic properties of the compounds 3 to 8 is given.
Die Chlorierung des Hexamethyl‐Dewar‐Benzols
Authors: Burger Ulrich , Delay Arlette
Published: December 2004

It has been shown that addition of chlorine to hexamethyl‐Dewar‐benzene is a stereospecific process and yields exclusively 5‐endo‐chloro‐hexamethyl‐bicyclo[2.1.1]hexenyl chloride. This supports the suitability of SbCl5 as a model reagent for olefin chlorination.
Crystal Structure Analysis of a trans, trans‐Cyclodeca‐1, 6‐diene Derivative
Authors: White David N. J.
Published: December 2004

An X‐ray crystal structure analysis of the higher melting diastereoisomer of 2,7‐dibromo‐3,8‐dimethoxy‐trans,trans‐cyclodeca‐1,6‐diene (Monoclinic; a = 5.76, b = 10.43, c = 11.32 Å, β = 94.04°; space group P21/n; Z = 2) has confirmed the NMR. assignment of the molecular conformation and the trans configuration of the methoxy groups. The trans,trans‐cyclodeca‐1,6‐diene ring adopts a centrosymmetric crown conformation with a CCCC torsion angle of 162°.