bluuebunny/crossref_metadata_2025_split huggingface dataset:
Katalytische Effekte bei der Reaktion von 2,4‐Dinitrofluorbenzol mit Morpholin in Benzol. 7. Mitteilung über nucleophile aromatische Substitutionsreaktionen
Authors: Becker G. , Bernasconi C. F. , Zollinger Hch. 
Published: December 2004

Abstract
The rates of reaction of 2, 4‐dinitrofluorobenzene with morpholine have been measured in benzene solution, with and without the addition of pyridine or 1, 4‐diaza‐bicyclo[2.2.2]octane (DABCO) as catalysts.
The reaction is catalyzed by morpholine, pyridine and DABCO; the rate laws as functions of these bases are expressed by equations (2)–(4).
The reaction is considerably more sensitive to pyridine and DABCO catalysis than that of 2, 4‐dinitrofluorobenzene with the sterically identical, but more basic piperidine. These findings confirm a previously found trend of greater sensitivity to base catalysis with decreasing base strength of the reacting amine.
Über eine aussergewöhnliche Stereospezifität bei der Hydroborierung der diastereomeren (1R)‐Isopulegole mit Diboran
Authors: Schulte‐Elte K. H. , Ohloff G. 
Published: December 2004

AbstractDie Umsetzung der stereoisomeren Isopulegole 1–4 mit Diboran erfolgt unter hoher Stereospezifität. Aus der nachfolgenden oxydativen Aufarbeitung resultieren die Gemische der 9‐Hydroxymenthole, in denen eines der Diastereomeren stark überwiegt. Die Konstitution von 7 Diolen (5–11) wurde ermittelt und zum Teil unabhängige Wege zu ihrer Synthese entwickelt.
Sur l'acylation des métylfuorènes I. Benzoylation et acétylation du méthyl‐1‐fluorène
Authors: Chardonnens Louis , Dousse Roland 
Published: December 2004

AbstractBenzoylation and acetylation of 1‐methylfluorene according Friedel‐Crafts in carbon disulfide with aluminium chloride yielded the corresponding 2‐acyl derivatives. By oxydation the benzoyl derivative gave 2‐benzoyl‐9‐oxo‐fluorene‐1‐carboxylic acid, cyclizable into 1,2‐phthalyl‐fluorenone.
Schmelzreaktionen mit Aluminiumchlorid 3. Mitteilung [1] Zur Kenntnis der Pyridinio‐anthrachinon‐Derivate aus der Pyridin‐Aluminiumchloridschmelze von Aminoanthrachinonen
Authors: Wick A. K. 
Published: December 2004

AbstractIn continuation of previous work, the behaviour of amino‐anthraquinones on fusion in pyridine ‐ aluminium chloride in the presence of oxidants is studied. Instead of dimerisation the reaction leads to salts of pyridinio‐aminoanthraquinones and further to condensed “anthraimidazopyridine” derivatives.
Die Cardenolide und Pregnan‐Glykoside der Wurzeln von Asclepias lilacina WEIMARCK. I. Isolierungen Glykoside und Aglykone, 290. Mitteilung
Authors: Sawlewicz Ludwika , Weiss Ek. , Reichstein T. 
Published: December 2004

AbstractThe dried roots of Asclepias lilacina contain ca. 14% glykosides, in which both cardenolides and ester glycosides of pregnane derivatives are present, the latter predominating. Uzarigenin, coroglaucigenin, and their corresponding glycosides ascleposide and frugoside, resp., were shown to be present; of these four, uzarigenin was isolated in crystalline form. The ester glycosides, some of which could be isolated in a crystalline state, are predominantly composed of the aglycones 20‐O‐acetyl‐12‐O‐benzoyl‐sarcostin and 12,20‐di‐O‐benzoyl‐sarcostin, besides which esters of desacetyl‐metaplexigenin, lineolon, and dihydrosarcostin are also present. These aglycones are mostly attached to various trisaccharides which are composed of at least two 2‐deoxy‐sugar residues. Mild acid hydrolysis gave, besides the genins, 7 sugars, namely cymarose, oleandrose, digitoxose, 3‐O‐methyl‐6‐deoxy‐D‐allose (U3), as well as 3 unknown sugars U1, U2 and U5 which are probably disaccharides. U1 and U2 were isolated in crystalline form; they are isomeric and have been named asclepobiose and lilacinobiose; they are probably composed of units similar to those in the isomeric pachybiose.
Notiz über die Isolierung quartärer Alkaloide aus Pleiocarpa tubicina STAPF
Authors: Khan Zaheer M. , Hesse M. , Schmid H. 
Published: December 2004

AbstractThe following quaternary indole alkaloids have been isolated from the root bark of the Apocynaceae species Pleiocarpa tubicina Stapf: huntrabrine methochloride, kopsinic acid methochloride, N(a)‐methyl‐sarpagine methochloride and macusine B chloride.
Die Massenspektren von Vitamin B1 und von einigen Modellverbindungen 6. Mitteilung über das massenspektrometrische verhalten quartärer Stickstoffverbindungen
Authors: Hesse M. , Bild N. , Schmid H. 
Published: December 2004

AbstractVitamin B1, in chloride (1) or iodide form, decomposes thermally in the mass spectrometer mainly into 2‐methyl‐4‐amino‐5‐chloromethyl(iodomethyl)‐pyrimidine and 4‐methyl‐5‐β‐hydroxyethyl‐thiazole, and partly, by loss of HCl (HI) under cyclisation, into the base 2. The mass spectrum exhibits peaks due to these products and their fragments. The mass spectra of some model compounds are discussed.
Magnetische Kernresonanz‐Untersuchungen über die struktur der Komplexe aus Nitroaromaten mit azid‐ionen 9. Mitteilung über nucleophile aromatische Subsitutionsreaktionen [1]
Authors: Caveng P. , Zollinger H. 
Published: December 2004

Abstract1. NMR. spectra of solutions of tetraethylammonium azide and 2,4,6‐trinitro;benzene derivatives (methyl picrate, picryl chloride and picryl azide, respectively) demonstrate that the reactants probably form σ complexes.
Recherches dans la série des cyclitols XXXV sur des complexes molybdiques, tungstiques et boriques de cyclitols
Authors: Posternak T. H. , Janjic D. , Lucken E. A. C. , Szente A. 
Published: December 2004

AbstractOn a isolé sous forme de son sel di‐ammonique cristallisé, un complexe épi‐inositol dimolybdique, qui a été transformé en son sel disodique C6H8O11Mo2Na2. On a préparé de même le sel disodique C6H8O11W2Na2 d'un complexe épi‐inositol ditungstique. Les poids moléculaires ont été confirmés par cryoscopie dans le sel de Glauber. Ces complexes présentent une forte mobilité électrophorétique. Il en est de même d'autres cyclitols susceptibles de contenir un groupement de 4 OH cis de conformation 1a, 2e, 3a, 5a, qui se condenserait avec les acides dimolybdique et ditungstique. Cette structure a été confirmée par le spectre de RMN. du complexe épi‐inositol dimolybdique.
Anionische Polymerisationen von 1, 3‐Cyclohexadien
Authors: Lüssi H. , Barman J. 
Published: December 2004

AbstractThe molecular weights obtained in the anionic polymerization of 1.3‐cyclohexadiene are exclusively determined by chain transfer with monomer. No dissociation of the ion pairs on the active chain ends seems to occur. Arrhenius plots of the intrinsic viscosities against polymerization temperature yield straight lines going through a common isocinetic point. The activation energy differences of propagation and transfer could be estimated. The extent of chain transfer depends on the solvent and counter‐ion present. The disproportionation of cyclohexadiene to benzene and cyclohexene, sometimes observed instead of the polymerization, is shown to occur if the transfer constant approaches the magnitude of unity.
Über Pyrrolizidinchemie. 8. Mitteilung [1]. Synthese von 1, 7‐Dioxopyrrolizidin
Authors: Viscontini M. , Bühler H. 
Published: December 2004

AbstractDas als Zwischenprodukt der 1,7‐Dioxopyrrolizidin(I)‐Synthese dienende, sehr unbeständige 3‐Oxopyrrolidin (IV) wurde durch Ketalisierung stabilisiert. Mit Hilfe dieser Methode sind Jetzt N‐substituierte 3‐Oxopyrrolidine relativ leicht zugänglich. Die Synthese des 1,7‐Dioxopyrrolizidins (I) als Natriumenolat IX mit 3‐[3‐Oxopyrrolidinyl‐(1)]‐propionsäure‐methylester (VIII) als Edukt wird beschrieben. Das 1, 7‐Dioxopyrrolizidin (I) selbst konnte nicht isoliert werden; es scheint ebenso unbeständig zu sein wie das 3‐Oxopyrrolidin (IV).
Über die Aldolase aus Drosophila melanogaster. 12. Mitteilung über Aldolasen
Authors: Brenner‐Holzach O. , Leuthardt F. 
Published: December 2004

AbstractFructose 1,6‐diphosphate aldolase has been extracted from Drosophila m. and has been purified about 65‐fold. After precipitation with ammonium sulfate, purification on DEAE Sephadex A 50 and Sephadex G 200, we have obtained activities as high as 1350 BÜCHER units/mg protein (12,3 international units). As Drosophila aldolase is not dependent on metal ions (not influenced by EDTA) and has a broad pH optimum, it belongs to class I aldolases according to RUTTER'S classification. The KM values for both substrates FDP and F‐1‐P closely resemble those of the rabbit muscle enzyme [A], but the FDP/F‐1‐P activity ratio at substrate saturation is only 10 to 15, i.e. considerably lower than that of rabbit muscle aldolase.
Über 9β, 10α‐Steroide. 3. Mitteilung [1]. Überführung von 11‐Keto‐9β, 10α‐steroiden in 10α‐Verbindungen Synthese von 10α‐Cortison, 11‐Oxo‐10α‐progesteron, 10α‐Adrenosteron und analogen 11‐Hydroxy‐Verbindungen
Authors: Saucy G. , Müller M. , Fürst A. 
Published: December 2004

AbstractIsomerisation of 11‐keto‐9β, 10α(retro)‐steroids by acid or base led to the thermo‐dynamically more stable 11‐keto‐10α‐isomers, which have not yet been described in the literature. This epimerisation at C‐9 constitutes a new route for the synthesis of 10α‐steroids. The steric factors responsible for this isomerisation are discussed.
Über einige Umwandlungsprodukte des «BLIX‐Sulfatids» und die Herstellung von quartären Dihydro‐sphingosinium‐Salzen
Authors: Kiss J. 
Published: December 2004

AbstractIn the sulfatide fraction of beef spinal‐cord, isolated according to the method of BLIX [9] and LEES [14], there are also sulfatides present derived from 2S, 3R‐1, 3‐dihydroxy‐2‐amino‐octadecane.
Synthese von 5‐Methyl‐3‐oxa‐A‐nor‐5β‐cholestan und 3‐Oxa‐Δ4‐cholesten‐2‐on
Authors: Heskendorn R. , Tamm Ch. 
Published: December 2004

Abstract2, 3‐seco‐Δ4‐Cholestene‐2, 3‐dicarboxylic acid (5) was prepared in 30% yield from 2‐hydroxymethylene‐Δ4‐cholestene‐3‐one (1) by ozonolysis under special conditions. Pyrolysis of the pure di‐acid 5 gave A‐nor‐Δ3(5)‐cholestene‐2‐one (6), the anhydride 2 and 5‐methyl‐3‐oxa‐A‐nor‐5β‐cholestane‐2‐one (8). Pyrolysis of amorphous acidic material obtained by the ozonolysis of 1 yielded the enol‐lactones 7 and 9 as additional products. LiA1H4‐reduction of the γ‐lactone 8 gave the diol 10, which was transformed into 5‐methyl‐3‐oxa‐A‐nor‐5β‐cholestane (13) by treatment with tosyl chloride in pyridine.
Über das «pK» elektronisch angeregter Azulenium‐Kationen
Authors: Hagen R. , Heilbronner E. , Meier W. , Seiler P. 
Published: December 2004

AbstractIt is shown that azulenium cations in the first electronically excited state S1 are stronger acids than in the ground state S0. Their apparent pK″*, obtained from the H0‐dependence of the quenching of the azulenium cation S1 → S0 fluorescence does not correspond to a true acid‐base equilibrium in the electronically excited state S1. The pK″* values are kinetically controlled, the rate of reprotonation of azulene in the S1 state being too low to compete with the internal conversion to S0.
Die Strukturen der mittleren Ringverbidungen. XIII. Zwei neue Konformationen des Cyclodecanringes
Authors: Dunitz J. D. , Eser H. , Bixon M. , Lifson S. 
Published: December 2004

AbstractThe results of the X‐ray analysis of 1,1,5,5‐tetramethylcyclodecane‐8‐carboxylic acid do not correspond to a reasonable molecular structure. When used as a startingpoint for a strain‐energy minimization calculation based on semi‐empirical potential functions, they lead to two new conformations for the cyclodecane ring. It is shown that the X‐ray results can be explained by assuming that the crystal consists of a random mixture of these two conformations.
ESR.‐Spektren der Radikal‐Ionen alkylsubstituierter nicht‐alternierender Kohlenwasserstoffe
Authors: Gerson F. , Heinzer J. 
Published: December 2004

AbstractESR.‐spectra of the radical‐anions and the radical‐cations derived from two alkyl‐substituted, non‐alternant hydrocarbons, acepleiadiene (APH2) and 3,5,8,10‐tetramethyl‐cyclopenta[ef]heptalene (TMCP) have been recorded and analysed. The large differences in the total widths of the spectra of the corresponding ions (APH2⊖: 32; APH2⊕: 57; TMCP⊖: 69 and TMCP⊕: 36 Gauss) are well accounted for by the simple HMO model. The excellent agreement between the experimental and the theoretical values allows one to make a reliable assignment of the coupling constants to sets containing equal numbers of equivalent protons.
Über die Konstitution des Macralstonidins. 124. Mitteilung über Alkaloide
Authors: Waldner E. E. , Hesse M. , Taylor W. I. , Schmid H. 
Published: December 2004

AbstractThe alkaloid macralstonidine, which was originally isolated from Alstonia macrophylla WALL. by T. M. SHARP in 1934, has the molecular formula C41H48O3N4. The hydrolysis of this dimeric alkaloid yielded the macroline derivative 5, N(a)‐methyl‐sarpagine (6) and formaldehyde. Partial acid cleavage under deuterating conditions gave 5‐d9, 6‐d3 and decadeuterated macralstonidine. On the basis of spectral data, particularly an analysis of the mass spectra of macralstonidine and its decadeutero derivative, structure 2 has been elucidated for this alkaloid.
Synthese der 2,5‐Diole des A‐nor‐5α‐Cholestans und A‐nor‐5β‐Cholestans
Authors: Heckendorn R. , Tamm Ch. 
Published: December 2004

AbstractTreatment of A‐nor‐Δ3(5)‐cholestene‐2‐one (1) with alkaline hydrogen peroxide gave 3β,5‐epoxy‐A‐nor‐cholestane‐2‐one (2) and the epoxylactone 3 (BAEYER‐VILLIGER reaction). LiAlH4‐reduction of 2 yielded A‐nor‐5β‐cholestane‐2β,5‐diol(4) (main product) and A‐nor‐5β‐cholestane‐2α,5‐diol (5). LiAlH4‐reduction of 1 led mainly to A‐nor‐Δ3(5)‐cholestene‐2α‐ol (8). Catalytic hydrogenation of 8 gave the known A‐nor‐5α‐cholestane‐2α‐01 (10), A‐nor‐5β‐cholestane‐2α‐01 (11) (main product), A‐nor‐5β‐cholestane (9) and A‐nor‐5β‐cholestane‐2‐one (12). By LiAlH4‐reduction of the ketones 12 and 13 the two additional alcohols 14 and 15 were obtained.
Opposid, vermutliche Struktur. Glykoside und Aglykone, 302. Mitt.
Authors: Hausschild‐rogat P. , Weiss E. K. , Reichstein T. 
Published: December 2004

AbstractThe hypothetical structure 1 is proposed for opposide (C29H44O11), a new glycoside from the seeds of Acokanthera oppositifolia (LAM.) CODD. Opposide is derived from the new aglycone gratogenin, which is most probably the 1β, 3β, 5β, 11α, 14β‐pentahydroxy‐card‐20:22‐enolide (8) (C23H34O7) and which is bound glycosidically through position 3 to the α‐pyranosidic form of 6‐desoxy‐L‐talose. The hydrolysis of opposide by HCl in acetone gave an anhydrogenin (C23H32O6) instead of the intact aglycone. In analogy to the reaction sequence observed by VOLPP and TAMM for ouabagenin, the structure of the anhydrogenin is deduced to be that of a 3β, 5β, 14β‐trihydroxy‐1α, 11α‐epoxy‐card‐20:22‐enolide (6). The above mentioned structures are based on the course of acetylation and especially on NMR.‐spectra.
Rac. cis‐ und trans‐ 1, 2‐Dimethyl‐4‐hydroxy‐6, 7‐dimethoxy‐1, 2, 3, 4‐tetrahydro‐isochinolin, Synthese und Stereochemie
Authors: Grethe G. , Uskokovice M. , Williams T. , Brossi A. 
Published: December 2004

AbstractThe synthesis of rac. cis‐ and trans‐1,2‐dimethyl‐4‐hydroxy‐6,7‐dimethoxy‐1,2,3,4‐tetrahydro‐isoquinoline (respectively 8 and 9) is described. The relative configuration of these amino alcohols was determined by a detailed analysis of nmr.‐ and ir.‐spectra. The comparison of the nmr.‐spectra of 8 and 9 with that of gigantine reveals the non identity of these compounds.
Neues über 1,3‐Cycloadditionen
Authors: Huisgen Rolf 
Published: December 2004

AbstractEm Wort aufrichtigen Dankes gilt tüchtigen und begeisterten jungen Wissenschaftlern, die an den skizzierten Arbeiten mitwirkten. Mit der Chemie der Nitril‐ylide befassten sich die Herren Dr. H. STANGL, Dr. H. J. STURM, Dr. R. RAAB, Dip1.‐Chem. K.BUNGE und Dr. R. SUSTMANN, Die Ringöffnungen der Aziridine wurden untersucht von Dip1.‐Chem. W. SCHEER, Dr. G. SZEIMIES, Dr. L. SZABÓ und Herrn H. HUBER.
Schmelzreaktionen mit Aluminiumchlorid 4. Mitteilung [1]. Thermische Analyse des Systems Pyridin‐Aluminiumchlorid
Authors: Wick A. K. 
Published: December 2004

AbstractThe phase diagram of the technical important fusion system pyridine‐aluminiumchloride was determined by classical thermo‐analysis, proving the existance of a hitherto unknown pyridine‐aluminium chloride 2:1 complex.
Die Kinetik der Murexid‐Komplexbildung mit Kationen verschiedenen Koordinationscharakters
Authors: Geier G. 
Published: December 2004

AbstractThe kinetics of the reaction of murexide with different divalent metal ions of class A and B have been measured by the temperature‐jump‐relaxation method. The second‐order formation rate constant increases in the sequence Ni2+ < Co2+ < Mn2+ < Zn2+ < Cd2+ ˜ Cu2+ ˜ Ca2+ < Sr2+ < Ba2+ < Pb2+.Thermodynamic data obtained from kinetic and equilibrium studies, respectively, are in good agreement. The results are compared with the characteristic rate constants for H2O‐exchange in the inner coordination sphere of these metal ions, which follow the same sequence. The rate constants of the reaction of murexide with various trivalent metal ions, including the lanthanides, are also discussed in terms of current ideas on metal complex formation.
Etudes sur les composés organométalliques IV [1] Stabilité et nature des liaisons de quelques complexes organostanniques
Authors: Affolter Jean , Jacot‐Guillarmod André , Bernauer Klaus 
Published: December 2004

AbstractThe complexes between different diorganotin cations and substituted 1, 10‐phenanthrolines in aqueous solution containing acetate ion have been investigated. Diorganotin cations can co‐ordinate two acetate ions. One of these may be replaced by a 1, 10‐phenanthroline derivative. A comparison of the different equilibrium constants shows that the acid hardness of diorganotin cations is markedly modified if the organic groups bound to the tin are α,β‐unsaturated.
Über ein‐ und zweiphasige Reduktion von γ‐MnO2 durch Zimtalkohol
Authors: Giovanoli R. , Bernhard K. , Feitknecht W. 
Published: December 2004

AbstractThe reduction of γ‐MnO2 with cinnamic alcohol in xylene at 90° leads (1) to γ‐MnOOH in a double phase reaction with germination if the α‐MnO2 is extremely disperse, and (2) to α‐MnOOH in a strictly topotactical (single phase) reaction without germination if the γ‐MnO2 is relatively well crystallised. The hexagonality of the densest packed oxygens is not a linear function of the reduction rate but shows a discontinuity when about half of the Mn4+ are reduced, which is consistent with results of GABANO. The αMnOOH obtained by this reaction shows still the selective and asymmetric X‐ ray and electron reflection broadening of the reactant. Hence, the authors consider the product to possess an intergrowth structure of a Groutite matrix with statistically and layerwise distributed Manganite microdomains, according to a model proposed by DE WOLFF for α‐MnO2. The domains are supposed to have the size of one cell only in the b direction, and of a few cells in the a direction, and to be present in relatively small concentration.
Das biologische Verhalten von Fettsäuren mit Dreifachbindung: III. Der Abbau der Taririnsäure
Authors: Bernhard Karl , Yekundi Kushal , Kaempf Ekkehard 
Published: December 2004

AbstractOctadec‐6‐ynoic acid (tariric acid) fed to rats as triglyceride is incorporated both into depot fat and liver lipids. As a metabolite the so far undesdribed dec‐4‐ene‐6‐ynedioic acid, HOOC(CH2)2CHCHCGC(CH2)2COOH, was isolated from the urine.
Réactions du diazométhane III. Etude de la réaction d'insertion entre diazométhane et phénylcarbamates: comportement de la N‐(phénoxy‐carbonyl)‐aniline et de la N‐(p‐nitrophénoxy‐carbonyl)‐aniline
Authors: Baudet P. , Calin M. 
Published: December 2004

AbstractDiazomethane reacts with N‐(p‐nitrophenoxy‐carbonyl)‐aniline giving on the one hand p‐nitroanisole and phenylisocyanate, the latter being transformed into N‐phenyl‐β‐propiolactam, and on the other hand N‐(p‐nitrophenoxy)‐acetanilide by insertion. N‐(phenoxy‐carbonyl)‐aniline does not react. The insertion reaction seems to depend on the heterolysis of the bond between the oxygen of the p‐nitrophenoxy group and the carbamic carbonyl function, which is strongly polarized (existence of a mesomeric nitro‐phenoxonium). The insertion is equally influenced y the nature of the radical R attached to the carbamic nitrogen: with R = CH2COOC2H5 the reaction yields only isocyanate, with R = C6H5 it yields at the same time the isocyanate and the insertion product.
Über siliciumaromatische Verbindungen II. 5‐ Trimethylsilyl‐isophtalsäure und Trimethylsilyl‐terephthalsäure
Authors: Hopff H. , Gallegra P. 
Published: December 2004

Abstract5‐Trimethylsilyl‐isophthalic acid (III) and trimethylsilyl‐terephthalic acid (II) have been prepared and converted into some derivatives.
Oxetane von A‐nor‐Steroiden: 2α, 5‐Oxido‐A‐nor‐5α‐cholestan, 2β, 5‐Oxido‐A‐nor‐5β‐cholestan und 2α‐Äthyl‐2β, 2′‐oxido‐A‐nor‐5α‐cholestan
Authors: Heckendorn R. , Tamm Ch. 
Published: December 2004

AbstractTreatment of 2β‐tosyloxy‐A‐nor‐5α‐cholestane‐5‐ol (2) with t‐butoxide in t‐butanol gave 2α, 5‐epoxy‐A‐nor‐5α‐cholestane (3) in quantitative yield.When A‐nor‐5β‐cholestane‐2α, 5‐diol (4) was treated with tosyl chloride in pyridine 2β‐chloro‐A‐nor‐5β‐cholestane‐5‐ol (7) and 2α‐tosyloxy‐A‐nor‐5β‐cholestane‐5‐ol (8) were obtained. Whereas the chloride 7 was resistant to t‐butoxide the tosylate 8 was transformed into an 1 : 1 mixture of 2α, 5‐epoxy‐5β‐cholestane (10) and 2ξ‐t‐butoxy‐A‐nor‐5β‐cholestane‐5‐ol (11). In 2α‐tosyloxy‐A‐nor‐5α‐cholestane‐5‐ol (12) substitution occurred as the only reaction.Both oxetanes 3 and 10 isomerize after heating above 50° and in polar or protic solvents to form A‐nor‐Δ3(5)‐cholestene‐2α‐ol (6) and ‐2β‐ol (14) respectively. Also, 2, 5‐diols are encountered.2α‐Ethyl‐2β, 2′‐epoxy‐A‐nor‐5α‐cholestane (23) was synthesized starting from A‐nor‐5α‐cholestane‐2‐one (17). The intermediates were the ester 16, the diol 18, the hydroxy‐tosylate 19 and the chlorhydrin 20. The spirocyclic oxetane 23 was reduced by LiAlH4 in dioxane (not in ether). By chromatography on silica gel 23 was isomerized to the homoallylic alcohol 21 and transformed into 2‐methylene‐A‐nor‐5α‐cholestane (24) by fragmentation.The IR. and NMR. spectra of the new oxetanes were compared with those of a series of known oxetanes.
Fluorénacènes et fluorénaphènes Synthèses dans la série des indéno‐fluorènes XI [1]. Trans‐Fluorénacène et dérivés méthylés
Authors: Chardonnens Louis , Salamin Luc 
Published: December 2004

AbstractOn décrit la préparation, à partir de la dibromo‐2, 5‐téréphtalophénone et de quelques‐uns de ses dérivés méthylés, par déshydrobromation accompagnée d'une double cyclisation, de la trans‐fluorénacène‐dione (dioxo‐6, 12‐dihydro‐6, 12‐indéno [1, 2‐b] fluorène) et de quelques dérivés méthylés. Ces dicétones polycycliques sont colorées en orangé, rouge ou violet, et cuvables. Leur réduction selon WOLFF‐KISHNER fournit les hydrocarbures correspondants.
Die Strukturen der mittleren Ringverbindungen. XVI. Cyclooctan‐cis‐1, 2‐dicarbonsäure
Authors: Bürgi H. B. , Dunitz J. D. 
Published: December 2004

AbstractCrystals of cyclooctane‐cis‐1, 2‐dicarboxylic acid are monoclinic, a = 10.37, b = 8.52, c = 11.95 Å, β = 103.65°, space group P21/c, with 4 molecules in the unit cell. The structure has been solved with the help of direct methods and refined by full‐matrix least‐squares analysis of three‐dimensional intensity data. The cyclooctane ring is found to occur in the same, approximately mirror‐symmetric (‘boat‐chair’), conformation as was previously found for the trans‐isomer.