bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Loss of CH3COCH2 Moieties from Methylketo Esters upon Electron Impact: A discussion of possible long‐range functional group interaction
Authors: Richter W. J. , Liehr J. G. 
Published: December 2004

AbstractMethyl 10‐oxoundecanoate and related long‐chain methylketo esters exhibit loss of the terminal CH3COCH2 moiety as one of the most prominent modes of fragmentation in analogy to comparable long‐chain diketones. In view of its absence in simple monoketonic analogues this process is thought to be induced by the distant ester function, e.g. via hydrogen abstraction from a suitable site (C(7)) within the alkyl portion of the molecule to be retained in the fragment. Rearrangement indicative of functional group interaction is thus concealed, and the attempt is made to unravel its incidence and true course by analysis of the further decomposition of the (M‐CH3COCH2) fragment via sequential losses of MeOH and CO, with the emphasis on establishing the origin of the OH hydrogen of the former of these two particles. Extensive deuterium labelling of most of the positions of the central chain, as well as analysis of pertinent high‐resolution data and metastable transitions, is employed in the pursuit of this objective.
Geijerone (3‐Isopropenyl‐4‐methyl‐4‐vinylcyclohexanone), a New, Naturally Occurring C12 Terpenoid
Authors: Thomas Alan F. 
Published: December 2004

AbstractIn the essential oil of Juniperus communis L. (fruit), the title compound (trans‐ isomer) has been identified; its structure being confirmed by synthesis from elemol. The optical rotation of the natural compound was nearly the same as the synthetic sample, suggesting that it is not an artefact formed from a ten‐membered ring precursor during the isolation.
Methylierungs‐Reaktionen an 30‐Oxa‐[14]cytochalasanen
Authors: Binder M. , Tamm Ch. 
Published: December 2004

AbstractFor synthetic studies the protection of the hydroxyl groups of phomin (cytochalasin B) ((7S,22R,26R)‐7,26‐dihydroxy‐22‐methyl‐30‐oxa‐[14]cytochalasa‐6(18), 19t 27t‐trien‐1,29‐dion) (1), the dodecahydro‐derivative 2, and the dihydro‐derivative 4 by methylation was investigated. Treatment of 1 with CH3I/Ag2O gave the iminoether 6. The reaction of 4 with CH2N2/BF3 led to the di‐O‐methyl derivative 8 and to the N‐methyl‐di‐O‐methyl derivative 9, whereas 2 was transformed to the N‐methyl‐di‐O‐methyl compound 10 and to the iminoether 11.NaBH4 reduction of 3 yielded not only 4 but also the epimeric dihydro derivative 5.
1H‐NMR‐Untersuchungen an Droso‐ und Isodrosopterin – ein Beitrag zur Strukturaufklärung. Pteridine, LV
Authors: Schlobach Heinrich , Pfleiderer Wolfgang 
Published: December 2004

AbstractThe NMR. spectra of droso‐ and isodrosopterin (1) in DMSO‐d6, 1% DCl/D2O solution, CF3CO2D, and conc. sulfuric acid are discussed in detail. Missing of methine and methyl groups and proof for the presence of three isolated methylene functions of which two show a geminal coupling are consistent with the proposed structure of atropisomeric di(7,8‐dihydropterinyl)‐ methane dye stuffs.
Weitere Bufadienolide aus Ch'an Su. Über Krötengifte, 39. Mitteilung
Authors: Höriger Niklaus , Živanov Dobrila , Linde Horst H. A. , Meyer Kuno 
Published: December 2004

AbstractFrom the toad venom Ch'an Su the bufadienolides 1, 4, 9, 10, 12, 15, 17, 20, 22, 25 and 18, the latter as diacetate 19 were isolated and their structure elucidated.
Steroide und Sexualhormone. 247. Mitteilung. Die Partialsynthese von Tetrahydrostapelogenin. Vorläufige Mitteilung
Authors: Schaffner B. P. , Wehrli H. 
Published: December 2004

AbstractA partial synthesis of tetrahydrostapelogenin (5), a hydrogenation product of stapelogenin (4), is described, proofing the structure of 4 proposed by Reichstein [2–3].
Eine Apparatur zur automatischen Bestimmung von Wasserdampf‐Sorptions‐Isothermen und ‐Isobaren
Authors: Bolliger W. , Gál S. , Signer R. 
Published: December 2004

AbstractAn apparatus for the automatic determination of water vapor sorption isotherm and isobares is described. Its main parts are a Cahn electrobalance and a gas circulating system. The gas can be held at constant dew points between – 85 and + 25 degree by an ultracryostal and an ultrathermostate and brings the sorbens to hygroscopic equilibrium.
Steroide und Sexualhormone. 246. Mitteilung [1]. Die Partialsynthese von Batrachotoxinin A
Authors: Imhof R. , Gössinger E. , Graf Walter , Berner‐Fenz L. , Berner H. , Schaufelberger R. , Wehrli Heinrich 
Published: December 2004

AbstractIn addition to the preliminary communication [1] a detailed description of the first partial synthesis of steroidal alkaloid batrochotoxinin A (1) is presented.
Arbeiten über Phosphorsäure‐ und Thiophosphorsäure‐ester mit einem heterocyclischen Substituenten. 6. Mitteilung. 3‐Acyl‐thio‐ und ‐dithio‐carbazinsäure‐alkylester und 2′‐(Dialkoxy‐phosphinothioyl)‐carbonsäurehydrazide sowie deren Ringschluss zu 3‐Acyl‐5‐alkoxy‐ und ‐5‐alkylthio‐1,3,4‐thiadiazol‐2(3H)‐onen bzw. 3‐(Dialkoxy‐phosphinothioyl)‐5‐substit.‐1,3,4‐oxadiazol‐2(3H)‐onen
Authors: Rüfenacht Kurt 
Published: December 2004

AbstractThio‐ and dithio‐carbazic acid alkyl esters, acylated in position 3 by radicals of carboxylic, sulfonic, phosphoric, thiophosphoric or thiophosphonic acids, undergo spontaneous ring closure with phosgene, in absence of any acid binding agent, to form the corresponding 3‐acyl‐5‐alkoxy‐ and ‐5‐alkylthio‐l,3,4‐thiadiazol‐2(3H)‐ones. Similarly 3‐thiophosphorylated 5‐substituted 1,3,4‐oxadiazol‐2(3H)‐ones can be prepared from carboxylic acid hydrazides acylated by thiophosphoric acid radicals. In the latter case, however, a stoichiometric amount of pyridine is necessary to avoid cleavage of the PN‐bonding.
Eine stereospezifische Synthese von syn‐Bishomochinon über p‐Benzochinon‐bis(äthylen)ketal
Authors: Heller Jürg E. , Dreiding André S. , O'Connor B. R. , Simmons H. E. , Buchanan G. L. , Raphael R. A. , Taylor R. 
Published: December 2004

AbstractThe bis(ethylene)ketal of p‐benzoquinone (6) has been prepared from the bis(ethylene)ketal of cyclohexane‐1,4‐dione (3) by bromination with bromine in ether followed by dehydrobromination with potassium t‐butoxide. Two intermediate dibromides (4 and 5) were isolated and their constitutions as well as their configurations determined from spectroscopic properties.Partial hydrolysis of 6 furnished the mono(ethylene)ketal of p‐benzoquinone (9), which was converted stereospecifically to syn‐bishomoquinone (2) by the double addition of sodium dimethylsulfoxonium‐methylide. The intermediate mono(ethylene)ketals of syn‐bishomoquinone (11) as well as of the mono(methylene) addition product (10) were also isolated.
Contribution à la phytochimie du genre Gentiana I. Etude des composés flavoniques et xanthoniques dans les feuilles de Gentiana lutea L. (1re communication)
Authors: Bellmann Günter , Jacot‐Guillarmod André 
Published: December 2004

AbstractSix polyphenolheterosides have been isolated from the leaves of G. lutea L. by means of thin layer and column chromatography on polyamide. The xanthones mangiferin (III) and gentioside (IV), the flavones isoorientin (V) isovitexin (VI) and two new heterosides (E and F) have been isolated. E gave isoorientin and glucose on hydrolysis and F isovitexin, glucose and gentiobiose. Structure identification has been achieved by UV., IR. and NMR. spectroscopy as well as by synthesis of the corresponding aglycones.
Demethylierungen am Mesembrin
Authors: Pfäffli P. , Hauth H. 
Published: December 2004

AbstractThe N‐methyl group of mesembrine (1) was split off via reaction of chloroformic acid p‐nitrophenyl ester on the keto‐protected alkaloid. O‐Demethylation of 1 with borontribromide produced simultaneous ring closure between the carbonyl function and the aromatic part of the molecule.
Stereoselektive Bildung der C‐C‐Bindung in der Kopplungsreaktion zwischen sek. Alkylmagnesiumbromiden und ungesättigten Halogeniden: Asymmetrische Induktion durch einen optisch aktiven Diphosphin‐Nickel‐Komplex
Authors: Consiglio Giambattista , Botteghi Carlo 
Published: December 2004

AbstractThe catalyzed cross‐coupling reaction of secondary racemic Grignard reagents with unsaturated halides takes place stereospecifically in the presence of the nickel chiral complex 4 although some isomerisation is occurring this reaction can be useful to prepare optically active hydrocarbons.
Die Struktur von Maytenin
Authors: Englert G. , Klinga K. , Raymond‐Hamet  , Schlittler Emil , Vetter W. 
Published: December 2004

AbstractIn den Jahren 1933–37 sind eine Reihe von Arbeiten über die Inhaltsstoffe von Maytenus Chuchuhuasha und über die pharmakologische Wirkung von Chuchuhuasha‐Extrakten. publizier worden [1], deren Inhalt sehr eingehend in der Dissertation von Robert Colas zusammengefasst wurde [2].Die verschiedenen Maytenus‐Sendungen (hauptsächlich Wurzeln und Stammrinde), die Colas erhielt, stammten aus dem oberen Amazonasgebiet: drei Muster aus Iquitos (Peru) und drei Sendungen aus Leticia (Columbien). Wässerige Extrakte dieser Pflanzen werden von den Eingeborenen jener Gegenden als Aphrodisiakum eingenommen.Die botanische Bestimmung des Pflanzenmaterials wurde damals von dem einen von uns (R. H.) vorgenommen. Anhand von makroskopischen und mikroskopischen Untersuchungen der Stammrinde, der Blätter und Blüten wurde festgestellt, dass es sich bei einer der Sendungen ein wandfrei um eine neue Maytenus‐Spezies handelte, die als Maytenus Chuchuhuasha (Raymond Hamet et Colas) bezeichnet und die botanisch auch gegen Maytenus communis abgegrenzt wurde. Weniger sicher war die Bestimmung einer zweiten Maytenus‐Spezies, die gelegentlich erhalten wurde. Sie wurde in der Dissertation Colas als «Maytenus non déterminé» bezeichnet und wurde chemisch nicht weiter bearbeitet. Gelegentlich enthielten Pflanzensendungen auch eine neue Salacia‐Spezies (Hippocrataceae), die Salacia Colasi (R. Ben.) benannt wurde. Auch diese Salacia wurde chemisch nicht weiter untersucht.
Organic Phosphorus Compounds 56. The addition of hypophosphite esters to activated olefins, a new method for preparing 2‐substituted ethyl phosphinates
Authors: Maier Ludwig 
Published: December 2004

AbstractThe addition of methylhypophosphite, H2P(O)OCH3, to acrylic acid derivatives, CH2CHX (X  CONH2, CN, CO2R), is described and the physical properties of three new 2‐substituted ethylphosphinates are reported.
Alkyl Transition Metal Compounds IX. Synthesis and structure of [(Me3SiCH2)2Cr(bipy)2] I
Authors: Daly J. J. , Sanz F. , Sneeden R. P. A. , Zeiss H. H. 
Published: December 2004

AbstractBis(trimethylsilylmethyyl)‐bis‐(2,2′‐bipyridyl)chromium(III) iodide has been synthesized and its structure determined; the Cr‐C(sp3) bond length is 2.107(9) Å.
Radiolyse des hydrocarbures. 20e communication. n‐Alcanes en phase liquide de l'heptane au dodécane
Authors: Rappoport Serge , Gäumann Tino 
Published: December 2004

AbstractEffects of dose and temperature on the yields of the majority of the radiolysis products of the n‐heptane, n‐octane, n‐nonane, n‐decane and n‐dodecane have been determined. The G‐values of the products, excepting dimers are approximately the same for all the above n‐alcanes. The temperature dependence, expressed as an apparent activation energy is shown to be equal for all n‐alcanes.
Méthylène‐10,11‐ et méthyl‐11‐prostaglandine
Authors: Vogel Pierre , Crabbé Pierre 
Published: December 2004

AbstractThe title compounds 6 and 7 have been prepared from a natural occurring PG‐A2 derivative. The structure and configuration of these novel prostaglandins are deduced from their mode of preparation and from their spectroscopic properties.
Über kristallines Chrom(III)hydroxid. I
Authors: Giovanoli Rudolf , Stadelmann Willy , Feitknecht Walter 
Published: December 2004

AbstractWhen hydroxide ions are added to a solution of Cr(H2O)63+ ions at low temperature a well crystallized chromium hydroxide hydrate is formed, corresponding to the formula [Cr(OH)3‐(H2O)3]∞. Its structure is the inverse of bayerite type, two thirds of the octahedral M3+ positions being vacant. It loses water easily and turns into a totally amorphous hydroxide of variable water content. An amorphous hydroxide is also obtained when solutions are alkalized at higher temperatures or when aged solutions (containing polynuclear complexes) are used.
Electron Paramagnetic Resonance Spectra of planar low‐spin Complexes of Cobalt(II) with Schiff's Bases. I. N,N′‐ethylene‐bis(salicylideneimine)‐cobalt(II). Preliminary communication
Authors: von Zelewsky Alexander , Fierz Hans 
Published: December 2004

AbstractThe anisotropic EPR. parameters of N,N′‐ethylene‐bis(salicylideneimine)‐cobalt(II), magnetically diluted with the corresponding nickel complex, have been determined from single‐crystal measurements. From these data it is concluded that in the cobalt complex dyz and d differ only slightly in energy, the former being the orbital accomodating the unpaired electron in the ground state.
Über die Wirkung von Auxochromen in Flavyliumsalzen, I. 7‐Hydroxy‐flavyliumsalze
Authors: Kokkinos Konstantinos , Wizinger Robert 
Published: December 2004

Abstract7‐Hydroxy‐flavylium salts absorb at longer wave lengths than the corresponding flavylium salts, yet auxochromes in 4′‐position have a less bathochromic effect in the 7‐hydroxy‐flavylium series than in the flavylium series. As a result the absorption maxima converge. 4′‐Dimethylamino derivatives show a convergence of 22 nm.
Über die Wirkung von Auxochromen in Flavyliumsalzen, II. 5,6‐Benzo‐flavyliumsalze
Authors: Kokkinos Konstantinos , Wizinger Robert 
Published: December 2004

AbstractAnalogously to the 7‐hydroxyflavyliumion the 5,6‐benzoflavyliumion affects auxochromes in 4′‐position not as strongly as the flavylium ion. In the flavylium series the dimethyl‐amino group e.g. causes a bathochromic effect of 137 nm; in the 5,6‐benzoflavylium series however the bathochromic effect is only 109 nm. The absorption maxima of both series converge; in the case of the dimethylamino group the convergence amounts to 28 nm.
Biosynthèse de la proferrorosamine A à partir de la L‐lysine
Authors: Pouteau‐Thouvenot Micheline , Padikkala José , Barbier Michel , Viscontini Max 
Published: December 2004

AbstractNous montrons dans ce travail que chez Pseudomonas roseus fluorescens, la L‐lysine semble être le précurseur de l'acide picolique, lui‐même directement incorporé dans le noyau pyridinique de la proferrorosamine A. La L‐lysine, de même que nous l'avons montré pour l'acide L‐glutamique, ne prend pas part à la biosynthèse de la chaîne latérale du propigment.
La séparation d'éléments des terres cériques par chromatographie sur échangeurs d'ions à l'aide de l'acide N‐(2‐hydroxyéthyl)‐iminodiacétique
Authors: Quinche Jean‐Pierre 
Published: December 2004

AbstractNous décrivons un procédé de séparation d'éléments des terres cériques par chromatographie de déplacement sur échangeurs d'ions permettant d'obtenir des effluents riches en lanthanides (jusqu'à 0,18M). Les meilleurs résultats ont été obtenus avec la résine Dowex 50 WX2 [VO2+] (200–400 mesh) et une solution éluante de HIDA 0,20M (pH = 8,70).
Photochemische Reaktionen. 72. Mitt. [1]. Zur Photofragmentierung von 14β‐Hydroxy‐20‐oxo‐Δ16‐Steroiden
Authors: Marti Franz , Wehrli Hansuli , Jeger Oskar 
Published: December 2004

AbstractOn UV. irradiation in i‐octane or t‐butyl alcohol the α,β‐unsaturated δ‐hydroxy ketone 2 undergoes fragmentation to the novel 14,15‐seco‐steroid 3.
Struktur von Coleon F
Authors: Rüedi Peter , Eugster Conrad Hans 
Published: December 2004

AbstractColeon F is a new, very labile p‐methylenequinone, C20H20O4, which has been 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. 10 431. It has been shown to be 18 (or 19) (4 → 3), 16 (or 17) (15 → 16 (or 17))‐diabeo‐abieta‐3,5,7,9,13,16‐hexaen‐11,14‐diol‐2,12‐dione (2).
Zur Problematik der Peptidsynthese an Trägern: Beitrag eines neuen Verfahrens mit löslichen Trägern
Authors: Andreatta R. H. , Rink H. 
Published: December 2004

AbstractA new procedure for the synthesis of peptides on a soluble carrier is described. It relies on gel filtration for the removal of low molecular weight reactants from the peptide‐polymer complex after each cycle. The advantages of the method are assessed and the insight into the problematics of the carrier synthesis which it provides are discussed. Finally, the use of a monovalent, soluble carrieer molecule of defined chemistry is proposed. Such a carrier should reduce the problems of carrier synthesis to the purely chemical ones commonly associated with peptide synthesis.
Synthese von rac. N‐t‐Butyloxycarbonyl‐thiobenzylglycyl‐thiobenzylglycin und Versuche zur Darstellung des 3,6‐Epidithio‐2,5‐piperazindions
Authors: Petrzilka T. , Fehr Ch. 
Published: December 2004

AbstractThe synthesis of rac. N‐t‐butyloxycarbonylthiobenzylglycyl‐thiobenzylglycine is described. Cyclisation experiments to the corresponding 3,6‐epi‐dithio‐piperazindion(2,5) were unsuccessful.
Chaenorhin, ein macrocyclisches Spermin‐Alkaloid. 149. Mitteilung über Alkaloide
Authors: Bernhard Heinz O. , Kompiš Ivan , Johne Siegfried , Groöger Detlef , Hesse Manfred , Schmid Hans 
Published: December 2004

AbstractStructure 1 has been elucidated for chaenorhine, an alkaloid isolated from Chaenorhinum organifolium (Scrophulariaceae). The key derivative for the structural elucidation is 13,14,21,22‐tetrahydro‐21,22‐seco‐chaenorhine (21). 21 gave upon hydrolysis spermine and 4‐hydroxydihydrocinnamic acid characterized as the tetraacetyl derivative 18 and as the dimethyl derivative respectively.
Utilisation d'ylides du phosphore en chimie des sucres. XV. Synthèse de sucres à insaturation terminale
Authors: Tronchet Jean M. J. , Baehler Bruno , Eder Hansjörg , Le‐Hong Nghiep , Perret Françloise , Poncet Joëlle , Zumwald Jean‐Bernard 
Published: December 2004

AbstractTreatment of 3‐O‐benzyl‐1, 2‐O‐isopropylidene‐3‐O‐methyl‐α‐D‐xylo‐pentodialdlo‐1,4‐furanose and 2,5‐anhydro‐3,4‐O‐isopropylidene‐aldehydo‐D‐ribose with moderately stable and stable phosphonium ylides led to the corresponding terminal‐unsaturated sugars obtained as a mixture of cis and trans isomers. The cis:trans ratios were determined by 1H‐NMR. and (or) GLC. They showed that steric factors play an important role in the control of the stereochemistry of these reactions.
Die gezielte Synthese offenkettiger asymmetrischer Cystinpeptide mittels thiol‐induzierter Fragmentierung von Sulfenylthiocarbonanten. Insulinfragmente mit intakter Disulfidbrücke A20‐B19.
Authors: Kamber Bruno 
Published: December 2004

AbstractThe thiol‐induced fragmentations of sulfenyl thiocarbonates (RSSCOOCH3) leading to mixed disulfides was applied to the synthesis of open‐chain asymmetrical cystine peptides. Various fragments of insulin containing the disulfide bridge between A20 and B19 were prepared by this method.
Reinvestigation of the Classical Synthesis of Cinchona Alkaloids. I. A new synthesis of homomeroquinene and quinotoxine
Authors: Grethe Guenter , Lee Hsi Lin , Mitt Toomas , Uskoković Milan R. 
Published: December 2004

AbstractEine neue Synthese von N‐benzoyl‐homomerochinen‐äthylester (10 b) und dessen Überführung in Chinotoxin (18) wird beschrieben.
Homopolar and Heteropolar Bond Dissociation Energies and Heats of Formation of Radicals and Ions in the Gas Phase II. The relationship between structure and bond dissociation in organic molecules
Authors: Egger Kurt W. , Cocks Alan T. 
Published: December 2004

AbstractThe preceeding paper presents a critical tabular compilation of 2‐center homo‐ and heteropolar bond dissociation energies. This paper deals with some empirically derived general aspects of these data, particularly regarding relationships between structure and reactivity, i.e. substituent effects on bond dissociation energies. ‘Extra’ stabilization energies generated in electronically delocalized radicals or ions derived from these experimental data are also presented.
Etude conformationnelle dans l'approximation CNDO/BW: barrière de rotation interne de petites molécules organiques
Authors: Weber Jacques , Gerdil Raymond 
Published: December 2004

AbstractThe potential functions for internal rotation of several representative small organic molecules are calculated by the CNDO/BW method. For ethane, methanol, propylene, methyl‐cyclopropane and ethylene the most stable conformation is predicted correctly; although too small a value is calculated for the height of the rotational barrier, with the exception of ethylene for which the calculated value is very close to the experimental one. For glyoxal, butadiene and hydrazine the number of minima in the energy profiles or the or the associated values of the torsional angle are predicted incorrrectly (for butadiene, see however the note added to the proofs).
Die Synthese von all‐trans‐Retinylamin und anderen Polyenaminen
Authors: Kienzle Frank 
Published: December 2004

AbstractThe preparation of various polyene phthalimides using the azocarboxylate method is described. The imides are converted into the corresponding amines by reaction with hydrazine. In this way all‐trans‐retinylamine and β‐ionylamine have been obtained.
Untersuchungen über eine Carbonyl‐Olefinierung mit α‐metallierten Isocyaniden. Die Synthese von β‐Carotin und anderen Polyenen
Authors: Kienzle Frank 
Published: December 2004

AbstractThe synthesis of various polyene isocyanides, e.g. β‐ionyl isocyanide and all‐trans‐retinyl isocyanide is reported. Their use in carbonyl‐olefination was investigated and compared with the Wittig reaction. β‐Carotene was obtained from all‐traws‐retinal and all‐trans‐retinyl isocyanide in good yield.