bluuebunny/crossref_metadata_2025_split huggingface dataset:
Menthatrienes and the Oxidation of Limonene
Authors: Thomas Alan F. , Bucher Waltraud 
Published: December 2004

AbstractThe oxidation of limonene with mercuric acetate gives a mixture containing mentha‐1. 3. 8‐triene, the hydrocarbon of parsley, and its isomer, mentha‐1. 4. 8‐triene. Selenium dioxide oxidation of limonene in alcohol gives as the main product mentha‐1. 8‐dien‐4‐ol, and pyrolysis of the acetate of the latter, or of mentha‐1. 8‐dien‐10‐yl acetate (the main product of the oxidation of limonene with selenium dioxide in acetic anhydride), also gives a mixture of menthatrienes. A discussion of the selenium dioxide oxidation of limonene is presented.
Synthese von 2‐Methyl‐3‐amino‐inden‐1‐onen
Authors: Allisson S. , Hunziker P. , Lüthi P. 
Published: December 2004

Abstract2‐methyl‐2, 3‐dibromo‐indan‐1‐ones II reacted with primary or secondary amines yield the corresponding inden‐1‐ones with a basic substituent in position 3 (IV). These compounds possess indicator properties, but are stable over longer periods only as perchlorates.
Chimie et pharmacologie de l'apiose II. Synthèse de l'(hydroxyméthyl‐3‐β‐L‐érythrofurannosyl)‐9‐adénine Communication préliminaire
Authors: Tronchet J. M. J. , Tronchet Mme J. 
Published: December 2004

AbstractA synthesis of the L enantiomer of a very close analog of adenosine is described. Some properties of that compound are compared with those of the D enantiomer of its 3‐epimer which has also been prepared.
Cyclisations par l'intermédiaire de fonctions phénylthioet phénoxy‐carbamoyle. II. Formation d'anhydrides azasucciniques et de leurs produits de polycondensation. Intervention du cation carbamoyle‐pyridinium
Authors: Baudet P. , Otten Cl. , Rao D. 
Published: December 2004

AbstractThe N‐(p‐nitrophenoxy‐carbonyl) derivatives of glycine, DL‐alanine and DL‐leucine are transformed by the action of pyridine into azasuccinic, 3‐methyl‐2‐azasuccinic and 3‐isobutyl‐2‐azasuccinic anhydride, respectively. These cyclisations occur probably via the intermediate N‐carbamoyl‐pyridinium cation magnified image, the rate of cyclisation seems to depend on the concentration of the intermediate in the form of the dipolar ion magnified image, i.e. the ionised carboxyl is necessary for the reaction. In γ‐collidine the cyclisation occurs very slowly; this is attributed to the slowness due to steric hindrance of the production of N‐carbamoyl‐γ‐collidinium cation and its instability.The azasuccinic anhydrides mentioned polycondense, yielding the corresponding polyglycine, poly‐DL‐alanine and poly‐DL‐leucine. This reaction too is catalysed by pyridine; it can also be effected by γ‐collidine, but the efficacity of the latter in comparison with pyridine is even less than in the catalysis of the cyclisation described above. N‐(p‐nitrophenoxy‐carbonyl)‐glycine reacts with lysozyme in the presence of pyridine; several glycine residues are introduced into the enzyme molecule, the product being insoluble and poorly active.
Synthèse par réaction de Friedel‐Crafts d'analogues partiellement saturés de l'amitriptyline. 1re Communication sur les antidépresseurs et les neuroleptiques tricycliques
Authors: Dostert P. , Kyburz E. 
Published: December 2004

AbstractIt is postulated that one aromatic ring and the amine group in the side chain could be sufficient for the specific fixation of the molecule of a tricyclic antidepressant and for warranting its activity. Some partially saturated derivatives of amitriptyline were prepared, in order to check if pharmacologic activity is retained.
α‐Oximierung von gesättigten Ketonen durch das photochemisch angeregte Nitrit‐Ion
Authors: Pfoertner K. 
Published: December 2004

AbstractThe photochemical behaviour of the nitrite ion must be considered as being similar to that of the carbonyl group. Like the carbonyl group, the nitrite ion in n, π* excitation is capable of abstracting hydrogen atoms from various compounds. During this reaction the nitrite ion is reduced to NO. The radicals obtained by abstracting α‐H atoms from saturated ketones then react with the NO to give nitroso derivatives which undergo a rearrangement to the corresponding oximes ‐ provided that the same carbon bears further hydrogen atoms.Dimethylformamide and probably also acetylacetone act as quenchers in this photoreaction, whereas aromatic aldehydes and excess NO do not.
Über die Synthese von Verbindungen mit dem Skelett der Homoproaporphine. 7. Mitteilung über natürliche und synthetische Isochinolinderivate
Authors: Schneider Fernand , Bernauer Karl 
Published: December 2004

AbstractThe synthesis of the tetracyclic spiro compounds 11, 12, 13, 14, 17, 18, 19 and 20 with homoproaporphine skeleton is described. Crucial intermediates are the secondary alcohols 10and 16. The structure of the spiro compounds is proved by transformation of 11into the dihydronaphthalene derivative 24 and NMR.‐spectroscopic studies of the latter.
Synthese von zwei Metaboliten des 2,4‐Diamino‐5‐(3,4,5‐tri‐methoxybenzyl)‐pyrimidins (Trimethoprim)
Authors: Rey‐Bellet G. , Reiner R. 
Published: December 2004

AbstractThe synthesis of two metabolites M3 and M4 of 2,4‐diamino‐5‐(3, 4, 5‐trimethoxybenzyl)‐pyrimidine (trimethoprim, 1) is reported. M3 (trimethoprim 1‐oxide) as well as the isomeric 3‐oxide were prepared by oxidation of 1 with m‐chloroperbenzoic acid. The structure of M3 was finally established by x‐ra analysis [4]. The metabolite M4 [2, 4‐diamino‐5‐(3‐hydroxy‐4, 5‐dimethoxy‐benzyl)‐pyrimidine] was prepared by condensation of 3‐benzyloxy‐4, 5‐dimethoxybenzaldehyde (2) with 3‐methoxypropionitrile (3) and guanidine followed by hydrogenolysis of the intermediate 3‐benzyloxy compound 4.
Sur quelques aspects de la polysubstitution de l'amino‐2‐fluorène et de l'acide amino‐2‐fluorène‐sulfonique‐7
Authors: Benz J. , Doré J. , Fleury J.‐P. 
Published: December 2004

AbstractElectrophilic sulfonation and cyclisation orientation studies were carried out with 2‐aminofluorene and 2‐aminofluorene‐7‐sulfonic acid. Positions 1 and 3 are competing.A new synthesis of 2‐aminofluorene‐7‐sulfonic acid and the syntheses of derived sulfonamides are described.
Langsame Inversion am pyramidal gebundenen Stickstoff: Konfiguration und Konformation beim Strukturtyp der N, N‐Dialkoxy‐alkylamine aus der Sicht eines semiempirischen MO‐Modells
Authors: Müller K. 
Published: December 2004

AbstractNitrogen inversion and rotation around the N‐O single bond in N, N‐dialkoxyalkylamine systems are discussed in terms of a semi‐empirical MO method which is essentially based on the concepts discussed by Mulliken in connection with the “magic formula”. By taking a simplified structural model and adjusting one empirical parameter, a satisfying agreement with experimental results is obtained. The results allow a chemically transparent interpretation and confirm, to a more quantitative extent, the previously discussed concepts [1].The (spx → p) promotion of the nitrogen lone pair strongly inhibits the inversion process and dominates the simultanous lowering of the σ‐bond energies due to (i) the gain of s‐character in the σ‐involved nitrogen hybrid‐AO's and (ii) the increased σ‐bond overlaps. This dominance is considerably enhanced when electronegative ligands are attached to nitrogen. The total repulsion energy turns out to favour strongly the planar transition state and is essentially determined by the repulsions between the lone pair and the σ‐bonds at nitrogen. Factorization into several repulsive contributions reveals that among these only one inhibits the inversion process, namely the repulsions between the nitrogen lone pair and the bonded and non‐bonded electron pairs on the ligands.For the process of rotation around the N‐O single bond a potential curve is obtained with two energy minima. The repulsion energy analysis shows that the shape of the potential curve is governed by the repulsions between the lone pairs on oxygen and nitrogen as well as the formally more or less “lone pair‐like” σNC‐bond. This situation is compared to the more general one in which essentially two lone pairs or formally more or less “lone pair‐like” σ‐bonds, on each of two adjacent centers, repel each other by conjugative destabilization; a situation which is realized for instance in molecules that show the anomeric effect.
Addition of a Functionalized Isoprene Unit to an Allyl Alcohol. III. The reaction with optically active cis‐carveol
Authors: Thomas Alan F. , Ohloff G. 
Published: December 2004

AbstractProvided the temperature is kept under 150°, diene ethers of allyl alcohols rearrange in the double Claisen‐Cope reaction largely by a sigmatropic process in both stages. This was demonstrated by using the 2‐methylbutadienyl ether of (−)‐cis‐carveol, when the product obtained after the two rearrangements was optically active. To check the extent of chirality loss, the same product was synthesized by a route involving only one sigmatropic reaction instead of two. When the reaction occurs at higher temperature, much more chirality is lost, corresponding to the intervention of a diradical process.
Synthese von Ergonin und Ergoptin, zweier Mutterkornalkaloid‐Analoga der Ergoxin‐Gruppe 72. Mitteilung über Mutterkornalkaloide
Authors: Stütz P. , Stadler P. A. , Hofmann A. 
Published: December 2004

AbstractThe syntheses of ergonine and ergoptine, two new analogues of ergot alkaloids possessing the stereochemistry of the already known peptide type alkaloids, are described. The synthetic pathway corresponds to that used already for the synthesis of the natural ergot peptide alkaloids.
Über die Stereochemie der Hydrogenolyse von N‐Benzyl‐Bindungen II. Die Deuteriolyse von chiralem N,N‐Dimethyl‐phenylglycin und die Konfiguration von (+)‐Phenyl‐essigsäure‐2‐d1
Authors: Dahn H. , O'Murchu C. 
Published: December 2004

AbstractThe steric course of the hydrogenolytic cleavage of benzyl‐N‐bonds using Pd‐C catalyst was determined by deuteriolysis of R(−)‐N,N‐dimethyl‐phenylglycine I, which gave (+)‐phenylacetic acid containing 70% of the monodeutero compound. The configuration of (+)‐phenylacetic acid‐2‐d1 was determined (S) and its optical purity estimated by Schmidt degradation to chiral S(+)‐benzylamine‐α‐d1. On the basis of these results, hydrogenolysis of I can be evaluated to proceed by 80% inversion and 20% retention of configuration. Methyl N,N‐dimethyl‐phenyl‐glycinate yielded racemized methyl phenylacetate‐2‐d1.
Neuartige Isomeriefälle bei 1:2‐CrIII‐ und CoIII‐Komplexen von o, o'‐Dihydroxyazoverbindungen: Pyramidal gebundener Stickstoff mit hoher Inversionsbarriere?
Authors: Schetty G. 
Published: December 2004

AbstractFrom the dimensions described in previously known X‐ray structure analyses and from NMR.‐spectroscopical datas of a 1:2 CoIII complex it is concluded that metal chelates of two and tri‐dentated azo compounds are present in the diketo or quinone mono hydrazone form, provided that such a form is possible. As the metal atoms replaces the hydrazone proton the coordinating nitrogen atom can be predetermined.For the first time in the case of 1:2 Cr complexes from o,o'‐dihydroxy azo compounds small amounts of byproducts have been observed which have the empirical composition of the main complexes. As the coordinated nitrogen atom is sp3‐hybridized, its three bonds should be arranged in a pyramidal form. Therefore the ligands should be slightly bent. In the 1:2 Cr complexes where two of these ligands are coordinated to the metal atom perpendicularly to each other (Drew‐Pfitzner‐arrangement) 3 conformers (+ 3 mirror images) are possible. These conformers are ascribed to one group of the observed isomeric complexes. For another group it is supposed that at least one ligand is coordinated in the plane azo form.The postulated thrice bonded nitrogen atom possesses the requirements for a high inversion barrier: it is a member of two ortho condensed rings; moreover, it is bound to a Lewis acid.No such system seems to have been described, but in some published X‐ray structure analyses, there is evidence to be found of its existence.
études sur les composés organométalliques IX. étude spectrophotométrique de quelques complexes du tétrachlorure de titane avec des di‐ et triamines tertiaires
Authors: Tabacchi R. , Vuitel L. , Jacot‐Guillarmod A. 
Published: December 2004

AbstractThe complexes of TiCl4 with various tertiary di‐ and triamines are studied by using IR, spectroscopy. Assignments for the observed frequencies are proposed.
Electronenstruktur und physikalisch‐chemische Eigenschaften von Azo‐Verbindungen, Teil XV. Über die Struktur der protonierten Azobrücke in Azobenzolderivaten
Authors: Haselbach E. 
Published: December 2004

AbstractThe pKa‐values of a number of para‐ and ortho‐substituted azobenzenes have been measured. The effects of the substituents have been parametrized using a modified Hammett‐equation. The results support the classical view that protonation of the azo‐bridge takes place on a distinct N‐atom with formation of a N‐H σ‐bond.
Kernresonanz‐spektroskopische Untersuchung protonierter Stickstoffverbindungen in Trifluoressigsäure
Authors: Giger W. , Simon W. 
Published: December 2004

AbstractThe nuclear magnetic resonance spectra of a series of protonated organic nitrogen compounds in trifluoroacetic acid solution have been studied. A direct correlation between the exchange rate of the ammonium protons and the acidity constant of the functional group is established. Substituted anilinium and pyridinium ions with pK values below 4 show coalescence for the signals of N⊕H protons and disappearence of the coupling with the α protons.
Hetero‐“Tickling” am A3X‐System von 13CH312CN, eine Bestimmungsmethode hoher Genauigkeit von Methylkohlenstoffverschiebungen
Authors: Wehrli F. W. , Simon W. 
Published: December 2004

AbstractHeteronuclear spin tickling experiments in the degenerate A3X spin system of a 13CH3 group have proved to be suitable for accurate carbon shift determinations in methyl groups. A weak perturbation of one of the 13C quadruplet lines splits both proton doublet lines into a sub‐triplet with the relative signal strengths depending on whether an outer or inner 13C line is irradiated. Deviation from exact resonance with one of the 13C transitions modifies the relative intensities, and finally further splitting of the outer subtriplet lines occurs in accordance with theory. The amount of this additional splitting is equal to the difference between the double resonance frequency and the 13C transition frequency to be measured. Signal distortions observed when the double resonance spectra are recorded in the INDOR sweep mode have to be ascribed to the fact that the tickling effect competes with the generation of transient nutations.
Die Glykoside der Wurzeln von Xysmalobium dilatatum WEIMARCK. 1. Mitteilung: Isolierungen. Glykoside und Aglykone, 327. Mitteilung
Authors: Meister L. , Kaufmann H. , Stöcklin W. , Reichstein T. 
Published: December 2004

AbstractThe roots of Xysmalobium dilatatum Weimarck contain uzarin and xysmalorin as major glycosides. The same two compounds are also present as main components in the glycoside mixture from the roots of Xysmalobium undulatum. In addition to that, X. dilatatum also contains appreciable amounts of pregnane derivatives, linked to 2‐deoxy‐sugars. Four such xanthydrolpositive compounds (the dilatoides A, B, C and D) have been isolated in amorphous but pure or nearly pure form; they have not been detected in the roots of X. undulatum.
Photoelektron‐Spektren von Cycloalkenen und Cycloalkadienen. Vorläufige Mitteilung
Authors: Bischof P. , Heilbronner E. 
Published: December 2004

AbstractThe photoelectron spectra of cis‐cycloalkenes (with three to ten carbon atoms in the ring), of three isomeric, non‐conjugated cyclodecadienes, and of cis, cis, ‐1, 3‐cycloalkadienes (with five to eight carbon atoms in the ring) have been recorded. The essential features of their π‐bands and of the first σ‐bands are briefly discussed.
Alkalikationen‐Spezifität und Träger‐Eigenschaften der Antibiotica Nigericin und Monensin
Authors: Lutz W. K. , Wipf H.‐K. , Simon W. 
Published: December 2004

AbstractIt is shown by means of IR. spectroscopic methods that nigericin and monensin have a cyclic conformation similar to that of their silver salts. Complex formation constants with sodium and potassium ions follow the selectivity order determined by EMF. measurements on liquid membranes: nigericin: K+ > Rb+ > Na+ > Cs+ > Li+; monensin: Na+ > K+ > Li+ > Rb+ > Cs+. Transport experiments show that nigericin and monensin facilitate the diffusion of potassiumions across model membranes, although in electrolytic transport experiments the permeability is not affected.
Photochemical Reactions. Part 60 [1]. The photorearrangement of a 2, 5‐diene‐1, 7‐dione
Authors: Domb S. , Schaffner K. 
Published: December 2004

AbstractThe 2, 5‐diene‐1, 7‐dione 12 rearranges photochemically to the cyclopentenonyl‐cyclopropyl ketone 13. Dienone 12 does not emit phosphorescence at 78K. Sensitization and quenching experiments indicate that the photorearrangement occurs in an excited triplet state with ET between ca. 61–65 kcal/mol according to sensitization data, and between ca. 54–58 kcal/mol according to quenching results. By comparison, the 2, 5‐dienone 1 behaves similarly with respect to sensitization and quenching of its photorearrangement [3] (indicating ET < 61 and ca. 54–58 kcal/mol, respectively) and to its lack of phosphorescence, while the 2‐ene‐1, 5‐dione 8 emits phosphorescence (ET = 72.4 kcal/mol) and sensitization, and quenching data indicate ET between ca. 68–72 and >61 kcal/mol for its photorearrangement, respectively. It is concluded that the triplet energy of the reactive state of compound 12 extends either over the two enone groups involving strong interaction or is localized on the ring A enone only.Photoproduct 13 rearranges further to the stereoisomer 14 on direct excitation and sensitization with acetophenone. Thioxanthone as triplet sensitizer and naphthalene as triplet quencher are ineffective. The reverse isomerization process, i.e. 14 → 13, is not observed.
Die Struktur des Antibioticums Roridin H. Verrucarine und Roridine, 20. Mitt. [1]
Authors: Traxler P. , Tamm Ch. 
Published: December 2004

AbstractStructure 1 has been established for roridin H (C29H36O8), an antibiotic isolated from Myrothecium verrucaria and formerly namend verrucarin H [3]. Base catalysed hydrolysis of 1 gave the known terpene alcohol verrucarol (8; C15H22O4) and myrothecinic acid (3; C14H18O6), a previously undescribed dicarboxylic acid. The structure of 3 was determined by spectral methods and by chemical cleavage of the unusual acetal group of dimethyl hexahydromyrothecinoate (6) by hydrolysis with HCl in the presence of 2, 4‐dinitrophenylhydrazine, producing the 2, 4‐dinitrophenylhydrazone 13 of 3‐methylglutaric acid semialdehyde 10 and methyl 6, 7‐dihydroxy‐octanoate (11). 13 was transformed in to dimethyl 3‐methylglutarate (15). Cleavage of 11 with HIO4 gave acetaldehyde and adipic acid semialdehyde (17) which was oxidized to adipic acid (19). The 220 MHz NMR spectra of roridin H (1) and dimethyl hexahydromyrothecinoate (6) allowed unequivocal assignment of the signals to the majority of the protons in the antibiotic.
Arsenomethane Polymer: A ladder structure
Authors: Daly J. J. , Sanz F. 
Published: December 2004

AbstractPurple arsenomethane crystallises in the orthorhombic system, space group Ima2 (C) with a = 5.81, b = 5.79, c = 13.64 Å and 8 units of CH3As in the cell. The structure is polymeric, the arsenic atoms lying on infinite coplanar ladders parallel to a. The distance between two arsenic atoms on one rung of the ladder is 2.4 Å, the distance between two arsenic atoms on the same upright and adjacent rungs is 2.9 Å, and the shortest distance between two arsenic atoms in neighbouring ladders is 3.4 Å. Each arsenic atom is bonded to one methyl group (1.97 Å), and along the ladder upright or on any one rung these methyl groups lie on alternate sides of the ladder.
Über die Struktur eines neuartigen Indolalkaloids, des Talbotins. 141. Mitteilung über Alkaloide [1]
Authors: Pinar M. , Hanaoka M. , Hesse M. , Schmid H. 
Published: December 2004

AbstractFrom the leaves of the African Apocynacea Pleiocarpa talbotii Wernham a novel indole alkaloid, talbotine, C21H24N2O4, has been isolated. Talbotine (1) contains a secondary N(b)‐atom and a cyclic hemiacetal group. Catalytic hydrogenation leads to 19, 20‐dihydrotalbotine (6), hydrogenation in the presence of formaldehyde gives N(b)‐methyl‐19, 20‐dihydrotalbotine (8). In the presence of sodium methoxide and methanol, 1 is converted into the lactone 12 and the methyl ester 13. In these reactions carbon 17 is lost as formic acid. These data, together with the analyses of the NMR. spectra of talbotine and its derivatives as well as the interpretation of the various types of the mass spectral fragmentation, lead to formula 1 for the alkaloid.Dehydrogenation of talbotine methyl ether (3) with palladium and maleic acid gives the ß‐carboline derivative 26. The N(b)‐methiodide of the latter is converted into N(b)‐methyl‐talbotine methyl ether on reduction with sodium borohydride. From these data as well as from the analyses of NMR. and IR. spectra the complete relative stereochemistry of talbotine could be derived. Application of the Horeau method to the nitrogen atom b of the methyl ether 3 on the one hand and to the hydroxyl group on C17 in N(b)‐methyl‐19, 20‐dihydrotalbotine (8) on the other hand gives consistent results and establishes S configuration of centre 15.
Die Kristallstruktur der 2,4, 6‐Trimethylpimelinsäuren 1. Mitteilung
Authors: Brufani M. , Fedeli W. 
Published: December 2004

AbstractThe crystal structure of the stereoisomer m.p. 130° of 2,4,6‐trimethylpimelic acid has been determined by three‐dimensional X‐ray analysis. The cristals are monoclinic, a = 10.35, b = 10.70, c = 11.61 Å, β = 110°12′, Z = 4, space group P2 1/c, the structure has been solved by direct methods and refined by least‐squares methods.The configuration of the acid is given by formula I; the chirality of the asymmetric centres is (2‐R, 4‐r, 6‐S).
Crystallographic Studies of Synthetic Corrinoids. I. Nickel(II)‐1, 8, 8, 13, 13‐pentamethyl‐5‐cyano‐trans‐corrin chloride
Authors: Dunitz J. D. , Meyer E. F. 
Published: December 2004

AbstractThe crystal and molecular structure of nickel(II)‐1, 8, 8, 13, 13‐pentamethyl‐5‐cyano‐trans‐corrin chloride has been determined by X‐ray analysis. The shape and dimensions of the corrin nucleus are discussed in some detail.
The 35Cl Nuclear Quadrupole Resonance Frequencies of Complexes of Boron Trichloride
Authors: Ardjomand S. , Lucken E. A. C. 
Published: December 2004

AbstractLes fréquences de résonance quadripolaire du noyau 35CI dans les complexes du tri chlorure de bore avec une variété de donneurs organiques ont été mesurées à 77 K. Quoique ces fréquences dans l'accepteur soient assez peu sensibles à la nature du ligand, la tendance observée est en accord avec d'autres mesures du pouvoir donneur des ligands. Certains des ligands étudiés ici contiennent un atome de chlore et les changements de fréquence amenés par la complexation sont également en accord avec les résultats prévus. Le trichloracetonitrile et le dichloracétonitrile réagissent avec le trichlorure de bore pour donner un composé d'addition sur la triple liaison do groupementCN plutǒt qu'un complexe donneur‐accepteur. Ce comportement est clairement mis en évidence par la spectroscopie de résonance quadripolaire.