bluuebunny/crossref_metadata_2025 huggingface dataset:
Mapping the musician brain
Authors: Sergent Justine
Published: December 2004

The understanding of the relationships between music and the brain is a legitimate goal of neuroscientific research. In spite of an already large body of experimental investigation, however, the outcome has not been as satisfactory as expected, to the point that some have voiced their incredulity at the feasibility of mapping musical functions onto cerebral structures. There are indeed considerable inconsistencies in the literature bearing on the neurobiological substrates of musical functions. Before giving in to skepticism, though, it is appropriate to examine whether such inconsistencies are unavoidable and a necessary outcome of neuroscientific investigation into musical functions. This paper, therefore, examines some of the reasons that may be responsible for the inconsistencies. Beyond the superficial similarities between language and music, these two domains are functionally distinct, yet neuropsychological research in music and its neurobiological substrates has been modeled after that in verbal language, borrowing concepts and methods that were not entirely suited to the study of musical functions. An examination of the diverse factors inherent in any study of music‐brain relationships reveals a variety of potential sources of difficulties, which, if properly controlled, would guarantee higher consistency and enhance the reliability of experimental findings. It is thus suggested that progress in understanding music‐brain relationships may result from (1) explicitly outlining the structural cognitive architecture of musical functions; (2) formulating the problems in terms of underlying operations rather than in terms of vague and unspecified dichotomic views of hemisphere processing; (3) designing experiments that are musically valid and coherent, and that do not lend themselves to multiple strategies; (4) setting up appropriate controls to ensure that subjects are performing as expected; (5) restricting the investigation to musically literate individuals; (6) selecting, among such individuals, a homogeneous set of subjects sharing common musical abilities; and (7) using investigatory techniques that yield reliable evidence of local cerebral involvement in realizing the tasks under study. © 1993 Wiley‐Liss, Inc.
La perméabilité des membranes. IV. Analyse de la structure de membranes végétales et animales
Authors: Meyer Kurt H. , Sievers J.‐F.
Published: December 2004

Nous avons étudié la perméabilité ionique de quelques objets d'origine animale ou végétale.
Der Zusammenhang von Kalium‐ und Kohlehydratstoffwechsel bei der Hefe
Authors: Pulver R. , Verzár F.
Published: December 2004

1. Zwischen Kohlehydratstoffwechsel und Kaliumstoffwechsel der Hefezelle besteht ein enger Zusammenhang. In der ersten Phase der Gärung, bei der Glucose‐Aufnahme und Polysaccharidbildung, nimmt 1 g Hefe mit 10 mg Glucose etwa 0,5 mg Kalium auf. Wenn nach etwa 10 Minuten die Kohlendioxydbildung beginnt, wird Kalium wieder abgegeben, so lange die Gärung dauert.
Die Wirkungen einiger kreislaufaktiver Substanzen auf Fermente
Authors: Schär‐Wüthrich Bertha
Published: December 2004

1. Die Imidazoline Privin, Otrivin und Priscol hemmen in der angeführten Reihenfolge die Monamin‐oxydase im Substrat‐Inhibitor‐Verhältnis von ea. 1 : 1, die Diamin‐oxydase 1 : 10, die Cholin‐esterase des Serums 1 : 100.
Formule glycoprotéidique du plasma sanguin
Authors: Jayle M.‐F. , Judas O.
Published: December 2004

Le sucre protéldique se répartit en trois fractions principales dans le sérum sanguin. La première est représentée par un polyholoside qui précipite à 0,75 M du mélange de phosphates et nous émettons l'hypothèse selon laquelle ce mucoïde F se détacherait de la molécule de fibrinogène au moment de la coagulation.
Sur deux trichloro‐anisidines
Authors: de Traz Clément
Published: December 2004

La 2,5,6‐trichloro‐p‐anisidine (−OCH31) obtenue de manière certaine par la synthèse proposée, diffère de la x,x,x‐trichloroanisidine de M. et F. cette dernière est donc la 2,3,5‐trichloro‐panisidine.
Eine Dialysierkolonne zur Zerlegung von Gemischen niedermolekularer Stoffe. 2. Mitteilung: Die Berechnung von Dialysierkolonnen
Authors: von Tavel P.
Published: December 2004

1. Die Wirkungsweise der Signer'schen Dialysierkolonne lässt sich berechnen. In einer einzelnen Dialysierzelle, wie sie mehrfach in der Dialysierkolonne enthalten ist, wird die Durchlässigkeitkonstante der Zelle für jede Komponente bestimmt. Mit den angegebenen Formeln können, wie in einem Beispiel gezeigt worden ist, die Ausbeute, die Dialysatmenge für jede Komponente und die Anreicherung berechnet werden.
Synthèse de l'acide ptéroysulfo‐L(+)‐glutamique
Authors: Viscontini Max , Meier Jean
Published: December 2004

Nous avons effectué la synthèse de l'acide ptéroylsulfoglutamique, produit semblable à l'acide folique, dans lequel le noyau benzoylé est remplacé par un noyau benzosulfoné. Cette synthèse a été effectuée avec la réductone comme produit intermédiaire.
Über die Oxydation von 3‐Oxyanthranilsäure durch Leberhomogenat
Authors: Viollier G. , Süllmann H.
Published: December 2004

3‐Oxyanthranilsäure, ein Zwischenprodukt bei der Bildung von Nikotinsäure aus Tryptophan, wird duch homogenisierte Rattenlberoxydiert. Das wirksame Enzym findet sich im Rückstand des zentrifugierten Homogenats. Es ist hitze‐ und cyanidempfindlich. Die Oxydation führt zu einem tief rot gefärbten Produkt. Kohlendioxyd und Ammoniak entstehen bei dieser Oxydation nicht.
Glykoside aus den Samen von Adenium multiflorum Kl.. Glykoside und Aglykone, 64. Mitteilung
Authors: Hunger A. , Reichstein T.
Published: December 2004

Die Isolierung einer besonders wirksamen rohen Glykosidase aus den Samen von Adenium multiflorum Kl. wird beschrieben.
Über Andrographolid
Authors: Schwyzer R. , Biswas H. G. , Karrer P.
Published: December 2004

Die vorliegende Arbeit befasst sich mit der Konstitutionsaufklärung des Andrographolids, eines Bitterstoffes der indischen Medizinalpflanze Andrographis paniculata Nees. Verschiedene, in der früheren Literatur vorkommende Widersprüche und Unstimmigkeiten konnten dabei abgeklärt werden.
Eine interferometrische Mikro‐Methode für Diffusionsmessungen
Authors: Labhart H. , Lotmar W. , Schmid P.
Published: December 2004

Es werden Diffusionsmessungen mit einem interferometrischen Mikro‐Elektrophoreseapparat der Firma Kern & Co. beschrieben. Die Ergebnisse an zwei Testsubstanzen (Kaliumchlorid und Saccharose) stimmen auf 1,5% mit den Literaturwerten überein. Eine einfache Auswertemethode der erhaltenen Diagramme wird angegeben, sowie ein Vergleich mit andern Messmethoden gezogen.
Recherches sur la formation et les transformations des esters. II. Sur l'hydrolyse des esters phosphoriques et celle des esters en général
Authors: Cherbuliez Emile , Leber Jean‐Pierre
Published: December 2004

From the study of the hydrolytic splitting of phosphoric esters the authors conclude that the saponification of an ester containing a hemipolar oxygen atom, and in which the acyl function is saturated in coordinative valency, proceeds by the intervention of a cation which fixes itself on this oxygen atom, thus giving rise to the formation of a complex cation. The further reaction may take place along the two following paths:

By interposition an anion replaces one OR− group of the complex; this OR− ion fixes a proton and gives ROH.

By dissociation one of the OR groups of the cation loses one R radical thus forming the compound “R‐anion”. The oxygen involved becomes hemipolar.
Recherches sur la formation et les transformations des esters. III. De l'action catalysatrice de l'ion calcium sur l'hydrolyse alcaline des esters et anhydrides phosphoriques. Sur la formation du phosphate quaternaire de calcium
Authors: Cherbuliez E. , Leber J.‐P. , Stucki P.
Published: December 2004

The calcium ion is acting as a very active catalyst in the alcaline hydrolysis of pyrophosphoric acid, poly‐ and metaphosphoric acids, of ethylphosphate, ethyl pyrophosphate (splitting of the POP bond) as well as in the alcoholysis of the latter. We suggest that there may be a relation between this phenomenon and the fact that tricalcium phosphate is able to fix still one equivalent of calcium ion, giving tetrabasic calcium phosphate (PO4Ca2)OH. If this view is justified, the catalytic activity of calcium ion is a confirmation of the mechanism we have admitted for the hydrolysis of phosphoric esters (and anhydride functions).
Zur Kenntnis der Triterpene. 190. Mitteilung. Eine stereochemische Interpretation der biogenetischen Isoprenregel bei den Triterpenen
Authors: Eschenmoser A. , Ruzicka L. , Jeger O. , Arigoni D.
Published: December 2004

The biogenetic isoprene rule in its application to the triterpenes is discussed from a stereochemical standpoint. On the basis of a well defined system of arbitrary assumptions a scheme has been developed leading from squalene to the formulae of the basic representatives of all known cyclic triterpene groups ‐ i.e. euphol, tirucallol, lupeol, taraxasterol, germanicol, β‐amyrin, taraxerol, friedelin, α‐amyrin, lanosterol ‐ in their full structural and configurational detail. This result is considered to support the squalene hypothesis of the biogenesis of cyclic triterpenes.
Über eine neue Synthese von Citral und verwandten Verbindungen
Authors: Saucy G. , Marbet R. , Lindlar H. , Isler O.
Published: December 2004

A new method for the preparation of α,β‐unsaturated aldehydes and α,β;γ,δ‐unsaturated ketones is described. The method is based upon the rearrangement of acetates of tertiary ethynyl carbinols to allenic acetates in the presence of acetic acid and silver or copper catalyst; partial conversion of the allenic acetates to diacetates takes place under the reaction conditions. In some cases enol acetates could be isolated.
Vollautomatische Anlage zur gleichzeitigen Bestimmung von Kohlenstoff, Wasserstoff und Stickstoff in organischen Verbindungen an Milligramm‐ und Submilligramm‐Mengen unter Verwendung einer selbstintegrierenden Wärmeleitfähigkeitsmessmethodik
Authors: Clerc J. T. , Dohner R. , Sauter W. , Simon W.
Published: December 2004

An analyser for the simultaneous determination of carbon, hydrogen and nitrogen in organic compounds is described. The samples are burned in a static system in oxygen and the combustion products are determined using a self‐integrating thermal conductivity method. Up to 16 previously weighed samples of 0.5 ÷ 2.0 mg are analysed without any manual help and the results are presented in digital form. One determination takes between 7 and 13 minutes. At present the standard error of a single determination is 0.20, 0.08 and 0.30% (absolute) for carbon, hydrogen and nitrogen, respectively, but these figures may easily be improved by minor modifications.
Polarographie an Festelektroden V. Adsorptionskonkurrenz in binären metallischen Monoschichten an Festelektroden
Authors: Schmidt E. , Gygax H. R.
Published: December 2004

The simultaneous reduction of binary mixtures of the depolarizers Tl+, Pb2+, and Bi3+ from aqueous solutions on the surface of Ag‐ and Cu‐electrodes is studied chronoamperometrically in view of the behaviour of the metallic monolayer, using a chamber type cell. The current balance of the electrode reaction is verified by coulometrical evaluation of the chronoamperograms.
Photochemische Cycloadditionen von 3‐Phenyl‐2H‐azirinen mit kumulierten Doppelbindungen. Vorläufige Mitteilung
Authors: Jackson B. , Gakis N. , Märky M. , Hansen H.‐J. , von Philipsborn W. , Schmid H.
Published: December 2004

Irradiation of 2‐methyl‐ (1c) and 2,2‐dimethyl‐3‐phenyl‐2H‐azirine (1d) in benzene solution in the presence of carbon dioxide yields 2‐methyl‐4‐phenyl‐ (3c) and 2,2‐dimethyl‐4‐phenyl‐3‐oxazolin‐5‐one (3d), respectively. Similar cycloadducts are observed (see table) when 2,3‐diphenyl‐2H‐azirine (1b) and 1d are irradiated in the presence of phenylisocyanate, o‐tolylisocyanate, phenylisothiocyanate or di‐o‐tolyl‐carbodiimide.
Ionisation Energies and the Electronic Structures of the N‐oxides of diazabenzenes
Authors: Maier John P. , Muller Jean‐François , Kubota Tanekazu
Published: December 2004

The ionisation energies and the HeI photoelectron spectra of the N‐oxides of diazabenzenes are presented. The valence electronic structures of the N‐oxides are discussed in view of the ionisation energies, and the profiles, of the bands. The interpreted data are compared to calculations which are in good agreement. The results are correlated to the physicochemical studies, and particularly to the electronic absorption spectroscopy, of the N‐oxides. The assignment of the photoelectron spectra of the azabenzenes are considered with reference to the spectra of their N‐oxides.
The Reduction of Some 1, 2‐Epoxides with Lithium Aluminium Hydride. Preliminary Communication
Authors: Mihailović Milhailo Lj. , Andrejević Vladimir , Milovanović Jovan , Janković Jovan
Published: December 2004

The factors influencing the ease of the lithium aluminium hydride reduction of various 1,2‐epoxycycloalkanes and 1,2‐epoxyalkanes are described and discussed.
Neutraler Ionophor für Flüssigmembranelektroden mit hoher Selektivität für Natrium‐ gegenüber Kalium‐Ionen
Authors: Güggi Marc , Oehme Michael , Pretsch Ernö , Simon Wilhelm
Published: December 2004

Neutral Ionophore for Liquid Membrane Electrodes of High Selectivity for Sodium Over Potassium Ions.

The preparation of a neutral ion carrier suitable as a component for liquid membrane electrodes is described. These sensors may be used for the potentiometric determination of sodium ion activities with a discrimination of potassium ions by a factor of up to 250.
Synthese und absolute Konfiguration von Clemastin und seiner Isomeren
Authors: Ebnöther Anton , Weber Hans‐Peter
Published: December 2004

Synthesis and Absolute Configuration of Clemastine and its Isomers.

Condensation of 4‐chloro‐α‐methylbenzhydrylalkohol (1) with 2‐(2‐chloroethyl)‐1‐methylpyrrolidine (2) gave an isomeric mixture of 2‐[2‐(p‐chloro‐α‐methyl‐=‐phenylbenzyloxy)ethyl]‐1‐methylpyrrolidine (3) and 4‐(p‐chloro‐=‐phenylbenzyloxy)‐1‐methyl‐hexahydroazepin (4). The separation of the four possible optically active isomers of 3 is described and their absolute configuration established by degradation to (R)‐ and (S)‐1‐methyl‐2‐pyrrolidineethanol (6), respectively, and by an X‐ray cristallographic analysis of the quarternary methiodide of the isomer 3‐A. Clemastine (3‐A) is (+)‐(2R)‐2‐[2‐((αR)‐(p‐chloro‐α‐methyl‐α‐phenylbenzyloxy)ethyl)]‐1‐methylpyrrolidine.
Thermolyse von Carbamoylaziden I. Hochvakuumthermolyse von Dialkylcarbamoylaziden
Authors: Reichen Werner
Published: December 2004

Flash vacuum thermolysis of dialkylcarbamoyl azides.

Thermolysis of several N,N‐dialkylcarbamoyl azides 1 in high vacuum gave good yields of 5,5‐dialkyl‐3‐dial‐kylamino‐2,4‐dioxo‐5‐azonia‐imidazolidin‐l‐id (4) formed by thermal Curtius rearrangements and dimerisation of the resulting N,N‐dialkylaminoisocyanates 2.
Steric Effects on Reaction Rates. Rate and equilibrium constants for oxidation of cyclanols
Authors: Müller Paul , Blanc Jacky
Published: December 2004

Equilibrium constants for oxidations of cyclanols by cyclohexanone in benzene have been determined in the presence of aluminium isopropoxide. The free energies of the equilibrium (ΔGox) are correlated with equilibrium constants for dissociation of cyanohydrins, rate constants for cyclanol oxidation with chromic acid, ketone reduction with sodium borohydride and trifluoroethanolysis of tosylates.
Anil‐Synthese. 23. Mitteilung. Über die Herstellung von Styryl‐ und Stilbenyl‐Derivaten des Pyrimidins
Authors: Burdeska Kurt , Fuhrer Hermann , Kabas Guglielmo , Siegrist Adolf Emil
Published: December 2004

Preparation of Styryl and Stilbenyl Derivatives of Pyrimidines

2‐ and 4‐(p‐Tolyl)‐substituted pyrimidines react with anils of hetero‐aromatic aldehydes in the presence of dimethylformamide and potassium hydroxide or potassium t‐butoxide to yield the corresponding 2‐ and 4‐[4″‐(heteroaryl)stilben‐4′‐yl]pyrimidines or the 2‐ and 4‐[a‐(heteroaryl)‐4′‐styryl]pyrimidines respectively (‘Anil synthesis’). Furthermore, the Schiff′s bases derived from p‐chloroaniline and 4‐(pyrimidine‐2‐yl and 4‐yl)benzaldehydes give, with methyl‐ and with p‐tolyl‐substituted heterocycles, the corresponding heterocyclic substituted styryl and stilbenyl derivatives. Alkyl‐, alkoxy‐ or phenyl‐substituted pyrimidines undergo also the ‘Anil synthesis’.
Pseurotin B, C, D, and E. Further New Metabolites of Pseudeurotium ovalis STOLK
Authors: Breitenstein Werner , Chexal Kuldip K. , Mohr Peter , Tamm Christoph
Published: December 2004

The structures 2–5 are assigned to the pseurotin B, C, D and E, which are new metabolites of Pseudeutorium ovalis STOLK, based on spectroscopic data and chemical transformations.
Total Synthesis of (±)‐Lysergic Acid by an Intramolecular Imino‐Diels‐Alder Reaction. Preliminary communication
Authors: Oppolzer Wolfgang , Francotte Eric , Bättig Kurt
Published: December 2004

(±)‐Lysergic acid (1) has been synthesized from 4‐hydroxymethyl‐1‐tosylindole (2) by a sequence of 9 steps. The crucial thermolysis 9 → 10 involves the in situ‐generation of the transient diene III which undergoes an intramolecular cycloaddition to a C, N‐double bond at 200° and at low stationary concentration of III.
The Reaction of Pyruvic Acid with Amines and Aminoesters Reexamined. Preliminary communication
Authors: Bradamante Silvia , Colombo Silvana , Pagani Giorgio A. , Roelens Stefano
Published: December 2004

Phenylglycine esters react with pyruvic acid to give α‐methylsuccinic amides 9 instead of the expected Schiff bases 8, analogously to p‐anisidine but unlike aniline.
Methylierung von 4‐Hydroxy‐4‐(2‐piperidyl)‐4H‐pyrazolo [1,5‐a]indol mit Formaldehyd und Ameisensäure. 11. Mitteilung über metallorganische Reaktionen und Folgeprodukte
Authors: Rihs Grety , Fuhrer Hermann , Marxer Adrian
Published: December 2004

In the 10th communication of this series [1] the synthesis of 4‐hydroxy‐4‐(2‐piperidyl)‐4H‐pyrazolo[1,5‐a]indole (4) was described (Scheme). Surprisingly enough, methylation of this compound with formaldehyde and formic acid led via ring closure and a subsequent rearrangement to a pentacyclic ketone. By means of 13C‐NMR.‐spectroscopy and mass spectroscopy, this ketone could be identified as a indolizino‐pyrazolo‐indole (9). Its structure and configuration were determined by X‐ray structure analysis.
Photolysis of dimethylnitrosamine in the gas phase
Authors: Geiger Georg , Huber J. Robert
Published: December 2004

Photodecomposition of dimethylnitrosamine in the gas phase ( ∼ 1 Torr) has been investigated following irradiation into the S1 (nπ*) ← S0 (363.5 nm) and S2 (ππ*) ← S0 (248.1 nm) transitions at room temperature. With a quantum yield of unity, excitation into the S1 state yields the fragments (CH3)2N⋅ and NO which then recombine leaving no photoproducts. The addition of O2 results in only one photoproduct, (CH3)2NNO2. Irradiating into the S2 state, the products CH2NCH3, (CH2NCH3)3, CH2NOH, N2O, NO, H2, and N2 were identified by capillary gas chromatography mass spectrometry. In the presence of N2 as a buffer gas the photoproducts are only CH2NCH3, (CH2NCH3)3, N2O, and H2. For both excitation conditions a mechanism is proposed involving cleavage of the N, N‐bond as the main primary photolytic process.
Synthesis of Open‐Chain 2,3‐Disubstituted 4‐nitroketones by Diastereoselective Michael‐addition of (E)‐Enamines to (E)‐Nitroolefins. A topological rule for C, C‐bond forming processes between prochiral centres. Preliminary communication
Authors: Seebach Dieter , Goliński Jerzy
Published: December 2004

The Michael‐additions of aliphatic, alicyclic, and arylsubstituted nitroolefins and enamines lead to γ‐nitroketones 3 in good chemical and excellent (> 90%) diastereomeric yields (see Table 1).

The known threo‐configuration of one type of adducts 3 (entries 8, 10, and 11 of Table 1) can be arrived at by assuming the approach 8 of the Michael‐acceptor and ‐donor; the reaction follows a topological rule, which is formulated and which is applicable to such diverse reactions as the diene synthesis, cyclopropanations, carbonyl olefinations and methylenations, aldol‐ and nitroaldol‐type additions, as well as additions of lithium, boron, and chromium derivatives to aldehydes (see 9, 10, 11, and Table 2).
Röntgenstrukturanalysen von Chiralen Ionophoren: NH4NCS‐Komplex von 9,9′‐Spirobifluoren‐22‐Krone‐5
Authors: Neupert‐Laves Katarina , Dobler Max
Published: December 2004

X‐ray Structure Analyses of Chiral Ionophores: The NH4NCS Complex of 9,9′‐Spirobifluorene‐22‐crown‐5

In the crystalline NH4NCS complex of 9,9′‐spirobifluorene‐22‐crown‐5 (1) the NH ion sits in the centre of the polyether ring, with distances of 2.92–3.15 Å to the five O‐atoms and shows at least twofold orientational disorder. In one orientation, three H‐atoms point toward O‐atoms and the fourth to the N‐atom of the anion situated 2.78 Å above the polyether ring. In another, only two H‐bonds are formed. The mean planes of the two fluorene parts of the molecule are perpendicular to each other.

Crystals of 2,2′‐bis (hydroxymethyl)‐9,9′‐spirobifluorene (2), an intermediate for the synthesis of 1, contain occluded benzene, which cannot be removed under vacuum. X‐ray analysis shows that the benzene molecule does not interact with the spirobifluorene in a specific way but merely occupies cages in the crystal packing.
The π‐Anisotropy of the Double Bond of a syn‐11‐Oxasesquinorbornene Derivative.. Stereoselectivity of the Diels–Alder additions of (2‐norborneno)[c]furan. Crystal structure of 11‐oxa‐endo‐tetracyclo[6.2.1.13,6.02,7]‐dodec‐2(7)‐ene‐9,10‐exo‐dicarboxylic anhydride
Authors: Hagenbuch Jean‐Pierre , Vogel Pierre , Pinkerton A. Alan , Schwarzenbach Dieter
Published: December 2004

The reaction of (2‐norborneno)[c]furan (4) with maleic anhydride gave 11‐oxa‐endo‐tetracyclo[6.2.1.13,6.02,7]dodec‐2(7)‐ene‐9,10‐exo‐dicarboxylic anhydride (5) and, with methyl acetylenedicarboxylate, methyl 11‐oxa‐endo‐tetracyclo [6.2.1.13,6.02,7]dodeca‐2(7),9‐diene‐9,10‐dicarboxylate (7). The syn‐11‐oxa‐sesquinorbornenes 5 and 7 could be equilibrated with their cycloaddents. They are at least 2 kcal/mol more stable than the corresponding anti‐sesquinorbornenes 6 and 8. The structure of 7 was deduced from its spectral data, by epoxidation with air or a peracid to give the exo‐epoxide 13 and by catalytic hydrogenation to give 14. The structure of 5 was established by single‐crystal X‐ray diffraction. A dihedral angle of 163° was measured between the C(1,2,7,8) and C(2,3,6,7) planes in 5. This important deviation from planarity for the C(2,7) double bond is attributed to (π, ω)‐repulsive interactions that make the π‐electron density of 2‐norbornene and 7‐oxa‐2‐norbornene derivatives preferentially polarized toward the exo‐face. This finding is discussed in relation with the relative stability of the syn‐ and anti‐ 11‐oxasesquinorbornenes and with the endo‐stereoselectivity of the cycloadditions of the norbornenofuran 4.
Isolation of Four Hexaketides from Verticillium intertextum. Preliminary communication
Authors: Trifonov Latchezar S. , Dreiding André S. , Hoesch Lienhard , Rast Dora M.
Published: December 2004

Aus dem Kulturmedium von Verticillium intertextum wurden vier Metabolite isoliert: Vertinolid (1) und Bisvertinochinol (2), beide bisher unbekannt, sowie das auch von Penicillium chrysogenum (= P. notatum) gebildete Sorbicillin (3) und das früher synthetisch hergestellte, aber noch nicht als Naturprodukt bekannte Dihydrosorbicillin (4). Hypothesen über gemeinsame Biosynthesewege werden erörtert.
The Photoelectron Spectra of 4, 13‐Diaza‐ and 4, 16‐Diaza [24] (1,2,4,5)cyclophanes
Authors: Zhong‐zhi Yang , Heilbronner Edgar , Kang Hee Chol , Boekelheide Virgil
Published: December 2004

A tentative assignment is proposed for the He (Ia) photoelectron (PE.) spectra of the title compounds. It is based on the assumption that the first four π‐bands occupy the same position in both spectra, as suggested by a qualitative correlation with the PE. spectrum of [24](1,2,4,5)cyclophane and by a previously proposed molecular orbital model. If this is accepted, then the bands due to electron ejection from the lone‐pair orbitals are split by roughly 0.8 eV in the case of the 4, 13‐diaza isomer, whereas no split can be detected in the case of the 4, 16‐diaza isomer.
Crystal Structure and Absolute Configuration of (+)‐(1S, 2R)‐5, 6‐Dimethylidene‐2exo‐norbornyl‐exo‐irontricarbonyl p‐Bromobenzoate
Authors: Barras Charles , Roulet Raymond , Chapuis Gervais , Chapuis Gervais
Published: December 2004

The title complex (+)‐13x has been prepared in an enantiomerically pure form. Its absolute configuration has been determined by single‐crystal X‐ray diffraction and has been correlated chemically to that of the 5, 6‐dimethylidene‐2‐norbornyl derivatives (—)‐1, (—)‐2, (—)‐3 and to (—)‐(1S, 2R)‐benzonorborn‐5‐en‐2‐yl acetate (s. Scheme 1), whose configuration was deduced by indirect techniques. A critical analysis of the chiroptical properties of the exocyclic dienes 1–3 is now possible. These compounds are limiting systems for the application of the allylic axial chirality rule, the generalized octant rule and the symmetry rule for βγ‐unsaturated ketones.
One‐Bond 13C, 13C‐Spin Coupling in η4‐, η3‐ and η2‐Olefin Transition Metal Complexes
Authors: Zobl‐Ruh Susanne , von Philipsborn Wolfgang
Published: December 2004

One‐bond 13C, 13C‐spin‐coupling constants have been measured, with natural isotope abundance, in η4‐diene, η3‐allyl and η2‐ene transition‐metal carbonyl complexes. Typical values of 1J(C,C) are given for Fe‐, Ru‐ and Os‐complexes with the three types of olefinic ligands. The effects of substituents and the structural significance of the C,C‐coupling constants are discussed.
Synthese von Astaxanthin aus β‐Jonon. I. Erschliessung der enantiomeren C15‐Wittigsalze durch chemische und mikrobiologische Racematspaltung von (±)‐3‐Acetoxy‐4‐oxo‐β‐jonon
Authors: Becher Elisabeth , Albrecht Robert , Bernhard Kurt , Leuenberger Hans G. W. , Mayer Hans , Müller Robert K. , Schüep Willy , Wagner Hans P.
Published: December 2004

Synthesis of Astaxanthin from β‐Ionone. I. A Route to the Enantiomeric C15‐Wittig Salts by Chemical and Microbial Resolution of (±)‐3‐Acetoxy‐4‐oxo‐β‐ionone

Racemic 3‐acetoxy‐4‐oxo‐β‐ionone (10) was synthesized from the industrially accessible intermediate β‐ionone (5). Resolution of 10 into its enantiomers was achieved via the corresponding diastereomeric camphanates and by microbial resolution. Site‐selective alkylation of racemic and of optically pure 3‐acyloxy‐4‐oxo‐β‐ionones with vinyl magnesium chloride at −70° furnished the corresponding 3‐acyloxy‐4‐oxo‐9‐vinyl‐β‐ionols which could be transformed to the Wittig salts 1, 3 and 4, respectively, following known procedures [1].
Technische Verfahren zur Synthese von Carotinoiden und verwandten Verbindungen aus 6‐Oxo‐isophoron. II. Ein neues Konzept für die Synthese von (3RS, 3′RS)‐Astaxanthin
Authors: Widmer Erich , Zell Reinhard , Broger Emil Albin , Crameri Yvo , Wagner Hans Peter , Dinkel Josef , Schlageter Markus , Lukáč T+odor
Published: December 2004

Technical Procedures for the Synthesis of Carotenoids and Related Compounds from 6‐Oxo‐isophorone. II. A Novel Concept for the Synthesis of (3RS, 3′RS)‐Astaxanthin

Starting from 6‐oxo‐isophorone (2) a new concept for a seven‐step synthesis of (3RS, 3′RS)‐astaxanthin (1) has been developed. As a key feature of the new approach, the oxidation state of astaxanthin (1) is adjusted already at an early stage of the synthesis. Thus, manipulation on more complex intermediates later in the synthesis is reduced to a minimum. Acetonide 10 or dimer 13 represent the key intermediates of this concept (Scheme 2). The whole sequence has been run on a kg scale with an overall yield of 52% (s. Scheme 5).
Umlagerung von α‐Halogen‐ in α′‐Halogen‐cyclobutanone, Schlüsselstufe einer variationsreichen Synthese von Pyrethroiden
Authors: Martin Pierre , Greuter Hans , Winkler Tammo , Belluš Daniel , Rihs Grety
Published: December 2004

Rearrangement of α‐Halogen‐ to α′‐Halogen‐cyclobutanones, Key Step of a Highly Versatile Synthesis of Pyrethroids

α‐Halogenocyclobutanones, which are readily available by [2 + 2]‐cycloaddition of haloketenes to terminal olefins (e. g. 5 → 6), undergo an efficient and stereoselective cine‐rearrangement to α′‐halogenocyclobutanones in the presence of catalysts such as tertiary amines, HX acids or quaternary ammonium salts (e. g. 6 → 7, Table 1). Preparative as well as mechanistic aspects of the cine‐rearrangement are discussed. The 2,4‐cis‐disubstituted cyclobutanones 7–32 thus formed represent valuable intermediates in a new synthesis of pyrethroids 1.

The X‐ray structure of 2‐chloro‐4‐(2,2,2‐trichloroethyl)‐3,3‐dimethylcyclobutanone (7), the most important precursor of cis‐3 (X = Cl) shows the following features: a puckered cyclobutanone ring (dihedral angle 31°), 2,4‐cis‐di‐pseudoequatorial arrangement of the chloro and trichloroethyl substituents, and an endo‐deviation (0.225 Å; 11°) of the carbonyl O‐atom from the plane formed by C(1), C(2) and C(4) (Fig. 2).
Azimine. VI. 1‐Alkoxycarbony 1‐2,3‐dialkyl‐ und ‐2,3‐diaryl‐azimine
Authors: Leuenberger Christian , Hoesch Lienhard , Dreiding André S.
Published: December 2004

Azimines VI: 1‐Alkoxycarbonyl‐2,3‐dialkyl‐ and ‐2,3‐diarylazimines

Alkoxycarbonyl‐nitrenes 2 – generated in situ by α‐elimination from N‐[(4‐nitrophenyl)‐sulfonyloxy]carbamates 4 – were reacted with six aliphatic and aromatic azo compounds to yield 1‐alkoxycarbonyl‐azimines 11 (R′ = Alkyl). Thus, (2Z)‐ or (2E)‐ 1 ‐alkoxycarbonyl‐2,3‐diisopropyl‐azimines (8 or 9) were obtained stereospecifically from (E)‐ or (Z)‐1,1′‐dimethylazoethane (5 or 6) and 1‐alkoxycarbonyl ‐2,3‐(cis‐1,3‐cyclopentylene)‐azimines (10) resulted from 2,3‐diazabicyclo[2.2.1]‐2‐heptene (7), always using both ethoxy‐ and methoxycarbonyl‐nitrene (2a and 2b). With 2a, (E)‐azobenzene (14) was converted only to a single stereoisomer of 1‐ethoxycarbonyl‐2,3‐diphenyl‐azimine (17) and both stereoisomers of azo(p‐toluene) (15 or 16) reacted to give the same stereoisomer of 1‐ethoxycarbonyl‐2,3‐di(p‐tolyl)‐azimine (18).
On the Absolute Configuration of Indane‐1‐carboxylic Acid
Authors: Brewster James H.
Published: December 2004

Doubts that have recently been expressed [1] about the currently accepted (+)‐(R), (−)‐(S) [2] absolute configuration of indane‐1‐carboxylic acid appear to be unwarranted. Our ORD. values for 1‐methylindane [12] are in error.
Über die Enantiomerentrennung durch Verteilung zwischen flüssigen Phasen
Authors: Prelog Vpm Vladimir , Stojanac Žarko , Kovčević Krunoslav
Published: December 2004

Separation of Enantiomers by Partition between Liquid Phases

Salts of enantiomeric α‐aminoalocohols such as norephedrin, with lipophilic anions, such as hexafluorophosphate ion, can be separated by partition between aqueous and lipophilic phase containing esters of tartaric acid.
Structures of Ganoderic Acid A and B, Two New Lanostane Type Bitter Triterpenes from Ganoderma lucidum (FR.) KARST.
Authors: Kubota Takashi , Asaka Yukihiro , Miura Iwao , Mori Hideo
Published: December 2004

The structures of two new bitter triterpenes, ganoderic acid A and B. isolated from a mushroom Ganoderma lucidum (FR.) Karst. (Polyporaceae) were determined as 1 and 2 on the basis of spectral data. Ganoderic acid A is a novel highly oxidized triterpene bearing a boat‐shaped A‐ring of lanostane.
Desoxy‐nitrozucker. 2. Mitteilung Herstellung geschützter 1‐Desoxy‐1‐nitroaldosen
Authors: Aebischer Bernard , Vasella Andrea , Weber Hans‐Peter
Published: December 2004

Synthesis of Protected 1‐Deoxy‐1‐nitroaldoses

The direct oxidation of the oxime 1 with t‐butyl hydroperoxide and vanadyl acetylacetonate yielding the nitro derivative 2 (54%, Scheme 1) could not be applied to other oximes. Diastereoselective bromination of the aldonolactone oxims 7 and 10–12 according to known procedures gave the corresponding bromonitroso compounds which were oxidized to the bromonitro compounds 9, 14, 18 and 22, respectively. Oxidation of the bromonitroso compound in the D‐mannopyranose series proved difficult, but the corresponding chloronitro derivative 23 was easily obtained according to Corey & Estreicher (Scheme 2 and 3). The structure of the bromonitro compound 9 was determined by an X‐ray analysis, and the configurations of the bromonitro compounds 14, 18 and 22 were deduced from their molecular rotations. Reduction of the bromonitro compounds gave the protected 1‐deoxy‐l‐nitroaldoses 2, 15/16, 19/20, and 24/25, respectively, in good overall yields. The ribose derivatives 15 and 16 were detritylated to give the nitro compound 4, and the mannose derivative 2 was partially deprotected to give the monoisopropylidene compound 26. The nitro group shows a normal anomeric effect which is reflected in the IR. spectra of the pyranose derivatives 19 and 20, and 24 and 25.
Studies Related to Biological Detoxification of Kraft Pulp Mill Effluent. III. The Biodegradation of Abietic Acid with Mortierella isabellina
Authors: Kutney James P. , Dimitriadis Eugene , Hewitt Gary M. , Singh Mahatam , Worth Brian R.
Published: December 2004

A study relating to the biological detoxification of resin acids is described. Abietic acid was transformed into a number of non‐toxic hydroxylated derivatives by Mortierella isabellina. The biotransformation products have been identified and shown to be less toxic than abietic acid.
Synthesis and Mesomorphic Properties of 2,6‐Disubstituted Tetralins
Authors: Cereghetti Marco , Marbet Roman , Schleich Kuno
Published: December 2004

Synthesis and mesomorphic behavior of nine members of each of the two classes of 6‐phenyl‐ and 2‐phenyltetralins and five members of the 2‐trans‐cyclohexyltetralins are reported. The synthesis of one member of each class is described in detail. Besides the target compounds, more than twenty intermediates showed liquid crystalline properties; their transition temperatures are recorded (see Tables 1‐6).
Isozeaxanthine: Chiralität und enantioselektive Synthese von (4R,4′R)‐Isozeaxanthin ((−)‐(4R, 4′R)‐β, β‐Carotin‐4,4′‐diol)
Authors: Haag Andreas , Eugster Conrad Hans
Published: December 2004

Isozeaxanthin: Chirality and Enantioselective Synthesis of (4R,4′R)‐Isozeaxanthin ((−)‐(4R,4′R)‐β, β‐Carotin‐4,4′‐diol)

The absolute configuration of optically active isozeaxanthin was established by synthesis using (−)‐(R)‐4‐hydroxy‐β‐ionon (2) [18] as starting material.
Molecular Receptors. Structural Effects and Substrate Recognition in Binding of Organic and Biogenic Ammonium Ions by Chiral Polyfunctional Macrocyclic Polyethers Bearing Amino‐Acid and Other Side‐Chains
Authors: Behr Jean‐Paul , Lehn Jeau‐Marie , Vierling Pierre
Published: December 2004

The stability constants of the complexes formed by the polyfunctional macro‐cyclic receptor molecules of type 1 with cationic substrates have been determined and analyzed in terms of structural factors. The binding strength is dominated by electrostatic interactions; the tetracarboxylate 1 (O−) forms by far the most stable complexes of all known macrocyclic polyethers. Lipophilic groups also significantly enhance stabilities, stressing the role of such residues in biological receptor sites. The complexation selectivity of organic ammonium cations is determined by two main factors: (a) central discrimination, resulting from the macrocyclic cavity, strongly favors binding of primary ammonium cations with respect to more highly substituted ones and also distinguishes among (R‐NH3+)‐substrates differently substituted on the C(α)‐atom; (b) lateral discrimination arises from interactions between the substrate and the side chains borne by the macrocycle; again electrostatic and lipophilic group effects play the major role; diammonium cations are especially strongly bound. Complexation of biogenic amines follows the same trends; for instance noradrenaline and norephedrine are selectively bound with respect to adrenaline and ephedrine, pointing towards potential applications in selective binding and transport of biologically active substances.
Computer‐Assisted Structural Interpretation of 1H‐NMR. Spectral Data
Authors: Egli Huidrych , Smith Dennis H. , Djerassi Curl
Published: December 2004

Interactive computer programs for the establishment and maintenance of a 1H‐NMR. data base, the prediction of 1H‐NMR. shifts and the rank‐ordering of structural candidates based on comparison between observed and predicted spectra are presented. The programs take into account configuration, at stereocenters and double bonds, as well as diastereotopy. We demonstrate how, for purposes of structure elucidation, these new programs can be linked to the GENOA and STEREO programs.
Ringschlüsse an Chinonylmethanfarbstoffen und analogen Merocyaninen. 6. Mitteilung. Über die Reaktivität des Cyclohexylrestes in 2‐Chlor‐3‐[(1‐cyclohexyl‐6‐fluor‐3‐methyl‐1H‐chinoxalin‐2‐yliden)methyl]‐1,4‐naphthochinon
Authors: Schelz Dieter , Rotzler Niklaus
Published: December 2004

Ring Closure in Quinonylmethane Dyes On the Reactivity of the Cyciohexyl Moiety in 2‐Chloro‐3‐[(1‐cyclohexyl‐6‐fluoro‐3‐methyl‐1H‐quinoxalin‐2‐ylidene)niethyl]‐1,4‐naphthoquinonc

The reactive title compound (1a, X = F, R1 = C6H11, R2=Cl) was obtained from the reaction of 1‐cyclohexyl‐6‐fluoro‐2,3‐dimethylquinoxalinium perchlorate with 2,3‐dichloro‐1,4‐naphthoquinone. Upon treatment with pyridine and acetic acid in acetone and separation of the desired naphthophenazinone 2a, an unexpected azepinoquinoxaline 4a was isolated. The structure of 4a was determined by its mass and 360‐MHz‐1H‐NMR. spectra in connection with decoupling experiments.
Synthèse de la diméthyl‐4,4‐dihydrofuranedione‐2,3
Authors: Fizet Christian
Published: December 2004

4,4‐Dimethyl‐dihydro‐2,3‐furanedione (4), an intermediate in the synthesis of (+)‐D‐pantothenic acid, is obtained in good yield from readily available substances such as isopropyl chloride, diethyl oxalate and formaldehyde, without oxidative conditions.
1,2‐Shift of a Carboxyl Group in a Wagner‐Meerwein Rearrangement
Authors: Berner Daniel , Cox D. Philip , Dahn Hans
Published: December 2004

On treatment with HSO3F in SO2C1F at 0°, 3‐hydroxy‐2,2‐dimethyl‐3‐phenyl‐propionic acid (1a) is transformed into 2‐phenyl‐3‐methyl‐2‐butenoic acid (2a) (isolated yield: 40–44%). Using monolabelled [3‐13C]‐1a (1a*) and doubly labelled [1,3‐13C2]‐1a (1a**), the migration of HOOC (or a mechanistically equivalent group) was proved; a cross experiment established the intramolecular character of the rearrangement. By following the reaction at low temperature in an NMR. spectrometer, the formation of intermediates and side products was demonstrated.
Concerning the Stereochemical Course and Mechanism of the Photochemical 1,3‐Acetyl Shift in a β,γ‐Unsaturated Ketone. Preliminary Communication
Authors: Sadler David E. , Hildenbrand Knut , Schaffner Kurt
Published: December 2004

Enantiomerically enriched samples of 1,2‐dimethyl‐3‐(2H3)methyl‐2‐cyclopentenyl (1) and 1‐(2H3)methyl‐2,3‐dimethyl‐2‐cyclopentenyl methyl ketones (2) have been irradiated at 313 nm in methanol in the temperature range +50 to −45°. The 1,3‐acetyl shift, which interconverts the two isomeric ketones, occurs with a small change in the enantiomeric composition and independently of temperature in the range studied. This change corresponds to an upper limit of approximately 20% reaction with racemization. It is proposed that reaction occurs from both the S1(n, π*) and T2(n, π*) excited states with stereospecific reaction from S1 (rapid primary geminate recombination of a singlet radical pair, with a possible contribution by a concerted 1,3 shift) dominating throughout the temperature range, but with the proportion of reaction from T2 increasing as the temperature is lowered. The racemization results from secondary geminate recombination of the singlet and triplet radical pairs and the random recombination of free radicals. Viscosity effects are proposed to explain the independence of the racemization on temperature.
Carotenoids of the Carotenoprotein Asteriarubin. Optical Purity of Asterinic Acid
Authors: Bernhard Kurt , Englert Gerhard , Meister Walter , Vecchi Max , Renstrøm Britta , Liaaen‐Jensen Synnøve
Published: December 2004

The carotenoid composition of the carotenoprotein asteriarubin ex the starfish Asterias rubens, determined by HPLC, comprised canthaxanthin (6, 3% of total), all‐trans‐astaxanthin (1, 14%), all‐trans‐7,8‐didehydroastaxanthin (2, 24%), all‐trans‐7,8,7′,8′‐tetradehydroastaxanthin (3, 43%) and 4‐oxomytiloxanthin (7, 10%). The previously unknown 4‐oxomytiloxanthin was tentatively identified by the UV./VIS., 'H‐NMR. spectra and MS. data.

The optical purity was determined by HPLC. of the di‐(−)‐camphanates, by comparison with those of synthetic standards: 7,8,7′, 8′‐tetradehydroastaxanthin (92% (3S, 3′S), 2% meso), 7,8‐didehydroastaxanthin (89% (3S,3′S), 2% meso?), and astaxanthin (78% (3S,3′S), 14% (3R,3′S), and 5% (3R,3′R)). It is concluded that the acetylenic derivatives of astaxanthin in contrast to astaxanthin from marine animal sources are essentially pure (3S, 3′S)‐isomers. This might reflect their probable metabolic formation by 4‐oxo modification of acetylenic (3R,3′R)‐carotenols ex Mytilus edulis in their diet.
Addition of Vinylketenes to Enamines. A Method for the Preparation of 6,6‐Dialkylcyclohexa‐2,4‐dienones and 4,4‐Dialkyl‐2‐vinylcyclobutenones
Authors: Berge John M. , Rey Max , Dreiding André S.
Published: December 2004

Addition von Vinylketenen an Enamine. Eine Methode zur Herstellung von 6,6‐Dialkylcyclohexa‐2,4‐dienonenund4,4‐Dialkyl‐2‐vinylcyelobutenonen

Drei Enamine (1–3) wurden mit fünf Vinylketenen (5a–5e) (s. Schema 2) zur Reaktion gebracht. Die Vinylketene wurden in situ durch HCl‐Eliminierung aus α,β‐ungesättigten Säurechloriden mit Triäthylamin hergestellt. Die Cycloadditionen von 1–3 an 5a–5e führten zu 6,6‐Dialkyl‐5‐dialkylaminoeyclohex‐2‐enonen (kurz: Cyclohexenone) bzw. zu 3‐Dialkylamino‐4,4‐dimethyl‐2‐vinylcyclobutanonen (kurz: Vinylcyclobutanone) oder zu einem Gemisch der beiden, je nach Natur der Partner bzw. des Lösungsmittels (s. Tab. 1). Durch oxydative Amin‐Eliminierung wurden die Cyclohexenone in 6,6‐Dialkylcyclohexa‐2,4‐dienone und die Vinylcyclobutanone in 4,4‐Dialkyl‐2‐vinylcyclobutenone übergefuhrt.

Diese Reaktion stellt eine einfache Synthese von verschieden substituierten 6.6‐Dialkylcyclohexa‐2,4‐dienonen bzw. 4,4‐Dialkyl‐2‐vinylcyclobutenonen (siehe Schema 1) dar.
Nucleophilic addition to C, C‐double bonds. VI. Intramolecular addition of primary amines to C, C‐double bonds induced by steric compression
Authors: Tombo Gerardo M. Ramos , Ganter Camille
Published: December 2004

The tricyclic olefinic primary amine 1 readily cyclizes to the tetracyclic secondary amine 2 at approximately 200° in protic as well as aprotic solvents although the C, C‐double bond is not activated by electron‐attracting groups. This unusual intramolecular addition is the consequence of the close proximity of the nucleophile and the double bond.

For the synthesis of the sterically highly hindered amine 1, the tricyclic oxime 4 was reduced with TiCl3 to the remarkably stable imine 5 and the latter treated with AlH3. On the other hand, reaction of 4 with AlH3 yielded the pentacyclic aziridine 6.
Enantioselective Synthesis of Pseudomonic Acids. I. Synthesis of Key Intermediates
Authors: Schönenberger Bernhard , Summermatter Walter , Ganter Camille
Published: December 2004

An enantioselective synthesis of key intermediates for the synthesis of the anti‐microbially active pseudomonic acids A (1), B (2) and C (3) is described. D‐Ribose (4) was used as starting material.
Synthesis of (±)‐Desmarestene and (±)‐Viridiene, the Two Sperm Releasing and Attracting Pheromones from the Brown Algae Desmarestia aculeata and Desmarestia viridis
Authors: Boland Wilhelm , Jakoby Karin , Jaenicke Lothar
Published: December 2004

Desmarestene 1 6‐(1Z,3‐butadienyl)‐1,4‐cycloheptadiene and viridiene 3 cis‐3‐(1Z, 3‐butadienyl)‐4‐vinylcyclopentene are chemical messengers for male gametes of the brown algae Desmarestia aculeate and Desmarestia viridis. Total syntheses of 1, 3 and their stereoisomers 1a, 3a‐c are reported. Gas‐chromatographic comparison of synthetic 1 and 3 with the corresponding natural products has established their structural identity.
Photochemical Reactions 127th CommunicationPhotochemistry of Epoxy‐enones: Intramolecular Trapping of a Carbonyl Ylide
Authors: Ohta Shigeru , Frei Bruno , Jeger Oskar
Published: December 2004

On 1n, π* ‐excitation 5, 6‐epoxy‐2‐hydroxy‐5, 6‐dihydro‐β‐ionone ((E)‐4) shows the typical behaviour of a, β‐unsaturated γ, δ‐epoxy ketones undergoing primarily C(γ), O‐cleavage of the oxiran. However, 1π, π*‐excitation of (E)−4 leads to enol ether 10 which is formed by intramolecular insertion of the hydroxyl group of the ylide c.
Norbornanes. Part 10. Solvolysis of the Stereoisomeric 6‐Cyano‐2‐norbornyl p‐Toluenesulfonates. A Correction
Authors: Grob Cyril A. , Herzfeld Danielle
Published: December 2004

The solvolysis products of the stereoisomeric 6‐cyano‐2‐norbornyl p‐toluene sulfonates 1‐4 (R  CN) in dioxane/water 7 : 3 have been determined. In contrast to an earlier report the 6exo‐cyano‐2exo‐norbornyl p‐toluenesulfonate (1; RCN) yields 30% of the 2endo‐alcohol 9 (RCN) beside the 2exo‐alcohol 10 and the norbornenes 12 and 13. The results confirm that ‐ I substituents at C(6) reduce 1,3‐bridging in the intermediate norbornyl cation and hence its rate of rearrangement. The relatively high rate constants for some 6‐fluoro‐ and 6‐cyano‐2exo norbornyl p‐toluenesulfonates are ascribed to C, C‐hyperconjugation assisted by the conjugative effects of the 6‐fluoro and cyano substituents.
The Electronic Fine Structure of Co (11)‐Complexes with Schiff‐Base Ligands
Authors: Daul Claude , Weber Jacques
Published: December 2004

Multiple‐scattering‐Xα MO‐calculations are reported for Co (acacen). The results are essentially in agreement with extended Hückel calculations and EPR. data. Particular emphasis has been placed on the calculation of the electronic structure and one‐electron properties, i.e. state energies diagram, spin‐orbit coupling and hyperfine coupling based on a ligand field interpretation of the Xα‐results, which allow to rationalize the main features of the EPR. spectra.
Spectroscopic Investigation of Anhydrous Solutions of Europium Perchlorate and Europium Nitrate in N, N‐Dimethylformamide
Authors: Bünzli Jean‐Claude G. , Yersin Jean‐Robert
Published: December 2004

Anhydrous solutions of Eu(ClO4)3 and Eu (NO3)3 0.05m in N, N‐dimethyl formamide (DMF) are investigated by means of conductometric measurements, vibrational spectroscopy, electronic absorption and emission spectra, and fluorescence lifetime determinations. Eu (ClO4)3 is completely dissociated and no inner‐sphere interaction takes place between ClO4 and Eu3+ ions. The solvated species Eu (DMF) has a C2v‐symmetry and x is probably equal to 8.

A more complicated situation occurs for Eu (NO3)3, the solutions of which contain at least three different solvates; the predominant species is [Eu (NO3)2 (DMF)x−4]+ (≈80% of the total Eu‐concentration) and it is more stable than the mononitrato complex [Eu (NO3) (DMF) X−2]2+; the neutral complex Eu (NO3)3 (DMF) x−6 is also present, as can be inferred from a high‐resolution analysis of the 5D0→7F0 emission band. The absence of emission from the excited 5D1‐level can be rationalized in terms of an efficient non‐radiative deexcitation path through a vibrational mode of the DMF‐molecules bonded to the central metal ion.