bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nucleophilic Addition to a Triple Bond; Preliminary ab initio study
Authors: Eisenstein Odile , Procter Garry , Dunitz Jack D. 
Published: December 2004

AbstractPreliminary ab initio, calculations (minimal basis set STO‐3 G) suggest that the preferred direction of approach of a nucleophilic centre towards a CC triple bond makes an obtuse angle (∼120°) with this bond. The stereoelectronic requirements for nucleophilic addition to triple bonds and to ketones are thus rather similar.
Synthese von optisch aktiven, natürlichen Carotinoiden und strukturell verwandten Naturprodukten. II. Synthese von (3 S, 3′S)‐Astaxanthin
Authors: Kienzle Frank , Mayer Hans 
Published: December 2004

Synthesis of optically active natural carotenoids and structurally related compounds. II. Synthesis of (3S, 3′S)‐astaxanthinThe syntheses of rac. astaxanthin, (3 S, 3′S)‐astaxanthin (1), its 15‐cis isomer (21), its diacetate (22), and of (3 S, 3′ S)‐15, 15′‐didehydroastaxanthin (20) are reported.
Valenzisomerisierungsversuche an substituierten 2‐Phenyl‐4‐phenylazo‐benzotriazolen: Grenzen derBoulton‐Katritzky‐Umlagerung
Authors: Balli Heinz , Gunzenhauser Sigmund 
Published: December 2004

Attempts of Valence Isomerization on Substituted 2‐Phenyl‐4‐phenylazo‐benzotriazoles: Limits of theBoulton‐KatrizkyRearrangementSubstituted 2‐phenyl‐4‐phenylazo‐benzotriazoles are prepared and their UV./VIS.,1H‐NMR. and mass spectra discussed. A thermic or photochemical valence tautomerization according to theBoulton‐Katritzkyrearrangement could not be proved.
Die Struktur des Spermin‐Alkaloides Aphelandrin aus Aphelandra squarrosa NEES. 170. Mitteilung über organische Naturstoffe
Authors: Dätwyler Peter , Bosshardt Herbert , Bernhard Heinz O. , Hesse Manfred , Johne Siegfried 
Published: December 2004

The structure of the spermine alkaloid aphelandrine from Aphelandra squarrosa NEESThe new spermine alkaloid aphelandrine (2) has been isolated from Aphelandra squarrosa NEES. By oxidation of 2 with KMnO4 followed by methylation (CH2N2) 12 and 14 could be prepared (Scheme 2). Fusion of 2 with KOH yielded spermine (1) whereas hydrolysis of 2 in hot hydrochloric acid results in lacton 17, the structure of which could be elucidated by comparison with a synthetically prepared model compound (Scheme 3). The benzylic bonds N (10), C(11) as well as O(16), C(17) of 2 could be cleaved by hydrogenolysis (compare 23 and 26; Scheme 4). The elucidation of the correct linkage of the spermine moiety with the aromatic dicarboxylic acid is based mainly on chemical and spectroscopic evidence of the tetrahydro derivative 26, the Hofmann‐degradation products 28, 30 and 31 (Scheme 6) as well as the ester 35, prepared by partial hydrolysis of 2 (Scheme 7).
Neue Macrolide und einige Sesquiterpen‐Derivate aus dem Galbanum‐Harz
Authors: Kaiser Roman , Lamparsky Dietmar 
Published: December 2004

New Macrolides and Some Sesquiterpenoid Derivatives Occurring in Galbanum AbsoluteAnalytical investigations of a Galbanum absolute have revealed for the first time the presence of four macrolides 1–4 derived from the corresponding hydroxylated C13–C16 fatty acids by lactonization of a secondary alcoholic group with the carboxylic group. The musky odor strengthens with increasing number of members in the macrocycle, whereas the woody note is predominant in the smaller rings. Isolation, identification and synthesis of the new naturally occurring substances are described.Shyobunol (24) epishyobunol (25) as well as their acetates 26 and 27 were identified ‐ together with 10‐epijunenyl acetate (28) ‐ in the same substrate, thus indicating 25 and 26 to be natural products. The corresponding known and already naturally occurring ketones 23 and 24 are trace components in the investigated material derived from the so‐called Galbanum oleo‐gum‐resin.
Über Pterinchemie. 68 Mitteilung [1]. Regiospezifische Deuterierungen von Folsäure
Authors: Khalifa Esam , Furrer Hans‐Jürg , Bieri Jost H. , Viscontini Max 
Published: December 2004

Regiospecific deuteriation of folic acidIntroduction of a nitroso function at the N (10)‐position of folic acid activates the C(9)‐hydrogen atoms in such a way, that the exchange of H with D at this position, in NaOD‐solution, is extremely facilitated. This fact is utilized in the synthesis of 9,9‐dideuterio‐folic acid (IV), 7,9,9‐trideuterio‐folic acid (VII) and 7‐deuterio‐folic acid (IX). These three products are necessary for the 1H‐NMR.‐spectroscopical determination of the conformation of 5,6,7,8‐tetrahydrofolic acid and its derivatives.
Eine decarboxylative Dimerisierung von Maleinsäureanhydrid zu Dimethylmaleinsäureanhydrid
Authors: Baumann Marcus E. , Bosshard Hans 
Published: December 2004

Decarboxylative Dimerization of maleic Anhydride to Dimethylmaleic AnhydrideWe have found a simple synthesis of dimethylmaleic anhydride (1). Treatment of maleic anhydride (2) in boiling acetic acid in presence of 2‐aminopyridine gives, with decarboxylation, 1 in a one‐pot reaction in good yield.
Stoffwechselprodukte von Mikroorganismen. 193. Mitteilung. Ferrithiocin
Authors: Naegeli Hans‐Ulrich , Zähner Hans 
Published: December 2004

Metabolites of Microorganisms. FerrithiocinThe strain Tü 1998 from Streptomyces antibioticus produces besides the indicator antibiotics β‐ and γ‐rubromycins a new sulfur containing metabolite. This metabolite, called ferrithiocin, has been isolated in the form of a iron complex. The structure 1 of the iron‐free compound was elucidated by spectroscopic studies and chemical degradation.
Formation of N‐Hydroxy‐amines of Spin Labeled Nucleosides for 1H‐NMR. Analysis
Authors: Ozinskas Alvydas J. , Bobst Albert M. 
Published: December 2004

AbstractAmine‐oxide radical 1a was efficiently converted to the corresponding N‐hydroxy‐amine 2a with sodium dithionite in acetone/water. This reaction was used to develop a procedure for monitoring the NMR. spectra of sodium dithionite reduced amine‐oxide radicals and of novel reduced amine‐oxide‐labeled nucleosides.
Notizen zur Synthese von 2‐Aminophenylsulfonen
Authors: Courtin Alfred , von Tobel Hans‐Rudolf , Auerbach Günther 
Published: December 2004

Syntheses of some Alkyl, Cycloalkyl and Aryl 2‐Aminophenyl SulfonesSyntheses of the alkyl, cycloalkyl and aryl 2‐aminophenyl sulfones 10 were achieved by oxidation of the corresponding 2‐nitrophenyl sulfides 7 to the 2‐nitrophenyl sulfones 9 followed by ethanolic Béchamp‐reduction. The sulfides 7 in turn were obtained either by reactions of 2‐nitro‐thiophenol (8) with the appropriate alkyl and cycloalkyl halides or of 2‐chloro‐nitrobenzene (5) with the relevant thiols. Condensation of 2‐nitrobenzenesulfinic acid (3) with bromoacetic acid in aqueous alkaline solution led ‐ presumably via 2‐nitrophenylsulfonylacetic acid (4) ‐ to methyl 2 nitrophenyl sulfone (1), reduction of which gave 2‐aminophenyl methyl sulfone (2). Treatment of 2‐aminothiophenol (11) with t‐butyl alcohol in aqueous sulfuric acid gave 2‐aminophenyl t‐butyl sulfide (12), which was acetylated to o‐t‐butylthio‐acetanilide (13). Oxidation of the latter to o‐t‐butylsulfonyl‐acetanilide (14) followed by hydrolysis led to 2‐aminophenyl t‐butyl sulfone (15).
Selectivity of Intramolecular Radical Addition Reactions Cyclization of ω‐Alkenyl Radicals
Authors: Bischof Peter 
Published: December 2004

AbstractSmall ω‐alkenyl radicals are known to cyclize exclusively via the unexpected Anti‐Markownikow pathway which leads to cycloalkyl‐methyl radicals as the observed reaction products. The strong kinetic preference diminishes, as the linking methylene chain becomes larger. Semiempirical calculations using MINDO/3‐UHF allow to classify the observed reaction pathways as individual probes between allowed (n = 1, route A) and electronically favourable (n = ∞, route M) routes of reactions.
Synthese von optisch aktiven, natürlichen Carotinoiden und strukturell verwandten Naturprodukten. IV. Synthese von (3R, 3′R, 6′R)‐Lutein. Vorläufige Mitteilung
Authors: Mayer Hans , Rüttimann August 
Published: December 2004

Synthesis of optically active natural carotenoids and structurally related compounds. IV. Synthesis of (3R, 3′R, 6′R)‐luteinThe synthesis of (3R, 3′R, 6′R)‐lutein (19) according to the building principle C25+C15C40 is reported utilizing (R)‐4‐hydroxy‐2,6,6‐trimethyl‐2‐cyclohexen‐1‐one (4) as a readily available key intermediate.
Synthese von optisch aktiven, natürlichen Carotinoiden und strukturell verwandten Naturprodukten. VI. Synthese von Picrocrocin
Authors: Mayer Hans , Santer Jean‐Marie 
Published: December 2004

Synthesis of optically active natural carotenoids and structurally related compounds. VI. Synthesis of PicrocrocinThe synthesis of picrocrocin (6), the bitter essence of saffron (Crocus sativus L.) is reported utilizing (3R)‐3‐hydroxy‐β‐cyclogeranyl acetate (3) as a readily available building unit.
Photochemische Reaktionen. 110. Mitteilung [1]. Zur Photochemie γ,δ‐Methano‐α‐enone
Authors: Ishii Keitaro , Wolf Hans Richard , Jeger Oskar 
Published: December 2004

Photochemistry of γ,δ‐Methano‐α‐enonesDirect excitation (λ = 254 or ≥ 347 nm) converts the γ,δ‐methano‐α‐enone (E)‐10 into the isomeric ether 23 and the isomeric diene‐ketone 24. Furthermore, on 1π,π*‐excitation (λ = 254 nm) (E)‐10 undergoes an 1,3‐homosigmatropic rearrangement yielding the enone (E)‐25. In addition (E → Z)‐isomerization of (E)‐10 and conversion of 10 to the isomeric furan 28 is observed.The isomerization (E)‐10 → 23, 24 and (E)‐25 proceeds by photocleavage of the C(γ), C(δ)‐bond, whereas the formation of 28 occurs by photocleavage the C(γ), C(δ)‐bond together with that of the C(γ), C(δ′)‐bond of 10.On direct excitation the bicyclic diene‐ether 23 yields the methano‐enone 10, the dieneketone 24 and the tricyclic ether 29. Evidence is given, that the conversion 23 → 10 is a singulet process. On the other hand, the isomerization 23 → 24 and the intramolecular [2 + 2]‐photocycloaddition 23 → 29 are shown to be triplet reactions.Irradiation (λ = 254 nm) of the homoconjugated ketone 24 yields the isomeric ketone 27 by an 1,3‐acyl shift. The excitation of the (E)‐enone 25 induces (E → Z)‐isomerization and photoenolization to give the homoconjugated ketone 26.
Differential Hydrogen Exchange During Biosynthesis of Cytochalasins B and D
Authors: Wyss Ronald , Tamm Christoph , Vederas John C. 
Published: December 2004

AbstractSodium [2‐13C,2‐2H3]acetate was incorporated into cytochalasin B(1) by Phoma exigua and into cytochalasin D (2) by Zygosporium masonii. The 13C‐NMR. and 2H‐NMR. of the metabolites showed that most of the deuterium was lost except at carbon atoms which are in polyketide chain‐initiating units.
Steroide und Sexualhormone. 260. Mitteilung. Limonoide Bitterstoffe V. Untersuchungen zur Stereochemie der C(8)‐Alkylierung von 7‐Oxo‐13,17‐secosteroiden
Authors: Schlatter Hans‐Rudolf , Graf Walter 
Published: December 2004

On the Stereochemistry of the C(8)‐Alkylation of 7‐Oxo‐13,17‐secosteroidsIt is shown that the title compounds, e.g. 10, can be alkylated with methyl iodide under strongly basic conditions to afford 8α‐methylated products, e.g. 11 (Scheme 1). The configuration was assigned by 13C‐NMR.‐spectroscopy, CD. measurements, and finally proved by a X‐ray crystallographic structure analysis.
Steroide und Sexualhormone. 261. Mitteilung. Quassinoide Bitterstoffe II. Partialsynthetischer Zugang zu Quassin: Überführung von Testosteron in eine Schlüsselverbindung mit angulärer 8β‐Methylgruppe
Authors: Pfenninger Johannes , Graf Walter 
Published: December 2004

Partial Synthesis of Quassin: Synthesis of a Key Intermediate with an Angular 8β‐Methyl Group from TestosteroneA key intermediate in the partial synthesis of quassin (1) was synthesized in 28 steps starting from testosterone (9) (Scheme 3). The key features are: (i) The conversion of testosterone (9) into the 1α, 2β, 3β‐O‐substituted 4α‐methylandrostane 19 (Scheme 3) and its transformation into an intermediate 26 with the ring A partial structure of quassin (Scheme 4). (ii) The conversion of 19 to the vinylogous α‐hydroxyketone 5 (Scheme 6 and 7). (iii) The photochemically induced [2+2]‐cycloaddition of allene to hydroxyenone 5, affording the 8β, 14β‐cyclobutano‐derivative 6 (Scheme 2 and 8). (iv) The conversion of 6 into the key compound 7.In connection with this last transformation a new method for the degradation of phenylselenoesters of carboxylic acids to the corresponding nor‐alkanes was developed (see Scheme 8). Details of this reaction will be published elsewhere [18].
Synthese bicyclischer Retinoide aus Retinsäure
Authors: Loeliger Peter , Mayer Hans 
Published: December 2004

Synthesis of Bicyclic RetinoidsThermally induced ring formation of 2 and of its 1‐alkenyl silyl ether derivative leads selectively to new bicyclic derivatives. The new retinoid 8 was synthesized and found to have potent biological activity.
Beitrag zur Analytik und Synthese von 3‐Hydroxy‐4‐oxocarotinoiden
Authors: Müller Robert K. , Bernhard Kurt , Mayer Hans , Rüttimann August , Vecchi Max 
Published: December 2004

Contribution to the Analytical Separation and the Synthesis of 3‐Hydroxy‐4‐oxocarotenoids(3RS,3′RS)‐Astaxanthin (= 3,3′‐dihydroxy‐β,β‐carotene‐4,4′‐dione, 1:1‐mixture of racemate and meso‐form; 1) can be separated into its optical isomers (3S,3′S)‐1a, (3R,3′R)‐1b and meso‐(3R,3′S)‐1c via the corresponding diastereomeric di‐(−)‐camphanates. Some aspects of the configurational stability of astaxanthin are discussed. ‐ HPLC. analysis of the (−)‐camphanates of 3‐hydroxy‐4‐oxocarotenoids provides, in suitable cases and supported by spectroscopic data, an analytical method for the simultaneous determination of constitution and chirality.
1,3‐Dipolare Additionen an 7‐Methylthieno[2,3‐c]pyridin‐1,1‐dioxid
Authors: Fischer Ulf , Schneider Fernand 
Published: December 2004

1,3‐Dipolar Additions to 7‐Methylthieno[2,3‐c]pyridine 1,1‐dioxide1,3‐Dipolar additions of diazomethane, diazoethane, ethyl diazoacetate, phenyldiazomethane and phenyl azide to 7‐methylthieno[2,3‐c]pyridine 1,1‐dioxide have been examined. The structures of the primary products e.g. 2, 8, 18, 25 have been established and their behaviour towards elevated temperatures and/or basic conditions was investigated. Under these conditions the primary products lost SO2 or N2 to yield e.g. 4, 11, 19, 21, 23, 27, 28.
Synthese und Eigenschaften von 6‐Desoxy‐6‐halogen‐Derivaten der L‐Ascorbinsäure
Authors: Kiss Joseph , Berg Klaus Peter , Dirscherl Adolf , Oberhänsli Willi E. , Arnold Wolf 
Published: December 2004

Synthesis and Properties of 6‐Deoxy‐6‐halogeno‐Derivatives of L‐Ascorbic Acid6‐Deoxy‐6‐chloro‐, ‐6‐bromo‐, ‐6‐iodo‐ and ‐6‐fluoro derivatives of L‐ascorbic acid have been synthesized and characterized. The physiological properties of the chloro derivative have been investigated. It shows a high antiscurvy activity.The chloro‐ and bromo‐derivatives have been reduced to the corresponding deoxy compound, which is an interesting chiral intermediate for the preparation of rare ω‐deoxy sugars.
Evidence for an Iminium Cation Intermediate and its Non‐Oxidative Decarboxylation in a Cerium (IV)‐Mediated Oxidative Decarboxylation. Preliminary communication
Authors: Hanna Samir B. , Moehlenkamp Marilyn E. 
Published: December 2004

AbstractEvidence is provided for the occurrence of a non‐oxidative decarboxylation in an iminium cation intermediate which is produced in an oxidative decarboxylation induced by cerium (IV).
The chiral recognition of guest molecules in trio‐o‐thymotide clathrates: A semi‐empirical approach. Preliminary communication
Authors: Gerdil Raymond , Allemand Jacques 
Published: December 2004

AbstractThe enantiomers of a chiral solvent can be enclathrated to a different extent in a crystal lattice consisting of tri‐o‐thymotide (1) molecules of a given handedness. This property affords a mean of studying the stereoselective interaction of a chiral environment with an enclosed chiral component. The general approach to account for the observed differences in stereoselectivity is based on the calculation and comparison of the minimum energies for the respective inclusion of enantiomeric guest molecules within a rigid cage of given chirality. An interpretation of the fair chiral recognition of 2‐bromobutane as opposed to the unselective inclusion of 2‐butanol is attempted.
Stereoselective binding of 11C‐labelled piquindone (Ro 22–1319) to dopamine‐D2 receptors in the living human brain
Authors: Sedvall G. , Ehrin E. , Farde L. 
Published: December 2004

AbstractThe stereoenantiomers of piquindone (Ro 22–1319), a new antipsychotic pyrroloisoquinoline derivative, were labelled with the positron‐emitting isotope 11C. Only the (−)‐enantiomer inherits most of the biological activity of racemic piquindone. The compounds were examined by positron emission tomography (PET) for dopamine‐D2 receptor binding in the living brain of Cynomolgus monkeys and healthy human subjects. After i.v. administration of tracer doses the (−)‐enantiomer but not the (+)‐enantiomer was shown to accumulate markedly in the dopamine‐D2 receptor rich caudate/putamen in both species. After (−) 11C piquindone injection, radioactivity in the human caudate/putamen, and the putamen/cerebellar activity ratio increased to about 2 during the hour when radioactivity could be followed. (−)11C piquindone binding in the monkey putamen was not easily displaceable by haloperidol. The results demonstrate that (−) but not (+)‐11C piquindone has a high affinity for dopamine‐D2 receptors in the living human brain. The results are compatible with the view that clinical administration of piquindone produces a long‐lasting effect on central dopamine‐D2 receptors. (−)11C Piquindone is a useful ligand for visualization of dopamine‐D2 receptor binding by PET and for analysing relationships between antipsychotic effects of piquindone and blockade of specific binding sites in the brain of schizophrenic patients.
The pitfalls of the dexamethasone suppression test: A biological marker of endogenous depression?
Authors: Klein H. E. , Berger M. 
Published: December 2004

AbstractIn the past few years there have been numerous publications which have stressed the value of the dexamethasone suppression test (DST) as a diagnostic marker of endogenous depression. Our own studies in 333 psychiatric inpatients and 121 healthy subjects did not reveal a differential diagnostic use for the DST. This result is in good agreement with other results in the literature. Our data demonstrate that intervening variables such as severity of illness, weight loss, sleep disturbances, situational stress, drug and alcohol withdrawal, and the pharmacokinetics of dexamethasone have an important influence on DST results, regardless of the diagnostic classification.
Residual effects of zopiclone on subsequent daytime functions in normal humans
Authors: Mizuki Yasushi , Hirano Hitoshi , Miyoshi Akira , Hamasaki Junko , Yamada Michio , Tanaka Masatoshi , Inanaga Kazutoyo 
Published: December 2004

AbstractThe influence of zopiclone and nitrazepam on arousal level, muscle strength, psychomotor performance and memory function using the photopalpebral reflex (PPR), critical flicker frequency (CFF), tapping test, pursuit rotor test (PRT), choice reaction test (CRT) and memory drum test (MDT) were investigated on the day following drug administration. After the control tests were completed at 1800 h, nine healthy male university students were given zopiclone 10 mg, nitrazepam 10 mg and placebo in a double‐blind, crossover design at 2300 h. The performance on the tests, as well as the recording of subjective assessments, were repeated at 0800, 1100 and 1400 h the next day. Both nitrazepam and zopiclone produced a prolongation of PPR latency and a decrease of CFF. The effects of zopiclone were weaker and shorter in duration than those of nitrazepam. Tapping rate, PRT and CRT improved or did not change, and there were no significant differences between the drugs. The MDT was impaired by both drugs in the morning, with nitrazepam continuing to produce memory impairment, while zopiclone did not produce further deterioration. No significant changes were observed in the subjective assessment of the subjects. These results suggest that a medium dose of zopiclone lowers arousal level and impairs memory, especially during the morning following drug administration, but produces no change in muscle strength, psychomotor performance or self‐assessment. Finally, the residual effects of zopiclone appear to be weaker than those of nitrazepam.
Lithium prophylaxis of periodic hypersomnia unaccompanied by affective symptoms: A further adolescent case
Authors: Abe Kazuhiko 
Published: December 2004

AbstractLithium was administered to a 15‐year‐old boy who had four episodes of hypersomnia following his recovery from influenza. The episodes lasted about a week and were not associated with depression, hypomania or polyphagia, but were heralded by depersonalization. The episode did not recur during prophylactic lithium administration in the latter half of 1983, but recurred later on three occasions when lithium was discontinued or taken less than prescribed. This finding, together with a few cases reported in the literature, appear to indicate that lithium is potentially effective in preventing hypersomnia even in cases unassociated with affective symptoms. However, its preventive effect may not always be complete, as depersonalization recurred in the present case in March 1985 when the serum lithium level was in the therapeutic range.
Plasma concentration of neuroleptic and serum prolactin in patients chronically receiving depot fluphenazine: No evidence of tolerance
Authors: Cohen Bruce M. , Chouinard Guy , Waternaux Christine , Schachter Hyme , Jones Barry , Sommer Barbara R. 
Published: December 2004

AbstractThe authors determined neuroleptic dose, plasma level of drug, and serum prolactin in 76 outpatients receiving depot fluphenazine. The patients had received neuroleptic treatment for periods ranging from 3 to 23 years (median 13 years). Plasma level of drug correlated with dose (rs = 0·73, p>0·0001). Prolactin levels were linearly correlated with dose (rs = 0·42, p = 0·0001) and plasma level of drug (rs = 0·64, p>0·0001). There was a tendency for dose and, concomitantly, plasma level of drug, to decrease with age (rs = −0·29, p = 0·01, for each). However, dose, plasma level of drug adjusted for dose, and serum prolactin adjusted for plasma level of drug did not correlate with duration of treatment. Neither did any of these measures correlate with treatment duration when adjusted for age. The findings suggest that while older patients were given lower doses of medication, changes in the metabolism of fluphenazine or tolerance to its prolactin‐elevating effects did not occur during extended treatment.
Residual effects of temazepam versus nitrazepam on memory and vigilance in the normal subject
Authors: Bourin M. , Hubert C. , Colombel M. C. , Larousse C. 
Published: December 2004

AbstractEighteen normal volunteers with no sleep difficulties were given psychological tests and asked to fill out a self‐evaluation questionnaire 11 h after administration of a hypnotic drug, nitrazepam 5 mg or temazepam 20 mg (in the form of soft gelatin capsules), which was compared to a placebo. Subjects received all three treatments at 1‐week intervals, with the administration sequence determined by drawing lots. The tests used were the images test, the digit/symbol substitution test (DSST), choice reaction time and critical fusion frequency. The two benzodiazepines proved to be efficient hypnotics, improving sleep induction and quality, but nitrazepam caued residual effects, as evidenced by difficult awakening and modified behaviour in the morning, as well as disturbed performance during DSST.