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  • Surface physics, nanoscale physics, low-dimensional systems  (32)
  • Chemistry  (22)
  • ACROSS; Advanced Remote Sensing – Ground-Truth Demo and Test Facilities; AWIPEV; AWIPEV_based; AWIPEV_UW-Observatory; BAH; Chlorophyll a; Chlorophyll a, confidence value; Coastal Observing System for Northern and Arctic Seas; COSYNA; DATE/TIME; Kongsfjorden, Spitsbergen, Arctic; Number of observations; OBSE; Observation; Oxygen saturation; Oxygen saturation, confidence value; Salinity; Salinity, confidence value; See further details: Metadata for the AWIPEV underwater observatory; Shelf Seas Systems Ecology @ AWI (former Biologische Anstalt Helgoland); Temperature, water; Temperature, water, confidence value; Turbidity, confidence value; Turbidity (Formazin Turbidity Unit)  (6)
  • 27.30+t  (2)
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  • 1
    ISSN: 1434-601X
    Keywords: 27.30+t ; 21.10 Hw ; 21.60 Cs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Theγ-decays of levels in26Mg have been investigated up to 12.5 MeV excitation energy by proton-γ-ray coincidence measurements in the23Na(α, pγ) reaction at 14.2 and 16 MeV bombarding energy. Lifetime-measurements, made with the Doppler-shift attenuation method, and proton-γ-ray angular-correlation measurements were performed at Eα=14.2 MeV. Many high-spin states were observed, among them levels at 6,978 (5+), 7,283(4−), 7,395(5+), 7,953(5−), 8,202(6+), 8,472(6+), 9,065(5), 9,112(6+), 9,169(6−), 9,383 (6+), 9,542(5), 9,829(7+), 9,989(6+) and 12,479(8+, 7−) keV excitation energy. The spectrum of positive-parity states and their electromagnetic properties are reproduced with good accuracy by shell-model calculations which employ a unifieds-d shell Hamiltonian and the unrestricted configuration space of the 0d 5/2 1s 1/2 0d 3/2 shell. Members of five inferred rotational bands, withK π=0+, 2+, 3+, 0+ and 3− have been observed up to at leastI=6. TheK π=2+ band shows strong anomalies of excitation energies andE2 transition rates near theI=6 state. The static intrinsic quadrupole moments calculated from the shell model wave functions indicate transitions from prolate to oblate deformation within theK π=2+ band and also the ground state band. The lowest lyingI π=4+ state appears to be “spherical” and cannot be associated with a rotational band.
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  • 2
    ISSN: 1434-601X
    Keywords: 27.30+t ; 21.10 Hw ; 21.60 Cs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract New shell model calculations have predicted several high-spin (I π=5+ and 6+) levels in28Si near 10 MeV excitation energy which are missing from or ambiguous in existing experimental studies. Angular distributions, linear polarizations and Doppler-shifts ofγ-rays have been measured for theγ-decay of theE p=1,911 and 2,073 KeV resonances of the27Al(p, γ) reaction in an attempt to discover these missing states or confirm the discrepancies between experiment and theory. The excitation energies and spin-parities of the resonances were determined as 13,424.4±0.2 keV,I π=5+ and 13,582.3±0.5 keV,I π=6+. States populated in theγ-decay of these resonances were assigned spins and parities as follows: 11,777 keV,I π=5+; 11,331 keV,I π=6+; 10,417 keV,I π=5+; 9,417 keV,I π=4+ and 8,945 keV,I π=5+. On the basis ofγ-ray transition rates T=1 is assigned to the 13,424 keV level and T=0 to the 10,417 and 11,777 keV levels. With the new data excellent agreement is achieved between the experimental spectrum of28Si and the new shell model predictions. These data provide evidence for aK π=3+ rotational band comprised by the 6,276, 6,889, 8,945 and 11,331 keV levels. This band emerges also from the shell model wave functions as do theK π=0+ bands based on the ground state and the 6,691 keV state.
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  • 3
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A 1:1 mixture of the racemic trans- and cis-1-p-menthene-3,8-diols ((±)-3 and (±)-4, resp.) was readily prepared in 3 steps starting from 3-methyl-2-cyclohexen-1-one. The relative configuration of the diols, purified via the corresponding cyclocarbonates, was assigned by 1H-NMR spectroscopy and found to be at variance with tentative claims in the literature. Optically active samples of 3 and 4 were prepared by resolution of the racemates with (R)-1-phenylethylamine. The absolute configuration of the resulting diols was determined by chemical correlation with standards of known absolute configuration.
    Additional Material: 4 Tab.
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  • 4
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N-Allyl- and N-[(Cyclopropyl)methyl]-3,4-dimethoxy-5-methylmorphinan-6-one (9 and 10, resp.) were synthesized from 5-methyldih drothebainone (1). This essential intermediate was prepared from the baine via 5-methylthebaine (5) employing a novel route. The Pharmacological studies showed 9 and 10 to be potent opioid agonists. Compound 10 was found to have preference for kappa rather than mu opioid receptors.
    Additional Material: 5 Tab.
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  • 5
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A convergent diastereoselective synthesis of racemic aristoserratine ((±)-24) via an intramolecular iminium-ion cyclization is described. The pivotal imine (±)-19 was prepared by condensation of the two building blocks (± )-trans-8-amino-3-(2,6-difluorobenzyloxy)-1-p-menthene ((±)-11) and N-(p-methoxybenzenesulfonyl)-3-indo-leacetaldehyde (18) which were synthesized from (±)-trans-1-p-menthene-3,8-diol ((±)-7) and 3-indoleacetic acid, respectively. On the route to the target (±)-24, two previously unknown indole alkaloids have been characterized, namely (±)-‘anti’-hobartin-15-ol ((±)-22) and (±)-‘anti’-aristotelin-15-ol ((±)-23).
    Additional Material: 1 Tab.
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  • 6
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the title compound 2 and its diastereoisomer 3 was accomplished using tricarbonyl[1-5-n-(4-methoxycyclohexa-2,4-dien-1-yl)]iron tetrafluoroborate (4) as a precursor to the cyclohexanone ring. The assignments of the relative configurations of 2 and 3 are based on the X-ray analysis of compound 3. Both compounds 2 and 3 are potent inhibitors of neuronal noradrenaline uptake in rats with similar potencies in vitro as compared to amitriptyline and desipramine. Compounds 2 and 3 are less potent as serotonin-uptake inhibitors, very weak inhibitors of dopamine uptake, and virtually devoid of antinociceptive activity.
    Additional Material: 1 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 74 (1991), S. 275-289 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The imine obtained by condensing indole-protected 2-(indol-3-yl)acetaldehyde (5) with the terpinylamine derivative (±)-4 was cyclized in 51% yield to the 19-substituted hobartine derivative (±)-20 upon exposure to anhydrous HCOOH. This pivotal intermediate was further elaborated into the indole alkaloids (±)-serratenone ((±)-22) and (±)-sorelline ((±)-29). In the course of these investigations, a novel rearrangement was uncovered; a Lewis acid-catalyzed 1,3-migration of an arylsulfonyl group from the indole N-atom into the benzene ring. The discovery that synthetic (±)-aristotelin-19-one ((±)-34) has decidedly different spectroscopic properties than aristolasicone, a metabolite for which the structure has been recently proposed, led to a revision of the structure of the latter.
    Additional Material: 1 Ill.
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  • 8
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The N-(cyclobutylmethyl)morphinans 12, 19, 20, 21, 27, and 29 and the N-(2-cyanoethyl) analogue 33 were prepared from different precursors. Pharmacological evaluation (e.g. opioid receptor binding assays, acetic-acid writhing test, hot-plate assay) points to a partial opioid agonism of compounds 12, 27, 29, and 33, and to full opioid agonism of compounds 19-21.
    Additional Material: 3 Tab.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 73 (1990), S. 298-302 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Biomimetic syntheses of racemic aristomakinine ((±)-3) and aristomakine ((±)-4), an unusual indole alkaloid bearing an N-isopropyl group, are described. The key step is a Grob-type fragmentation of anti-15-aristotelinyl methanesulfonate ((±)-2) to the intermediate iminium ion I which, upon subsequent hydrolysis, furnished aristomakinine ((±)-3). On the other hand, the same intermediate could be reduced in situ to aristomakine ((±)-4). The controversial relative configurations of the two alkaloids have been firmly established by means of NOE difference experiments.
    Additional Material: 2 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 1594-1612 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Substitution of 2-(Sulfonyloxy)carboxylates with Oxygene and Sulfur Nucleophiles without RacemizationThe ethyl 2-(sulfonyloxy)propionates (S)-1a - c react with phenolates formed from 2 and with carboxylates 8 to give the respective 2-(aryloxy)- (R)-3 and 2-(acyloxy)propionates (R)-9 with inversion of configuration. Due to the high leaving tendency of the triflate group, (S)-1a generally give higher yields of substitution products under milder conditions than the corresponding mesylate (S)-1b and tosylate (S)-1c. In the case of the reaction of malic and succinic acid derivatives only the triflate (S)-10a is converted to the acyloxy compounds (R)-12 with carboxylates 8 at low temperature (-45°C); with the mesylates 10b and the bromide 10d only elimination is observed. Mercaptides and thiophenolates formed from 17 react with (S)-1a - c analogously. With potassium thiocyanate 1a, b react almost exclusively to give the thiocyanate 19; only traces of the corresponding isothiocyanate 20 are obtained.
    Notes: Die 2-(Sulfonyloxy)propionsäureester (S)-1a - c reagieren mit aus 2 gebildeten Phenolaten bzw. mit Carboxylaten 8 unter Inversion zu den 2-(Aryloxy)- (R)-3 bzw. 2-(Acyloxy)propionsäureestern (R)-9. Die durch die große Austrittstendenz des Trifluormethansulfonats bedingte hohe Reaktivität von (S)-1a führt, im Vergleich zu den Umsetzungen mit (S)-1b bzw. (S)-1c, unter milderen Reaktionsbedingungen zu besseren Ausbeuten an Substitutionsprodukten. Von den Äpfel- bzw. Bernsteinsäurederivaten 10a, 10b bzw. 10d läßt sich lediglich das Trifluormethansulfonat (S)-10a mit Carboxylaten bei tiefer Temp. (-45 °C) unter Konfigurationsumkehr zu entsprechenden Acyloxyverbindungen (R)-12 umsetzen, während das Mesylat 10b und die Br-Verbindung 10d ausschließlich Eliminierung zu 11 geben. Aus 17 gebildete Mercaptide und Thiophenolate reagieren mit (S)-1a - c ebenfalls unter Substitution und Konfigurationsumkehr; mit Kaliumrhodanid entsteht fast ausschließlich das Thiocyanat 19 neben nur Spuren von Isothiocyanat 20.
    Additional Material: 9 Tab.
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