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  • 1
    ISSN: 0947-3440
    Keywords: Thioketones ; Sulfurization ; Sulfur ylides ; Sulfur heterocycles ; Conformational analysis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By treatment with elemental sulfur and a catalytic amount of sodium thiophenolate in acetone at room temp., the title compound 9 is converted to the bis-spiro derivatives of 1,2,4,5-tetrathiane, 13, and 1,2,3,5,6-pentathiepane, 14. The initial attack by the phenyl oligosulfide anion takes place at the C-atom of the thiocarbonyl group. There is 13C NMR evidence for the twist conformation 15 of the tetrathiane ring; dynamic 1H NMR led to ΔG≠ = 15.9 ± 1.0 kcal mol-1 for the enantiomerization. For the pentathiepane 14, twelve coalescence phenomena in the 1H and 13C NMR spectra point to ΔG≠ = 13.4 ± 0.2 kcal mol-1; the process is interpreted as a stereomutation on the pseudorotation circuit for twist-chair and chair. The MS of 13 reveals a diversity of fragmentation patterns with several “thiologous” sequences. By prolonged treatment with the thiophenolate catalyst, 13 and 14 are converted to a γ-butyrodithiolactone 36 in a Baeyer-Villiger type reaction.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0947-3440
    Keywords: 1,2-Dithiin ; Cycloadditions ; Sulfur extrusion ; Thiophenes ; Reaction mechanisms ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tetracyanoethylene combines with two molecules of thiobenzophenone in refluxing benzene to give the tetrasubstituted 1,2-dithiin 8 (21-29%) besides the corresponding thiophene derivative 9 (40-52%). The X-ray analysis of the ruby-red 8 reveals a half-chair conformation with a torsion angle of 58.9° at the disulfide bond. The thermal desulfurization 8 → 9 (benzonitrile, 100°C) proceeds with t1/2 = 26.7 h, whereas the sulfur loss induced by triethyl phosphite is a billion times faster. The mechanisms of the formation of 8 and its sulfur extrusion are discussed in the light or recent literature.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 586 (1954), S. 52-69 
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 224 (1884), S. 156-178 
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 302 (1898), S. 153-171 
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Ein neuer Vertreter der Antibiotikaklasse mit Thiotetronsäure-Struktur aus Streptomyces olivaceus Tü 3010Ein lipophiles Antibiotikum wurde aus dem Kulturfiltrat von Streptomyces olivaceus Tü 3010 isoliert. Seine Struktur wurde spektroskopisch mittels 1H- und 13C-NMR-2D-Experimenten wie COLOC und NOESY, FD- und GC-MS, sowie durch chemischen Abbau und Derivatisierung bestimmt. Das Antibiotikum Tü 3010 wurde als (2S)-4-Ethyl-2,5-dihydro-3-hydroxy-2-[(1E)-2-methyl-1,3-butadienyl]-5-oxo-2-thienylacetamid (1) bestimmt; somit ist es ein neuer Vertreter der Naturstoffe mit Thiotetronsäure-Struktur. Der Metabolit zeigt antibakterielle Aktivität besonders gegen Streptomyceten.
    Notes: A lipophilic antibiotic was isolated from the culture filtrate of Streptomuces olivaceus Tü 3010. Its structure was elucidated spectroscopically using 2D-1H- and 13C-NMR experiments (e. g. COLOC, NOESY), FD- and GC-MS, and by chemical degradation and derivatization. The antibiotic Tü 3010 was identified as (2S)-4-ethyl-2,5-dihydro-3-hydroxy-2-[(1E)-2-methyl-1,3-butadiyl]-5-oxo-2-thienylacetamide (1), therefore it is a new member of natural compounds with thiotetronic acid structure. The metabolite shows antibacterial activity especially against Streptomycetes.
    Additional Material: 1 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1988 (1988), S. 655-661 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Rhizocticine  -  neue Phosphono-Oligopeptide mit antifungischer AktivitätDer weltweit benutzte Stamm Bacillus subtilis ATCC 6633 produziert zwei neuartige hydrophile Peptidantibiotika, L-Arginyl-L-2-amino-5-phosphono-3-cis-pentensäure (L-Arg-L-APPA, Rhizocticin A) und L-Valyl-L-arginyl-L-2-amino-5-phosphono -3-cis-pentensäure (L-Val-L-Arg-L-APPA, Rhizocticin B). Neben den Rhizocticinen A und B, den Hauptkomponenten, wurden geringe Mengen an Tripeptid-Analogen entdeckt, die L-Ile bzw. L-Leu anstelle von L-Val enthalten. Der C-terminale Rest wurde NMR-spektroskopisch als die ungesättigte Phosphono-Aminosäure-L-APPA bestimmt, die vorher nur als D-Enantiomer bekannt war. Enzymatische Spaltungen von Rhizocticin B ergaben neben L-APPA auch Rhizocticin A.
    Notes: The widely used and well-known bacterial strain Bacillus subtilis ATCC 6633 was found to produce two novel, antifungal hydrophilic peptide antibiotics, L-arginyl-L-2-amino-5-phosphono-3-cis-pentenoic acid (L-Arg-L-APPA, rhizocticin A) and L-valyl-L-arginyl-L-2-amino-5-phosphono-3-cis-pentenoic acid (L-Val-L-Arg-L-APPA, rhizocticin B). Besides rhizocticin A and B, the main components, small amounts of related tripeptides were detected. Instead of the L-Val of rhizocticin B they contain L-Ile or L-Leu and are referred to as rhizocticins C and D, respectively. The C-terminal residue was identified by NMR spectroscopy as the unsaturated phosphono amino acid L-APPA, known till now only as D enantiomer. Enzymatic cleavages of rhizocticin B yielded both L-APPA and rhizocticin A.
    Additional Material: 3 Ill.
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  • 9
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    In:  CASI
    Publication Date: 2006-01-12
    Description: The principles and problems relative to the determination of the geoid are outlined. Factors discussed include: gravity data requirements for a precise geoid; mean sea level; and satellite altimetry. It is indicated that geoid undulations can be determined on a global basis to plus or minus 3 m. Application of geoid information to oceanography and the determination of sea surface topography considered.
    Keywords: GEOPHYSICS
    Type: Proc. of the Geodesy/Solid Earth and Ocean; 69-77
    Format: text
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  • 10
    Publication Date: 2013-08-31
    Description: A natural extension of the recent satellite derived potential coefficient models is the development of high degree (maximum 180 or 360) expansions. Such expansions are based on the combination of the satellite derived models with terrestrial gravity data and satellite altimeter data. Such models are useful for more precise geoid undulation computations, for simulation studies involving different typed of future missions (e.g., gradiometry), and as reference fields for different types of gravimetric computations. The attention is to the effect of the terrain, ellipsoidal terms, and weighting. The basic methods used for the high degree solutions are reviewed. Various correction terms are described and recent models are discussed and compared.
    Keywords: GEOPHYSICS
    Type: Progress in the Determination of the Earth's Gravity Field; p 12-14
    Format: application/pdf
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