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  • 1
    ISSN: 0947-3440
    Schlagwort(e): Apionucleosides ; Nucleosides ; Antiviral agents ; Tris(trimethylsilyl)silane ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A Convenient Route to D-Apio-β-D-furanosyl- and 2′-Deoxyapio-β-D-furanosyl Nucleosides2,3-O-Isopropylidene-D-apio-β-D-furanose (1), available in 40% overall yield by modified literature procedures, is acylated regioselectively to the new 3′-O-benzoyl-derivative 2. This is converted to the anomeric triacetates 4 (β-4; α-4 = 1.8:1) by cleavage of the isopropylidene protecting group from 2 followed by peracetylation. Reaction of compounds 4 with silylated nucleobases and subsequent deprotection gives the D-apio-β-D-furanosyl nucleosides 8-10 in good yields. Regioselective hydrazinolysis of the protected nucleosides 5 and 6 affords the 2′-hydroxy-derivatives 11 and 12, respectively, which are converted to the 2′-deoxyapio-β-D-furanosyl nucleosides 17 and 18, respectively, via deoxygenation of the corresponding thionocarbonates 13 and 14 with tris(trimethylsilyl)silane and subsequent deprotection. The 2′-deoxyapio-β-D-furanosyl cytosine 20 is prepared from the 2′-deoxyapio-β-D-furanosyl uracil derivative 16.
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    ISSN: 0947-3440
    Schlagwort(e): Apionucleosides ; Nucleosides ; Antiviral agents ; Branched nucleosides ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A Convenient Route to 3′-Deoxy-α-L- and 3′-Deoxy-β-D-apionucleosidesThe cyclic thionocarbonate 3, easily available in three steps from 3′-O-benzoyl-2,3-O-isopropylidene-D-apio-β-D-furanose (1), is deoxygenated with n-Bu3SnH to yield the 3′-deoxy epimers 4 [methyl 3-C-(benzoyloxymethyl)-3-deoxy-α-L-threo-tetrofuranoside] and 6 [methyl 3-C-(benzoyloxymethyl)-3-deoxy-β-D-erythro-tetrofuranoside]. These are separated by chromatography and further converted to the 3′-deoxy-α-L-apionucleosides 11-13, and the 3′-deoxy-β-D-apionucleosides 17-19, respectively.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Publikationsdatum: 2013-12-11
    Beschreibung: The Curiosity rover discovered fine-grained sedimentary rocks, which are inferred to represent an ancient lake and preserve evidence of an environment that would have been suited to support a martian biosphere founded on chemolithoautotrophy. This aqueous environment was characterized by neutral pH, low salinity, and variable redox states of both iron and sulfur species. Carbon, hydrogen, oxygen, sulfur, nitrogen, and phosphorus were measured directly as key biogenic elements; by inference, phosphorus is assumed to have been available. The environment probably had a minimum duration of hundreds to tens of thousands of years. These results highlight the biological viability of fluvial-lacustrine environments in the post-Noachian history of Mars.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Grotzinger, J P -- Sumner, D Y -- Kah, L C -- Stack, K -- Gupta, S -- Edgar, L -- Rubin, D -- Lewis, K -- Schieber, J -- Mangold, N -- Milliken, R -- Conrad, P G -- DesMarais, D -- Farmer, J -- Siebach, K -- Calef, F 3rd -- Hurowitz, J -- McLennan, S M -- Ming, D -- Vaniman, D -- Crisp, J -- Vasavada, A -- Edgett, K S -- Malin, M -- Blake, D -- Gellert, R -- Mahaffy, P -- Wiens, R C -- Maurice, S -- Grant, J A -- Wilson, S -- Anderson, R C -- Beegle, L -- Arvidson, R -- Hallet, B -- Sletten, R S -- Rice, M -- Bell, J 3rd -- Griffes, J -- Ehlmann, B -- Anderson, R B -- Bristow, T F -- Dietrich, W E -- Dromart, G -- Eigenbrode, J -- Fraeman, A -- Hardgrove, C -- Herkenhoff, K -- Jandura, L -- Kocurek, G -- Lee, S -- Leshin, L A -- Leveille, R -- Limonadi, D -- Maki, J -- McCloskey, S -- Meyer, M -- Minitti, M -- Newsom, H -- Oehler, D -- Okon, A -- Palucis, M -- Parker, T -- Rowland, S -- Schmidt, M -- Squyres, S -- Steele, A -- Stolper, E -- Summons, R -- Treiman, A -- Williams, R -- Yingst, A -- MSL Science Team -- New York, N.Y. -- Science. 2014 Jan 24;343(6169):1242777. doi: 10.1126/science.1242777. Epub 2013 Dec 9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Geologic and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24324272" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Bays ; Carbon/analysis ; *Exobiology ; *Extraterrestrial Environment ; Geologic Sediments/analysis/classification ; Hydrogen/analysis ; Hydrogen-Ion Concentration ; Iron/analysis/chemistry ; *Mars ; Nitrogen/analysis ; Oxidation-Reduction ; Oxygen/analysis ; Phosphorus/analysis ; Salinity ; Sulfur/analysis/chemistry ; *Water
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Publikationsdatum: 2015-10-10
    Beschreibung: The landforms of northern Gale crater on Mars expose thick sequences of sedimentary rocks. Based on images obtained by the Curiosity rover, we interpret these outcrops as evidence for past fluvial, deltaic, and lacustrine environments. Degradation of the crater wall and rim probably supplied these sediments, which advanced inward from the wall, infilling both the crater and an internal lake basin to a thickness of at least 75 meters. This intracrater lake system probably existed intermittently for thousands to millions of years, implying a relatively wet climate that supplied moisture to the crater rim and transported sediment via streams into the lake basin. The deposits in Gale crater were then exhumed, probably by wind-driven erosion, creating Aeolis Mons (Mount Sharp).〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Grotzinger, J P -- Gupta, S -- Malin, M C -- Rubin, D M -- Schieber, J -- Siebach, K -- Sumner, D Y -- Stack, K M -- Vasavada, A R -- Arvidson, R E -- Calef, F 3rd -- Edgar, L -- Fischer, W F -- Grant, J A -- Griffes, J -- Kah, L C -- Lamb, M P -- Lewis, K W -- Mangold, N -- Minitti, M E -- Palucis, M -- Rice, M -- Williams, R M E -- Yingst, R A -- Blake, D -- Blaney, D -- Conrad, P -- Crisp, J -- Dietrich, W E -- Dromart, G -- Edgett, K S -- Ewing, R C -- Gellert, R -- Hurowitz, J A -- Kocurek, G -- Mahaffy, P -- McBride, M J -- McLennan, S M -- Mischna, M -- Ming, D -- Milliken, R -- Newsom, H -- Oehler, D -- Parker, T J -- Vaniman, D -- Wiens, R C -- Wilson, S A -- New York, N.Y. -- Science. 2015 Oct 9;350(6257):aac7575. doi: 10.1126/science.aac7575.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Geologic and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA. ; Department of Earth Science and Engineering, Imperial College London, London SW7 2AZ, UK. ; Malin Space Science Systems, Post Office Box 910148, San Diego, CA 92121, USA. ; Department of Earth and Planetary Sciences, University of California-Santa Cruz, Santa Cruz, CA 95064, USA. ; Department of Geological Sciences, Indiana University, Bloomington, IN 47405, USA. ; Department of Earth and Planetary Sciences, University of California-Davis, Davis, CA 95616, USA. ; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA. ; Department of Earth and Planetary Sciences, Washington University in St. Louis, St. Louis, MO 63130, USA. ; Astrogeology Science Center, U.S. Geological Survey, Flagstaff, AZ 86001, USA. ; Center for Earth and Planetary Studies, National Air and Space Museum, Smithsonian Institution, Washington, DC 20560, USA. ; Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, TN 37996, USA. ; Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD 21218, USA. ; Laboratoire Planetologie et Geodynamique de Nantes-Le Centre National de la Recherche, Unite Mixte de Recherche 6112 and Universite de Nantes, 44322 Nantes, France. ; Planetary Science Institute, Tucson, AZ 85719, USA. ; Department of Geology, Western Washington University, Bellingham, WA 98225, USA. ; Department of Space Sciences, NASA Ames Research Center, Moffett Field, CA 94035, USA. ; NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA. ; Department of Earth and Planetary Science, University of California-Berkeley, Berkeley, CA 94720, USA. ; Laboratoire de Geologie de Lyon, Universite de Lyon, 69364 Lyon, France. ; Department of Geology and Geophysics, Texas A&M University, College Station, TX 77843, USA. ; Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1, Canada. ; Department of Geosciences, Stony Brook University, Stony Brook, NY 11794-2100, USA. ; Department of Geological Sciences, University of Texas at Austin, Austin, TX 78712, USA. ; Astromaterials Research and Exploration Science Division, NASA Johnson Space Center, Houston, TX 77058, USA. ; Department of Geological Sciences, Brown University, Providence, RI 02912, USA. ; Institute of Meteoritics, University of New Mexico, Albuquerque, NM 87131 USA. ; LZ Technology, NASA Johnson Space Center, Houston, TX 77058, USA. ; Space Remote Sensing, Los Alamos National Laboratory, Los Alamos, NM 87544, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26450214" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Climate ; Exhumation ; *Lakes ; *Mars ; Paleontology
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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