1977
DOI: 10.1002/cber.19771100611
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Verzweigte Zucker, XVIII. Stereoselektivität der 1,4‐Addition von Carbanionen an Pyranosid‐Enone zu verzweigten Zuckern

Abstract: ~~Pyranosid-Enone vom Typ 14 reagieren mit 2-Lithio-1,3-dithiolan-2-carbonsaure-ethylester (15) unter 1,4-Addition und Einfuhrung einer C-Kettenverzweigung am C-2. Die Addition erfolgt streng stereoselektiv und liefert nur das Addukt, in dem die Seitenkette am C-2 und die l-OCH3-Gruppe ,,trans" zueinander angeordnet sind. Die Lenkung der Reaktion erfolgt durch die anomere OCH3-Gruppe. Dieses zeigen die vier Beispiele der Pyranosid-Enone 4, 14, 26 und 36. Die eingefuhrte Seitenkette kann in eine Glycoloylverzwe… Show more

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Cited by 32 publications
(5 citation statements)
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“…For formation of the olefinic sugars 6 and 7 , the MsCl/pyridine and TsCl/pyridine methods were employed, but no satisfactory results were obtained. However, if the iodohydrin 2 and the mixture of 4 and 5 were treated with POCl 3 in pyridine at −40 °C, the unsaturated sugars 6 and 7 were isolated in 70% and 55% yield, respectively. After deacetylation of 7 with a mixture of MeOH/H 2 O/Et 3 N (3:2:1), the allyl alcohol 8 was obtained in quantitative yield.…”
Section: Resultsmentioning
confidence: 99%
See 2 more Smart Citations
“…For formation of the olefinic sugars 6 and 7 , the MsCl/pyridine and TsCl/pyridine methods were employed, but no satisfactory results were obtained. However, if the iodohydrin 2 and the mixture of 4 and 5 were treated with POCl 3 in pyridine at −40 °C, the unsaturated sugars 6 and 7 were isolated in 70% and 55% yield, respectively. After deacetylation of 7 with a mixture of MeOH/H 2 O/Et 3 N (3:2:1), the allyl alcohol 8 was obtained in quantitative yield.…”
Section: Resultsmentioning
confidence: 99%
“…Synthesis of Unsaturated Sugars. The starting sugars 6 and 9 , needed for the present study, were prepared from easily accessible benzyl 2- O - p -tosyl-3,4-anhydro-β- l -arabinopyranoside ( 1 ) and benzyl 2,3-anhydro-4- O -acetyl-α- d -ribopyranoside ( 3 ), respectively. , The first step proceeds via epoxide ring opening of 1 and 3 . When 1 was refluxed with sodium acetate, sodium iodide and acetic acid in acetone for 4−5 h, the iodohydrin 2 was obtained as a single product adopting the 4 C 1 conformation.…”
Section: Resultsmentioning
confidence: 99%
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“…The substrate 81 for enantiodivergent synthesis would be obtained by Wittig reaction with lactol 82 . The pyranonaphthalene skeleton of 82 might be synthesized by tandem Michael−Dieckmann reaction to connect lactone 83 and enone 84 …”
Section: 21 Total Syntheses Of Nanaomycin D and Kalafungin: “Enantiod...mentioning
confidence: 99%
“…The pyranonaphthalene skeleton of 82 might be synthesized by tandem Michael-Dieckmann reaction to connect lactone 83 48 and enone 84. 49 The chiral enone 84 would be derived from commercially available L-rhamnose 85.…”
Section: Total Syntheses Of Nanaomycin D and Kalafungin: "Enantiodive...mentioning
confidence: 99%