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Synthesis of peracetylated D-galactopyranosylidene dihalides

Praly, J P and Brendle, J C and Klett, J and Pequery, F (2001) Synthesis of peracetylated D-galactopyranosylidene dihalides. Comptes Rendus - Academie des Sciences Paris Serie 2 Chimie Fascicule C, 4 (7). pp. 611-617. ISSN 1387-1609

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Abstract

Upon treatment with aluminium trichloride in absolute chloroform, beta -D-galactopyranose penta-O-acetate was converted in high yield into tetra-O-acetyl-beta -D-galactopyranosyl chloride. In the presence of N-bromosuccinimide in boiling carbon tetrachloride, homolytic substitution of the anomeric hydrogen atom in this beta -chloride occurred selectively to afford tetra-O-acetyl-1-bromo-beta -D-galactopyranosyl chloride, in admixture with minor amounts of tetra-O-acetyl-D-galactopyranosylidene chloride. Bromine substitution by fluorine took place with a low stereoselectivity in tetra-O-acetyl-1-bromo-beta -D-galactopyranosyl chloride when treated with 1.25 equiv silver fluoride in acetonitrile, whereas tetra-O-acetyl-beta -galactopyranosylidene fluoride could be prepared in 54% yield with 3.3 equiv AgF. The gem-difluoride could be deacetylated quantitatively. Upon treatment with 1,4-diazabicyclo[2.2.2] octane, peracetylated 1-bromo-beta -D-galactopyranosyl chloride underwent 1,2-elimination of hydrogen bromide to afford 2,3,4,6-tetra-0-acetyl-D-lyxo-hex-1-enopyranosyl chloride in 33 % yield. (C) 2001 Academie des sciences / Editions scientifiques et medicales Elsevier SAS.

Item type: Article
ID code: 33997
Keywords: radical bromination of tetra-O-acetyl-beta-D-galactopyranosyl chloride, pyranosylgem-dihalides, sugars, spectroscopy, fluoride, glycals, Chemistry
Subjects: Science > Chemistry
Department: Faculty of Science > Pure and Applied Chemistry
Related URLs:
    Depositing user: Pure Administrator
    Date Deposited: 18 Oct 2011 14:10
    Last modified: 17 Jul 2013 10:58
    URI: http://strathprints.strath.ac.uk/id/eprint/33997

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