Divergent synthesis of 2-C-branched pyranosides and oxepines from 1,2-gem-dibromocyclopropyl carbohydrates |
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| Authors: | Peter W Moore Julia K Schuster Russell J Hewitt M Rhia L Stone Paul H Teesdale-Spittle Joanne E Harvey |
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| Institution: | 1. School of Chemical and Physical Sciences, Centre for Biodiscovery, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand;2. School of Biological Sciences, Centre for Biodisovery, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand |
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| Abstract: | The ring opening of 1,2-(gem-dibromo)cyclopropyl carbohydrates by two different modes leads to either 2-C-(bromomethylene)pyranosides (using base) or 2-bromooxepines (using silver salts), as shown previously by us for a d-glucal-derived cyclopropane. The base-promoted ring opening is extended to encompass additional alcohol, thiol and amine nucleophiles, and diastereoisomeric cyclopropane precursors. Cross-coupling of the 2-C-(bromomethylene)pyranosides leads to extended 2-C-branched pyranosides. Silver-promoted ring expansion of the cyclopropyl carbohydrates in the presence of various alcohols is described. Cross-coupling of the resulting benzyl 2-bromooxepines affords 2-C-substituted oxepines. |
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| Keywords: | gem-Dihalocyclopropanes Glycal-derived cyclopropanes Modified carbohydrates 2-Branched sugars Oxepines |
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