Highly Functionalised Cyclopentanes by Radical Cyclisation of Unsaturated Bromolactones III. Preparation of Carbaaldohexofuranoses. - Determination of the Relative Configuration at C-4/C-5 of 2,3-Unsaturated heptono-1,4-lactones by Means of 1-H NMR Spectroscopy

Inge Lundt, Anne Marie Horneman

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    Two new carbaaldohexofuranoses, carba--D-glucofuranose and carba--L-mannofuranose have been prepared using 5,6-O-isopropylidene-D-glycero-L-galacto-heptono-1,4-lactone (6) as the starting material. The key step was a highly stereoselective intramolecular 5-exo-trig radical cyclisation of C-2-substituted 2,3-unsaturated 7-bromo-7-deoxy-heptono-1,4-lactones promoted by tributyltin hydride. Assignment of the configuration of the unsaturated lactones was based upon NMR data of related compounds. The starting material, compound 6, was obtained by chain elongation of D-gulose, and a facile method for separation of the epimers from the chain elongation has been developed, thus 5,6-O-isopropylidene-D-glycero-L-galacto-heptono-1,4-lactone (6) and D-glycero-L-talo-heptono-1,4-lactone (5) were isolated in ca. 30% and 10% yield, respectively.
    Original languageEnglish
    JournalSYNTHESIS
    Pages (from-to)317-325
    Publication statusPublished - 1999

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