title: An appraisal of oxoketene cycloaddition methodology for the synthesis of 2,6-dideoxysugars and fluorinated 2,6-dideoxysugars.
abstract: The cycloaddition reaction of acylketenes with vinyl ethers affords an extremely direct route to 2,6-dideoxysugars and their methyl ethers. The lithium enolate of commercial 2,6,6-trimethyldioxinone 3 was fluorinated in good yield to afford fluorinated dioxinone 8. An illustrative range of fluorinated 2,6-dideoxysugar derivatives was prepared via the acetyl ketene-vinyl ether cycloadduct. Electronic structure calculations were carried out to investigate the effect of the fluorine atom on ease of formation and subsequent reaction of the (fluoroacetyl)ketene reactive intermediate. A single fluorine atom lowers the barrier to fragmentation by ca. 7.5 kJ mol(-1), consistent with experimental findings, but has almost no effect on the barrier to rate determining vinyl ether addition, or to oxoketene dimerisation.
authors.affiliation: Department of Chemistry, University of Leicester, University Road, Leicester, UK LE1 7RH.
authors.forename: Christophe
authors.initials: C
authors.lastname: Audouard
authors.forename: Kim
authors.initials: K
authors.lastname: Bettaney
authors.forename: Châu T
authors.initials: CT
authors.lastname: Doan
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Rinaudo
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Jervis
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Percy