title: Completely β-selective glycosylation using 3,6-O-(o-xylylene)-bridged axial-rich glucosyl fluoride.
abstract: A completely β-selective glycosylation that does not rely on neighboring group participation is described. The novelty of this work is the design of the glycosyl donor locked into the axial-rich form by the o-xylylene bridge between the 3-O and 6-O of d-glucopyranose. The synthesized 2,4-di-O-benzyl-3,6-O-(o-xylyene)glucopyranosyl fluoride could efficiently react with various alcohols in a SnCl(2)-AgB(C(6)F(5))(4) catalytic system. The mechanism composed of the glycosylation and isomerization cycles was revealed through comparative experiments using acidic and basic molecular sieves. The achieved perfect stereocontrol is attributed to the synergy of the axial-rich conformation and convergent isomerization caused by HB(C(6)F(5))(4) generated in situ.
authors.affiliation: School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda 669-1337, Japan.
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Okada
authors.forename: Noriaki
authors.initials: N
authors.lastname: Asakura
authors.forename: Masafumi
authors.initials: M
authors.lastname: Bando
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Ashikaga
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Yamada
mesh_terms: D005947:Glucose / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D006031:Glycosylation; D015394:Molecular Structure; D014992:Xylenes / Q000737:chemistry*
chemical_list: D014992:Xylenes; C030364:glucosyl fluoride; D005947:Glucose; C026114:2-xylene