title: Structural, mechanistic, and computational analysis of the effects of anomeric fluorines on anomeric fluoride departure in 5-fluoroxylosyl fluorides.
abstract: The effects of fluorine substitution at the C-5 center of pyranosyl fluorides on the reactivity at the C-1 anomeric center was probed by studying a series of 5-fluoroxylosyl fluoride derivatives. X-ray structures of their per-O-acetates detailed the effects on the ground-state structures. First-order rate constants for spontaneous hydrolysis, in conjunction with computational studies, revealed that changes in the stereochemistry of the 5-fluorine had minimal effects on the solvolysis rate constants and that the observed rate reductions were broadly similar to those caused by additional fluorine substitution at C-1 but significantly less than those due to substitution at C-2. Differences in the trapping behavior of 5- versus 2-fluoro-substituted glycosyl fluorides with α- and β-glycosidases arise more from differences in steric effects and hydrogen-bonding interactions than from intrinsic reactivity differences.
authors.affiliation: Department of Chemistry, University of British Columbia, Vancouver, BC, Canada V6T 1Z1.
authors.forename: Seung Seo
authors.initials: SS
authors.lastname: Lee
authors.forename: Ian R
authors.initials: IR
authors.lastname: Greig
authors.forename: David J
authors.initials: DJ
authors.lastname: Vocadlo
authors.forename: John D
authors.initials: JD
authors.lastname: McCarter
authors.forename: Brian O
authors.initials: BO
authors.lastname: Patrick
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Withers
mesh_terms: D018360:Crystallography, X-Ray; D005459:Fluorides / Q000737:chemistry*; D005461:Fluorine / Q000737:chemistry*; D007536:Isomerism; D008958:Models, Molecular; D014994:Xylose / Q000737:chemistry*
chemical_list: D005461:Fluorine; D014994:Xylose; D005459:Fluorides