title: Contact ion pairs and solvent-separated ion pairs from D-mannopyranosyl and D-glucopyranosyl triflates.
abstract: The chemical nature of contact ion pairs and solvent-separated ion pairs from 2,3,4,6-tetra-O-methyl-α-D-mannopyranosyl triflate was investigated at the DFT(M06-2X) level of theory. Comparison of the present results to those obtained for the D-glucopyranosyl counterpart in our previous study indicated that the ion pairs from the D-mannopyranosyl triflate adopt B2,5-like conformations more preferably than those from the D-glucopyranosyl triflate. Similarly, 1,6-anhydro-D-mannopyranosyl dioxacarbenium ions bearing a (1)C4 conformation were shown to be more stable than the D-glucopyranosyl counterparts.
authors.affiliation: Department of Chemistry, University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria. Electronic address: takashi.hosoya@boku.ac.at.
authors.forename: Takashi
authors.initials: T
authors.lastname: Hosoya
authors.affiliation: Department of Chemistry, University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria.
authors.forename: Paul
authors.initials: P
authors.lastname: Kosma
authors.affiliation: Department of Chemistry, University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria.
authors.forename: Thomas
authors.initials: T
authors.lastname: Rosenau
mesh_terms: D002236:Carbohydrate Conformation; D005947:Glucose / Q000031:analogs & derivatives* / Q000737:chemistry*; D008358:Mannose / Q000737:chemistry*; D008698:Mesylates / Q000737:chemistry*; D008958:Models, Molecular; D011789:Quantum Theory; D012997:Solvents / Q000737:chemistry*
chemical_list: D008698:Mesylates; D012997:Solvents; D005947:Glucose; C012077:trifluoromethanesulfonic acid; D008358:Mannose
keywords: DFT; Glycosylation; Ion pairs; Oxacarbenium ions; d-Glucose; d-Mannose