ARS | Publication request: B3LYP/6-311++G** STUDY OF THE BOAT FORMS OF ALPHA- AND BETA-GLUCOPYRANOSE AND ITS MONOSUBSTITUTED EPIMERS

Submitted to: Midwest Theoretical Chemistry Conference
Publication Type: Abstract Only
Publication Acceptance Date: April 2, 2003
Publication Date: June 12, 2003
Citation: APPELL, M.D., MOMANY, F.A., WILLETT, J.L. B3LYP/6-311++G** STUDY OF THE BOAT FORMS OF ALPHA- AND BETA-GLUCOPYRANOSE AND ITS MONOSUBSTITUTED EPIMERS. MIDWEST THEORETICAL CHEMISTRY CONFERENCE. 2003. Abstract p. 103.

Technical Abstract: Density functional/ab initio methods were applied to gradient geometry optimize the gg, gt and tg rotamers of the boat forms of glucopyranose and its epimers in vacuo. Preliminary optimization was carried out at the B3LYP/6-31+G* level and further optimization was carried out at the B3LYP/6-311++G** level of theory. Comparisons of the boat conformers of glucopyranose with epimer boat forms will be discussed. Many optimer conformers retained their initial boat forms following geometry/energy optimization, however, some did not. For the gg and gt rotamers of alpha-glucopyranose, there exists a transition without barrier from the B3,0 boat to the 4C1 chair. However, the tg twist-boat of alpha-glucopyranose and all of the rotamers of beta-glucopyranose in the B3,0 boat retained the boat conformation upon geometry/energy optimization. All of the beta-mannopyranose rotamers considered have a transition without barrier from the 3,0B boat to the twist-boat form. Only the tg and a selected gg 3,0B form of beta-allopyranose underwent a transition without barrier to the twist-boat conformer, while the other hydroxymethyl conformers remained near the starting boat conformation.