Glycosyl donors have been experimentally shown to have a high tendency for acyl transfer
to the alcohol nucleophile as a major side product during glycosylation reactions. Therefore, a neighbouring
group participatory mechanism of glycosylation is explored using D-galactopyranose based
donor having 2-O-acyl functionality by employing density functional theory. The reaction proceeds via
galactopyranosyl dioxolenium ion as a stable intermediate, which leads to the formation of α-glycoside
4, orthoester (5 or 6) and acyl transfer 7 as side products. The mechanism of the stereoselective formation
of β-glycoside is investigated. Moreover, all the possible intermediates and transition states
have been explored.
Keywords: Selective glycosylation, Density functional theory, Glycosyl donor, Dioxolenium ion, Glycoside.
Rights & PermissionsPrintExport