MIGRATION OF THIOLTHIOCARBONYL GROUPS IN SELECTIVELY PROTECTED METHYL ALPHA-D-GLUCOPYRANOSIDE XANTHATES

A series of benzylxanthate esters of methyl α-d-glucopyranoside selectively methylated at various hydroxyl groups was synthesized. The esters were converted into the corresponding xanthate salts, and their behavior was investigated under alkaline conditions typical of xanthation media. Results reveal that migration of thiolthiocarbonyl groups from the 2- or 3-position to the 6-position proceeds via the hydroxyl group at C-4. Direct migration across the pyranose ring from the 2- or 3-position to the 6-position was negligible. The (benzylthio)thiocarbonyl position for each ester was identified by n.m.r. spectroscopy. Primary substitution caused the signals for the two protons at C-6 to be displaced downfield by about 1.0 p.p.m., and secondary substitution caused a 2.4-p.p.m. downfield shift of the signals for protons at C-2, C-3, and C-4. © 1969.