Previous studies (J. Org. Chem. 2012  , 77, 3724) showed that the racemic 1-methyl 1'-cyclopropylmethyl, MCPM, protecting group at O-2 of deactivated glucopyranosyl donors showed preferential formation of one stereoisomer in glycosylation reactions, especially for �-glycosides. Due to the previously determined syn bimodal conformational preference about C-2--O-2 in glucopyranosyl oxacarbenium ions (Carbohydr. Res. 2007  , 342, 2793) this result was interpreted to indicate the presence of oxacarbenium ions in these particular glycosylation reactions. Since mannopyranosyl oxacarbenium ions exhibit the same syn bimodal conformational preference about C-2--O-2 it was decided to prepare 4,6-benzylidene protected mannopyranosyl donors with MCPM at O-2 and directly test if the formation of �-mannosides under preactivation glycosylation conditions exhibited any suggestions of oxacarbenium ion formation. Subsequently, similar donors were used to explore the feasability of synthesizing Man(�1,2)Man oligomers as oligosaccharide donors for immunological studies.

O-2 Chiral non-participating groups on mannose donors to test for oxacarbenium ions

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.