The methylsulfonylethoxymethyl (Msem) as a hydroxyl protecting group in oligosaccharide synthesis

The methylsulfonylethoxymethyl (Msem) is introduced as a base-labile, non-participating protecting group in carbohydrate chemistry. Conditions to introduce the Msem on primary and secondary alcohols are described. Removal of the Msem is best achieved using a catalytic amount of tetrabutylammonium fluoride (TBAF), with or without a nucleophilic scavenger. Applicability of the Msem group is illustrated in the assembly of an all 1,3-cis-linked mannotrioside.