First, we established acceptor reactivity-stereoselectivity trends of the benzylidene mannosyl and glucosyl donors using a series of model acceptors of gradually increasing nucleophilicity (i.e., 2,2,2-trifluoroethanol, TFE; 2,2-difluoroethanol, DFE; 2fluoroethanol, MFE; ethanol, EtOH), in a set of pre-activation glycosylation reactions, in which the glycosyl triflates are generated prior to the addition of the acceptors. The results of these model glycosylation reactions are summarized in Table . As previously reported, the stereoselectivity of the glycosylation reactions of the 2,3-di-O-benzyl benzylidene glucose donor 1 gradually shifts from αto β-stereoselectivity as the nucleophilicity of the acceptor increases. Conversely, the reactions of the 2,3-di-O-benzyl benzylidene mannose donor proceeded with β-selectivity irrespective of the reactivity of the nucleophile. Installation of a benzoate group on the C-3 of the glucosyl donor had no effect on the stereochemical outcome of the glycosylation reactions. However, a tremendous shift in stereoselectivity was observed for the glycosylations of the mannosyl donors, providing exclusively the α-product, in line with previous experiments with a 3-O-benzoyl-2,4,6-tri-O-benzyl mannosyl donor.