Catalytic and chemoselective glycosylation between novel "armed" and "disarmed" glycosyl p-trifluoromethylbenzylthio-p-trifluoromethylphenyl formimidates was effectively performed in the presence of a catalytic amount of TfOH and MS 4A in CH2Cl2, at -78degreesC. In addition, it was noted that highly 1,2-cis or 1,2-trans stereoselective synthesis was established when the above glycosylation was carried out at -78degreesC in (BuOMe)-Bu-t or EtCN, respectively.