A catalytic and stereoselective glycosylation with beta-glycosyl fluorides

A catalytic and stereoselective glycosylation of several glycosyl accepters with beta-D-glycosyl fluoride was successfully performed in the presence o f a catalytic amount of trityl tetrakis(pentafluorophenyl)borate (TrB(C6F5) (4)) or trifluoromethanesulfonic acid (TfOH). When TrB(C6F5)(4) was used as a catalyst in the solvent pivalonitrile/(trifluoromethyl)benzene 1:5, the glycosylation proceeded smoothly to afford the glycosides in high yields wi th high beta-D-stereoselectivities (see Table 3). Further, the glycosylatio n by the armed-disarmed strategy in the presence of this catalyst was estab lished (see Table 4). Similarly, glycosylation catalyzed by the strong prot ic acid TfOH afforded the corresponding beta-D-glycosides in good-to-excell ent yields on treating beta-D-glycosyl fluorides having a 2-O-benzoyl group with various glycosyl accepters including thioglycosides (see Tables 6 and 7).