Pre-activation protocol leading to highly stereoselectivity-controllable glycosylations of oxazolidinone protected glucosamines.

Under pre-activation glycosylation conditions, the 4,6-di-O-acetyl-N-acetyloxazolidinone protected donor afforded either excellent beta- or alpha-stereoselectivity simply by means of the addition of hindered base TTBP or the absence of base, leading to the controllable stereochemistry of coupling reactions.