Additive-controlled stereoselective glycosylations of 2,3-oxazolidinone protected glucosamine or galactosamine thioglycoside donors with phenols based on preactivation protocol

- Additive-controlled stereoselective glycosylations of aminosugar donors with phenols were achieved.
- BF3·Et2O worked as α-directing additive.
- TTBP acted as β-directing additive.
- The stereochemistry could be reversed by altering additives.