Total Synthesis of Repeating Unit of O-Polysaccharide of Providencia alcalifaciens O22 via One-Pot Glycosylation.

The first total synthesis of the phosphorylated trisaccharide repeating unit of Providencia alcalifaciens O22 is reported. The trisaccharide contains rare deoxyamino sugar AAT at the reducing end and d-glyceramide 2-phosphate at the other end. The efficient synthesis involves one-pot assembly of trisaccharide and late-stage phosphorylation as key steps.