Total Synthesis of the Repeating Unit of Streptococcus pneumoniae Zwitterionic Polysaccharide Sp1

Reported herein is the total synthesis of the trisaccharide repeating unit of Streptococcus pneumoniae zwitter-ionic polysaccharide Sp1 containing a rare sugar, 2-acetamido-4-amino-2,4,6-trideoxy-D-galactose (AAT), and three consecutive 1,2-cis-glycosidic linkages. The total synthesis was completed via highly stereoselective glycosylations and late-stage oxidation as key steps involving a longest linear sequence of 21 steps with 4.4% overall yield.

Automated summary

The total synthesis of the trisaccharide repeating unit of Streptococcus pneumoniae zwitter-ionic polysaccharide Sp1, containing a rare sugar, was achieved via highly stereoselective glycosylations and late-stage oxidation in 21 steps with an overall yield of 4.4%.