Zwitterionic polysaccharides, such as that found in Streptococcus pneumoniae type 1 capsular polysaccharide (CPS), display unique T-cell activating properties.[1] To investigation in more detail the immune response to the CPS, well-defined part structures of the CPS are required. Recently other groups have reported the synthesis of the trisaccharide repeating unit and a dimer of this.[2] In our approach towards these structures we are investigating various donor types in the construction of the 2,4,6-trideoxy-4-amino-2-acetamido-α-D-galactose moiety. Amongst others the 2,3-N,O-oxazolidinone protected variant has been prepared and was found to give α-selectivity (Fig.2).[3] A summary of the donors and their couplings will be presented.
(Figure 1) α-selective glycosylation with N,O-oxazolidinone protected variant
[1] Cell 117 (2004) 677-687
[2] Chemistry-A European Journal 16 (2010) 3476-3488; Journal of Organic Chemistry 76 (2011) 1692-1706
[3] Journal of Organic Chemistry 73 (2008) 7181-7188
