Synthesis of the conjugation ready tetrasaccharide repeating unit of the O-polysaccharide from Halomonas fontilapidosi KR26.

Synthesis of the tetrasaccharide repeating unit of the O-polysaccharide from Halomonas fontilapidosi KR26 was accomplished through a convergent [2 + 2]-block strategy using rationally protected monosaccharide synthons derived from commercially available sugars. The target tetrasaccharide was synthesized in the form of its 2-azidoethyl glycoside to ensure further conjugation with specific aglycons without hampering the reducing end stereochemistry. Use of only acyl/aryl protecting groups was targeted to keep the terminal azido-group intact for the utilization of "Click chemistry" for further conjugations.