Synthesis of a Potential 10E4 Tetrasaccharide Antigen Involved in Scrapie Pathogenesis

To test the hypothesis that tetrasaccharide 3 is involved in scrapie pathogenesis, tetrasaccharide derivative 32 functionalized with an amine linker at the reducing end was synthesized. A (2 + 2) glycosylation approach was chosen to furnish the target compound in fully protected form. To investigate its biological role, tetrasaccharide 32 was further functionalized to the corresponding thiol 33 using Traut's reagent. During the course of the synthesis, the N,N-diacetyl protecting group proved surprisingly labile to radical and acidic conditions.