Synthesis of galactofuranosyl-containing oligosaccharides corresponding tothe glycosylinositolphospholipid of Trypanosoma cruzi

The oligosaccharide beta-D-Ga1f-(1-->3)-alpha-D-Manp-(1-->2)-[beta-D-Ga1f-( 1-->3)]-alpha-D-Manp-(1-->2)-alpha-D-Manp corresponds to the terminal end o f the glycosylinositolphospholipid oligosaccharide of the protozoan Trypano soma cruzi, the causative agent of Chagas' disease. Syntheses of methyl or ethylthio glycosides of the terminal disaccharide, trisaccharide, tetrasacc haride, and pentasaccharide corresponding to this structure are described. These syntheses employ the selective activation of a phenyl 1-selenogalacto furanoside or a phenyl 1-selenomannopyranoside donor over ethyl 1-thioglyco side accepters with NIS-TfOH. (C) 2000 Elsevier Science Ltd. All rights res erved.