Synthesis of oligosaccharide fragments of the glycosylinositolphospholipidof Trypanosoma cruzi: a new selenoglycoside glycosyl donor for the preparation of 4-thiogalactofuranosyl analogues

A new selenoglycoside, phenyl 2,3,5,6-tetra-O-acetyl-4-thio-1-selenogalacto furanose, has been synthesized. This 4-thiogalactofuranosyl donor was used in the syntheses of heteroatom analogues of the di-, tri-, and tetrasacchar ides corresponding to the oligosaccharide beta-D-Galf-(1-->3)-alpha-D-Manp- (1-->2)-(beta-D-Galf-(1-->3))-alpha-D-Manp. These compounds represent fragm ents of the terminal end of the glycosylinositolphospholipid oligosaccharid e found in the protozoan Trypanosoma cruzi, the causative agent of Chagas d isease, and are intended for use as inhibitors of the enzymes that construc t the native oligosaccharides. The syntheses employed the selective activat ion of a phenyl 4-thio-1-selenogalactofuranoside glycosyl donor over ethyl 1-thioglycoside glycosyl accepters with NIS/TfOH. (C) 2000 Elsevier Science Ltd. All rights reserved.