Use of a phenyl 1-selenogalactofuranoside as a glycosyl donor for the synthesis of galactofuranosyl-containing disaccharides

The use of acetylated phenyl 1-seleno-β-d-galactofuranoside as a glycosyl donor for the synthesis of protected d-Gal>-β-(1 → 3)-α-d-Manp as its methyl or ethylthio glycoside has been demonstrated. Activation of the selenoglycoside over a thioglycoside acceptor by NIS/TfOH is extremely selective and gives the ethylthio disaccharide in 91% yield. The parent disaccharide is found as a terminal and branched unit in the lipopeptidophosphoglycan oligosaccharides of the protozoan Trypanosoma cruzi, the causative agent of Chagasʹ disease.