Two straightforward strategies for the synthesis of thiodisaccharides with a furanose unit as the nonreducing end

Thiodisaccharides having a 1-thiopentofuranose nonreducing end were synthesized by two routes starting from per-O-acylaldofuranoses with arabino, ribo, and xylo configurations. These glycosyl donors were converted into S-glycosyl isothiourea derivatives as precursors of 1-thiofuranose units, which were generated in situ and trapped by a sugar enone to produce, by Michael addition, the thioglycosidic linkage. Alternatively, the MoO2Cl2-promoted glycosylation of the thiol group of 6-thiosugar derivatives by per-O-acylfuranose led to thiodisaccharides with exclusive 1,2-trans diastereocontrol. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).