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.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)