The first synthesis of the trisaccharide unit of versipelostatin, a down regulator of grp78, was achieved, utilizing methyl triflate promoted glycosidations of thioethyl glycosyl donors of d-digitoxose and d-cymarose with protected digitoxal. The synthesis was terminated by the preparation of a thioglycoside based on diethyldithionophosphonic acid which is ready for further glycosidations with aglycons. Comparison of NMR spectroscopic data of two trisaccharides with the data reported for versipelostatin supported the configuration of the monosaccharide units as well as glycosidic linkages.
antibiotics - deoxy sugars - glycols - glycosidations - glycoconjugates - thioglycosides
