Versatile use of ytterbium(III) triflate and acid washed molecular sieves in the activation of glycosyl trifluoroacetimidate donors. Assemblage of a biologically relevant tetrasaccharide sequence of Globo H.

The nonreducing tetrasaccharide terminus of Globo H has been assembled in good yield and excellent stereocontrol exclusively by using mild and moisture stable agents such as Yb(OTf)(3) and acid washed molecular sieves for the activation of glycosyltrifluoroacetimidate donors in the glycosylation steps.