The use of Kdo thioglycosides as glycosyl donors using DMTST, IBr/AgOTf and NIS/AgOTf as promoters has been evaluated. Activation at low temp. allowed to escape the formation of 2,3-glycal byproducts to give glycosides in high yield and with good b-anomeric selectivity. The use of di-Et ether as solvent and (esp.) isopropylidene acetals as protecting groups improved the a-anomeric selectivity. NIS/AgOTf as promoter surprisingly yielded the 3-iodo-product via the glycal intermediate. [on SciFinder (R)]