Me [ethyl 2-O-acetyl-3,4-O-( 1,1,3,3-tetraisopropyl-1,3-disiloxane-1,3-diyl)-1-thio-b-D-glucopyranosid]uronate, and its 2-O-benzoyl and -pivaloyl analogs, have been synthesized from Me 2,3,4-tri-O-acetyl-a-D-glucopyranosyluronate bromide, via formation and rearrangement of a 1,2-thioorthoester, in a stereospecific and high-yielding manner. Dimethyl(methylthio)sulfonium trifluoromethanesulfonate (DMTST)-promoted glycosylations with these derivs. as donors gave high to excellent yields (59-95%) of exclusively b-linked disaccharides in coupling with monosaccharide acceptors. Removal of the tetraisopropyldisiloxyl acetal with tetrabutylammonium fluoride in THF from one of the obtained disaccharides gave a 3',4'-diol, which was used as acceptor in a DMTST-promoted coupling with Et 2,3,4-tri-O-acetyl-2-deoxy-2-phthalimido-1-thio-b-D-glucopyranoside as donor to give trisaccharides, albeit with low regioselectivity (3-O-linked 38%, 4-O-linked 57%). [on SciFinder (R)]