Two asymmetrically branched oligosaccharides, Lewis
X anddimeric Lewis
X, were assembled in one pot with high yieldsand exclusive regio- and stereoselectivities.
p-Tolyl thioglycosides were utilized as the sole type of building blocks,thus simplifying the overall synthetic design. The reactivity-independent nature of the preactivation based method allowsmodular assembly of the dimeric Lewis
X octasaccharidewithout the need for tedious protective group manipulationto achieve exact anomeric reactivities.