ChemInform Abstract: Syntheses of LewisXand Dimeric LewisX: Construction of Branched Oligosaccharides by a Combination of Preactivation and Reactivity Based Chemoselective One-Pot Glycosylations

Two asymmetrically branched oligosaccharides, LewisX and dimeric LewisX, were assembled in one pot with high yields and 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 allows modular assembly of the dimeric LewisX octasaccharide without the need for tedious protective group manipulation to achieve exact anomeric reactivities.