Chemical synthesis of oligosaccharides: Efficiency and selectivity

Due to high demand to access biologically important oligosaccharide structu res, efficient and stereoselective synthetic methods are required. This art icle addresses these two issues from our recent studies. The first part dea ls with P-mannosylation and cr-sialylation known as the two most difficult glycosylation reactions which were now made possible by means of an "intram olecular aglycon delivery" system and control by "auxiliary", respectively. In the second part, the remarkably efficient "orthogonal glycosylation str ategy" which was developed based on tactical analysis of oligosaccharide sy nthesis is described.