Stereocontrolled syntheses of O-glycans of core class 2 with a linear tetrameric lactosamine chain and with three lactosamine branches

Synthetic routes to O-glycans of core class 2 with a linearly extended tetralactosamine moiety and with three lactosamine branches are discussed. By a glycosyl fluoride-method, the mono- and the di-lactosaminyl units were attached to the core disaccharide (Galβ1 å 3GalN3) derivatives in high stereoselectivity.