Synthesis of histo blood-group antigens A and B (type 2), xenoantigen Galα1-3Galβ1-4GlcNAc and related type 2 backbone oligosaccharides as haptens in spacered form

The partial α-fucosylation of spacered (sp = CH₂CH₂CH₂NH₂) N-acetyl β-lactosamine derivative having free hydroxy groups at C-3 and C-2′ gives rise to oligosaccharides H (type 2), Le^x and Le^y, the first one was further elongated giving rise to A (type 2) or B (type 2) tetrasaccharides; spacered trisaccharides Galα1-3Galβ1-4GlcNAc and Galα1-4Galβ1-4GlcNAc were synthesised by the partial α-galactosylation of N-acetyl β-lactosamine derivative, having free hydroxy groups at C-4′ and C-3′.