Synthesis of N-acetyllactosamine-containing oligosaccharides, galectin ligands

The following spacered oligosaccharides were synthesized: GlcNAc beta 1-3Gal beta 1-4GlcNAc beta-sp, GlcNAc beta 1-6Gal beta 1-4GlcNAc beta-sp, GlcNAc beta 1-3(GlcNAc beta 1-6)Gal beta 1-4GlcNAc beta-sp, Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4GlcNAc beta-sp, Gal beta 1-4GlcNAc beta 1-6Gal beta 1-4GlcNAc beta-sp, Gal beta 1-4GlcNAc beta 1-3(Gal beta 1-4GlcNAc beta 1-6)Gal beta 1-4GlcNAc beta-sp, GlcNAc beta 1-3(Gal beta 1-4GlcNAc beta 1-6)Gal beta 1-4GlcNAc beta-sp, and Gal beta 1-4GlcNAc beta 1-3(GlcNAc beta 1-6)Gal beta 1-4GlcNAc beta-sp (sp = O(CH2)(2)NH2). They represent N-acetyllactosamines substituted with N-acetylglycosamine or N-acetyllalctosamine residue at O3, O6, or at both positions of galactose. Glycosylation was achieved by coupling with N-trichloroethoxycarbonyl-protected glucosamine bromide in the presence of silver triflate.