The syntheses of δ-NCS-butyl α-L-fucosides and fucobiosides and their clustering to triantennary glycomimetics

L-Fucose is an especially important monosaccharide constituent in eukaryotic glycoconjugates. Its recognition by fucose specific lectins might play an important role in embryonic development, cancer development and metastasis. Therefore it is of great interest to develop potent inhibitors of fucose specific lectins, both to investigate as well as to manipulate the respective interactions. A promising approach to high affinity fucoside ligands is the synthesis of oligovalent fucosyl clusters. The synthesis of isothiocyanato-functionalized spacer alpha-fucosides and fucobiosides is described together with their clustering on tris(2-aminoethyl)amine giving rise to the first thiourea bridged cluster fucosides 14 and 16 in excellent yields.