SYNTHESE DER TETRA- UND TRISACCHARID-SEQUENZEN VON ASIALO-GM1 UND -GM2. LENKUNG DER REGIOSELEKTIVITAET DER GLYCOSIDIERUNG VON LACTOSE

Article abstract of DOI:10.1016/0008-6215(85)85148-X

A regioselective β-glycosidation of lactose derivatives unsubstituted at OH-3' and -4' is possible, depending on the catalyst system applied.With silver silicate or silver carbonate as catalyst under hetrogeneous conditions, β-glycosidation occured selectively at the less reactive OH-4'group of the acceptor, whereas with trimethylsilyl triflate or soluble mercury salt as catalyst under homogeneous conditions, it occured almost exclusively at the more reactive OH-3' group.The reactivity of the glycosyl donor, acceptor, and catalyst had to be properly matched for successful regioselective coupling.In this way, the trisaccharide unit of asialo-G_M2-ganglioside, O-(2-acetamido-2-deoxy-β-D-galactopyranosyl)-(1--4)-(β-D-galactopyranosyl-(1--4)-D-glucopyranose, and the tetrasaccharide unit of asialo-G_M1-ganglioside, O-(β-D-galactopyranosyl)-(1--3)-(2-acetamido-2-deoxy-β-D-galactopyranosyl)-(1--4)-(β-D-galactopyranosyl)-(1--4)-β-D-glucopyranose were synthesized.This new method constitutes a very useful approach in the field of ganglioside synthesis.