Studies On Synthesis Of Protected α-D-Gal(1→4)-β-D-Glc And Its Analogues

Oligosaccharides and complexes act various biologic function as information matters. Their important biologic significance asks for abundant and pure oligosaccharides for supporting farther researches and applications on biologic medicine. It is very important to synthesisαorβstereo-selectively in order to synthesis complicated oligosaccharides and their complexes by chemical strategies. we have synthisised protectedα-D-Gal(1→4)-D-Glc and other steoro-selective oligosaccharides with galactosyl by chemical strategies.In this paper, The presence of 4,6-O-benzylidene and 3-O-allyl changed the effect of the existence of a C-2-ester substituent capable of neighboring-group participation. Protected disaccharideα-D-Gal(1→4)-D-Glc, p-methoxyphenyl 3-O-allyl-2-O-benzoyl-4,6-O- benzylidene-α-D-galactopyranosyl-(1→4)-6-O-acetyl-2,3-di-O-benzoyl-β-D- glucopyranoside was achieved stereo-specifically by coupling of a donor, isopropyl 3-O-allyl-2-O-benzoyl-4,6-O-benzylidene-1-thio-β-D-galactopyranoside with a acceptor p-methoxyphenyl 6-O-acetyl-2,3-di-O-benzoyl-β-D-glucopyranoside .Disaccharides with terminal non-reducedβ-galactosyl residue were synthesised in the effect of neighboring-group participation. p-Methoxyphenyl 2,3,4,6-tetra-O-acetyl-β-D- galactopyranosyl-(1→6)-2,3,4-tri -O-benzoyl-β-D-glucopyranoside and p-methoxyphenyl 2,3,4,6-tetra-O-acetyl-β-D-galactopyranosyl-(1→4)-2,3-di-O-benzoyl-6-O-acetyl-β-D- glucopyranoside were achieved by coupling of a donor, isopropyl 2,3,4,6-tetra-O-acetyl- 1-thio-β-D-galactopyranoside , with acceptors p-methoxyphenyl 2,3,4-tri-O-benzoyl-β-D- glucopyranoside and p-methoxyphenyl 6-O-acetyl-2,3-di-O-benzoyl-β-D-glucopyranoside respectively in catalysis of NIS/TMSOTf.Relative acceptors of lactose were synthesised. Pilot studies on stereo-selective trisaccharides were carride out in this paper.