Synthetic mucin fragments. Benzyl O-β- d-galactopyranosyl-(1→3)- O-(2-acetamido-2-deoxy-β- d-glucopyranosyl)-(1→6)-2-acetamido-2-deoxy-α- d-galactopyranoside and O-α- l-fucopyranosyl-(1→3)- O-(2-acetamido-2-deoxy-β- d-glucopyranosyl)-(1→6)-2-acetamido-2-deoxy- d-galactopyranose

Abstract

Benzyl 2-acetamido-6- O-(2-acetamido-2-deoxy-4,6- O-isopropylidene-β- d-glucopyranosyl)-2-deoxy-3,4- O-isopropylidene-α- d- galactopyranoside ( 2) was obtained by acetalation of its parent disaccharide with 2,2-dimethoxypropane in hot N,N-dimethylformamide and in the presence of 4-toluenesulfonic acid. Glycosylation of 2 with 2,3,4,6-tetra- O-acetyl-α- d-galactopyranosyl bromide (catalyzed by mercuric cyanide), followed by removal of the protecting groups afforded the title trisaccharide 7. A second product was also isolated, which was identified as a derivative of 7 having a 2-cyanopropyl group. Glycosylation of diacetal 2 with 2,3,4-tri- O-benzyl-α- l-fucopyranosyl bromide (under catalysis by bromide ion), followed by systematic removal of the protecting groups furnished the title trisaccharide 13. The structures of both 7 and 13 were established by 13C-n.m.r. spectroscopy.