Synthesis of tri- and tetrasaccharide haptens related to the Asialo forms of the gangliosides GM2 and GM1

Publisher Website
Google Scholar
Abstract
Synthesis of βDGalNAc(1→4)βDGal(1→4)βDGlc—O(CH2)8COOCH3 (21) and βDGal(1→3)βDGalNAc(1→4)βDGal(1→4)βDGlc—O(CH2)8COOCH3 (33) are presented starting from βDGal(1→4)βDGlc—O(CH2)8COOCH3 (1) and D-galactose. Improvements in the preparations of D-galactal triacetate (7) and tri-O-acetyl-2-azido-2-deoxy-α-D-galactopyranosyl bromide (11) are reported. The syntheses proceeded by way of the tri-O-acetyl-2-deoxy-2-phthalimido-β-D-galacto-pyranosyl and 4,6-di-O-acetyl-3-O-(tetra-O-acetyl-β-D-galactopyranosyl)-2-deoxy-2-phthalimido-β-D-galactopyranosyl bromides (18 and 30), which, in turn, were prepared from the corresponding allyl glycosides (15 and 23). The 13C chemical shifts for the tri- and tetrasaccharide portions of 21 and 33 are assigned from the chemical shifts that were observed for the carbon atoms in the disaccharides which make up these structures. The trisaccharide (21) only very weakly inhibited the agglutination of human A red cells by the lectin of Dolichosbiflorus. The tetrasaccharide (33) was inactive.