STREPTOCOCCUS PNEUMONIAE TYPE XIV POLISACCHARIDE: SYNTHESIS OF A REPEATING BRANCHED TETRASACCHARIDE WITH DIOXA-TYPE SPACER-ARMS

Article abstract of DOI:10.1016/0008-6215(86)80016-7

β-Glycosides of 2-acetamido-2-deoxy-D-glucopyranose were synthesised, using either 7-methoxycarbonyl-3,6-dioxa-1-heptanol or 8-azido-3,6-dioxa-1-octanol.Selective β-lactosylation of 7-methoxycarbonyl-3,6-dioxaheptyl 2-acetamido-3-O-benzyl-2-deoxy-β-D-glucopyranoside with hepta-O-acetyl-lactosyltrichloroacetimidate, followed by β-galactosylation of the secondary hydroxyl group with O-(2,3,4,6-tetra-O-acetyl-α-D-galactopyranosyl)trichloroacetamidate, catalytic hydrogenolysis, and O-deacetylation, gave 7-methoxycarbonyl-3,6-dioxaheptyl 2-acetamido-2-deoxy-4-O-β-D-galactopyranosyl-6-O-(4-O-β-D-galactopyranosyl-β-D-glucopyranosyl)-β-D-glucopyranoside.Selective β-lactosilation of 8-azido-3,6-dioxaoctyl 2-acetamido-3-O-benzyl-2-deoxy-β-D-glucopyranoside with hepta-O-acetyl-lactosyl bromide in the presence of silver triflate, followed by condensation with 2,3,4,6-tetra-O-acetyl-α-D-galactopyranosyl bromide in the presence of silver triflate, catalytic hydrogenolysis, and O-deacetylation, gave 8-azido-3,6-dioxaoctyl 2-acetamido-2-deoxy-4-O-β-D-galactopyranosyl-6-O-(4-O-β-D-galactopyranosyl-β-D-glucopyranosyl)-β-D-glucopyranoside.