SYNTHESIS OF METHYL O-(3-DEOXY-3-FLUORO-β-D-GALACTOPYRANOSYL)-(1->6)-β-D-GALACTOPYRANOSIDE AND METHYL O-(3-DEOXY-3-FLUORO-β-D-GALACTOPYRANOSYL)-(1->6)-O-β-D-GALACTOPYRANOSYL-(1->6)-β-D-GALACTOPYRANOSIDE

Article abstract of DOI:10.1016/0008-6215(85)85128-4

Condensation of 2,4,6-tri-O-acetyl-3-deoxy-3-fluoro-α-D-galactopyranosyl bromide (3) with methyl 2,3,4-tri-O-acetyl-β-D-galactopyranoside (4) gave a fully acetylated (1->6)-β-D-galactobiose fluorinated at the 3'-position which was deacetylated to give the title disaccharide.The corresponding trisaccharide was obtained by reaction of 4 with 2,3,4-tri-O-acetyl-6-O-chloroacetyl-α-D-galactopyranosyl bromide (5), dechloroacetylation of the formed methyl O-(2,3,4-tri-O-acetyl-6-O-chloroacetyl-β-D-galactopyranosyl)-(1->6)-2,3,4-tri-O-acetyl-β-D-galactopyranoside to give methyl O-(2,3,4-tri-O-acetyl-β-D-galactopyranosyl)-(1->6)-2,3,4-tri-O-acetyl-β-D-galactopyranoside (14), condensation with 3, and deacetylation.Dechloroacetylation of methyl O-(2,3,4-tri-O-acetyl-6-O-chloroacetyl-β-D-galactopyranosyl)-(1->6)-O-(2,3,4-tri-O-acetyl-β-D-galactopyranosyl)-(1->6)-2,3,4-tri-O-acetyl-β-D-galactopyranoside, obtained by condensation of disaccharide 14 with bromide 5, was accompained by extensive acetyl migration giving a mixture of products.These were deacetylated to give, crystalline for the first time, the methyl β-glycoside of (1->6)-β-D-galactotriose in high yield.The structures of the target compounds were confirmed by 500-MHz, 2D, 1H- and conventional 13C- and 19F-n.m.r. spectroscopy.