Kovác P, Yeh H J, Glaudemans C P
Carbohydr Res. 1985 Jul 15;140(2):277-88. doi: 10.1016/0008-6215(85)85128-4.
Condensation of 2,4,6-tri-O-acetyl-3-deoxy-3-fluoro-alpha-D-galactopyranosyl bromide (3) with methyl 2,3,4-tri-O-acetyl-beta-D-galactopyranoside (4) gave a fully acetylated (1----6)-beta-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-chloracetyl-alpha-D-galactopyranosyl bromide (5), dechloroacetylation of the formed methyl O-(2,3,4-tri-O-acetyl-6-O-chloroacetyl-beta-D-galactopyranosyl)-(1----6) -2,3, 4-tri-O-acetyl-beta-D-galactopyranoside to give methyl O-(2,3,4-tri-O-acetyl-beta-D-galactopyranosyl)-(1----6)-2,3, 4-tri-O-acetyl-beta-D-galactopyranoside (14), condensation with 3, and deacetylation. Dechloroacetylation of methyl O-(2,3,4-tri-O-acetyl-6-O-chloroacetyl-beta-D-galactopyranosyl)-(1----6) -O-(2,3 , 4-tri-O-acetyl-beta-D-galactopyranosyl)-(1----6)-2,3,4-tri-O-acetyl-beta -D- galactopyranoside, obtained by condensation of disaccharide 14 with bromide 5, was accompanied by extensive acetyl migration giving a mixture of products. These were deacetylated to give, crystalline for the first time, the methyl beta-glycoside of (1----6)-beta-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.
2,4,6-三-O-乙酰基-3-脱氧-3-氟-α-D-吡喃半乳糖基溴（3）与甲基 2,3,4-三-O-乙酰基-β-D-吡喃半乳糖苷（4）缩合得到在 3'-位氟化的完全乙酰化的（1→6）-β-D-半乳糖二糖，将其脱乙酰化得到标题二糖。通过 4 与 2,3,4-三-O-乙酰基-6-O-氯乙酰基-α-D-吡喃半乳糖基溴（5）反应、将生成的甲基 O-（2,3,4-三-O-乙酰基-6-O-氯乙酰基-β-D-吡喃半乳糖基）-（1→6）-2,3,4-三-O-乙酰基-β-D-吡喃半乳糖苷脱氯乙酰化得到甲基 O-（2,3,4-三-O-乙酰基-β-D-吡喃半乳糖基）-（1→6）-2,3,4-三-O-乙酰基-β-D-吡喃半乳糖苷（14）、与 3 缩合以及脱乙酰化得到相应的三糖。二糖 14 与溴化物 5 缩合得到的甲基 O-（2,3,4-三-O-乙酰基-6-O-氯乙酰基-β-D-吡喃半乳糖基）-（1→6）-O-（2,3,4-三-O-乙酰基-β-D-吡喃半乳糖基）-（1→6）-2,3,4-三-O-乙酰基-β-D-吡喃半乳糖苷脱氯乙酰化时伴随着广泛的乙酰基迁移，产生产物混合物。将这些产物脱乙酰化，首次以高产率得到（1→6）-β-D-半乳糖三糖的甲基β-糖苷晶体。目标化合物的结构通过 500 MHz 的二维 1H、常规 13C 和 19F 核磁共振光谱得到证实。
