Matta K L, Rana S S, Abbas S A
Carbohydr Res. 1984 Aug 15;131(2):265-72. doi: 10.1016/0008-6215(84)85248-9.
Acetalation of o-nitrophenyl 2-acetamido-2-deoxy-alpha-D-galactopyranoside with p-methoxybenzaldehyde-zinc chloride complex afforded the 4,6-O-(p-methoxybenzylidene) derivative (1). Acetylation of 1 with pyridine-acetic anhydride gave the crystalline monoacetate (2), the acetal group of which was cleaved by brief treatment with hot, 80% aqueous acetic acid to furnish the diol (3). The 1H-n.m.r. spectra of both 2 and 3 supported their overall structures. Glycosylation of 3 with 2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl bromide (5) in 1:1 nitromethane-benzene, in the presence of mercuric cyanide, afforded the disaccharide derivative (6). O-Deacetylation of 6 in methanolic sodium methoxide gave the title disaccharide (8). A similar glycosylation of benzyl 2-acetamido-3-O-acetyl-2-deoxy-alpha-D-galactopyranoside with bromide 5, followed by O-deacetylation of the resulting intermediate, produced disaccharide 9. The structures of 8 and 9 were confirmed by 13C-n.m.r. spectroscopy. Hydrogenolysis of the benzyl aglycon of 9 gave the free disaccharide 2-acetamido-2-deoxy-6-O-beta-D-galactopyranosyl-D-galactopyranose (13). The 13C-n.m.r. spectrum of 13 is recorded, and discussed in conjunction with those of the beta-(1----3)- and the beta-(1----4)-linked isomers.
邻硝基苯基 2-乙酰氨基-2-脱氧-α-D-吡喃半乳糖苷与对甲氧基苯甲醛-氯化锌络合物进行缩醛化反应，得到 4,6-O-(对甲氧基亚苄基)衍生物(1)。1 与吡啶-乙酸酐进行乙酰化反应，得到结晶性单乙酸酯(2)，其缩醛基团经用热的 80%乙酸水溶液短暂处理而裂解，得到二醇(3)。2 和 3 的 1H-核磁共振谱支持了它们的整体结构。3 与 2,3,4,6-四-O-乙酰基-α-D-吡喃半乳糖基溴(5)在 1:1 的硝基甲烷-苯中，在氰化汞存在下进行糖基化反应，得到二糖衍生物(6)。6 在甲醇钠的甲醇溶液中进行 O-脱乙酰化反应，得到标题二糖(8)。苄基 2-乙酰氨基-3-O-乙酰基-2-脱氧-α-D-吡喃半乳糖苷与溴化物 5 进行类似的糖基化反应，随后对所得中间体进行 O-脱乙酰化反应，得到二糖 9。8 和 9 的结构通过 13C-核磁共振光谱得到证实。9 的苄基糖苷配基进行氢解反应，得到游离二糖 2-乙酰氨基-2-脱氧-6-O-β-D-吡喃半乳糖基-D-吡喃半乳糖(13)。记录了 13 的 13C-核磁共振谱，并与β-(1→3)-和β-(1→4)-连接的异构体的谱图一起进行了讨论。
