13C-NMR study of methyl- and benzyl ethers of l-arabinose and oligasaccharides having l-arabinose at the reducing end. Synthesis of 2-O-β-d-glucopyranosyl-, 2-O-α-l-rhamnopyranosyl-, 3-O-β-d-glucopyranosyl-2- O-α-l-rhamnopyranosyl- and 4-O-β-d-glucopyranosyl-2-O-α-l-rhamnopyranosyl-l-arabinose
作者:András Lipták、Zoltán Szurmai、Pál Nánási、András Neszmélyi
DOI:10.1016/0040-4020(82)85034-5
日期:1982.1
The reaction of benzyl exo-3,4-O-benzylidene-β-l-arabinopyranoside 1 with α-acetobromo-d-glucose 3 resulted in a mixture of two disaccharides, 5 and 6, in which the configuration of the acetal ring was different. The reaction of 1 with α-acetobromo-l-rhamnose 4 gave the desired disaccharide 7 without isomerisation of the dioxolane-type benzylidene ring. The reason for the isomerisation, occuring during
苄基外-3,4-O-亚苄基-β-1-阿拉伯吡喃糖苷1与α-乙酰溴-d-葡萄糖3的反应产生了两种二糖5和6的混合物,其中乙缩醛环的构型为不同的。的反应1与α-乙酰溴L-鼠李糖4,得到所需的二糖7而不二氧戊环型亚苄基环的异构化。讨论了在Koenigs-Knorr反应过程中发生异构化的原因。用4对苄基内酯-3,4-O-亚苄基-β-1-阿拉伯吡喃果糖苷2进行类似处理,得到8。化合物6,7和8分别和脱乙酰化苄,得到9,10和11。对所有完全保护的二糖进行氢解(LiAlH 4 = AlCl 3)可得到具有游离OH-3的衍生物(9 → 13和11 → 15)。10的氢解也产生15,而具有游离OH-4的所需14只是反应的次要产物。化合物14和15的糖基化产生保护形式的两种三糖衍生物(16和17)。的脱保护6,7,16和17得到的四个标题化合物(22,23,18和19)。