Mechanism of anomerization of cyclohexyl 2-deoxy-3,4,6-tri-O-methyl-2-(N-methylacetamido)-α- and β-d-hexopyranosides under reductive-cleavage conditions
作者:Yu Mi Ahn、Gary R. Gray
DOI:10.1016/s0008-6215(96)00251-0
日期:1996.12
As expected, the fully methylated 1,2-trans-linked acetamido sugar derivatives were rapidly converted to their respective oxazolinium ions with all three promoters. Surprisingly, however, the fully methylated 1,2-cis-linked acetamido sugar derivatives were also converted to their respective oxazolinium ions, albeit at a much slower rate. In the latter case, evidence was obtained for anomerization
摘要用葡萄糖,甘露聚糖和半乳糖构型的2-乙酰氨基-2-脱氧-α-和β-d-六吡喃糖的完全甲基化的环己基糖苷分别使用三个启动子之一,即三甲基甲硅烷基三氟甲磺酸酯,进行还原裂解。甲磺酸三甲基甲硅烷基酯和三氟化硼醚化物的混合物,或单独的三氟化硼醚化物的混合物。如所预期的,具有全部三个启动子的完全甲基化的1,2-反式连接的乙酰氨基糖衍生物被迅速转化成它们各自的恶唑啉鎓离子。然而,令人惊讶的是,尽管以慢得多的速度,完全甲基化的1,2-顺式连接的乙酰氨基糖衍生物也被转化成它们各自的恶唑啉鎓离子。在后一种情况下,获得了证据证明可以异构化为1,在还原裂解条件下的2-反式连接的异构体。由于室温下在二氯甲烷中的异构化反应相对较慢,因此开发了一种改进的方法,其中该反应在70°C下于1,2-二氯乙烷中进行。使用改进的方法,将所有1,2-顺式和1,2-反式连接的乙酰氨基糖衍生物迅速转化为它们各自的恶唑啉离子,随后用无水甲醇淬灭反应,得到各自的1