Synthesis of Methyl N-Acetyl-4-amino-2,4,6-trideoxy-3-C-methyl-α-L-rhamnohexopyranoside − Towards Elucidation of the Relative Configuration of Saccharocarcin E Sugar
作者:Martin Langner、Sabine Laschat、Jörg Grunenberg
DOI:10.1002/ejoc.200390209
日期:2003.4
obtained from L-rhamnose (10) in six steps, was used as a precursor for the preparation of methyl N-acetyl-4-amino-2,4,6-trideoxy-3-C-methyl-α-L-rhamnohexopyranoside (5b). The amino group at C-4 of 5b was introduced by intramolecular nucleophilic displacement of a (trichloromethyl)imidate derived from 8, yielding the 3,4-trans-(trichloromethyl)oxazoline 13 with retention of configuration. Compound
L-Olivomycal 8,由 L-鼠李糖 (10) 分六步获得,用作制备甲基 N-乙酰基-4-氨基-2,4,6-trideoxy-3-C-methyl-α 的前体-L-鼠李糖己糖苷 (5b)。5b 的 C-4 处的氨基通过源自 8 的(三氯甲基)亚胺酸酯的分子内亲核置换引入,产生具有保留构型的 3,4-反式-(三氯甲基)恶唑啉 13。通过碱性水解和随后的乙酰化将化合物13进一步转化为N-乙酰胺14。N-碘代琥珀酰亚胺促进的糖基化和还原脱卤产生目标分子 5b,连同其 β 差向异构体 5c (α/β = 85:15)。5b 的 NMR 光谱数据与糖癌 E 糖和其他几种 4-氨基-2-脱氧己糖的 NMR 光谱数据的比较揭示了糖癌 E 糖和 kijanimicin 衍生物 23 之间的相似性,这表明所提出的糖癌的 β-L-xylo-hexopyranose 构型 4d乙糖。(© Wiley-VCH