Synthesis of a Typical Glucuronide-Containing Saponin, 28-<i>O</i>-β-<scp>d</scp>-Glucopyranosyl Oleanate 3-<i>O</i>-β-<scp>d</scp>-Galactopyranosyl-(1→2)-[β-<scp>d</scp>-glucopyranosyl-(1→3)]-β-<scp>d</scp>-glucuronopyranoside
作者:Biao Yu、Wenjie Peng、Xiuwen Han
DOI:10.1055/s-2004-829103
日期:——
28-O-β-d-Glucopyranosyl oleanate 3-O-β-d-galactopyranosyl-(1→2)-[β-d-glucopyranosyl-(1→3)]-β-d-glucuronopyranoside (1), a structurally typical glucuronide-containing triterpene saponin isolated from Aralia dasyphylla, was concisely synthesized in linear nine steps and 26% overall yield. The key features of the synthesis are: (1) attachment of the 28-glucosyl ester ahead of assembly of the 3-O-sugar chain; (2) elaboration of the glucuronide residue at a later stage via the TEMPO-mediated selective oxidation; (3) installation of 2-(azidomethyl)benzoyl group as a benzoylic neighboring participating group which is selectively removed afterwards for synthesis of the 1→2 sugar linkage.
28-O-β-d-Glucopyranosyl oleanate 3-O-β-d-galactopyranosyl-(1→2)-[δ-d-glucopyranosyl-(1→3)]-δ-d-glucuronopyranoside (1)是从旱金莲中分离出来的一种结构上典型的含葡糖醛酸的三萜皂甙,该化合物通过 9 个步骤线性合成,总收率为 26%。合成的主要特点是(1) 在组装 3-O 糖链之前连接 28-葡萄糖基酯;(2) 在后期通过 TEMPO 介导的选择性氧化作用详细说明葡萄糖醛酸残基;(3) 安装 2-(叠氮甲基)苯甲酰基作为苯甲酰基邻接参与基团,之后选择性地去除该基团以合成 1→2 糖链。