Synthesis of a Typical Glucuronide-Containing Saponin,28-0-P-D-Glucopyranosyl O1eanate3-O-p-D-Galactopyranosyl-(l->2)-[beta-D-glucopyranosyl-(l->3)]-p-D-glucuronopyranoside

摘要

28-O-beta-D-Glucopyranosyl oleanate 3-O-beta-D-galactopyr-anosyl-(l-^2)-[P-D-glucopyranosyl-(l-^3)]-P-D-glucuronopyrano-side (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; beta) installation of 2-(azidomethyl)benzoyl group as abenzoyl-ic neighboring participating group which is selectively removed afterwards for synthesis of the 1->2 sugar linkage.