Synthesis of rhamnogalacturonan I oligosaccharides: synthesis of a tetrasaccharide intermediate

Synthesis and Solution-Phase Conformation of the RG-I Fragment of the Plant Polysaccharide Pectin Reveals a Modification-Modulated Assembly Mechanism

“…In regard to synthetic studies on pectin regions (RG-I/II, HGA), see the SI for an extended discussion and refs − for leading examples of protected RG-I oligosaccharide precursors/analogues.…”

“…Analysis of the RG-I structure (Figure ) initially suggested stereoselective oligomer assembly − through a late-stage coupling of an l -rhamnosyl ( l -Rha)-terminated glycosyl donor fragment to a d -GalA-terminated acceptor fragment (assembly a in Figure ); this logic was suggested by a typically strong preference in l -rhamnosylation for the required α- l -Rha linkage in RG-I, which contrasts with the typically poor selectivity in the formation of the cis linkage of α- d -GalA. However, despite the synthesis of a variety of appropriate building blocks [see the Supporting Information (SI)], their use in convergent disaccharide-to-disaccharide (2 + 2) coupling surprisingly failed.…”

Synthesis of a Backbone Hexasaccharide Fragment of the Pectic Polysaccharide Rhamnogalacturonan I

“…Some of the strategies used galacturonic acid as the starting material, while others favored the oxidation of galactose to galacturonic acid at a late stage, i.e., pre- and postglycosylation–oxidation strategies, respectively. Reimer and co-workers reported the synthesis of a protected tetrasaccharide containing galactose instead of galacturonic acid as an intermediate for the preparation of RG-I fragments. The protective group pattern was designed to allow for further chain elongation and introduction of branching.…”