Synthesis of an apiose-containing disaccharide fragment of rhamnogalacturonan-II and some analogues Original Research Article

β-Rhamnosylation of methyl 2-C-hydroxymethyl-2,3-O-isopropylidene-β-d-erythrofuranoside and methyl 2,3-O-isopropylidene-β-d-ribofuranoside was achieved using 4-O-acetyl-2,3-O-carbonyl-α-l-rhamnopyranosyl bromide and Ag2O as a promoter. Deprotected disaccharides β-l-Rhap-(1 → 3′)-β-d-Apif-OMe and β-l-Rhap-(1 → 3′)-β-d-Ribf-OMe were compared to their α-rhamnosyl isomers which were prepared using conventional Helferich glycosylation.