Isolation of three oligosaccharides from the mucilage from the bark of Ulmus fulva (slippery-elm mucilage). Synthesis of O-(3-O-methyl-β-D-galactopyranosyl)-(1→4)-L-rhamnose

Borohydride reduction of the periodate-oxidized polysaccharide obtained from slippery-elm mucilage, affords, on partial hydrolysis with hot acid, three oligosaccharides: O-(3-O-methyl-β-D-galactopyranosyl)-(1→4)-O-(3-O-methyl-β-D-galactopyranosyl)-(1→4)-L-rhamnose (2), O-(3-O-methyl-β-D-galactopyranosyl)-(1→4)-L-rhamnose (3), and O-(3-O-methyl-β-D-galactopyranosyl)-(1→4)-3-O-methyl-D-galactose (4). The structure assigned to 3 was corroborated by a synthesis of the disaccharide.