Steric control in the polymerization of 1,2-anhydro-3,4,6-tri-O-benzyl-beta-D-mannopyranose

One-pot synthesis of glycyrrhetic acid polyglycosides based on grafting-from method using cyclic sulfite

Glycyrrhetic acid polyglycosides were synthesized in one-pot via cationic ring-opening condensation polymerization of cyclic sulfite (4) initiated by glycyrrhetic acid as an aglycon. Sulfite 4 worked as a practical monomer for the preparation of (1 → 2)-linked polysaccharide skeletons. The chemical stability of 4 was evaluated by the comparison of thermodynamic parameters with those of conventional epoxide (2). The grafting reaction of 4 from glycyrrhetic acid (5) was performed in the presence of TfOH and MS 3A in CH2Cl2 at room temperature. The polymerization degree was moderately controllable by the change of feed ratio of initiator.

Galactan synthesis in a single step via oligomerization of monosaccharides

Galactans ranging in length from one to five residues were prepared in a single step by treatment of the glycosyl donor 2,3,4-tri-O-benzoyl-β-D-galactopyranosyl fluoride with lanthanum perchlorate in the presence of an initiator alcohol. The product oligosaccharides were readily chromatographically separable. This oligomerization was used to synthesize a pentagalactan in a single step from monosaccharide building blocks in reasonable overall yields.