Synthesis of Oligosaccharide‐Branched Ribofuranan by Ring‐Opening Polymerization of a New Anhydroribo Trisaccharide Monomer

Abstract

A new anhydroribotrisaccharide monomer, A2B3LR (1), was synthesized and ROP was carried out to elucidate the polymerizability and to obtain oligosaccharide-branched polysaccharides with defined structures. The new trisaccharide monomer was found to be polymerized readily with BF(3) . OEt(2) as a catalyst at -40 degrees C to give a lactose-branched polymer. Copolymerization with ADBR gave the corresponding copolymers in good yields. After removal of protective benzyl groups, D-lactose-branched ribofuranans with free hydroxyl groups were obtained in good yields. The structure of polymers was analyzed by (1)H, 13C, and two-dimensional NMR measurements, suggesting that D-lactose-branched ribofuranans had (1 --> 5)-alpha stereoregularity.

Sulfated Polysaccharides as Specific Biologically Active Materials

“…The trisaccharide monomer A2B3LR was found to have high polymerizability with BF 3 OEt 2 as a catalyst to give the corresponding lactosebranched ribofuranans after deprotection to recover hydroxyl groups. These branched polysaccharides with defined structures should be useful model branched polysaccharides to study the relationship between structure and biological activity (20,21).…”

Biologically Active Branched Polysaccharide Mimetics: Synthesis via Ring-Opening Polymerization of a Maltose-Based β-Lactam

“…6 It offers precise regio-and stereoselective control over the branching structure at the monomer level. 7 However, this method suffers from the low reactivity of anhydrodisaccharide monomers, thus it is difficult to obtain branched polysaccharides with high molecular weights. 8 For example, the polymerization of a 1,6-anhydrocellobiose derivative gave benzylated polymers with number-average molecular weights (M n ) up to 7300 g/mol, which corresponds to a degree of polymerization (DP) of 8.5.…”

“…Cationic ring-opening polymerization of anhydrodisaccharides has been studied since the 1970s as a method to prepare branched polysaccharides . It offers precise regio- and stereoselective control over the branching structure at the monomer level . However, this method suffers from the low reactivity of anhydrodisaccharide monomers, thus it is difficult to obtain branched polysaccharides with high molecular weights .…”