Ring‐opening polymerization of 5,6‐anhydro‐glucose and ‐allose derivatives. Effect of substitutional or configurational difference at the position of sugar monomers on polymerization behavior

Abstract

AbstractThe ring‐opening polymerization of 5, 6‐anhydro sugar derivatives, which are substituted oxiranes, was carried out to obtain (5→6)‐glycan derivatives and to elucidate the reactivities of the monomers. 5,6‐Anhydro‐3‐O‐benzyl‐1,2‐O‐isopropylidene‐α‐D‐glucofuranose (BAIGF) (1), 5,6‐anhydro‐1,2‐O‐isopropylidene‐α‐D‐allofuranose (AIAF) (2), and 5,6‐anhydro‐3‐O‐benzyl‐1,2‐O‐isopropylidene‐α‐D‐allofuranose (BAIAF) (3) were used for polymerization. The monomer 1 was polymerized by anionic catalysts KOH and tert‐BuOK in high yield, while cationic catalysts gave polymers in low yield. On the other hand, the monomer 2 was polymerized by a variety of Lewis acids and strong bases as catalyst in high yield. The monomer 3 was polymerized by anionic catalyst into insoluble polymer. The polymers anionically obtained from these monomers have stereoregular structures composed of CH2CHRO backbone, but the degree of polymerization was limited below 20 by various factors such as termination and chain transfer. The effects of substitution and difference of the configuration at position 3 on polymerization behavior were elucidated by comparing the polymerizabilities and the polymer structure prepared from these monomers with those from 5,6‐anhydro‐1,2‐O‐isopropylidene‐α‐D‐glucofuranose (AIGF) (4). In addition, copolymerization of AIGF with AIAF was carried out using PF5 and NaOH as catalysts in order to examine the difference in monomer reactivity, giving rAIGF = 0.81 and rAIAF = 0.29 for the anionic polymerization.