Ring-opening polymerization polysaccharide synthesis

Ring-opening polymerization has played an important role in systematic approaches to the chemical synthesis of polysaccharides and the clarification of their biomedically interesting characteristics in relation to their own molecular structures. The early... 

Uryu and coworkers also reported the first synthesis of a nonhydro-lyzable polysaccharide by cationic, ring-opening polymerization of an oxetane ring. The monomer was 3,5-anhydro-l,2-0-isopropylidene-a-D-xylofuranose, and it formed a polymer of molecular weight of 10,000-11,000. Spectral and optical data indicated regular polymerization to a (3— 5)-linked polymer of 1,2-O-isopropylidene-a-D-xylofuranose.14... 

K. Kobayashi and T. Kondo, Synthesis of a regiospecifically fluorinated polysaccharide 3-deoxy-3-fluoro-(l — 6)-o -D-glucopyranan via ring-opening polymerization, Macromolecules, 30 (1997) 6531-6535. 

T. Uryu, K. Hatanaka, Y. Sakomoto, K. Harima, A. Hagino, K. Ito, A. Funamoto, and K. Matsuzaki, Synthesis of substituted polysaccharides by ring-opening polymerization of 1,6-anhydro-D-glucose and 1,6-anhydro-D-mannose derivatives, Nippon Kagaku Kaishi, (1982) 1638-1644. 

T. Uryu, Y. Sakamoto, K. Hatanaka, and K. Matsuzaki, Chemical synthesis of a new polysaccharide ring-opening polymerization of l,6-anhydro-2,3,4-tn-0-benzyl-/S-D-allo-pyranose and preparation of stereoregular (1 - 6)-a-D-allopyranan, Macromolecules, 17 (1984) 1307-1312. 

K. Hattori, T. Yoshida, and T. Uryu, Ring-opening polymerization and copolymerization of a new benzylated l,6-anhydro-3-azido-3-deoxy-/S-D-allopyranose and synthesis of amino-polysaccharides with 1,6-u-allopyranosidic structure, Macromol. Chem. Phys., 198 (1997) 29-39. 

Scheme 1 a Ring-opening polymerization of cyclic esters in the presence of SnOct2 and hydroxo-initiator, and b its application to the synthesis of polysaccharide-gra/t-aliphatic polyesters (or poly(hydroxyalkanoate)s)... 

The first stereospedfic synthesis of a linear polysaccharide containing only (1 ->6)-linked ot-D-glucopyranosyl residues was achieved as early as 1961 by ring-opening polymerization of l,6-anhydro-2,3,4-tri-0-methyl-P-i>glucopyra-... 

In general, it is possible to obtain higher degrees of polymerization by ring-opening polymerization than with polycondensation. Two types are used in oligo and polysaccharide syntheses orthoester synthesis and cationic anhydrosugar polymerization. 

The polysaccharide synthesis via ring-opening polymerization method is an attractive method leading to structurally well-defined polysaccharides which are rarely attained by direct chemical modifications of natural polysaccharides. The synthetic polysaccharides obtained are useful tools to elucidate relations between the structure and functionality of polysaccharides and to develop new types of polysaccharides with novel properties. 

Figure 7.1 Synthesis of hyperbranched polysaccharide (Polyla-c) by cationic ring-opening polymerization of l,6-anhydro-j5-D-hexopyranose (la-c).

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