Synthesis of Hyperbranched Polysaccharide by Thermally Induced Cationic Polymerization of 1,6‐Anhydrohexopyranose

The thermally induced cationic polymerizations of 1,6‐anhydro‐β‐ D ‐glucopyranose ( 1a ), 1,6‐anhydro‐β‐ D ‐mannopyranose ( 1b ) and 1,6‐anhydro‐β‐ D ‐galactopyranose ( 1c ) as a latent cyclic AB 4 ‐type monomer were carried out using ( S ‐2‐butenyl)tetramethylenesulfonium hexafluoroantimonate ( 2 ) as an initiator. The solution polymerization in propylene carbonate proceeded without gelation to produce the water‐soluble hyperbranched polysaccharides ( 3a‐c ) with controlled molecular weights and narrow polydispersities. The degree of branching (DB), estimated by the methylation analysis of 3a‐c , was in the range of 0.38 – 0.49. The thermally induced cationic polymerization of 1a‐c using 2 is a facile method leading to a hyperbranched polysaccharide with a high DB value.