Cyclodextrin as Macrocyclic Monomer. Synthesis of Polysaccharide by Its Ring-Opening Polymerization

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1.α-,β-,and γ-O-permethylated cyclodextrins (MeCDs) were found to act as macrocyclic monomers and undergo cationic ring-opening polymerization giving linear polyglucopyranose.2.The relative reactivity of these three MeCDs is unusual : the monomer having the smaller ring-strain has the higher reactivity, which increases in an order of α,β,and γ. This is due to the unique shape of CD ; the propagating end has to go into the CD cavity to open the CD ring, so that the monomer having the larger ring size is preferable for the polymerization.3.The polymerization of γ-MeCD under appropriate conditions produces a unique glucan having large intervals (=1633,MW of γ-MeCD) in the molecular weight distribution.4.The combination of a functionalized initiator with an activator conducts the polymerization of MeCD to give the end-fuctionalized glucan to some extent.5.MeCD and THF are copolymerizable to yield the corresponding hybrid polymer.6.MeCDs selectively modified at the C6 hydroxy groups of the glucose units are also polymerizable.7.The C2 mono-modified MeCDs are successfully prepared and subjected to the polymerization.