The cyclopolymerizations of (2S,5S)-1,2:5,6-diepoxyhexane using BF3·OEt2 and tert-BuOK have been studied. The polymer yield and molecular weight of the polymer using tert-BuOK were higher than those using BF3·OEt2. For the polymers using BF3·OEt2, the mole fractions of the cyclized units were 0.76−0.90, and the cyclic constitutional repeating units were five- and six-membered rings. The polymer using tert-BuOK essentially consisted of the five-membered cyclic repeating unit.

The effect of 18-crown-6 ether (18C6) in the anionic cyclopolymerization of 1,2:5,6-dianhydro-3,4-di-O-methyl-D-mannitol (1) using potassium tert-butoxide (t-BuOK) was studied. The addition of 18C6 did not affect the regio-and stereoselectivity in the polymerization of 1, and the resultant polymer was (1f6)-2,5-anhydro-3,4-di-O-methyl-D-glucitol (2). The complexation of t-BuOK with 18C6 increased the initiator efficiency from 0.3 to 1.0, which was accompanied by enhancement of the apparent polymerization rate. The rate constant ratios of the transfer reaction to the propagation (ktr/kp) in the systems with and without 18C6 were 1 order of magnitude lower than the value in the polymerization of monoepoxides.The "living" nature of the t-BuOK/18C6 initiating system was evaluated by the two-step monomer resumption experiment.

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The anionic cyclopolymerization of 1,2:5,6-dianhydro-3,4-di-O-methyl-L-iditol (3) was carried out using t-BuOK and KOH. The resulting polymer 4 consisted of 2,5-anhydro-3,4-di-O-methyl-D-glucitol as a five-membered repeating unit, which was identical with that of polymer 2 obtained from 1,2:5,6-dianhydro-3,4-di-O-methyl-D-mannitol (1). The copolymerization of 1 with 3 produced a random copolymer consisting of (1f6)-, (6f1)-, (1f1)-, and (6f6)-linked 2,5-anhydro-3,4-di-O-methyl-D-glucitol. These facts elucidated the presence of two linkages during the homopolymerization of 1 and 3, i.e., the (1f6) and (6f1)-bonded 2,5-anhydro-3,4-di-O-methyl-D-glucitol units in polymers 2 and 4, respectively.

The anionic cyclopolymerizations of 1,2:5,6-dianhydro-3,4-di-O-methyl-D-mannitol (1) and 1,2:5,6-dianhydro-3,4-O-isopropylidene-D-mannitol (2) have been carried out using potassium tert-butoxide (t-BuOK) and potassium hydroxide (KOH). For the polymerization of 1, a well-defined carbohydrate polymer consisting of (1f6) linked 2,5-anhydro-3,4-di-O-methyl-D-glucitol units was synthesized through a regio-and stereoselective mechanism. When a [1]/[t-BuOK] molar ratio of 20 was used in toluene for 48 h, the yields and number-average molecular weights (Mn) of the polymers gradually increased with polymerization time. The Mn of the polymer varied with the molar ratio of monomer to initiator, and a linear relationship between them was found. The degree of polymerization was larger than that estimated from the molar ratio, resulting in an initiator efficiency of about 55%. KOH was also effective for converting monomer 1 to a gel-free polymer but was not as active as t-BuOK. The rate of polymerization was rather slow, and the polymerization was not complete, even after 100 h. The presence of a crown ether, 18-crown-6, in the cyclopolymerization allowed the Mn of the polymer to approach the value estimated from the [1]/[t-BuOK] molar ratio. On the other hand, monomer 2 tended to form a gel in the polymerization process, so soluble polymers were isolated only at early stages of the polymerization.