Asymmetric induction arising from the chiral twist of 2,2′-binaphthyl template in the cyclopolymerization of divinyl ethers

Cationic cyclopolymerization of divinyl ethers, which were derived from (R)- or (S)-1, 1′-bi-2-naphthol with methyl, phenyl, and bromo groups in the 3,3′-positions, yielded polymers with changing optical rotation according to the reaction conditions. Model compounds, therefore, corresponding to the three stereoisomeric forms of the constitutional units, i. e., two racemo (R,R-and S,S-) forms and one meso form, were synthesized to confirm the origin of changing optical rotation in the polymers. ¹H NMR analysis showed that the polymers change their optical rotation due to the configuration, which has a tendency to be preferentially a racemo-diisotactic structure at higher monomer concentrations and in less polar solvents. The chiral twist of the (R)-or (S)-binaphthyl template induces the main chain to form an asymmetric R,R- or S,S-racemo sequence, respectively, in the cyclopolymerization.