Asymmetric induction in the cyclopolymerization of divinyl ethers derived from (R)- or (S)-3,3′-dimethyl-1,1′-bi-2-naphthol

Optically active divinyl ethers, (?)-(R)- and (+)-(S)-2,2′-bis[2-(2-vinyloxyethoxy)ethoxy]-3,3′-dimethyl-1,1′-binaphthyl [(R)- 1b and (S)- 1b ] were polymerized to produce chiral poly(crown ether)s. Their optical rotation was found to be profoundly influenced by the polymerization conditions. When increasing the monomer concentration from 0,1 to 0,3 mol · 1^?1, after polymerization with SnCl₄ in CH₂Cl₂ at 0°C, the optical rotation of the resulting polymers is drastically changed from +44,5° to ?17,3° for (R)- 1b and from ?35,6° to +20,9° for (S)- 1b . The analysis of ¹H NMR showed that the polymers have changed their optical rotation due to a configuration which has a tendency to be preferentially racemic diad at higher monomer concentrations in a nonpolar solvent. There are indications that the twist of 2,2′-binaphtyl moieties, the methyl groups in 3-, and 3′-positions as steric barrier, and the intramolecular solvation of the growing carbo-cation cooperatively control the propagation to induce the asymmetry in the main chain.