Chirality Induction in Cyclocopolymerization. 14. Template Effect of 1,2-Cycloalkanediol in the Cyclocopolymerization of Bis(4-vinylbenzoate)s with Styrene

A series of chiral 1,2-cycloalkanediols including (1S,2S)-1,2-cyclopentanediol, (1S,2S)-1,2-cyclohexanediol, (1S,2S)-1,2-cycloheptanediol, and (1S,2S)-1,2-cyclooctanediol (<BO>a</BO>, <BO>b</BO>, <BO>c</BO>, and <BO>d</BO>) were used as chiral templates in the cyclocopolymerization of bis(4-vinylbenzoate)s (<BO>1a</BO>−<BO>d</BO>) with styrene. The copolymerizations of <BO>1a</BO> with styrene produced an insoluble gel at a high mole fraction of <BO>1a</BO> in the feed. On the other hand, the copolymerization of <BO>1b</BO>−<BO>d</BO> with styrene proceeded homogeneously to yield polymers <BO>2b</BO>−<BO>d</BO>, which were soluble in chloroform and tetrahydrofuran. After the removal of the chiral template from the resulting polymers <BO>2a</BO>−<BO>d</BO>, polymers <BO>3b</BO>−<BO>d</BO> exhibited optical rotations ([α]<INF>435</INF>, c 1.0, CHCl<INF>3</INF>) of −2.2 to −17.9° whose signs were opposite to those of polymers <BO>2b</BO>−<BO>d</BO>, while polymer <BO>3a</BO> showed little or no optical activity. Hence, the efficiency of templates on the chirality induction improved by expansion of the ring size of the chiral template; i.e., <BO>1a</BO> ≪ <BO>1b</BO> &lt; <BO>1c</BO> &lt; <BO>1d</BO>. The A values of the CD spectra of monomers <BO>1a</BO>−<BO>d</BO> related to the dihedral angle between two 4-vinylbenzoyl groups of the monomers which decreased with increasing ring size. Therefore, the results indicated that the dihedral angle affected the chiral inductivity of the template.