Asymmetric polymerization of N-ortho- or para-substituted phenylmaleimide using chiral anionic initiators

N-Phenylmaleimide (PhMI) and its derivatives were polymerized using chiral anionic initiators consisting of diethylzinc (Et2Zn) and chiral ligands to investigate the effect of the bulkiness, flexibility and polarity of the ortho- or para-substituents on optical activity of the obtained polymer. The optical activity of the polymer was extremely influenced by N-substituents, initiators, and other polymerization conditions. Poly(N-2-biphenylmaleimide) (poly(2-BPMI)) formed with Et2Zn-(-)-2,2'-(1-ethylpropylidene)bis(4-benzyl-2-oxazoline) (Bnbox) showed the highest specific rotation ([alpha](435)(25)) of +164.7degrees. From C-13 NMR spectroscopy, optically active poly(2-BPMI) and poly(N-(2-phenoxy)-phenylmaleimide) (poly(2-POPMI)) mainly possessed threo-diisotactic structures in the main chains. Chiral stationary phase prepared from optically active poly(PhMI) optically resolved racemic 1, 1'-bi-2-naphthol.