Asymmetric anionic polymerization of maleimide bearing an N-4′-benzo 15-crown-5 ether with an organometal/chiral ligand complex

Abstract

Asymmetric anionic homopolymerization of N-4′-benzo 15-crown-5 maleimide (B15C5MI) was carried out with a chiral anionic initiator consisting of organometal (n-butyllithium, diethylzinc (Et2Zn)) and chiral ligand ((–)-sparteine ((–)-Sp), (S, S)-(1-ethylpropylidene)-bis(4-benzyl-2-oxazoline) ((S, S)-Bnbox)) to obtain optically active polymers. The polymer obtained with the chiral ligand had an optical rotation, suggesting that asymmetric induction occurred on the main chain of the polymer. Poly(B15C5MI) obtained with Et2Zn/(S, S)-Bnbox in tetrahydrofuran showed the highest specific rotation of −64.1°. The chiroptical properties and structures of the polymers obtained were analyzed by circular dichroism, ultraviolet, nuclear magnetic resonance and gel permeation chromatography measurements. The effects of adding (R)-cyclohexylethylamine to the obtained poly(B15C5MI) were investigated. Asymmetric anionic homopolymerizations of N-4′-benzo 15-crown-5 maleimide (B15C5MI) were carried out with a chiral anionic initiator consisting of organometal and chiral ligand to obtain optically active polymers. Chiroptical properties and structures of the polymers obtained were analyzed by CD, UV, NMR and gel permeation chromatography measurements. The additional effects of (R)-cyclohexylethylamine ((R)-Cyc) to the obtained poly(B15C5MI) were investigated.