Asymmetric anionic polymerization of (S)-(-)-N-maleoyl-L-valine methyl ester

A kind of N-substituted maleimide (RMI), chiral (S)-(-)-N-maleoyl-L-valine methyl ester ((S)-(-)MVMI) was synthesized successfully from L-valine and maleic anhydride with a specific rotation of [alpha](435) = - 102.2degrees. The polymers of high specific rotations of [alpha](435) = -340.4degrees and [alpha](435) = -292.2degrees were obtained by the asymmetric anionic polymerizations of (S)-(-)-MVMI with diethylzinc (Et2Zn)/(S,S)-(1-ethylpropylidene)bis(4-benzyl-2-oxazoline) ((S,S)-Bnbox) (1.0/1.2) and Et2Zn/(-)-sparteine (Sp) (1.0/1.2) initiators, respectively. Asymmetric inductions in the main chains of polymers with threo-diisotactic structures were investigated by the measurements of gel permeation chromatography (GPC), circular dichroisms (CD), and C-13 NMR.