Asymmetric Anionic Polymerization of N-Substituted Maleimides with Et2Zn and Chiral Bisoxazolines

Abstract
Anionic polymerizations of N-substituted maleimides (RMI:R=cyclohexyl (CHMI), R=phenyl (PhMI)) were achieved by chiral anionic initiator such as diethylzinc (Et2Zn)–chiral bisoxazoline (R′box) to afford optically active poly(RMI). The polymerizability was enhanced by the accelerated nucleophilicity of the ethyl groups in Et2Zn due to R′box ligands. The specific rotations of poly(PhMI) ([α]25435 −28.4 to + 94.6°) were much improved than those initiated by n- BuLi - R′box.