Asymmetric anionic polymerization of chiral (R)-(+)-N-alpha methylbenzylmaleimide with chiral ligand/organometal complex

Asymmetric anionic polymerizations of chiral (R)-(+)-N-alpha-methylbenzylmaleimide (MBZMI) were performed with (-)-sparteine [Sp) or (S, S)-(1-ethylpropylidene)bis(4-benzyl-2-oxazoline) (Bnbox)/organometal complexes in toluene or tetrahydrofuran (THF). All polymers obtained were optically active. Specific optical rotations ([alpha](435)(25)) of the polymers initiated by Et2Zn/Sp and Et2Zn/Bnbox were - 113.5 degrees to - 195.7 degrees and + 56.0 degrees to + 170.2 degrees, respectively. Number-average molecular weights ((M) over bar(n)) of the polymers were from 7.2 x 10(3) to 2.9 x 10(4). Chirality of the polymers was attributed not only to chirality of optically active MBZMI units but also to stereogenic centers (S, S) and (R, R), in the main chain induced by the polymerization, judging from the results of circular dichroism (CD), H-1 and C-13 NMR spectra, and GPC curves obtained with polarimetric and UV detectors. Anionic polymerizability of MBZMI using organometal with and without chiral ligand, and chiroptical properties of the polymers are discussed.