Asymmetric anionic polymerization of maleimides bearing bulky substituents

Asymmetric anionic homopolymerizations of N-substituted maleimide (RMI) bea ring bulky substituents [R = benzyl, diphenylmethyl (DPhMI), 9-fluorenyl (9 FIMI), triphenylmethyl, (diphenylmethyloxycarbonyl)methyl, (9-fluorenyloxyc arbonyl)methyl] were carried out with complexes of organometal compounds (a lkyllithium, diethylzinc) with six chiral ligands to obtain optically activ e polymers. The chiroptical properties of the polymers were affected strong ly by the substituents on nitrogen in the maleimide ring, the organometal a nd chiral ligands. Poly(DPhMI) initiated by an n-butyllithium/(-)-sparteine (Sp) complex showed a positive specific rotation ([alpha](435)(25) +60.3 d egrees). Poly(9-FlMI) prepared with a florenyllithium/Sp complex exhibited the highest specific rotation (+65.7 degrees). The specific rotations of th e poly(RMI) obtained were attributed to different contents between the ster eogenic centers (S,S) and (R,R) based on threo-diisotactic structures of th e main chain. (C) 2000 John Wiley & Sons, Inc.