Stereocontrol of Optically Active Polymer by Asymmetric Anionic Polymerization of 7-Cyano-7-ethoxycarbonyl-1,4-benzoquinone Methide

Abstract

Asymmetric anionic polymerization of a prochiral quinone methide monomer, 7-cyano-7-ethoxycarbonyl-1,4-benzoquinone methide (1), was examined using two chiral anionic initiators, lithium 4-isopropylphenoxide (iPrPhOLi)/(−)-sparteine((−)-Sp) and iPrPhOLi/(S)-(−)-2,2′-isopropylidenebis(4-phenyl-2-oxazoline) ((−)-PhBox) initiators, in a mixture solution of dichloromethane/toluene (30/70 in vol %), and optical activities of the resulting polymers and oligomers (1-mer and 2-mer) were investigated in detail. On asymmetric anionic polymerization of 1 with iPrPhOLi/(−)-Sp initiator, stereoselectivity was quite low on both initiation and propagation reactions, while in the case of iPrPhOLi/(−)-PhBox initiator, stereoselectivity was quite low on the initiation reaction, but the propagation reaction proceeded stereoselectively, resulting in an optically active polymer of 1 (poly(1)) with a large positive specific rotation.