ASYMMETRIC POLYMERIZATION OF ISOCYANATES WITH OPTICALLY-ACTIVE ANIONIC INITIATORS

Anionic polymerization of 3-phenylpropyl, 4-phenylbutyl, and butyl isocyanates was carried out with chiral anionic initiators such as tert-butyllithium-(-)-sparteine complex (t-BuLi-(-)-Sp), lithium (-)-menthoxide, and (+)-1-(2-pyrrolidinylmethyl)pyrrolidine lithium amide. The t-BuLi-(-)-Sp did not afford optically active polymers. However, the alkoxide and amide gave optically active polymers for 4-phenylbutyl and butyl isocyanates. The optical activities are probably based on the prevailing helicity of the polymer chains induced by chiral initiator residues attaching to an alpha-end group of the polymer chain. The optical rotation of the polymers depended greatly on molecular weight and temperature.