Synthesis and polymerization of some optically active 2- and 1,2-substituted butadienes

Dehydration of (S)-3,5-dimethyl-1-hepten-3-ol gave: (3E)- (I) and (3Z)-(5S)-3,5-dimethyl-1,3-heptadienes (II) and 2-(S)- 2-methylbutyl]-1,3-butadiene (III). 2-(S)-1-Methylpropyl]-1,3-butadiene (IV) was also prepared similarly by dehydration of (S)-3,4-dimethyl-1-hexene-3-ol. Monomers I–IV we polymerized in the presence of the TiCl₄–Al(i-C₄H₉)₃ catalyst system and in emulsion with K₂S₂O₈ as initiator. Monomer IV was also polymerized in the presence of butyllithium. Specific rotations of polymers are of the same order of magnitude as that of monomers, with exception of polymers prepared by stereospecific polymerization of (S)-I and (S)-II. The acetone-soluble fraction of these polymers has a molar rotation similar to that of monomer, while the acetone-insoluble part has a lower rotation (M]_D of monomer +53.2°; M]_D of polymer, +5.9°).