New double 1,1-diphenylethylene (DDPE) compounds with different substituent groups on 1,3-bis(1-phenylethenyl)benzene (PEB) and samples of 1,3-bis[1-(methylphenyl)ethenyl]benzene (MPEB) with different methyl group positions on the phenyl rings were prepared. Included in the preparation was also a non-DDPE diolefinic compound in which the center phenyl ring of PEB was replaced by a saturated one. The behavior of isoprene polymerization initiated by the dilithium initiators obtained by the addition reaction of sec-butyllithium (s-BuLi) with these diolefinic compounds was studied. The slow propagation from the initial initiator-isoprene adduct observed for the initiators based on PEB and MPEB was not affected by any of the structural variations. Structural variations, however, had an influence on the relative reaction rate of the two double bonds on the diolefinic compounds with s-BuLi. Replacement of the center phenyl ring with a saturated cyclohexane ring drastically reduced the double bond reaction rate with s-BuLi.