Cationic polymerization of bis(1‐alkylvinyl)benzenes and related monomers, 4. Synthesis of monomers with long alkyl side chains

Homologues of the series 1,4‐bis(2‐methyl‐2‐alkenyl)benzene (6) are potential monomers for the systematic synthesis of alkyl‐substituted polyindans. The first five homologues were prepared by Witting‐synthesis, starting from 1,4‐diacetylbenzene (5) and the corresponding n‐alkyltriphenyl‐phosphonium bromide (3). Three double‐bond isomers were qualitatively and quantitatively identified by 1H and 13C NMR spectroscopy. The reaction conditions chosen favour Z‐olefination, and the selectivity ratio of Z‐ and E‐olefin formation in each step was estimated.