Substituent Effect of Polar Functional Groups in the Anionic Polymerization of (Z)‐1‐Phenyl[3]Dendralene Derivatives

Dendralene is an acyclic hydrocarbon with a branched π‐conjugation system (i.e., cross‐conjugation system), making it a unique structural motif for the synthesis of polymers with conjugated diene backbones. Anionic polymerizations of ( Z )‐1‐(4‐methoxyphenyl)[3]dendralene (1Z‐MP3D) and ( Z )‐1‐(4‐fluorophenyl)[3]dendralene (1Z‐FP3D) were performed to investigate the effect of polar functional groups in the polymerization of 1‐phenyl‐substituted [3]dendralene derivatives. The anionic polymerizations using potassium naphthalenide as an initiator in tetrahydrofuran of both proceeded in a controlled manner and yielded polymers of predictable molecular weight with narrow and unimodal molecular weight distributions. The polymerization proceeded more rapidly upon introduction of substituents with unshared electron pairs, methoxy (−OMe) groups, and fluoro (−F) groups. The electron density on the reactive methylene carbon of the monomer, evaluated by the chemical shift observed in 13 C nuclear magnetic resonance spectra, was not affected by these substituents. Hence, the change in the polymerization behavior was attributed to the enhanced nucleophilicity of the chain‐end carbanion derived from the 1Z‐P3D derivatives.