Controlled Helix‐Sense‐Selective Polymerization of 4‐Alkoxy‐3,5‐Bis(hydroxymethyl)phenylacetylene Derivative Initiated by Chiral Hexa‐1,3,5‐Trienylrhodium(I) Complex

Helix‐sense‐selective polymerization (HSSP) is a powerful method for the synthesis of preferred‐handed helical macromolecules. This article presents a new method for controlling the HSSP of an achiral 4‐alkoxy‐3,5‐bis(hydroxymethyl)phenylacetylene derivative, using an axially chiral heptaarylhexa‐1,3,5‐trienylrhodium(I) complex as an initiator. Hydrophobic components, such as a tert ‐butyl group and tetrafluorobenzobarrelene (tfb) ligand, are introduced into the rhodium complex to increase its solubility in eluents, including n ‐hexane, and sufficient amounts of enantioenriched samples are obtained by optical resolution using chiral high performance liquid chromatography. The complex is used as an initiator for the HSSP of an achiral 4‐alkoxy‐3,5‐bis(hydroxymethyl)phenylacetylene derivative at a lower temperature. The HSSP proceeds in a controlled manner, yielding the corresponding poly(phenylacetylene) derivative with a molecular weight roughly consistent with the value expected from the feed ratio of the monomer to the initiator. Circular dichroism (CD) spectra of the resultant polymers indicate the formation of a one‐handed helical structure in the polymer backbone. The CD intensity of the resultant polymers increases with increasing feed ratio up to ≈150 but gradually decreases beyond that point, indicating that the helical sense of the polymer determined in the initiation step by the chirality of the initiator can persist up to 150 repeating units.