Helix-Sense-Selective Polymerization of Phenylacetylenes Having a Porphyrin and a Zinc-Porphyrin Group: One-Handed Helical Arrangement of Porphyrin Pendants.

Newly synthesized two kinds of achiral phenylacetylenes having a free-base- or a zinc-porphyrin ( and , respectively) were polymerized by using a chiral rhodium catalyst system, Rh⁺(nbd)[(⁶-C₆H₅)B(C₆H₅)₃] catalyst and ()-(+)- or ()-(⁻)-1-phenylethylamine (()- or ()-PEA, respectively) cocatalyst. Poly() and poly() in THF showed a Cotton signal at the absorption region of the porphyrin and the main chain in the circular dichroism (CD) spectra. This result suggests that poly() and poly() exist in a conformation with an excess of one-handed helix sense and the porphyrin moiety arranged in chiral helical fashion.