Asymmetric polymerisation of substituted phenylacetylene using chiral Rh(2,5-norbornadiene)(l-proline) catalyst

The Rh(nbd)(l-proline) (nbd = 2,5-norbornadiene) catalyst was synthesised with l-proline as ligand. The achiral monomer phenylacetylene, having two hydroxyl groups and a dodecyl group (DoDHPA), was polymerised for the first time using an isolated chiral Rh(nbd)(l-proline) as catalyst to afford polymers of Mr of 28.5 × 104 and 36.2 × 104. The resulting polymers exhibited the Cotton effect at wavelengths assignable to the main chain, indicating that the polymers adopted one-handed helical conformation. These findings suggest that the rhodium complex with chiral amine may be the true active species for helix-sense-selective polymerisation (HSSP) of DoDHPA.