Pd-catalyzed asymmetric alternating co-polymerization of propene with carbon monoxide using ionic liquids

A protocol for Pd-catalyzed stereoselective co-polymerization of propene and carbon monoxide using chiral ligands, such as (2S,3S)-DIOP and (R)-P-Phos in C₄mim]PF₆]/C₆mim]PF₆] as an ionic liquid medium was developed. With (2S,3S)-DIOP as chiral ligand and C₄mim]PF₆] as medium, the Pd-catalyzed co-polymerization of propene and CO gave almost completely regioregular polyketones, and the product polymer showed moderate stereoregularity (61% of ℓ-diads). The highest molar optical rotation = +15.9 and polydispersity = 1.2 were attained when (R)-P-Phos was used as the ligand and C₆mim]PF₆ as the solvent. The co-polymer exhibited regioregularity of H–H/H–T/T–T (%) = 17:66:17.