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.