Expedient Synthetic Identification of a P‐Stereogenic Ligand Motif for the Palladium‐Catalyzed Preparation of Isotactic Polar Polypropylenes

Abstract

Abstract The iso ‐specific statistical copolymerization of unprotected polar monomers with propylene remains a grand challenge in the field of polymer chemistry. Current research is hampered because only a single natural‐product‐derived dimenthylphosphine‐motif is known to allow for the preparation of moderately isotactic polypropylene copolymers. To overcome this structural limitation, we developed time‐efficient synthetic methods that facilitate P‐donor ligand development. The strength of these methods was demonstrated with preparation of twenty‐five new P‐stereogenic phosphine/sulfonate‐ and bisphosphine‐monoxide‐type palladium catalysts, which could typically be developed in parallel. A lead candidate was identified for iso ‐specific propylene polymerization. The best‐performing catalysts utilizing the P‐stereogenic donor motif achieved triad isotacticities of up to mm =0.75—the highest value within those reported for group 10 metal catalysts—for the homo‐ and copolymerization of propylene with unprotected polar monomers at an industrially relevant temperature of 50 °C.