Phosphine ligands play an essential role in determining the selectivity of Pd catalyzed olefin carbonylations to form either polyketones or polyesters. Depending on the phosphine ligand, olefins are known to undergo either alkene/CO copolymerization or hydroesterification in alcoholic solvents. Despite sharing a common intermediate, the underlying structural and electronic properties of phosphine ligands that dictate catalytic chemoselectivity are not well understood. Here, we systematically probe bisphosphine ligands to identify conditions where both reactions are kinetically competitive in order to synthesize new polymers that contain ketone and ester functional groups. The relative ketone (alkene/CO copolymerization) to ester (hydroesterification) ratio was investigated through initial rate studies of a small molecule system with (P-P)Pd(OTs)<sub>2</sub> (P-P = bisphosphine) precatalysts made from commercial bisphosphine ligands and dppp/dppb derivatives. The chemoselectivity of alkene insertion and alcoholysis can be tuned by the substituents of dppp and dppb derivatives. Applying carbonylation of 1-hexene, 10-undecen-1-ol under conditions that favor both ketone and ester formation allows for the formation of new polyketoesters.

Tunable phosphine ligands for Pd catalyzed polyketoester synthesis

ACS Spring Meeting 2021

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