Sulfonate-Modified Picolinamide Diphosphine: A Ligand for Room-Temperature Palladium-Catalyzed Hydrocarboxylation in Water with High Branched Selectivity

Alkyne hydrocarboxylation represents a powerful and industrially significant approach to α,β-unsaturated carboxylic acids. Herein, we report the development of a picolinamide-derived diphosphine ligand with a hydrophilic sulfonate (SO₃^–) group. The implementation of this ligand enabled the Pd-catalyzed hydrocarboxylation of alkynes at room temperature in water, allowing the reaction to proceed with various substrates in high yields and generally excellent branched selectivity. Further experimental and theoretical investigations highlight the role of ligand–metal cooperativity from basic pyridine and hydrophilic sulfonate in accelerating the key catalytic steps.