Sulfonate(SO₃^-)-built-in phosphines for Pd-catalyzed aminocarbonylation/hydroxycarbonylation of alkynes under acid-additive free condition

The Pd-catalyzed aminocarbonylation as well as hydroxycarbonylation of terminal alkynes was achieved with aid of a sulfonate-built-in zwitterionic phosphine (L2), under acid-additive free condition. With L2-Pd(OAc)₂ catalytic system, the terminal alkynes smoothly converted to the corresponding α,β-unsaturated carbonyl compounds (amides or carboxylic acids) in moderate to excellent isolated yields, with 100 % branched regio-selectivity. It was believed that L2 with the matched steric-demand and the bulit-in-SO₃^--unit not only tuned the catalytic performance of Pd(OAc)₂ to activate CO and alkyne but also exhibited the synergetic activating ability towards the nucleophiles of (primary/secondary) amines or H₂O via developing hydrogen-bond interaction, which facilitated the observed successful carbonylation. It means the developed L2-Pd(OAc)₂ system could serve as a bifunctional catalyst.