Kinetic Studies of Palladium-Catalyzed Tsuji-Trost Allylations

Significance

The authors studied the effect of varying the electronic properties of phosphine ligands in palladium-catalyzed allylations. They observed a counterintuitive result: while electron-withdrawing palladium-phosphine complexes are more susceptible to nucleophilic attack, they gave lower turnover compared to electron-donating ­analogues. With the help of cross-over experiments, NMR spectroscopy studies, and kinetic experiments, the authors hypothesized that electron-withdrawing ligands increase the occurrence of ion-pair return (see above) contributing to lower turnover. These findings provide important insights into enantioselective allylations.