A syn outer-sphere oxidative addition: the reaction mechanism in Pd/Senphos-catalyzed carboboration of 1,3-enynes

We report a combined experimental and computational study of Pd/Senphos-catalyzed carboboration of 1,3-enynes utilizing DFT calculations, P-31 NMR study, kinetic study, Hammett analysis and Arrhenius/Eyring analysis. Our mechanistic study provides evidence against the conventional inner-sphere beta-migratory insertion mechanism. Instead, a syn outer-sphere oxidative addition mechanism featuring a Pd-pi-allyl intermediate followed by coordination-assisted rearrangements is consistent with all the experimental observations.

Automated summary

We present a study on Pd/Senphos-catalyzed carboboration of 1,3-enynes using a combination of experimental and computational methods. The study involves DFT calculations, P-31 NMR analysis, kinetic study, Hammett analysis, and Arrhenius/Eyring analysis. Our findings provide evidence against the conventional inner-sphere beta-migratory insertion mechanism and support a syn outer-sphere oxidative addition mechanism involving a Pd-pi-allyl intermediate and coordination-assisted rearrangements.