A Syn Outer-Sphere Oxidative Addition: The Reaction Mechanism in Pd/Senphos-Catalyzed Carboboration of 1,3-Enynes

Abstract

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

COAP/Pd-Catalyzed Linear Asymmetric Allylic Alkylation for Optically Active 3,3-Disubstituted Oxindole Derivatives with a Four-Carbon Amino Side Chain

“…CHCl 3 complex. Then, in situ 31 P NMR was conducted to deduce the possible catalytically active species 29 (Figure 2b). After the ligand L14 was coordinated with Pd 2 (dba) 3 •CHCl 3 , two peaks were observed at 22.5 and 34.0 ppm in the 31 P NMR spectrum.…”

“…As shown in Figure a, a strong positive nonlinear effect was observed for the product 3aa , suggesting that the reaction system involved the species of dimeric or polymeric L14 (COAP-Bn-OMe- p )–Pd 2 (dba) 3 ·CHCl 3 complex. Then, in situ 31 P NMR was conducted to deduce the possible catalytically active species (Figure b). After the ligand L14 was coordinated with Pd 2 (dba) 3 ·CHCl 3 , two peaks were observed at 22.5 and 34.0 ppm in the 31 P NMR spectrum.…”