title: Mechanism of palladium-catalyzed Suzuki-Miyaura reactions: multiple and antagonistic roles of anionic "bases" and their countercations.
abstract: In Suzuki-Miyaura reactions, anionic bases F(-) and OH(-) (used as is or generated from CO3(2-) in water) play multiple antagonistic roles. Two are positive: 1) formation of trans-[Pd(Ar)F(L)2] or trans-[Pd(Ar)-(L)2(OH)] (L = PPh3) that react with Ar'B(OH)2 in the rate-determining step (rds) transmetallation and 2) catalysis of the reductive elimination from intermediate trans-[Pd(Ar)(Ar')(L)2]. Two roles are negative: 1) formation of unreactive arylborates (or fluoroborates) and 2) complexation of the OH group of [Pd(Ar)(L)2(OH)] by the countercation of the base (Na(+), Cs(+), K(+)).
authors.affiliation: Ecole Normale Supérieure, Département de Chimie, UMR CNRS-ENS-UPMC 8640, 24 Rue Lhomond, 75231 Paris Cedex 5, France. christian.amatore@ens.fr
authors.forename: Christian
authors.initials: C
authors.lastname: Amatore
authors.forename: Gaëtan
authors.initials: G
authors.lastname: Le Duc
authors.forename: Anny
authors.initials: A
authors.lastname: Jutand
keywords: Suzuki-Miyaura reactions; bases; kinetics; palladium; reaction mechanisms