889649-64-3Relevant academic research and scientific papers
On the Triple Role of Fluoride Ions in Palladium-Catalyzed Stille Reactions
Hervé, Marius,Lefèvre, Guillaume,Mitchell, Emily A.,Maes, Bert U. W.,Jutand, Anny
, p. 18401 - 18406 (2015)
The mechanism of Stille reactions (cross-coupling of ArX with Ar′SnnBu3) performed in the presence of fluoride ions is established. A triple role for fluoride ions is identified from kinetic data on the rate of the reactions of trans-[ArPdBr(PPh3)2] (Ar=Ph, p-(CN)C6H4) with Ar′SnBu3 (Ar′=2-thiophenyl) in the presence of fluoride ions. Fluoride ions promote the rate-determining transmetallation by formation of trans-[ArPdF(PPh3)2], which reacts with Ar′SnBu3 (Ar′=Ph, 2-thiophenyl) at room temperature, in contrast to trans-[ArPdBr(PPh3)2], which is unreactive. However, the concentration ratio [F-]/[Ar′SnBu3] must not be too high, because of the formation of unreactive anionic stannate [Ar′Sn(F)Bu3]-. This rationalises the two kinetically antagonistic roles exerted by the fluoride ions that are observed experimentally, and is found to be in agreement with the kinetic law. In addition, fluoride ions promote reductive elimination from trans-[ArPdAr′(PPh3)2] generated in the transmetallation step.
The triple role of fluoride ions in palladium-catalyzed Suzuki-Miyaura reactions: Unprecedented transmetalation from [ArPdFL2] complexes
Amatore, Christian,Jutand, Anny,Leduc, Gaatan
, p. 1379 - 1382 (2012/03/27)
Fluoride ions play three roles in the Suzuki-Miyaura reaction. They favor the reaction by formation of trans-[ArPdF(PPh3)2], which reacts with Ar B(OH)2 in an unprecedented rate-determining transmetalation, and by promoting the reductive elimination from the trans-[ArPdAr (PPh3)2] intermediate. Conversely, F - disfavors the reaction by formation of unreactive anionic Ar B(OH)n-3Fn- (n=1-3), leading to two antagonistic effects of F- in the transmetalation. Copyright
Mechanism of the palladium-catalyzed homocoupling of arylboronic acids: Key involvement of a palladium peroxo complex
Adamo, Carlo,Amatore, Christian,Ciofini, Ilaria,Jutand, Anny,Lakmini, Hakim
, p. 6829 - 6836 (2007/10/03)
The mechanism of the palladium-catalyzed homocoupling of arylboronic acids Arb(OH)2 (Ar = 4-z-C6H4 with Z = MeO, H, CN) in the presence of dioxygen, leading to symmetrical biaryls, has been fully elucidated. The peroxo complex (η2-O2)PdL2 (L = PPh3), generated in the reaction of dioxygen with the Pd(0) catalyst, was found to play a crucial role. Indeed, it reacts with the arylboronic acid to generatye an adduct (coordination of one oxygen atom of the peroxo complex to the oxophilic boron atom of the arylboronic acid) characterized by 21P NMR spectroscopy and ab initio calculations. This adducts reacts with a second molecule of arylboronic acid to generate trans-ArPd(OH)L2 complexes. A transmetalation by the arylboronic acid gives trans-ArPdArL2 complexes. The biaryl is then released in a reductive elimination. This reaction is at the origin of the formation of biaryls as byproducts in palladium-catalyzed Suzuki-Miyaura reactions when they are not conducted under oxygen-free atmosphere.
