Evidence for an Equilibrium between Neutral and Cationic Arylpalladium(II) Complexes in DMF. Mechanism of the Reduction of Cationic Arylpalladium(II) Complexes.

Amatore, Christian; Carré, Emmanuelle; Jutand, Anny; Miller, Larry L.; Sebastiani, Giovanni V.; Francis, George W.; Szúnyog, József; Långström, Bengt

doi:10.3891/acta.chem.scand.52-0100

Cited by 45 publications

(53 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…57 Furthermore, the required palladium cation (L n Pd(O 2 CCF 3 ) + ) is known to form under these conditions. 58,59,60,61 Overall our experimental observations and computational efforts described below support mechanism C as the operative pathway.…”

Section: Mechanistic Studiessupporting

confidence: 60%

Mild Aromatic Palladium-Catalyzed Protodecarboxylation: Kinetic Assessment of the Decarboxylative Palladation and the Protodepalladation Steps

et al. 2013

View full text Add to dashboard Cite

Mechanism studies of a mild palladium catalyzed decarboxylation of aromatic carboxylic acids are described. In particular, reaction orders and activation parameters for the two stages of the transformation were determined. These studies guided development of a catalytic system capable of turnover. Further evidence reinforces that the second stage, protonation of the aryl palladium intermediate, is the rate-determining step of the reaction. The first step, decarboxylative palladation is proposed to occur through an intramolecular electrophilic palladation pathway, which is supported by computational and mechansim studies. In contrast to the reverse reaction (C-H insertion), the data support an electrophilic aromatic substitution mechanism involving a stepwise intramolecular protonation sequence for the protodepalladation portion of the reaction.

show abstract

Section: Mechanistic Studiessupporting

confidence: 60%

Mild Aromatic Palladium-Catalyzed Protodecarboxylation: Kinetic Assessment of the Decarboxylative Palladation and the Protodepalladation Steps

et al. 2013

View full text Add to dashboard Cite

show abstract

“…[28] Thus, when 4 is II (X = I), with an iodide ligand (Scheme 3). [28] On the other hand, it has also been found [29] that the acetate ion is easily dissociable, and equilibrium could be established between trans-…”

Section: Resultsmentioning

confidence: 99%

“…According to the general procedure, PdA C H T U N G T R E N N U N G (OAc) 2 (2.2 mg, 0.01 mmol) was added to a mixture of N-benzylpyrrole 3b (210 mg, 0.45 mmol), PPh 3 (10.5 mg, 0.04 mmol) and (n-Bu) 4 NOAc (202 mg, 0.67 mmol) in DMSO and this mixture was stirred at 60 8C for 1.5 h. After work-up, purification by column chromatography (silica gel, hexane/AcOEt 80%) gave 4b as an oil as an isomeric mixture Z/E in a 1/3 ratio; yield: 129 mg (84% 13 (20) [M] + , 256 (29), 212 (15), 123 (11), 111 (15), 109 (16), 97 (23), 95 (28), 93 (11), 85 (65), 83 (26), 83 (100), 81 (32), 79 (13), 71 (30), 70 (11)…”

Section: Discussionmentioning

confidence: 99%

Intramolecular Palladium‐Catalyzed Direct Arylation vs. Heck Reactions: Synthesis of Pyrroloisoquinolines and Isoindoles

et al. 2009

View full text Add to dashboard Cite

show abstract

“…This shows that a second phenylpalladium( II ) complex is formed together with trans ‐[PhPdI(AsPh 3 ) 2 ]. The formation of a cationic complex trans ‐[PhPd(solv)(AsPh 3 ) 2 ] + , which could be involved in an equilibrium with trans ‐[PhPdI(AsPh 3 ) 2 ],12a was ruled out since a solution of trans ‐[PhPdI(AsPh 3 ) 2 ] (2 mmol dm −3 in DMF) did not exhibit any significant conductivity (2.5 μS) 13. Furthermore, after addition of AsPh 3 , the unusual set of three signals disappeared and only those that featured trans ‐[PhPdI(AsPh 3 ) 2 ] could be detected.…”

Section: Resultsmentioning

confidence: 99%

Rate and Mechanism of the Oxidative Addition of Phenyl Iodide to Pd0 Ligated by Triphenylarsine: Evidence for the Formation of a T-Shaped Complex [PhPdI(AsPh3)] and for the Decelerating Effect of CH2=CH−SnBu3 by Formation of [Pd0(η2-CH2=CH−SnBu3)(AsPh3)2]

et al. 2001

Self Cite

View full text Add to dashboard Cite

The oxidative addition of phenyl iodide to the palladium(o) generated from [Pd0(dba)2] and n equivalents of AsPh3 (the most efficient catalytic precursor in Stille reactions) proceeds from [(solv)Pd0(AsPh3)2] (solv= solvent). However, the latter is present only in trace concentrations because it is involved in an equilibrium with the major, but nonreactive, complex [Pd0(dba)(AsPh3)2]. As regards the phosphine ligands, dba has a decelerating effect on the rate of the oxidative addition by decreasing the concentration of the reactive species. Relative to PPh3, the effect of AsPh3 is to increase the rate of the oxidative addition of PhI by a factor ten in DMF and seven in THF, independent of the value of n, provided that n > or = 2. In contrast to PPh3, the addition of more than two equivalents of AsPh3 to [Pd0(dba)2] (dba= trans,trans-dibenzylideneacetone) does not affect the kinetics of the oxidative addition because of the very endergonic displacement of dba from [Pd0(dba)(AsPh3)2] to form [Pd0(AsPh3)3]. The complex trans-[PhPdI(AsPh3)2], formed in the oxidative addition, is involved in a slow equilibrium with the T-shaped complex [PhPdI(AsPh3)] after appreciable decomplexation of one AsPh3. Under catalytic conditions, that is, in the presence of a nucleophile, such as CH2=CH-SnBu3 which is able to coordinate to [Pd0(AsPh3)2], a new Pd0 complex is formed: [Pd0(eta2-CH2=CHSnBu3)(AsPh3)2]; however, this complex does not react with PhI. Consequently, CH2=CH-SnBu3 slows down the oxidative addition by decreasing the concentration of the reactive species [(solv)Pd0(AsPh3)2]. This demonstrates that a nucleophile may be not only involved in the transmetallation step, but may also interfere in the kinetics of the oxidative addition step by decreasing the concentration of reactive Pd0.

show abstract

Evidence for an Equilibrium between Neutral and Cationic Arylpalladium(II) Complexes in DMF. Mechanism of the Reduction of Cationic Arylpalladium(II) Complexes.

Cited by 45 publications

References 0 publications

Mild Aromatic Palladium-Catalyzed Protodecarboxylation: Kinetic Assessment of the Decarboxylative Palladation and the Protodepalladation Steps

Mild Aromatic Palladium-Catalyzed Protodecarboxylation: Kinetic Assessment of the Decarboxylative Palladation and the Protodepalladation Steps

Intramolecular Palladium‐Catalyzed Direct Arylation vs. Heck Reactions: Synthesis of Pyrroloisoquinolines and Isoindoles

Rate and Mechanism of the Oxidative Addition of Phenyl Iodide to Pd0 Ligated by Triphenylarsine: Evidence for the Formation of a T-Shaped Complex [PhPdI(AsPh3)] and for the Decelerating Effect of CH2=CH−SnBu3 by Formation of [Pd0(η2-CH2=CH−SnBu3)(AsPh3)2]

Contact Info

Product

Resources

About