Methyl/Phenyl Exchange between Palladium and a Phosphine Ligand. Consequences for Catalytic Coupling Reactions

Preparation of poly(fluorene)s using trans‐bis(dicyclohexylamine)palladium diacetate as a catalyst: Scope and limitations

“…A way of overcoming long reaction times is the use of microwave-assisted coupling reactions. [33][34][35] Besides, aryl-aryl interchange reactions between palladiumand phosphine-bound aryls [36][37][38][39][40][41] can lead to an unwanted incorporation of phosphines into the polymer chain. Last but not least, Pd(PPh 3 ) 4 is air-sensitive.…”

Pd0–Mediated Rapid C–[11C]Methylation and C–[18F]Fluoromethylation: Revolutionary Advanced Methods for General Incorporation of Short–Lived Positron–Emitting 11C and 18F Radionuclides in an Organic Framework

“…byproduct in 8% yield, suggesting that the promotion of the Stille reaction using methyl iodide as an sp 3 -carbon partner could be difficult (Morita et al, 1995) until our successful result was demonstrated (Suzuki et al, 1997).…”

“…The Stille reaction was thought to be useful for our purpose because of its favorable properties of the triorganostannane compounds, such as (1) their high tolerance to various chemical reactions and chromatographic purification conditions, enabling the incorporation of a radioisotope as the final step of the PET-probe synthesis; and (2) the extremely low polarity of a trialkyltin(IV) derivative, enabling an easy separation of the desired product from a large amount of the remaining tin substrate. However, to the best of our knowledge, at that time, there was little information on the Stille reaction using methyl iodide as an sp 3 -hybridized carbon partner in comparison to its wide applicability to sp 2 -hybridized arenyl or sp 3 -hybridized allylic halides; it seemed rather difficult to realize the methylation in high yield due to the unavoidable scrambling between the methyl group in methyl iodide and phenyl groups in the triphenylphosphine ligand, P(C 6 H 5 ) 3 , by the reaction of methyl iodide with the less reactive phenyltributylstannane in the presence of Pd{P(C 6 H 5 ) 3 } 4 (Morita et al, 1995). The use of the higher reactive phenyltrimethylsytannane as a substrate also induces the competition between 11 CH 3 in 11 CH 3 I and CH 3 groups in the stannane to produce [ 11 C]ethane as a byproduct (Suzuki et al, 1997, also see section 6).…”

New Chiral P-N Ligands for the Regio- and Stereoselective Pd-Catalyzed Dimerization of Styrene

“…This reaction might be seen as a nucleophilic attack of the methyl group, bonded to palladium, at the coordinated phosphine with the opening of the N-P-N heterocycle and the contemporary coordination of the amidic nitrogen to the metal centre. Transmethylation reaction was reported to occur on the complex trans-[Pd(CH 3 )I(PPh 3 ) 2 ] resulting in the exchange of the methyl group on palladium with one phenyl ring on the phosphorus to give [Pd(Ph)I(PPh 3 )(PPh 2 CH 3 )] as product [39]. The reaction here observed might be considered as another example of this type of reactivity, and in this case it occurs on a chiral phosphine.…”