Synthesis and characterization of ruthenium(II) complexes based on diphenyl-2-pyridylphosphine and their applications in transfer hydrogenation of ketones

Mechanism of Alkyne Alkoxycarbonylation at a Pd Catalyst with P,N Hemilabile Ligands: A Density Functional Study

“…[5,8] Through methylation at the 6 position of the pyridyl moiety, the selectivity towards MMA over the linear product, methyl crotonate (MC), can be enhanced even further from 98.9 % to 99.95 % with minor changes in activity. [3] Hemilabile P,N-type ligands with their wide range of coordination modes [11] have attracted considerable interest in homogeneous catalysis [12] and to fully elucidate the precise mode of action of 2-pyridyl diphenylphosphine (2-PyPPh 2 ) in achieving these extraordinary results we have applied state-of-the-art density functional computations. Drent's initial work implicated a carbomethoxy mechanism with termination involving intramolecular proton transfer from a protonated pyridyl ligand, [2] whilst subsequent labeling studies by Scrivanti et al [6,7] suggested that the cycle might be initiated by a proton transfer from 2-PyPPh 2 onto coordinated alkyne.…”

Methoxycarbonylation of Styrene Using a New Type of Palladium Complexes Bearing P,N-donor Ligands as Catalysts

“…Remarkably, the complex with the pyrimidine ligand [PdCl(Ph 2 PNHpym)(PPh 3 )]Cl, generated in situ by reaction between the neutral complex and PPh 3 , achieves practically complete conversion and chemoselectivity and 97 % regioselectivity in the branched ester (entry 3), as it happens with its pyridine analog [23]. This comparable result with the pyridine ligand indicates that the reported rollover cyclometalation of the aromatic ring in related complexes [24], which is prevented in the pyrimidine ligand, does not have a contribution to the noteworthy performance of the catalysts [PdCl(P,X) (PPh 3 In summary, these catalytic experiments confirm that [PdCl(Ph 2 PNHpy)(PPh 3 )]Cl and its pyrimidine analog here described are particularly appropriate catalysts for an efficient and selective methoxycarbonylation of styrene.…”

“…A mixture of PdCl 2 (200 mg, 1.13 mmol) and PPh 2-NHC 6 H 4 PPh 2 (352 mg, 1.13 mmol) was dissolved in CH 3 CN (20 mL) and heated to reflux for 3 h, producing a yellow precipitate. The suspension was cooled, and the solid was filtered off, rinsed with CH 3 …”

“…However, heterobidentate P,N-donor ligands have emerged lately as an important class of ligands that have been applied in various catalytic transformations, such as hydrogenation of alkenes [1,2], hydrogen transfer reactions [3], Suzuki-Miyura couplings [4,5], arylation of unactivated arenes [6], alkylation of anilines by alcohols [7] and allylic substitution [8,9], among others. Nevertheless, this type of ligands has been scarcely used in metal catalyzed carbonylation reactions, and almost in all reported cases Pd was the metal used.…”

Synthesis of C2-Symmetric Bisphosphines and Their Application in Enantioselective Transition Metal Catalysis

“…in combination with chiral ligands containing coordinating atoms (phosphorous, oxygen, nitrogen and sulfur) by many researchers. [36][37][38][39][40][41][42][43][44][45] Recently, we have reported on a set of six chiral modular bisphosphine ligands with dimethoxy backbone for enantioselective catalytic reactions (Figure 1.). [46] They have showed some promising results in the palladium(0)catalyzed enantioselective allylic alkylation reaction (70 % chemical yield and 43 % ee) and the ruthenium(II)-catalyzed transfer hydrogenation (up to > 99 % conversion).…”