18115-61-2Relevant academic research and scientific papers
Nuances in Fundamental Suzuki-Miyaura Cross-Couplings Employing [Pd(PPh3)4]: Poor Reactivity of Aryl Iodides at Lower Temperatures
Ho, Curtis C.,Olding, Angus,Smith, Jason A.,Bissember, Alex C.
, p. 1745 - 1750 (2018)
We have explored fundamental Pd-catalyzed Csp2-Csp2 Suzuki-Miyaura cross-couplings of aryl iodides (Ar-I) employing "classical" Pd/PPh3 catalyst systems. Surprisingly, we observed particularly inefficient couplings of these ostensibly reactive electrophiles in a range of conventional solvent mixtures at lower temperatures (50 °C), which was in stark contrast to analogous reactions featuring the equivalent aryl bromides. This feature of well-established Pd/PPh3-mediated Suzuki-Miyaura reactions has received scant attention in the literature. Most significantly, our studies suggest that the inefficient coupling of aryl iodides at lower temperatures derives from the unexpectedly poor turnover of the key on-cycle intermediate trans-[Pd(PPh3)2(Ar)(I)] (or related PdII-I species) in the presence of PPh3.
Pd(0)-catalyzed phosphorus-carbon bond formation. Mechanistic and synthetic studies on the role of the palladium sources and anionic additives
Kalek, Marcin,Stawinski, Jacek
, p. 5840 - 5847 (2007)
Pd(PPh3)4, Pd(dba)2, Pd(OAc)2, and PdCl2, have been evaluated as possible Pd(0) sources for the palladium-catalyzed P-C bond formation via a cross-coupling of aryl halides with H-phosphonate diesters. It was found that the most efficient catalytic system can be generated from Pd(OAc)2 with a key role being played by Pd(II) and Pd(0) species with coordinated acetate ions. The reactivity of differently ligated Pd(II) complexes was determined, and 31P NMR spectroscopy studies were carried out to provide mechanistic interpretations for the observed differences between the catalytic systems.
Stabilization of bis(triphenylphosphine)palladium(0) by chloride ions. Electrochemical generation of highly reactive zerovalent palladium complexes
Amatore, Christian,Azzabi, Mohamed,Jutand, Anny
, p. C41 - C54 (1989)
"Pd0(PPh3)2" has been generated by electroreduction of Cl2Pd(PPh3)2 in the absence of PPh3.Its structure is consistent with xPd0(PPh3)2>nnx-, with values of x and/or n depending on the chloride ion
Efficient acid fluoride synthesis via carbonylation of organic halides
Sakakura, Toshiyasu,Chaisupakitsin, Malinee,Hayashi, Teruyuki,Tanaka, Masato
, p. 205 - 212 (1987)
Palladium, platinum, cobalt, and rhodium triphenylphosphine complexes were found to catalyze the formation of acid fluorides via carbonylation of organic halides with fluoride salts.For palladium complex-catalyzed reactions, the use of cesium fluoride in polar solvents such as acetone and acetonitrile exhibited superior performance.The reaction took place even under an atmospheric pressure of carbon monoxide.The success of the acid fluoride synthesis is discussed in terms of the facility of oxidative addition of the starting material and the product.
Pd(0)-Catalyzed Asymmetric Carbohalogenation: H-Bonding-Driven C(sp3)-Halogen Reductive Elimination under Mild Conditions
Chen, Xin,Zhao, Jixiao,Dong, Ming,Yang, Ninglei,Wang, Jiaoyang,Zhang, Yueqi,Liu, Kun,Tong, Xiaofeng
, p. 1924 - 1931 (2021/02/06)
Carbon-halogen reductive elimination is a conceptually novel elementary reaction. Its emergence broadens the horizons of transition-metal catalysis and provides new access to organohalides of versatile synthetic value. However, as the reverse process of f
Electrochemical Palladium-Catalyzed Oxidative Sonogashira Carbonylation of Arylhydrazines and Alkynes to Ynones
Cao, Yue,Hu, Jingcheng,Lei, Aiwen,Li, Haoran,Shi, Renyi,Wu, Yong,Xu, Minghao,Yi, Hong,Zeng, Li
supporting information, p. 12460 - 12466 (2021/08/24)
Oxidative carbonylation using carbon monoxide has evolved as an attractive tool to valuable carbonyl-containing compounds, while mixing CO with a stoichiometric amount of a chemical oxidant especially oxygen is hazardous and limits its application in scale-up synthesis. By employing anodic oxidation, we developed an electrochemical palladium-catalyzed oxidative carbonylation of arylhydrazines with alkynes, which is regarded as an alternative supplement of the carbonylative Sonogashira reaction. Combining an undivided cell with constant current mode, oxygen-free conditions avoids the explosion hazard of CO. A diversity of ynones are efficiently obtained using accessible arylhydrazines and alkynes under copper-free conditions. A possible mechanism of the electrochemical Pd(0)/Pd(II) cycle is rationalized based upon cyclic voltammetry, kinetic studies, and intermediates experiments.
Stoichiometric Studies on the Carbonylative Trifluoromethylation of Aryl Pd(II) Complexes using TMSCF3 as the Trifluoromethyl Source
Daasbjerg, Kim,Domino, Katrine,Johansen, Martin B.,Skrydstrup, Troels
supporting information, (2020/03/04)
We have performed a series of stoichiometric studies in order to identify viable steps for a hypothetical catalytic cycle for the palladium-mediated carbonylative coupling of an aryl bromide with TMSCF3. Our work revealed that benzoyl Pd(II) complexes bearing Xantphos or tBu3P as the phosphine ligands, which are generated from the corresponding PdII(Ph)Br complexes exposed to stoichiometric 13CO from 13COgen, were unable to undergo transmetalation and reductive elimination to trifluoroacetophenone. Instead, in the presence of base and additional CO, these organometallic complexes readily underwent reductive elimination to the acid fluoride. Attempts to determine whether the acid fluoride could represent an intermediate for acetophenone production were unrewarding. Only in the presence of a boronic ester did we observe some formation of the desired product, although the efficiency of transformation was still low. Finally, we investigated the reactivity of four phosphine-ligated PdII(Ph)CF3 complexes (Xantphos, DtBPF, tBu3P, and triphenylphosphine) with carbon monoxide. With the exception of the tBu3P-ligated complex, all other metal complexes led to the facile formation of trifluoroacetophenone. We also determined in the case of triphenylphosphine that CO insertion occurred into the Pd-Ar bond, as trapping of this complex with n-hexylamine led to the formation of n-hexylbenzamide.
Palladium-Catalyzed Stereoselective Hydrodefluorination of Tetrasubstituted gem-Difluoroalkenes
Ma, Qiao,Liu, Caroline,Tsui, Gavin Chit
supporting information, p. 5193 - 5197 (2020/07/04)
A highly stereoselective palladium(0)-catalyzed hydrodefluorination (HDF) of tetrasubstituted gem-difluoroalkenes is developed. By using catalytic Pd(PPh3)4 (2.5-5 mol percent) and hydrosilane Me2PhSiH, various trisubstituted terminal (E)-monofluoroalkenes can be synthesized with excellent E/Z selectivity (>99:1) and good functional group tolerability. The key stereocontrol should be exerted by an ester-directed C-F bond oxidative addition step in the catalytic cycle.
The Difluoromethyl Group as a Masked Nucleophile: A Lewis Acid/Base Approach
Geri, Jacob B.,Wade Wolfe, Michael M.,Szymczak, Nathaniel K.
supporting information, p. 9404 - 9408 (2018/08/09)
The difluoromethyl group (R-CF2H) imparts desirable pharmacokinetic properties to drug molecules and is commonly targeted as a terminal functional group that is not amenable to further modification. Deprotonation of widely available Ar-CF2
Real-Time Mass Spectrometric Investigations into the Mechanism of the Suzuki-Miyaura Reaction
Yunker, Lars P. E.,Ahmadi, Zohrab,Logan, Jessamyn R.,Wu, Wenzhao,Li, Tengfei,Martindale,Oliver, Allen G.,McIndoe, J. Scott
supporting information, p. 4297 - 4308 (2018/11/23)
Real-time monitoring of the Suzuki-Miyaura reaction using mass spectrometry during sequential addition of the various reaction components suggests that a dynamic series of equilibria exist in these solutions. Depending on conditions, the boronic acid can
