Understanding Palladium Acetate from a User Perspective

Carole, William A.; Colacot, Thomas J.

doi:10.1002/chem.201601450

Cited by 88 publications

(59 citation statements)

References 64 publications

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“…of the phosphine ligand, which reached full conversion of 6 to 7 within 3 h. An analogous catalyst prepared at a 1:1 [PdCl 2 (cod)]:4d molar ratio ensued in only 30% conversion. Similar catalysts resulting from 4d and palladium(II) acetate, which is commonly used as a Pd-precursor in cross-coupling reactions [25] and even afforded very good yields of the coupling products in similar cyanation reactions [7,26], performed considerably worse (conversions <5%). Poor results were also obtained when [Pd(µ-Cl)(η-C 3 H 5 )] 2 was employed as the Pd source, whereas the reaction performed in the presence of [PdCl 2 (cod)] (2 mol.…”

Section: Catalytic Experimentsmentioning

confidence: 99%

Synthesis, Structural Characterization and Catalytic Evaluation of Anionic Phosphinoferrocene Amidosulfonate Ligands

et al. 2017

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Triethylammonium salts of phosphinoferrocene amidosulfonates with electron-rich dialkyphosphino substituents, R 2 PfcCONHCH 2 SO 3 (HNEt 3 ) (4a-c), where fc = ferrocene-1,1 -diyl, and R = i-Pr (a), cyclohexyl (Cy; b), and t-butyl (c), were synthesized from the corresponding phosphinocarboxylic acids-borane adducts, R 2 PfcCO 2 H·BH 3 (1a-c), via esters R 2 PfcCO 2 C 6 F 5 ·BH 3 (2a-c) and adducts R 2 PfcCONHCH 2 SO 3 (HNEt 3 )·BH 3 (3a-c). Compound 4b was shown to react with [Pd(µ-Cl)(η-C 3 H 5 )] 2 and AgClO 4 to afford the zwitterionic complex [Pd(η 3 -C 3 H 5 ) (Cy 2 PfcCONHCH 2 SO 3 -κ 2 O,P)] (5b), in which the amidosulfonate ligand coordinates as a chelating donor making use of its phosphine moiety and amide oxygen. The structures of 3b·CH 2 Cl 2 , 4b and 5b·CH 2 Cl 2 were determined by single-crystal X-ray diffraction analysis. Compounds 4a-c and their known diphenylphosphino analogue, Ph 2 PfcCONHCH 2 SO 3 (HNEt 3 ) (4d), were studied as supporting ligands in Pd-catalyzed cyanation of aryl bromides with K 4 [Fe(CN) 6 ] and in Suzuki-Miyaura biaryl cross-coupling performed in aqueous reaction media under mild reaction conditions. In the former reaction, the best results were achieved with a catalyst generated from [PdCl 2 (cod)] (cod = η 2 :η 2 -cycloocta-1,5-diene) and 2 equiv. of the least electron-rich ligand 4d in dioxane-water as a solvent. In contrast, the biaryl coupling was advantageously performed with a catalyst resulting from palladium(II) acetate and ligand 4a (1 equiv.) in the same solvent.

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Section: Catalytic Experimentsmentioning

confidence: 99%

Synthesis, Structural Characterization and Catalytic Evaluation of Anionic Phosphinoferrocene Amidosulfonate Ligands

et al. 2017

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“…We identified ArSOX ligand L1 (Table 1, entry 1) as effective for asymmetric Pd(II)-catalyzed [14] formation of isochroman 2a , though in low yield. Based on our recent studies showing that Brønsted acids enhance the reactivity of Pd(II)-sulfoxide catalyzed allylic C–H oxidations, [7g] we surveyed Brønsted acid additives (Table 1, entries 2–5) for the reaction.…”

mentioning

confidence: 99%

Enantioselective Allylic C−H Oxidation of Terminal Olefins to Isochromans by Palladium(II)/Chiral Sulfoxide Catalysis

2016

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The enantioselective synthesis of isochroman motifs has been accomplished via Pd(II)-catalyzed allylic C–H oxidation from terminal olefin precursors. Critical to the success of this goal was the development and utilization of a novel chiral aryl sulfoxide-oxazoline (ArSOX) ligand. The allylic C–H oxidation reaction proceeds with the broadest scope and highest levels asymmetric induction reported to date (avg. 92% ee, 13 examples ≥90% ee)

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“…[3,4] Under typical catalytic conditions, the concentration of the stoichiometric organometallic reagent will exceed that of the phosphine, which is only applied in catalytic amounts, much more than in the present experiments. This activation mechanism differs from the commonly assumed reduction by ap hosphine.…”

Section: Reduction Mechanismmentioning

confidence: 82%

“…[1,2] The vast majority of these reactions involve Pd 0 species as the catalytically active intermediates, which react with aryl halides( or other electrophiles) in the first step of the catalytic cycle (Scheme1). The active catalysti st hen generated by the in situ reduction of aP d II compound, most often Pd(OAc) 2 , [3] in the presence of the ligand (Scheme 1). However,i nm any cases, such complexes are not available.…”

Section: Introductionmentioning

confidence: 99%

Stability and Unimolecular Reactivity of Palladate(II) Complexes [L_nPdR₃]⁻ (L=Phosphine, R=Organyl, n=0 and 1)

Kolter

Koszinowski

2016

Chemistry A European J

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The reduction of Pd precatalysts to catalytically active Pd species is a key step in many palladium-mediated cross-coupling reactions. Besides phosphines, the stoichiometrically used organometallic reagents can afford this reduction, but do so in a poorly understood way. To elucidate the mechanism of this reaction, we have treated solutions of Pd(OAc) and a phosphine ligand L in tetrahydrofuran with RMgCl (R=Ph, Bn, Bu) as well as other organometallic reagents. Analysis of these model systems by electrospray- ionization mass spectrometry found palladate(II) complexes [L PdR ] (n=0 and 1), thus pointing to the occurrence of transmetallation reactions. Upon gas-phase fragmentation, the [L PdR ] anions preferentially underwent a reductive elimination to yield Pd species. The sequence of the transmetallation and reductive elimination, thus, constitutes a feasible mechanism for the reduction of the Pd(OAc) precatalyst. Other species of interest observed include the Pd complex [PdBn ] , which did not fragment via a reductive elimination but lost BnH instead.

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Understanding Palladium Acetate from a User Perspective

Cited by 88 publications

References 64 publications

Synthesis, Structural Characterization and Catalytic Evaluation of Anionic Phosphinoferrocene Amidosulfonate Ligands

Synthesis, Structural Characterization and Catalytic Evaluation of Anionic Phosphinoferrocene Amidosulfonate Ligands

Enantioselective Allylic C−H Oxidation of Terminal Olefins to Isochromans by Palladium(II)/Chiral Sulfoxide Catalysis

Stability and Unimolecular Reactivity of Palladate(II) Complexes [L_nPdR₃]⁻ (L=Phosphine, R=Organyl, n=0 and 1)

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Understanding Palladium Acetate from a User Perspective

Cited by 88 publications

References 64 publications

Synthesis, Structural Characterization and Catalytic Evaluation of Anionic Phosphinoferrocene Amidosulfonate Ligands

Synthesis, Structural Characterization and Catalytic Evaluation of Anionic Phosphinoferrocene Amidosulfonate Ligands

Enantioselective Allylic C−H Oxidation of Terminal Olefins to Isochromans by Palladium(II)/Chiral Sulfoxide Catalysis

Stability and Unimolecular Reactivity of Palladate(II) Complexes [LnPdR3]− (L=Phosphine, R=Organyl, n=0 and 1)

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Stability and Unimolecular Reactivity of Palladate(II) Complexes [L_nPdR₃]⁻ (L=Phosphine, R=Organyl, n=0 and 1)