- Amido PNP pincer complexes of palladium(II) and platinum(II): Synthesis, structure, and reactivity
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The synthesis of a series of divalent palladium and platinum complexes containing amido PNP pincer ligands of the type [N(o-C6H4PR2)2]? (R = Ph (1a), iPr (1b)) is reported. Metathetical reactions of [1a–b]PdCl or [1a–b]PtCl with a variety of alkyl Grignard reagents or LiHBEt3 in ethereal or arene solutions generate their corresponding alkyl or hydride complexes [1a]PdR1 (R1 = Me, Et, nBu), [1b]PdR1 (R1 = Me, Et, H), [1a]PtR1 (R1 = Me, Et, nBu, nHexyl, H), and [1b]PtR1 (R1 = Me, H). Although these organometallic complexes are all thermally stable, including those containing β-hydrogen atoms even at elevated temperatures, compounds [1a]PdH and [1b]PtR1 (R1 = Et, nBu, nHexyl) are not isolable due to facile decomposition. The stability and reactivity of these complexes are discussed. The chloro [1a]PdCl is a superior catalyst precursor to [1b]PdCl, [1a]PtCl, and [1b]PtCl in Kumada couplings, affording, for instance, n-butyl arenes nearly quantitatively. The X-ray structures of [1b]PtCl, [1b]PtMe, [1b]PdEt, [1a]PtnBu, [1b]PdH, and [1b]PtH are presented.
- Huang, Mei-Hui,Lee, Wei-Ying,Zou, Xue-Ru,Lee, Chia-Chin,Hong, Sheng-Bo,Liang, Lan-Chang
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- Water and Sodium Chloride: Essential Ingredients for Robust and Fast Pd-Catalysed Cross-Coupling Reactions between Organolithium Reagents and (Hetero)aryl Halides
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Direct palladium-catalysed cross-couplings between organolithium reagents and (hetero)aryl halides (Br, Cl) proceed fast, cleanly and selectively at room temperature in air, with water as the only reaction medium and in the presence of NaCl as a cheap additive. Under optimised reaction conditions, a water-accelerated catalysis is responsible for furnishing C(sp3)–C(sp2), C(sp2)–C(sp2), and C(sp)–C(sp2) cross-coupled products, in competition with protonolysis, within a reaction time of 20 s, in yields of up to 99 %, and in the absence of undesired dehalogenated/homocoupling side products even when challenging secondary organolithiums serve as the starting material. It is worth noting that the proposed protocol is scalable and the catalyst and water can easily and successfully be recycled up to 10 times, with an E-factor as low as 7.35.
- Dilauro, Giuseppe,Quivelli, Andrea Francesca,Vitale, Paola,Capriati, Vito,Perna, Filippo Maria
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supporting information
p. 1799 - 1802
(2019/01/25)
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- Oxidative Addition Complexes as Precatalysts for Cross-Coupling Reactions Requiring Extremely Bulky Biarylphosphine Ligands
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In this report, we describe the application of palladium-based oxidative addition complexes (OACs) as effective precatalysts for C-N, C-O, and C-F cross-coupling reactions with a variety of (hetero)arenes. These complexes offer a convenient alternative to previously developed classes of precatalysts, particularly in the case of the bulkiest biarylphosphine ligands, for which palladacycle-based precatalysts do not readily form. The precatalysts described herein are easily prepared and stable to long-term storage under air.
- Ingoglia, Bryan T.,Buchwald, Stephen L.
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supporting information
p. 2853 - 2856
(2017/06/07)
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- Spatially isolated palladium in porous organic polymers by direct knitting for versatile organic transformations
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We report here a direct knitting Method for preparation of highly robust, effective while air- and moisture-tolerant, and readily recyclable three-dimensional (3D) porous polymer-Pd network (PPPd) from the widely used Pd(PPh3)4. Electro-beam induced Pd atom crystallization was observed for the first time in organic polymer and revealed the ultrafine dispersion of palladium atoms. Challenging types of Suzuki-Miyaura couplings, reductive coupling of aryl halides and oxidative coupling of arylboronic acid were successively catalyzed by PPPd in aqueous media. Also catalytically selective C–H functionalization reactions were achieved with orders of magnitude more efficient than conventional Pd homogeneous catalysts. The strategy developed here provides a practical method for easy-to-make yet highly efficient heterogeneous catalysis.
- Wang, Xinbo,Min, Shixiong,Das, Swapan K.,Fan, Wei,Huang, Kuo-Wei,Lai, Zhiping
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p. 101 - 109
(2017/10/06)
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- A Fluorinated Ligand Enables Room-Temperature and Regioselective Pd-Catalyzed Fluorination of Aryl Triflates and Bromides
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A new biaryl monophosphine ligand (AlPhos, L1) allows for the room-temperature Pd-catalyzed fluorination of a variety of activated (hetero)aryl triflates. Furthermore, aryl triflates and bromides that are prone to give mixtures of regioisomeric aryl fluorides with Pd-catalysis can now be converted to the desired aryl fluorides with high regioselectivity. Analysis of the solid-state structures of several Pd(II) complexes, as well as density functional theory (DFT) calculations, shed light on the origin of the enhanced reactivity observed with L1.
- Sather, Aaron C.,Lee, Hong Geun,De La Rosa, Valentina Y.,Yang, Yang,Müller, Peter,Buchwald, Stephen L.
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supporting information
p. 13433 - 13438
(2015/11/09)
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- In-Depth Assessment of the Palladium-Catalyzed Fluorination of Five-Membered Heteroaryl Bromides
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A thorough investigation of the challenging Pd-catalyzed fluorination of five-membered heteroaryl bromides is presented. Crystallographic studies and density functional theory (DFT) calculations suggest that the challenging step of this transformation is
- Milner, Phillip J.,Yang, Yang,Buchwald, Stephen L.
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supporting information
p. 4775 - 4780
(2015/10/28)
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- Studying regioisomer formation in the pd-catalyzed fluorination of aryl triflates by deuterium labeling
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Isotopic labeling has been used to determine that a portion of the desired product in the Pd-catalyzed fluorination of electron-rich, non-ortho-substituted aryl triflates results from direct C-F cross-coupling. In some cases, formation of a Pd-aryne intermediate is responsible for producing undesired regioisomers. The generation of the Pd-aryne intermediate occurs primarily via ortho-deprotonation of a L·Pd(Ar)OTf (L = biaryl monophosphine) species by CsF and thus competes directly with the transmetalation step of the catalytic cycle. Deuterium labeling studies were conducted with a variety of aryl triflates.
- Milner, Phillip J.,Kinzel, Tom,Zhang, Yong,Buchwald, Stephen L.
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supporting information
p. 15757 - 15766
(2015/02/02)
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- FLUORINATION OF ARYL COMPOUNDS
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The invention provides compositions and methods of using the compositions in fluorinating aryl precursors containing a leaving group replaceable by a fluorine atom. The compositions include a metal ion source, a electrophilic fluorine source, a base, and a compound, which is an aryl precursor of the aryl fluoride, and which has a leaving group replaceable by the fluorine atom. Exemplary methods of the invention make use of such compositions and methods to prepare an aryl fluoride compound. In an exemplary embodiment, the electrophilic fluorine source is a source of 18F.
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Paragraph 00121
(2014/07/22)
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- Pd-catalyzed nucleophilic fluorination of aryl bromides
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On the basis of mechanism-driven reaction design, a Pd-catalyzed nucleophilic fluorination of aryl bromides and iodides has been developed. The method exhibits a broad substrate scope, especially with respect to nitrogen-containing heteroaryl bromides, and proceeds with minimal formation of the corresponding reduction products. A facilitated ligand modification process was shown to be critical to the success of the reaction.
- Lee, Hong Geun,Milner, Phillip J.,Buchwald, Stephen L.
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supporting information
p. 3792 - 3795
(2014/04/03)
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- Iron-catalysed, general and operationally simple formal hydrogenation using Fe(OTf)3 and NaBH4
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An operationally simple and environmentally benign formal hydrogenation protocol has been developed using highly abundant iron(iii) salts and an inexpensive, bench stable, stoichiometric reductant, NaBH4, in ethanol, under ambient conditions. This reaction has been applied to the reduction of terminal alkenes (22 examples, up to 95% yield) and nitro-groups (26 examples, up to 95% yield). Deuterium labelling studies indicate that this reaction proceeds via an ionic rather than radical mechanism.
- MacNair, Alistair J.,Tran, Ming-Ming,Nelson, Jennifer E.,Sloan, G. Usherwood,Ironmonger, Alan,Thomas, Stephen P.
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supporting information
p. 5082 - 5088
(2014/07/08)
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- FLUORINATION OF ARYL COMPOUNDS
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The invention provides compositions and methods of using the compositions in fluorinating aryl precursors containing a leaving group replaceable by fluoride ion. The compositions include a metal ion source, a fluoride ion source, and a compound, which is
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Paragraph 0076
(2014/01/08)
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- Fluorination of aryl boronic acids using acetyl hypofluorite made directly from diluted fluorine
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Aryl boronic acids or pinacol esters containing EDG were converted in good yields and fast reactions to the corresponding aryl fluorides using the readily obtainable solutions of AcOF. In reactions with aryl boronic acids containing EWG at the para position, there are two competing forces: one directing the fluorination to take place ortho to the boronic acid and the other, toward an ipso substitution. With EWG meta to the boronic acid, substitution ipso to the boron moiety takes place in good yields.
- Vints, Inna,Gatenyo, Julia,Rozen, Shlomo
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p. 11794 - 11797
(2014/01/06)
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- Copper-mediated fluorination of arylboronate esters. Identification of a Copper(III) fluoride complex
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A method for the direct conversion of arylboronate esters to aryl fluorides under mild conditions with readily available reagents is reported. Tandem reactions have also been developed for the fluorination of arenes and aryl bromides through arylboronate ester intermediates. Mechanistic studies suggest that this fluorination reaction occurs through facile oxidation of Cu(I) to Cu(III), followed by rate-limiting transmetalation of a bound arylboronate to Cu(III). Fast C-F reductive elimination is proposed to occur from an aryl-copper(III)-fluoride complex. Cu(III) intermediates have been generated independently and identified by NMR spectroscopy and ESI-MS.
- Fier, Patrick S.,Luo, Jingwei,Hartwig, John F.
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supporting information
p. 2552 - 2559
(2013/03/29)
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- POLYCYCLIC RING-FUSED COMPOUND AND ORGANIC THIN FILM TRANSISTOR UTILIZING SAME
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A compound for an organic thin film transistor represented by the following formula (1):
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Page/Page column 28
(2012/11/08)
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- Copper-mediated fluorination of aryl iodides
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The synthesis of aryl fluorides has been studied intensively because of the importance of aryl fluorides in pharmaceuticals, agrochemicals, and materials. The stability, reactivity, and biological properties of aryl fluorides can be distinct from those of the corresponding arenes. Methods for the synthesis of aryl fluorides, however, are limited. We report the conversion of a diverse set of aryl iodides to the corresponding aryl fluorides. This reaction occurs with a cationic copper reagent and silver fluoride. Preliminary results suggest this reaction is enabled by a facile reductive elimination from a cationic arylcopper(III) fluoride.
- Fier, Patrick S.,Hartwig, John F.
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supporting information; experimental part
p. 10795 - 10798
(2012/08/07)
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- Cuprous-catalyzed cross-coupling reaction of grignard reagents with alkyl halides
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For the first time in the presence of a catalytic amount of cuprous iodide, alkyl bromide reacted with aryl magnesium bromide (Grignard reagent) to obtain the cross-coupling product in good yields. The conditions of the cross-coupling reaction were studied. The suitable amount of catalyst, reaction temperature and time are 2 % mol (based on alkyl halide), 67 °C (reflux), 6 h, respectively. Under the optimal conditions, the yields of the cross-coupling could reach up to 90 %. Moreover, Grignard reagent with an electron-rich group reacted rapidly and with an electron-withdrawing group reacted sluggishly.
- Dai,Zhang,Zhang,Wei,Yang
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experimental part
p. 4087 - 4089
(2012/01/04)
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- Evidence for in situ catalyst modification during the Pd-catalyzed conversion of aryl triflates to aryl fluorides
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A mechanistic investigation of the Pd-catalyzed conversion of aryl triflates to fluorides is presented. Studies reveal that C-F reductive elimination from a LPdII(aryl)F complex (L = t-BuBrettPhos or RockPhos) does not occur when the aryl group is electron rich. Evidence is presented that a modified phosphine, generated in situ, serves as the actual supporting ligand during catalysis with such substrates. A preliminary study of the reactivity of a LPdII(aryl)F complex based on this modified ligand is reported.
- Maimone, Thomas J.,Milner, Phillip J.,Kinzel, Tom,Zhang, Yong,Takase, Michael K.,Buchwald, Stephen L.
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supporting information; experimental part
p. 18106 - 18109
(2012/01/02)
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- Metal-Catalyzed Carbon-Fluorine Bond Formation
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One aspect of the invention relates to a metal-catalyzed conversion of aryl halides and sulfonates to the corresponding aryl fluorides. Another aspect of the invention relates to a metal-catalyzed conversion of heteroaryl halides and sulfonates to the corresponding heteroaryl fluorides. Another aspect of the invention relates to a metal-catalyzed conversion of vinyl halides and sulfonates to the corresponding vinyl fluorides. In certain embodiments, simple fluoride sources, such as AgF and CsF, are used. In certain embodiments, the transformations tolerate a wide range of functional groups, allowing for introduction of fluorine atoms into highly functionalized organic molecules.
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Page/Page column 18-19
(2011/02/18)
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- Scope and limitation of the nickel-catalyzed coupling reaction between lithium borates and mesylates
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Coupling reaction of aryl borates and mesylates derived from phenols and enols was studied. Mesylates with an electron-with-drawing group or ring were highly reactive at room temperature in the presence of NiCl2(PPh3)2 to furnish the coupling products in good yields.
- Kobayashi, Yuichi,William, Anthony D.,Mizojiri, Ryo
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- Raney Nickel: An effective reagent for reductive dehalogenation of organic halides
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Raney Nickel is an effective reagent to achieve the chemoselective reductive dehalogenation of organic halides. Fluorides and vinyl halides are unreactive under the used experimental conditions.
- Barrero,Alvarez-Manzaneda,Chahboun,Meneses,Romera
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p. 485 - 488
(2007/10/03)
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- Structure of ω-Arylalkyl Radicals: A 13C CIDNP Investigation
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Thermolysis of a series of ω-arylalkanoyl m-chlorobenzoyl (and acetyl) peroxides at ca. 100 deg C in cyclohexanone and in hexachloroacetone was studied by using 13C chemically induced dynamic nuclear polarization.Analysis of the observed 13C polarizations indicate that all the three radicals (β-arylethyl, γ-arylpropyl and δ-arylbutyl) have open-chain structures with no evidence for aryl participation resulting in spirocycloalkylcyclohexadienyl radicals.
- Olah, George A.,Krishnamurthy, V. V.,Singh, Brij P.,Iyer, Pradeep S.
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p. 955 - 963
(2007/10/02)
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