Reaction Of Aryl Bromides Research Articles

Selective synthesis of ( E)-triethyl(2-arylethenyl)silane derivatives by reaction of aryl bromides with triethyl vinylsilane catalysed by a palladium–tetraphosphine complex

Cis, cis, cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane / 0.5 [PdCl(C 3H 5)] 2 system catalyses the Heck reaction of vinylsilane derivatives with a range of aryl bromides with high ratio substrate/catalyst in good yields. The formation of mixtures of styrene, ( E)-triethyl(2-arylethenyl)silane and triethyl(1-arylethenyl)silane derivatives was observed in some cases. Very high selectivities (up to 100%) in favour of the formation of ( E)-triethyl(2-arylethenyl)silane derivatives were obtained in the presence of sodium acetate as base. With other bases such as potassium carbonate, the formation of large amounts of styrene derivatives was observed. The reaction tolerates several functions such as fluoro, trifluoromethyl, methoxy, dimethylamino, acetyl, formyl, benzoyl, carboxylate, nitro or nitrile. Moreover, turnover numbers up to 10,000 can be obtained for this reaction.

Suzuki—Miyaura Cross‐Coupling Reaction of Aryl Bromides and Chlorides with Phenylboronic Acid under Aerobic Conditions Catalyzed by Palladium Complexes with Thiosemicarbazone Ligands.

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Monoligated Palladium Species as Catalysts in Cross‐Coupling Reactions

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First Microwave‐Accelerated Hiyama Coupling of Aryl‐ and Vinylsiloxane Derivatives: Clean Cross‐Coupling of Aryl Chlorides within Minutes

AbstractThe first microwave‐accelerated Hiyama cross‐coupling reactions are reported. The reactions of aryl bromides and activated aryl chlorides with PhSi(OMe)3 [or C2H3Si(OMe)3] are complete within minutes using a modified catalyst system that can be prepared from commercially available reagents in situ. The microwave‐accelerated reactions proceed under relatively mild conditions (110–115 °C)

A New Mixed P,S‐Bidentate Ligand Featuring a λ4‐Phosphinine Anion and a Phosphanyl Sulfide Group − Synthesis, X‐ray Crystal Structures and Catalytic Properties of Its Chloro(cymene)ruthenium and Allylpalladium Complexes

Abstract1,3,2‐Diazaphosphinine (1) reacts successively with diphenylacetylene and diphenyl(1‐propynyl)phosphane sulfide to afford the P,S‐bidentate phosphinine 3. Reaction of nBuLi with 3 followed by complexation with [RuCl2(C10H14)]2 gave two diastereoisomers 5a,b. Variable‐temperature NMR spectroscopy and ONIOM DFT calculations were carried out to rationalize their formation. Complexes 5a,b were used as catalysts in hydrogen‐transfer hydrogenation (TON up to 200). Reaction of MeLi with 3 followed by complexation with [PdCl2(η3‐C3H5)]2 yielded two diastereomers 7a,b, which were used as catalysts in the Suzuki−Miyaura cross‐coupling reaction of aryl bromides with pinacolborane to yield the corresponding arylboronic esters (TON up to 799000). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Monoligated Palladium Species as Catalysts in Cross‐Coupling Reactions

Palladium-mediated cross-coupling reactions are attractive organometallic transformations for the generation of C--C, C--N, C--O, and C--S bonds. Despite being widely employed in small-scale syntheses, cross-coupling reactions have not found important industrial applications because until recently, only reactive aryl bromides and iodides could be used as substrates. These substrates are generally more expensive and less widely available than their chloride counterparts. Over the past few years, new catalytic systems with the ability to activate unreactive and sterically hindered aryl chlorides have been developed. The new catalysts are based on palladium complexes that contain electron-rich and bulky phosphine or carbene ligands. The enhanced reactivity observed with these new systems has been attributed to the formation of unsaturated and reactive [PdL] species which can readily undergo oxidative addition reactions with ArX to yield [Pd(Ar)X(L)].

Iminophosphine—Palladium(0) Complexes as Highly Active Catalysts in the Suzuki Reaction. Synthesis of Undecaaryl Substituted Corroles.

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Iminophosphine–palladium(0) complexes as highly active catalysts in the Suzuki reaction. Synthesis of undecaaryl substituted corroles

The iminophosphine–palladium(0) complex [Pd(dmfu)(P-N)] [dmfu=dimethyl fumarate; P-N=2-(PPh2)C6H4-1-CHNC6H4-4-OMe] is a very efficient catalyst for the Suzuki coupling. In the reaction of aryl bromides with phenylboronic acid, turnover numbers up to ca. 200,000 are obtained at 110°C in 2h. Good rates are obtained also with the sterically hindered and electronically deactivated 2-bromo-1,3,5-trimethylbenzene. The complex is able to catalyze the exhaustive arylation of 2,3,7,8,12,13,17,18-octabromo-5,10,15-triphenylcorroleCu(III) to yield the corresponding undecaaryl substituted derivative.

Stereoselective Synthesis of Tetrahydrofurans via the Palladium‐Catalyzed Reaction of Aryl Bromides with γ‐Hydroxy Alkenes: Evidence for an Unusual Intramolecular Olefin Insertion into a Pd(Ar)(OR) Intermediate.

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High Yield Synthesis of Aryl Cyanides under Microwave Irradiation.

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Highly Efficient Suzuki Cross‐Coupling Catalyzed by Palladium/Phosphine‐Imidazolium Carbene System

AbstractNovel phosphine‐imidazolium salts 2 have been synthesized and successfully used in palladium‐catalyzed Suzuki cross‐coupling. A combination of 0.05 mol % of [Pd(η‐C3H5)Cl]2 and 0.1 mol % of 2b in the presence of 2 equivs. of K3PO4 as base provided coupling products in excellent yields in the reaction of aryl bromides and chlorides with aryl boronic acids.

Pyridine-derived palladium complexes immobilized on ordered mesoporous silica as catalysts for Heck-type reactions

Abstract Palladium complexes with pyridine–carboimine and quinoline–carboimine ligands immobilized on ordered mesoporous silica (FSM-16) were prepared by the following reactions: (1) surface modification of FSM-16 with 3-aminopropyl group via silylation; (2) preparation of pyridine–carboimine and quinoline–carboimine ligands on FSM-16; (3) formation of palladium complex on FSM-16 with PdCl2. The palladium complexes were characterized by X-ray diffraction (XRD), N2-adsorption, FT-IR, 29 Si and 13 C MAS NMR, inductively coupled plasma (ICP) and TG analysis. These catalysts were found to be active in the Heck vinylation of aryl iodides and activated aryl bromides with methyl acrylate. Conversion of 100% in 1–5 h reaction and selectivity for trans-stereoisomer higher than 99% have been achieved. In the case of less reactive aryl bromides, addition of quaternary ammonium salt increased activity of catalysts, but significant leaching of palladium into solution has been observed. The palladium complexes showed high catalytic activity even for Suzuki coupling of aryl iodides and aryl bromides with the yield of coupling products 50–100% after 1.5 h reaction. Hindered substrates such as 9-bromoanthracene and 9,10-dibromoanthracene were also coupled in yield of 40–65%. Nevertheless, slightly higher concentration of Pd (1.5 times as high as for mono-coupling) is required for complete di-coupling in the case of 9,10-dibromoanthracene. These immobilized catalysts can be easily separated from the reaction mixture by filtering and re-used for further reaction. Catalysis by these palladium complexes can offer an alternative to homogeneous catalysts.

Copper(I)‐Catalyzed Arylselenylation of Aryl Bromides and Iodides.

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A Palladium−Ferrocenyl Tetraphosphine System as Catalyst for Suzuki Cross-Coupling and Heck Vinylation of Aryl Halides: Dynamic Behavior of the Palladium/Phosphine Species

The system combining the new ferrocenyl tetraphosphine 1,1‘,2,2‘-tetrakis(diphenylphosphino)-4,4‘-di-tert-butylferrocene (called Fc(P)4tBu, 1) and [PdCl(η3-C3H5)]2 has been found to be an active catalyst for the cross-coupling of aryl halides with aryl boronic acids (i.e., Suzuki reaction) and for the vinylation of aryl halides with alkenes (Heck reaction). A variety of chlorides reacts in good yield with aryl boronic acids in the presence of 1−0.01% catalyst. The more reactive aryl bromides were reacted with aryl boronic acids or alkenes in the presence of 0.01−0.0001% catalyst. This system compares well with other catalytic systems that have been described for Suzuki or Heck reactions. 1H, 13C, and 31P NMR studies in solution were conducted with the view to obtain a better understanding of the interaction involving the palladium dimeric precursor and the tetraphosphine. The initial formation of kinetic and then different thermodynamic species was evidenced. A dynamic evolution from labile Pd(π-allyl)/tetraphosphine species toward the well-defined, stable, and nonfluxional complexes [PdCl2{Fc(P)4tBu}] (3) and [Pd2Cl4{Fc(P)4tBu}] (4) is observed. This behavior is different from the other known active tetraphosphine Tedicyp [cis,cis,cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane]. The palladium mononuclear 3 and dinuclear 4 complexes were isolated and fully characterized in the solid state by X-ray diffraction analysis and in solution by multinuclear NMR. The blocked conformation in solution of compounds 1, 3, and 4 respectively leads to original AA‘BB‘, ABMX, and A2B2 31P NMR spin-systems for the four phosphorus atoms.

Copper(I)-catalyzed arylselenylation of aryl bromides and iodides

A new protocol to prepare unsymmetrical diarylselenides using the reaction of aryl bromides and iodides with easily available Bu 3SnSeAr catalyzed by Cu(I) complexes under rather mild conditions and with a very high yield is described.

Arylation of Allylic Alcohols in Ionic Liquids Catalysed by a Pd‐Benzothiazole Carbene Complex

AbstractThe reaction of aryl bromides with allylic alcohols catalysed by a Pd‐benzothiazole carbene complex, in tetrabutylammonium bromide as solvent, leads principally to β‐arylated carbonyl compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Can We Aminate Grignard Reagents under Barbier Conditions?

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Suzuki Cross‐Coupling Reaction Catalyzed by Palladium‐Supported Sepiolite.

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A Practical Recycle of a Ligand-Free Palladium Catalyst for Heck Reactions

Ligand-free palladium can be recovered almost quantitatively from Heck reaction mixtures by filtration after its deposition on a carrier such as silica or celite. Subsequently, it is re-activated to its original activity by adding a small amount of iodine or bromine prior to the next reaction cycle. The catalyst results in excellent yields and selectivities, even for the less reactive aryl bromides. A catalytic cycle based on anionic palladium intermediates is proposed.

Can we aminate Grignard reagents under Barbier conditions?

The reaction of aryl bromides with acetone O-(2,4,6-trimethylphenylsulfonyl)oxime and magnesium in THF at reflux temperature for 3 h provides a one-pot procedure for amination of aryl Grignard reagents under Barbier conditions.