Cross-coupling Reactions Of Aryl Chlorides Research Articles

Suzuki-Miyaura Cross-Coupling Reaction Using Palladium Catalysts Supported on Phosphine Periodic Mesoporous Organosilica.

Phosphine periodic mesoporous organosilicas (R-P-PMO-TMS: R=Ph, tBu), which possess electron-donating alkyl substituents on the phosphorus atom, were synthesized using bifunctional compounds with alkoxysilyl- and phosphino groups, bis[3-(triethoxysilyl)propyl]phenylphosphine borane (1 a) and bis[3-(triethoxysilyl)propyl]-tert-butylphosphine borane (1 b). Immobilization of Pd(0) species was performed to give R-P-Pd-PMO-TMS: R=Ph (2 a), tBu (3 a), respectively. The Pd(0) immobilized 2 a and 3 a were applicable as catalysts for Suzuki-Miyaura cross-coupling reactions of aryl chlorides with phenylboronic acid. It was revealed that 3 a bearing more electron-donating tBu groups exhibited higher catalytic activity. Various functional groups including both electron withdrawing and donating substituents were compatible in the system. The recyclability of 3 a was examined to support its moderate utility for the recycle use.

Cu/Mn-Catalyzed C–N Cross-Coupling Reaction of Aryl Chlorides and Amines Promoted by a Polyamidoamine Dendrimer

AbstractA bimetallic catalytic combination of Mn(OAc)2 and Cu(OAc)2 was found to be significantly effective for the Buchwald-type C–N cross-coupling of aryl chlorides and amines. The reaction was markedly affected by the presence of a poly(amidoamine) dendrimer as a promoter that also possesses the advantages of being stable, nontoxic, biocompatible, nonimmunogenic, and acting as a soluble support for the transition-metal complex. Although, manganese is cheap and environmentally benign, it has not been fully exploited, due to its low intrinsic catalytic activity. Here, the catalytic potential of manganese was drastically increased by the presence of another metal salt, Cu(OAc)2. In the bimetallic composition, Mn significantly influenced the activity and selectivity, and played a vital role in catalysis. We have developed a novel, green, and economical procedure for Buchwald-type C–N cross-coupling of aryl chlorides and amines. This coupling method works under aerobic and solvent-free conditions and gives excellent yields of value-added N-arylated or N-alkylated products.

Pd(4-R3Si-IPr)(allyl)Cl]/K2CO3/EtOH: A highly effective catalytic system for the Suzuki-Miyaura cross-coupling reaction

A series of R3Si-NHC-Pd complexes 1Pd-7Pd was successfully tested as a pre-catalyst for the Suzuki-Miyaura cross-coupling reaction of aryl chlorides and arylboronic acid derivatives to form a wide range of valuable biphenyl products. Use of the readily available weakly basic potassium carbonate as a base and the highly polar protic ethanol as the reaction solvent gave the target coupling products in good-to-excellent yields. The experimental data pointed to the crucial importance of the preliminary pre-catalyst activation step [i.e., the conversion of Pd(II) to Pd(0)], which is remarkably facilitated by the electron-donating trialkylsilyl groups on the NHC ligands of 1Pd–7Pd, thereby rendering them superior compared to the commercially available IPr-Pd complexes. Computational analysis revealed the mechanism of the Pd(II)→Pd(0) activation step, demonstrating the critical role of the reaction solvent and the base in the preference of our 1Pd–7Pd pre-catalysts, for which this step is both thermodynamically and kinetically more feasible.

Synthesis of Xylyl-Linked Bis-Benzimidazolium Salts and Their Application in the Palladium-Catalyzed Suzuki–Miyaura Cross-Coupling Reaction of Aryl Chlorides

A new series of xylyl-linked bis-benzimidazolium salts were efficiently prepared using a simple preparation method from bis-benzimidazolium precursors featuring highly tunable linkers and wingtips. A highly efficient Suzuki–Miyaura cross-coupling reaction of aryl chlorides within the range of 0.5–2.0 mol% Pd-catalyst loading was observed. Also, di-ortho-substituted biaryl synthesis was achieved.

Magnetic chitosan-functionalized cobalt-NHC: Synthesis, characterization and catalytic activity toward Suzuki and Sonogashira cross-coupling reactions of aryl chlorides

• Co-NHC@MC is the first example of Cobalt-NHC catalyst catalyzed the reaction of substituted phenylboronic acid and phenlacethylene with derivatives of aryl chlorides. • Co-NHC@MC showed outstanding catalytic activity toward Suzuki and Sonogashira cross coupling reaction. • Co-NHC@MC catalyzed Suzuki and Sonogashira cross coupling reaction without any toxic reducing agent in PEG as green solvent. • Chitosan was used as an accessible, easily and non-toxic modification-support for cobalt catalyst. • Co-NHC@MC is easily recovered and reused for 7 runs for Suzuki and Sonogashira cross coupling reaction. Aryl chlorides are one of the most stable and available electrophiles, however, their coupling with nucleophiles remains a challenge in organic synthesis. Herein, we prepared a Cobalt-NHC (N-Heterocyclic carbene) complex anchored on magnetic chitosan nanoparticles and assayed its catalytic activity for the reactions of substituted phenylboronic acid and also phenlacetylene with derivatives of aryl chlorides. These reactions are of great importance since they are employed for the synthesis of unsymmetrical diarylethynes and biphenyls, which belong to a prime class of building blocks. The synthesized nanocatalyst was found to be highly efficient in Suzuki and Sonogashira coupling in terms of their activity and recyclability in polyethylene glycol (PEG) as a green reaction media under conditions of temperatures (70 and 100 °C) and Co loading (3 and 6 mol%). To the best of our knowledge, this is the first attempt of using cobalt-NHC complex for catalyzing the abovementioned reactions. Moreover, replacing the earth-abundant Cobalt-based catalyst as an alternative to high cost palladium make this approach promising from sustainable chemistry view.

Is oxidative addition indeed the rate-determining step of the Suzuki–Miyaura reaction with less-reactive aryl chlorides under “ligand-free” conditions?

The retarded oxidative addition of aryl chloride to Pd(0) is believed, by most scientists, to be the main hindrance in achieving effective conversion in the Suzuki–Miyaura reaction and other cross-coupling reactions of aryl chlorides. Herein, we have demonstrated by competing experiments, using two aryl chlorides under “ligand-free” catalytic conditions (absence of strong ligands; high ratio of substrate to catalyst), that the elementary step of oxidative addition is substantially reversible. This implies that the hypothesis on the rate-determining character of the oxidative addition step is incorrect, and the existing problems with aryl chloride conversion in the Suzuki–Miyaura reaction are caused by some other reasons that need to be investigated.

Microwave-assisted aqueous carbon–carbon cross-coupling reactions of aryl chlorides catalysed by reduced graphene oxide supported palladium nanoparticles

Microwave-assisted reduced graphene oxide supported palladium nanoparticles can efficiently promote aqueous Ullmann and Suzuki coupling reactions of aryl chlorides.

Development of Titanium Dioxide-Supported Pd Catalysts for Ligand-Free Suzuki–Miyaura Coupling of Aryl Chlorides

The catalyst activities of various heterogeneous palladium catalysts supported by anatase-, rutile- and brookite-type titanium oxide for ligand-free Suzuki–Miyaura cross-coupling reactions of aryl chlorides were evaluated. Palladium acetate [Pd(OAc)2], supported on anatase-type titanium oxide (TiO2) via acetonitrile solution impregnation process without reduction [Pd/TiO2 (anatase-type)], demonstrated the highest catalyst activity in comparison to those of other titanium oxide (rutile- or brookite-type) supported Pd(OAc)2 without reduction and reduced Pd/TiO2 (anatase-type) [Pd(red)/TiO2 (anatase-type)]. Various aryl chloride and bromide derivatives were smoothly coupled with arylboronic acids including heteroarylboronic acids in the presence of 5–10 mol% Pd/TiO2 (anatase-type) without the addition of any ligands. Although the fresh Pd/TiO2 (anatase-type) catalyst was surprisingly comprised of ca. 1:2 mixture of palladium(II) and palladium(0) species according to X-ray photoelectron spectroscopy (XPS), in spite of no reduction process, significant further increment of palladium(0) species was observed during the Suzuki–Miyaura coupling reaction, and Pd/TiO2 (anatase-type) was converted into a catalyst, which contained palladium(0) species as the main component [ca. 1:5 mixture of palladium(II) and palladium(0) species]. Therefore, the reduction via the electron donation process to the palladium(II) species may have occurred during the reaction on anatase-type titanium oxide.

Room temperature Pd(0)/Ad3P-catalyzed coupling reactions of aryl chlorides with bis(pinacolato)diboron

Room temperature Pd(0)/Ad3P-catalyzed cross-coupling reactions of aryl chlorides with bis(pinacolato)diboron are described. The Pd(0)/Ad3P catalyst, generated from Ad3P-coordinated acetanilide-based palladacycle complex, proved to be an efficient catalyst system for the Miyaura borylation reactions of a variety of aryl chlorides with bis(pinacolato)diboron. The mild reaction condition, the easy availability of the catalyst and good coupling yields make these reactions potentially useful in organic synthesis.

A Polystyrene-Cross-Linking Tricyclohexylphosphine: Synthesis, Characterization and Applications to Pd-Catalyzed Cross-Coupling Reactions of Aryl Chlorides.

A polystyrene-cross-linking tricyclohexylphosphine (PS-TCP) was synthesized through radical emulsion polymerization of 4-tert-butylstyrene as a monomer and tris(trans-4-styrylcyclohexyl)phosphine as a threefold cross-linker. The PS-TCP showed enhanced ligand performance compared to the corresponding polystyrene-triphenylphosphine hybrid PS-TPP and tricyclohexylphosphine in Pd-catalyzed Suzuki-Miyaura and Buchwald-Hartwig reactions of aryl chlorides.

Cyclometalated Palladium NHC Complexes Bearing PEG Chains for Suzuki–Miyaura Cross-Coupling in Water

We present the synthesis and characterization of four new polyethylene glycol (PEG) substituted palladium complexes bearing a cyclometalated 2-phenylimidazole ligand and an N-heterocyclic carbene (NHC) ligand. A solid-state structure reveals the chelating binding mode and the coiling of the PEG chain in the auxiliary ligand. The PEG substitution significantly increased the solubility of the complexes in several solvents, enabling the efficient Suzuki–Miyaura cross-coupling reaction of aryl chlorides in an aqueous medium. Under optimized reaction conditions, sterically demanding biphenyl compounds with up to three ortho substituents were accessible in good to excellent yields.

Room-temperature borylation and one-pot two-step borylation/Suzuki–Miyaura cross-coupling reaction of aryl chlorides

A highly efficient room-temperature borylation strategy of aryl chlorides is described. Utilizing Buchwald's second-generation preformed catalyst, boronate esters were obtained for a wide range of substrates in high yield. The method was also applied to Suzuki–Miyaura cross-coupling reaction in a one-pot two-step sequential manner, providing a facile and convenient access to the direct synthesis of biaryl compounds from aryl chlorides.

Iron-Catalyzed Cross-Coupling Reactions of Arylmagnesium Reagents with Aryl Chlorides and Tosylates: Influence of Ligand Structural Parameters and Identification of a General N-Heterocyclic Carbene Ligand

A systematic evaluation of N-heterocyclic carbene ligands in the iron-catalyzed cross-coupling reactions of aryl chlorides and arylmagnesium reagents is performed. There is no clear correlation between the donor strength of the N-heterocyclic carbene and the reaction outcome. Instead, the highest yields of the desired biaryl product are obtained with sterically demanding ligands possessing large %Vbur values. Through this study, SIPrNap has been identified as an efficient and general ligand for the coupling of both aryl chlorides and tosylates.

Suzuki-Miyaura cross-coupling reaction of aryl chlorides with aryl boronic acids catalyzed by a palladium dichloride adduct of N-diphenylphosphanyl-2-aminopyridine

One palladium dichloride adduct of a phosphine-pyridine ligand N-diphenylphosphanyl-2-aminopyridine (L1) [(L1)PdCl2] (1) has been prepared and structurally characterized. Compound 1 can be used as an effective catalyst for the Suzuki-Miyaura cross-coupling reactions of unreactive aryl chlorides with aryl boronic acids, and worked much better than its mono- or bidentate phosphine ligands. The reactions with a wide scope of substrates proceeded to give desired products in good to excellent yields.

C[sbnd]Cl bond activation with Pd(II)-NiO nanoparticles supported on zeolite-Y: The role of charge transfer transition

Well dispersed Pd-NiO nanoparticles (Pd-NiO NP’s) formed over zeolite-NaY was found to be highly efficient catalyst for the Suzuki-Miyaura cross-coupling reaction of aryl chlorides and phenylboronic acid derivatives. Exceptional CC coupling products up to 92% were obtained within short period of time with chlorobenzene and their derivatives under microwave irradiation. Cyclic voltammetry (CV) study predicted that the leached Pd-NiO species were the “true catalyst” in the CCl bond activation process. Insitu generation of active Pd(0) via a charge transfer transition from NiO→Pd(II) was confirmed from CV study and was believed to be the crucial step in CCl bond activation. Filtration and CV analysis suggested for quick re-deposition of Pd-NiO NP’s on zeolite-NaY surface and confirmed for the non-consumption of Ni(OH)2 species.

Efficient symmetrical bidentate dioxime ligand-accelerated homogeneous palladium-catalyzed Suzuki–Miyaura coupling reactions of aryl chlorides

A series of N,O-bidentate ligands were synthesized and studied as high activity ligands for palladium-catalyzed Suzuki–Miyaura cross-coupling reactions of aryl chlorides with arylboronic acids under mild conditions.

Synthesis and Reactivity of N-Heterocyclic PSiP Pincer Iron and Cobalt Complexes and Catalytic Application of Cobalt Hydride in Kumada Coupling Reactions

The new N-heterocyclic σ-silyl pincer ligand HSiMe(NCH2PPh2)2C6H4 (1) was designed. A series of tridentate silyl pincer Fe and Co complexes were prepared. Most of them were formed by chelate-assisted Si–H activation. The typical iron hydrido complex FeH(PMe3)2(SiMe(NCH2PPh2)2C6H4) (2) was obtained by Si–H activation of compound 1 with Fe(PMe3)4. The combination of compound 1 with CoMe(PMe3)4 afforded the Co(I) complex Co(PMe3)2(SiMe(NCH2PPh2)2C6H4) (3). The Co(III) complex CoHCl(PMe3)(SiMe(NCH2PPh2)2C6H4) (5) was generated by the reaction of complex 1 with CoCl(PMe3)3 or the combination of complex 3 with HCl. However, when complex 3 was treated with MeI, the Co(II) complex CoI(PMe3)(SiMe(NCH2PPh2)2C6H4) (4), rather than the Co(III) complex, was isolated. The catalytic performance of complex 5 for Kumada coupling reactions was explored. With a catalyst loading of 5 mol %, complex 5 displayed efficient catalytic activity for Kumada cross-coupling reactions of aryl chlorides and aryl bromides with Grignard r...

ChemInform Abstract: Diaminophosphine Oxides as Preligands for Ni‐Catalyzed Suzuki Cross‐Coupling Reactions of Aryl Chlorides with Arylboronic Acids.

Abstract The first investigation of air- and moisture-stable diaminophosphine oxides as preligands in the Ni-catalyzed Suzuki cross-coupling reactions of aryl chlorides with arylboronic acids has been reported. The results show that under the optimized reaction conditions, the new catalytic system with a Ni(II) σ-aryl complex as precatalyst and a diaminophosphine oxide as preligand tolerates a variety of functional groups and is efficient for both electron-rich and electron-deficient aryl chlorides, though it shows higher efficiency for activated arylboronic acids than deactivated ones. Steric effects were observed for both aryl chlorides and arylboronic acids.

Diaminophosphine oxides as preligands for Ni-catalyzed Suzuki cross-coupling reactions of aryl chlorides with arylboronic acids

The first investigation of air- and moisture-stable diaminophosphine oxides as preligands in the Ni-catalyzed Suzuki cross-coupling reactions of aryl chlorides with arylboronic acids has been reported. The results show that under the optimized reaction conditions, the new catalytic system with a Ni(II) σ-aryl complex as precatalyst and a diaminophosphine oxide as preligand tolerates a variety of functional groups and is efficient for both electron-rich and electron-deficient aryl chlorides, though it shows higher efficiency for activated arylboronic acids than deactivated ones. Steric effects were observed for both aryl chlorides and arylboronic acids.

Cyclometalated 2-Phenylimidazole Palladium Carbene Complexes in the Catalytic Suzuki–Miyaura Cross-Coupling Reaction

We present the syntheses of 12 cyclometalated palladium C∧N 2-phenylimidazole carbene complexes with different N-1 groups as well as different substituents at the C-2 phenyl group of the cyclometalating imidazole. We investigated the influence of these substituents by comparing the catalytic performance of the complexes in the Suzuki–Miyaura cross-coupling reaction of aryl chlorides. We can show a strong dependence between the steric demand of the N-1 substituent of the cyclometalating imidazole and the catalytic activity in the cross-coupling reaction. The most active complex shows a wide substrate scope, where several aryl as well as benzyl chlorides could be coupled with different boronic acids in excellent yields using very low catalyst concentrations of 0.05 mol %.