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The Sonogashira cross coupling reaction is an applied method for preparation of diarylethyne compounds from readily available aryl halide derivatives and phenyl acetylene. The coupling reaction using nickel complex of N,N′-Bis(2-hydroxyethyl)ethylenediamine onto core shell graphene oxide (GO@SiO2-BHED-Ni) as a catalyst was studied in this research. This heterogonous catalyst showed good thermal stability, highly efficiency and recyclability in the reaction. Moreover, the catalyst is simply separated and can be reused several times without significant loss of catalytic activity. A wide range of aryl halides was coupled successfully under palladium and phosphine free conditions. The use of this catalyst led to the formation of substituted aromatic alkynes in excellent yields and short reaction times.

A novel redox-driven method to synthesize Pd-γ-Fe 2 O 3 nanocomposite from Fe 3 O 4 and PdCl 2 under modified hydrothermal technique has been developed. The synthesized nanocomposite was characterized by XRD, FT-IR, XPS, FESEM, TEM and EDX to understand the composition as well as morphology. The Pd-γ-Fe 2 O 3 nanocomposite was found to show excellent catalytic activity towards Suzuki-Miyaura cross-coupling reactions in water without the assistance of ligands, organic solvents or phase transfer catalysts. A wide range of functional substitutions in aryl halide as well as arylboronic acid moieties is tolerated in the developed protocol. The nanocatalyst can be recovered magnetically, and reused up to six cycles without significant loss in its catalytic activity.

We report synthesis of two new palladium(II) complexes of abnormal N-heterocyclic carbene ligands. The catalytic activity of these palladium(II) complexes was examined for the decarboxylative arylation of N-methylindole-carboxylic acids. An exclusive regioselectivity and very good yields were obtained with a variety of aryl halide partners.

A systematic theoretical study has been carried out on the mechanism for the Pd-catalyzed aromatic C H activation reaction of aryl nitrile and aryl halide using cyano as the directing group. The entire catalytic cycle divides into four main processes involving C H activation, CF3COOH dissociation, oxidative addition, and reductive elimination and catalyst regeneration. The calculations indicate that the ortho carbon of the directing group cyano in aryl nitrile is activated by Pd(II) resulting in the activation of C H bond. In CF3COOH dissociation, it is found that the 5b is an essential intermediate, which facilitates the dissociation of CF3COOH ligand leading to the intermediate (η2-CF3COO−)(η2-aryl nitrile)Pd(II) (6). The Pd(II) intermediate further undergoes oxidative addition with PhI to form Pd(IV) intermediate, which proceeds by reductive elimination and catalyst regeneration to give the final product. And the reductive elimination and catalyst regeneration process can determine the reaction rate. Furthermore, the roles of additive Ag2O, directing group cyano, and solvent Trifluoroacetic acid have also been examined.

The convenient nickel-catalyzed carbonylative coupling of aryl iodides with Ph3SnCl or Ph3SnOEt for synthesis of unsymmetrical diaryl ketones under phosphine-free condition is reported. The reaction occurs efficiently in the presence of Cr(CO)6 as an easy handling solid source of carbon monoxide at atmospheric pressure and 100 °C in DMF under air to deliver the desired ketones in high yield.

Superparamagnetic nanoparticles functionalized with Schiff base complex of Pd (II) were simply synthesized by a two-step method. The catalyst was characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS),vibrating sample magnetometry (VSM), Fourier transform infrared (FT-IR), and N 2 adsorption–desorption isotherm analysis. Also, its Pd content was determined by Inductively Coupled Plasma (ICP) analyzer. The immobilized palladium complex was used as an efficient catalyst for copper- and phosphine ligand-free Sonogashira reaction of aryl halides with phenylacetylene. This catalyst shows notable advantages such as simplicity of operation, excellent yields, short reaction times, heterogeneous nature, easy magnetically work up and recyclability.

A polystyrene-supported triazine palladium complex was prepared and characterized. The catalyst exhibits excellent catalytic activity and stability for the Sonogashira coupling reaction under ambient conditions. Various aryl halides were coupled with a number of terminal alkynes under air in the presence of 0.1 mol% of the catalyst to afford the corresponding coupled products in high yields. Furthermore, the heterogeneous catalyst can be readily recovered by simple filtration and reused for several times without a significant loss in its activity.

Palladium (0) nanoparticles with small size and narrow size distribution were synthesized conveniently and supported on CNTs. The supported nano-Pd 0 was found to be a highly efficient and recyclable catalyst for the aminocarboranylation reaction of aryl halide. Thus, a series of carboranyl amides, 1-R-2-[CH 2 NHC(=O)Ar]-1,2-C 2 B 10 H 10 (R = H, Me; Ar = C 6 H 5 , 4-Me-C 6 H 5 , 4-MeO-C 6 H 5 and 2-C 5 NH 4 ), were synthesized and fully characterized. The catalyst was recyclable at least three times with sustained activity.

The use of an imidazolium-based phosphinite ionic liquid (IL-OPPh2) as both solvent and ligand for Pd offers an efficient catalytic system for silylation of aryl iodides, bromides and also chlorides by triethylsilane in the presence of Cs2CO3. In the absence of base, this system is also performed for catalytic dehalogenation of aryl halides. The ionic liquid containing its corresponding Pd(0) complex can be easily recovered and reused in several runs without losing its efficiency.

{Cis-1,3-bis[(di-tert-butylphosphino)methyl]cyclohexyl}palladium(II)trif luoroacetate (1) acts as a precatalyst for the Suzuki reaction of aryl halides with phenylboronic acid in the absence or presence of mercury to give the product in modest to reasonably good yields. The reaction was monitored by P-31- and H-1 NMR spectroscopy in a stepwise fashion, concluding that complex 1 reacts with activated boronic acids in the first reaction step to yield the corresponding phenyl complex 2. Complex 2 thereafter generates the Suzuki cross-coupling product upon addition of aryl halide. This shows that (PCP)Pd complexes, in addition to the previously demonstrated Pd(0)/Pd(II) mechanism, can mediate cross-coupling reactions using molecular species in a non-zero oxidation state. (C) 2009 Elsevier B.V. All rights reserved. (Less)

The use of an imidazolium-based phosphinite ionic liquid (IL-OPPh 2 ) as ligand for Pd offers an efficient reagent system for the selective dehalogenation or homocoupling of aryl halides in the presence of NaOPr i or Et 3 N, respectively. This ionic liquid plays a dual role as both the reaction media and also as the potential complexing agent with Pd via its phosphinite carrying group. The ionic liquid containing its corresponding Pd complex can be easily recovered and reused in several runs.

The Heck reaction of aryl halides with functionalised alk-1-enes should be a powerful method for the synthesis of functionalised (E)-1-arylalk-1-ene derivatives. The major problem of this reaction is the palladium-catalysed migration of the carbon–carbon double bond along the alkyl chain when there are no substituents on the C3 carbon of the alk-1-enes. We observed that for the arylation of ethyl pent-4-enoate, ethyl 2-methylpent-4-enoate or dimethyl allylmalonate this migration could be partially or completely controlled using appropriate reaction conditions. The ramification on the alkyl chain and the substituents on the aryl halide have also an important influence on this migration. Moreover, the cis,cis,cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane/1/2[PdCl(C3H5)]2 system catalyses this reaction with a wide range of aryl bromides using very high ratio substrate/catalyst in good yields.

Extremely efficient and high-speed ethynylation of acyl chlorides, aryl iodides and bromides was demonstrated by palladium-catalyzed cross-coupling reaction of N-t-butyl-Sb-ethynyl-5,6,7,12-tetrahydrodibenz[c,f][1,5]azastibocine under mild conditions. Optimization and generalization of the hypervalent antimony-mediated coupling reaction are presented in detail. Single-crystal X-ray analysis of the N-methyl-1,5-azastibocine revealed that the remarkable reactivity enhancement of the azastibocine was derived from elongation of the antimony–ethynyl carbon bond originated from Sb–N intramolecular non-bonding interaction.

An investigation of the kinetics of the Heck reaction between 4-iodoanisole and styrene catalysed by {cis-1,3-bis[(di-tert-butylphosphino)methyl]-cyclohexane} palladium (11) iodide (1) has been performed in DMF-d(7) solution. Based on mercury poisoning experiments a heterogeneous palladium catalyst formed from the PCsp3P Pd(II) pre-catalyst is proposed. Saturation behaviour with respect to the olefin concentration suggests a mechanism consisting of a pre-equilibrium association of the olefin followed by a rate determining reaction with aryl halide. The equilibrium constant for the olefin association, K-1, and the rate constant for the subsequent oxidative addition step, k(2), were determined to (5.7 +/- 2.5) x 10(-3) and 18.4 +/- 2.7 M-1 s(-1), respectively. (c) 2005 Elsevier B.V. All rights reserved.

The reaction of ethynylstibanes (1a–g) with vinyl halides or triflate in the presence of a palladium catalyst led to the formation of cross-coupling products (5a–g, 10–12) in good to moderate yield, along with homo-coupling products (6a–g). A similar reaction of ethynyldiphenylstibane (1a) with aryl iodides (13a–i) also gave cross-coupling products (14a–i), although the yields were relatively low. The yields of the cross-coupling products were highly dependent on the nature of the solvent employed, and good results were obtained when the reaction was carried out in HMPA or amines such as diethylamine and morpholine. The results imply that HMPA and amine used as solvents facilitate transmetallation of the ethynyl group on 1 to the palladium by intermolecular coordination between antimony and oxygen (for HMPA) or nitrogen (for amine).

This mini-review traces the initial ideas, discoveries and significant features of the cross-coupling reaction between Grignard reagents and C(sp2)-halides such as aryl and alkenyl halides in the presence of a nickel–phosphine complex as a catalyst, which was first reported by Kohei Tamao, Koji Sumitani, and Makoto Kumada in 1972.

The copper-catalyzed Meerwein reaction of activated olefins with arenediazonium halides leads to a formal addition of aryl halide to the olefinic double bond. Methyl acrylate, p -tolyldiazonium tetrafluoroborate and tetrabutylammonium chloride in anhydrous acetonitrile were used as a model system, the product being methyl α -chloro- β -tolylpropionate. Applying a newly established methodology, the isolated diazonium tetrafluoroborate and an equivalent amount of tetrabutylammonium chloride were added to the olefin and the copper catalyst, containing optically active ligands, such as 2- and 2,6-pyridinyloxazolines and bisoxazolines. The low optical inductions obtained in the room temperature reaction could be raised to 8.7% ee in the low temperature variant at −40°C. Two phenyl substituents in the neighborhood of the chiral centers in the bisoxazoline ligands of the catalyst and increasing steric bulk in the ester group of the substrate (methyl, ethyl, menthyl) increase the stereoselectivity of the Meerwein arylation. Replacement of the p -tolyldiazonium salt by the mesityldiazonium salt caused the optical induction in the formation of the corresponding mesityl product rise to 19.5% ee . Thus, though considered to be a radical reaction, the Meerwein arylation of activated olefins can be rendered enantioselective by using copper catalysts with optically active ligands.

The reactions of p -diiodobenzene with [( η 5 -C 5 H 5 )Fe(CO) 2 ] − and [( η 5 -C 5 H 5 W(CO) 3 ] − were studied using a complex of electrochemical techniques (cyclic voltammetry, rotating ring-disk electrode and preparative scale electrolysis). For [( η 5 -C 5 H 5 )Fe(CO) 2 ] − it was shown that aromatic nucleophilic substitution of either one or two iodine atoms in p -diiodobenzene for η 5 -cyclopentadienylirondicarbonyl can be performed through electrochemical activation of the aryl halide. The ratio of ( η 5 -C 5 H 5 )Fe(CO) 2 C 6 H 4 I and ( η 5 -C 5 H 5 )Fe(CO) 2 C 6 H 4 Fe(CO) 2 ( η 5 -C 5 H 5 ) was shown to depend strongly on the electrolysis conditions: electrode potential electrolysis duration, etc. The yield of ( η 5 -C 5 H 5 )Fe(CO) 2 C 6 H 4 Fe(CO) 2 ( η 5 -C 5 H 5 ) can be considerably increased when ( η 5 -C 5 H 5 )Fe(CO) 2 C 6 H 4 I is taken as a starting compound. For [( η 5 -C 5 H 5 )W(CO) 3 I − the main product of the reaction with p -diiodobenzene is ( η 5 -C 5 H 5 )W(CO) 3 I.

A metal free stannyl anion generated from Me 3 SiSnBu 3 and R 4NX in DMF reacted with an aryl halide bearing carbonyl group to produce an aryl anion via the so-called halogen-metal exchange process, which reacted with a carbonyl group to afford a cyclized product in good yield.

The CoCl(PPh 3 ) 3 , RhCl(PPh 3 ) 3 , and IrClCO(PPh 3 ) 2 catalysed vinylation of aryl iodides proceeds to give cinnamates and stilbene in high yields.

Oxidative addition of aryl halides, ArX, to chlorocarbonylbis(triphenylphos-phine)iridium(I) yields iridium(III) aryl complexes, IrCl(X)(Ar)(CO)(PPh3)2. The reactivity of the aryl halide decreases in the order I > Br > C1, and electron-withdrawing substituents in the aryl ring accelerate the reaction. The IrIII compounds may be utilised as arylating agents.

The thermal decomposition of arylmethylbis(triethylphosphine)nickel(II), ArNiMeL 2 , is studied in hydrocarbon solutions, both in the presence and absence of aryl halide. The direct thermolysis affords methylarenes without aryl scrambling, by first-order kinetics. The inverse phosphine dependence of the rate is related to a dissociative mechanism proceeding via reductive elimination directly from the coordinatively unsaturated ArNiMeL intermediate. In contrast, the reductive elimination of methylarene induced by aryl halide is a radical chain process in which there is extensive scrambling of aryl groups, consistent with paramagnetic nickel(I) and nickel(III) species, and not aryl radicals, as reactive intermediates. The induced reductive elimination is a significantly more facile process than direct thermolysis. However, the relative contributions from these pathways in the reductive elimination of ArNiMeL 2 can be deliberately manipulated by additives (inhibitors and promoters) which control the induction period relating the generation of nickel(I, III) intermediates required for chain initiation. The radical chain mechanism for the formation of carboncarbon bonds by reductive elimination in this system is essentially the same as that previously deduced for aryl coupling to biaryls from arylhalonickel(II) and aryl halides.

Reactions of aryl halide vapor and calcium metal vapor were found to give the corresponding arylcalcium halides, ArCaX (X = F, Cl, and Br). Phenylcalcium halides, PhCaX (X = F and Cl), reacted with trimethylchlorosilane to give phenyltrimethylsilane. The reactions of phenylcalcium halides with acetone and benzaldehyde readily gave good yields of 1-methyl-1-phenylethanol and diphenylmethanol, respectively. Phenylcalcium halides reacted slowly with acetonitrile to afford acetophenone in poor yields. With ethyl acetate, phenylcalcium halides gave a mixture of 1,1-di-phenylethanol and acetophenone.