Phosphine-free Conditions Research Articles

Anionic amido/carbocyclic carbene ligated palladium (II) complex for room temperature Suzuki reaction

The synthesis of anionic amido/carbocyclic carbene ligated Pd (II) complex has been reported. The palladium complex is an active catalyst for the cross-coupling reaction between aryl bromides and phenylboronic acids under phosphine-free conditions at room temperature.

Palladium complexes containing multidentate phenoxy–pyridyl–amidate ligands: Highly efficient catalyst for Heck coupling of deactivated aryl halides

N,N′,N″,O-Tetrafunctional Pd(II) complexes prepared from the easily available amino acids are shown to be highly efficient catalysts for the Heck reaction of deactivated aryl bromides and iodides with high turnover numbers up to ca.104 and moderate activity for the activation of aryl chlorides under phosphine-free conditions.

Phosphine-free polystyrene-supported palladium(II) complex as an efficient catalyst for the Heck and Suzuki coupling reactions in water

Abstract A palladium complex, 1-phenyl-1,2-propanedione-2-oxime thiosemi-carbazone-functionalized polystyrene resin supported Pd(II), is found to be a highly active catalyst for the Heck reaction of methyl acrylate with aryl halides and Suzuki reaction of phenylboronic acid with aryl iodides and bromides, giving excellent yields. The reactions were performed under phosphine-free conditions in an air atmosphere. The palladium catalyst is easily separated, and can be reused for several times without a significant loss in its catalytic activity.

Nickel and palladium nanocomposite carbon aerogels as recyclable catalysts for Suzuki–Miyaura reaction under aerobic and phosphine-free conditions in water

Recyclable and readily prepared Ni and Pd nanocomposite carbon aerogels have been successfully used in the Suzuki–Miyaura reaction in water medium and aerobic conditions. In these ligand-free and environmentally-friendly conditions the Ni–carbon aerogel shows better recyclability than the corresponding palladium material. No appreciable leaching of Nickel could be detected after six reaction cycles. Interestingly enough, we have demonstrated for the first time that metal embedded carbon aerogels can be also used in water medium.

ChemInform Abstract: Ruthenium and Rhodium‐Catalyzed Carbonylation Reactions

AbstractReview: about 100 refs.

ChemInform Abstract: Enantioselective α‐Arylation of Cyclic Ketones Catalyzed by a Combination of an Unmodified Cinchona Alkaloid and a Palladium Complex.

A palladium/Cinchona alkaloid-catalyzed α-arylation between cyclic ketones and aryl halides under phosphine-free conditions is presented. The use of a simple, unmodified Cinchona alkaloid results in high levels of activity and selectivity with up to 93% ee. These enantioinduction levels are comparable or even higher than the ones reported using palladium/BINAP complexes. To the best of our knowledge, this represents the first use of unmodified Cinchona alkaloids as ligands/catalysts in asymmetric transition metal complex-catalyzed cross-coupling reactions.

Palladium catalyzed the Suzuki cross-coupling reaction using a fluorous NHC ligand

The utilization of N-heterocyclic carbene palladium complex immobilized on fluorous silica gel through fluorous–fluorous interactions in the Suzuki cross-coupling reaction was described. The reactions were carried out under aerobic and phosphine-free conditions with moderate to excellent product yields. The catalyst was easily recovered and reused three times without significant loss of activity.

Perfluoro-tagged nano-palladium catalyst immobilized on fluorous silica gel: Application in the Suzuki–Miyaura reaction

The Suzuki–Miyaura reaction has been performed using a phosphine-free perfluoro-tagged palladium catalyst that is readily immobilized on fluorous silica gel through fluorous–fluorous interactions (Pd-1/FSG). The reactions are carried out under aerobic and phosphine-free conditions with excellent to quantitative product yields, and very low palladium content (< 0.8 ppm) in the products was detected by ICP-AES. The catalyst can be recovered by simple filtration and reused several times without significant loss of activity.

Ruthenium and Rhodium‐Catalyzed Carbonylation Reactions

AbstractOver the last few decades, carbonylation reactions have been accepted as important chemical transformations for both academic and industrial research. Carboxylic acid derivatives are the main product of carbonylation and are widely used in organic synthesis and fine chemicals preparation. Carbonylation reactions can increase the carbon chain of parent molecules, while introducing a carbonyl group. Herein, the main developments on ruthenium‐ and rhodium‐catalyzed carbonylation are summarized. Compared with palladium catalysts, ruthenium and rhodium catalyzed reactions are a powerful method for activating CH bonds under mild and phosphine free conditions.

Novel saccharinate-bridged palladium complexes for efficient C–O bond activation displaying promising luminescence properties

The synthesis of mono- and dinuclear cyclometallated palladium(II) complexes with deprotonated saccharinate ligands displaying different coordination modes is described. The new compounds were prepared by direct reaction between saccharine and the corresponding hydroxo-complexes [{Pd(μ-OH)(C^N)}(2)] (C^N = 2-(2-pyridyl)phenyl (Phpy) I; = 7,8-benzoquinolyl (Bzq) II), showing a general formula [{Pd(μ-sac)(C^N)}(2)] with saccharinate 1 displaying a bridging -NCO-coordination mode. Bridge splitting with neutral ligands (L = pyridine (py) 2, quinoline (quinol) 3 or acridine (acrid) 4) yielded new mononuclear derivatives with saccharinate acting as an N-monodentated ligand. Structural characterization by X-ray diffraction of complexes I1, I2 and II2 confirmed the proposed formulae. All complexes emit in the solution and solid state at room temperature. Emission features between 640-680 nm in the solid state for complexes I1 and II1 are significantly red-shifted if compared to the emission in solution. These broad emissions are consistent with the simultaneous presence of (3)ππ* and (3)MMLCT transitions indicating the existence of a strong intramolecular Pd-Pd ground state interaction. The dimeric complexes have also shown to catalyze Suzuki-Miyaura cross-coupling of coumaryl tosylate and aryl boronic acids under phosphine-free conditions. Initial studies suggest the involvement of palladium nanoparticles, which has been further investigated using mercury-drop test and poisoning experiments.

Aqueous-Phase Heck Coupling of 5-Iodouridine and Alkenes under Phosphine-Free Conditions

Palladium-catalyzed Heck couplings between 5-iodouridine and alkenes were carried out in aqueous media in the presence of triethylamine under phosphine-free conditions to give the desired products in high yields. In the absence of phosphine ligand, triethyl­amine appears to play a critical role in both generating the active catalyst species and serving as the base in the reaction.

Metal–Polymer Hybrid Material as a Catalyst for the Heck Coupling Reaction Under Phosphine-Free Conditions

A method is described for making a poly-aminophenol-based hybrid material by in situ polymerization of aminophenol using palladium acetate as the oxidant. The oxidative polymerization of aminophenol leads to the formation of poly-aminophenol, while the reduction of palladium acetate results in the formation of palladium nanoparticles. The palladium nanoparticles were found to be highly dispersed and stabilized throughout the polymer matrix. The hybrid nanocomposite material showed excellent catalytic efficiency with respect to a Heck coupling reaction at a relatively low temperature and under flexible conditions.

Recyclable nickel catalysed Suzuki–Miyaura reaction in the presence of polyethyleneimine under phosphine-free conditions in ethylene glycol#

In this report, Suzuki–Miyaura coupling reaction was performed in the presence of polyethyleneimine (PEI) as ligand, NiCl2·6H2O and K2CO3 in ethylene glycol at 80–100°C under phosphine-free conditions. By this method, structurally different aryl bromides and iodides were reacted with phenylboronic acid and potassium phenyltrifluoroborate. Under these simple reaction conditions a different biaryl derivatives have been prepared in high to excellent yields. Recycling experiments showed that catalyst can be used as recyclable catalyst in the Suzuki–Miyaura cross-coupling reactions.

Polystyrene-Anchored Palladium(II) Schiff Base Complex: A Reusable Catalyst for Phosphine-Free and Copper-Free Sonogashira Cross-Coupling Reaction in Aqueous Medium

A novel polystyrene-supported palladium(II) complex, an excellent and recyclable catalyst, was synthesized for Sonogashira reactions. The present complex shows high catalytic activity for Sonogashira cross-coupling reaction of aryl halides with phenylacetylene under phosphine-free and copper-free reaction conditions in aqueous (DMF–H2O) medium. The catalyst could be reused for at least six reaction cycles with almost unchanged catalytic properties.

ChemInform Abstract: Uridate/Pyridyl Pd(II) Complexes: Phosphine‐Free High Turnover Catalysts for the Heck Reaction of Deactivated Aryl Bromides.

Abstract The synthesis and structure of palladium(II) complexes bearing uridato/pyridyl ligands as an anionic N-donor coordination sites are reported. The complexes have been shown to be highly active catalysts for the Heck reaction of aryl bromides (TON 4.0×104–9.1×104) and moderate activity for the activation of aryl chlorides under phosphine-free conditions.

Intermolecular phosphine-free Heck reactions: Amino alcohols as effective ligands

Intermolecular phosphine-free Heck reactions occur in high yields, under basic conditions, using a catalytic mixture of Pd(OAc) 2 and a β-amino alcohol. It is assumed that the active catalytic species are N -liganded Pd 0 species. The recent mechanistic proposal, from Petrović et al., concerning Heck reactions catalyzed with PdCl 2 [NH(CH 2 CH 2 OH) 2 ] 2 is commented. ► Intermolecular Pd-catalyzed Heck reaction under phosphine-free conditions. ► Use of a mixture of Pd(OAc) 2 and a β-amino alcohol as an efficient catalyst. ► Mechanism of Heck reactions catalyzed with PdCl 2 [NH(CH 2 CH 2 OH) 2 ] 2 .

Bis(μ-iodo)bis((−)-sparteine)dicopper(I) catalyzed Sonogashira-type reaction under palladium and phosphine-free conditions

An efficient and inexpensive protocol for the Sonogashira-type cross coupling reactions of phenylacetylenes with a variety of haloarenes including activated aryl chlorides employing the structurally well-characterized bis(μ-iodo)bis((−)-sparteine)dicopper(I) catalyst is described.

Uridate/pyridyl Pd(II) complexes: Phosphine-free high turnover catalysts for the Heck reaction of deactivated aryl bromides

The synthesis and structure of palladium(II) complexes bearing uridato/pyridyl ligands as an anionic N-donor coordination sites are reported. The complexes have been shown to be highly active catalysts for the Heck reaction of aryl bromides (TON 4.0×10 4–9.1×10 4) and moderate activity for the activation of aryl chlorides under phosphine-free conditions.

In situ synthesis of a Pd–poly (1,8-diaminonaphthalene) nanocomposite: An efficient catalyst for Heck reactions under phosphine-free conditions

Polymerization of 1,8-diaminonaphthalene was performed using palladium acetate as an oxidizing agent. During the oxidative polymerization process the electrons liberated reduced the palladium (II) ions with the formation Pd nanoparticles, these colloidal particles being stabilized within the poly (1,8-diaminonaphthalene) matrix. Electron microscope images revealed that the palladium particles were well dispersed in the polymer matrix and had an average diameter of 2.5 nm. The metal–polymer composite material was initially tested for the coupling of iodobenzene with alkene (methyl acrylate) in the presence of a base. The yield of the substituted alkene derivative was found to be excellent. A series of iodo- and bromobenzene derivatives were tested for the coupling reaction with different alkenes. A coupled product was produced with high TOF values proving the efficiency of the composite material as an efficient catalyst for the Heck reaction under phosphine-free conditions. ► A metal–polymer composite material was synthesized using an ‘in situ polymerization and composite formation approach’ and used as a catalyst for the Heck reaction under phosphine-free conditions.

Copper- and phosphine-free Sonogashira coupling reactions of aryl iodides catalyzed by an N, N-bis(naphthylideneimino)diethylenetriamine-functionalized polystyrene resin supported Pd(II) complex under aerobic conditions

A polymer-supported palladium(II) N, N-bis(naphthylideneimino)diethylenetriamine complex is found to be a highly active catalyst for Sonogashira coupling reactions. The reactions are performed under copper- and phosphine-free conditions in an air atmosphere. The palladium catalyst is easily separated, and can be reused several times without significant loss in catalytic activity.