Highly Efficient Palladacycle/Dihydroimidazolium Chloride System for the Suzuki‐Miyaura Cross‐Coupling of Aryl Halides (I,Br, Cl) with Arylboronic Acids

A combination of a tertiary amine‐based palladacycle and an N‐heterocyclic carbene ligand precursor ( 1 , N,N‐bis‐mesityl‐4,5‐dihydroimidazolium chloride) has been applied to catalyze the Suzuki‐Miyaura cross‐coupling of aryl halides with arylboronic acids. The substrate scope is general: a variety of electron rich and deficient aryl halides (I, Br, Cl) and arylboronic acids were found to undergo the cross‐coupling reaction in good to excellent yields at low catalyst loading of 0.01–1 mol%.     

Palladium‐Catalyzed Suzuki‐Miyaura Type Coupling Reaction of Aryl Halides with Triphenylborane‐Pyridine

The Suzuki‐Miyaura type coupling reaction of aryl halides with triphenylborane‐pyridine was described. The reaction can be catalyzed by Pd(OAc)₂ (5 mol%) in presence of Cs₂CO₃ at 50°C or 80°C, and functionalized biaryls were obtained in good to excellent yields. This protocol is general and can tolerate a wide range of functional groups.     

在催化体系可回收和无配体条件下溴化四丁基铵中钯催化卤代芳烃与芳基硼酸的Suzuki-Miyaura交叉偶联反应

我们发展一种在催化体系可回收和无配体条件下溴化四丁基铵（TBAB）中钯催化卤代芳烃与芳基硼酸的Suzuki-Miyaura交叉偶联反应方法。我们发现水的量对反应有很大的影响。当水的用量为1 %（质量比）时,反应的结果最好。在3 mol%的醋酸钯和1.5 g的TBAB（含1%的水）,一系列卤代芳烃与芳基硼酸的顺利地发生Suzuki-Miyaura交叉偶联反应,得到中等及良好的产率。而且在溴代芳烃和活泼的氯代芳烃的交叉反应中,Pd(OAc)2/TBAB催化体系可以回收重复使用多次,并且催化活性基本不变。     

Highly efficient amine‐based catalytic system for room temperature Suzuki–Miyaura reactions of aryl halides with arylboronic acids

An in situ‐generated catalytic system based on PdCl₂ and primary amine‐based ligand exhibited excellent activity (up to 98% isolated yield) in the Suzuki–Miyaura cross‐coupling reactions of aryl bromides with arylboronic acids in water, at room temperature, without any additive. The efficiencies of the ligands follow the order: (C₆H₅)₃CNH₂ > C₆H₅CH₂ NH₂ > C₆H₅ NH₂ > C₆H₁₁ NH₂, which is in accordance with the palladacycle forming capacity of the respective ligands. Moderate‐to‐good yields (up to 78% isolated yield) of the coupling products were also obtained with less reactive aryl chlorides as substrates at room temperature in isopropanol using an alternative protocol based on Pd(OAc)₂ and (C₆H₅)₃CNH₂. Copyright © 2011 John Wiley & Sons, Ltd.     

氯化钯在氟化四丁基铵中当场生成纳米钯：一种高效、可回收的催化体系，在无配体和无溶剂条件下催化Suzuki-Miyaura反应

氯化钯在氟化四丁基铵中当场生成纳米钯,该钯催化剂在Suzuki-Miyaura交叉偶联反应中显示很高的催化效率。在氯化钯和氟化四丁基铵存在下,许多芳基卤代烃可以顺利与芳基硼酸发生偶联反应,得到中等到高的产率。此外,在Suzuki-Miyaura偶联反应中该氯化钯/氟化四丁基铵催化体系可以回收重复使用多次,并且芳基溴代烃可以在15-60分钟内反应完全。值得指出的是,该反应是在无溶剂、无配体和催化体系可回收重复使用的条件下进行的。这和无配体条件下TBAB中钯催化卤代芳烃与芳基硼酸的Suzuki-Miyaura交叉偶联反应方法。该氯化钯/氟化四丁基铵催化反应的反应机理也进行了讨论。     

Bis‐benzimidazolium‐palladium system catalyzed Suzuki‐Miyaura coupling reaction of aryl bromides under mild conditions

Bis‐benzimidazolium salts were prepared successfully from commercially available and inexpensive o‐phenylenediamine through a series of simple reactions. The bis‐NHC‐Pd complexes prepared in situ can catalyze Suzuki‐Miyaura cross‐coupling reaction under very mild conditions in aqueous media with excellent yields. The efficiency of this reaction is demonstrated by its compatibility with a range of functional groups. Di‐ortho‐substituted biaryls could be accomplished in 89–99% yields. Moreover, the rigorous exclusion of air or moisture is not required in these transformations.     

Palladium‐catalysed room‐temperature Suzuki–Miyaura coupling in water extract of pomegranate ash,a bio‐derived sustainable and renewable medium

An agro waste‐derived, ‘water extract of pomegranate ash’ (WEPA), has been utilized for the first time as a renewable medium for Pd(OAc)₂‐catalysed Suzuki–Miyaura cross‐coupling at room temperature. This method offers a simple and sustainable synthesis of biaryls from aryl halides and arylboronic acids under ligand‐ and external base‐free aerobic and ambient conditions. This method has been found effective for both activated and unactivated aryl halides in the production of biaryls with moderate to nearly quantitative yields. The protocol shows high chemoselectivity over identical/similar reactive sites in aryl halides (i.e. selectivity over identical halogens or different halogens of aryl halides). This method exhibits high regioselectivity, i.e. the selective reactivity of a halogen over other identical halogens at different positions on the aromatic nucleus. Therefore, we disclose here a clean, benign, substantial chemo‐ and regioselective and highly economic alternative method for the palladium‐assisted synthesis of biaryls using an agro waste‐derived medium.     

Diamine bis(phenolate) and pendant amine bis(phenolate) ligands: catalytic activity for the room temperature palladium‐catalyzed Suzuki–Miyaura coupling reaction

A series of amine bis(phenolate) ligands bearing aryl substituents of varying steric bulk are reported and characterized using single‐crystal X‐ray diffraction, NMR spectroscopy and high‐resolution mass spectrometry experiments. Palladium complexes derived in situ from these ligands are evaluated as catalysts for the Suzuki–Miyaura coupling of phenylboronic acid and aryl bromides. High conversions are observed for these reactions in methanol solvent at low catalyst loadings (0.01 mol%), short reaction times (30 min) and mild temperatures (30°C). Conversion is observed for a range of substrates, and is found to depend on the nature of the external base and solvent employed. These findings demonstrate the utility of catalysts derived from late transition metal complexes of amine bis(phenolate) ligands, particularly those bearing bulky cumyl substituents. Copyright © 2015 John Wiley & Sons, Ltd.     

Palladium Nanoparticles Supported on a Porous Organic Polymer: An Efficient Catalyst for Suzuki‐Miyaura and Sonogashira Coupling Reactions

A new porous organic polymer (POP) with high thermal stability and large surface area has been synthesized and applied in the preparation of Pd/POP catalyst. Pd/POP was characterized by XRD, TGA, SEM and TEM. The catalyst consists of highly dispersed palladium nanoparticles of 0.9–4 nm size on POP with a large surface area of 650 m²/g. It presents high catalytic activity for Suzuki‐Miyaura and Sonogashira reactions. The catalyst was reusable for three to five times without significant loss of activity.     

A Triptycene‐Based Microporous Organic Polymer Bearing Tridentate Ligands and Its Application in Suzuki–Miyaura Cross‐Coupling Reaction

A triptycene‐based microporous organic polymer (MOP) in which 2,6‐bis(benzimidazol‐2‐yl)pyridine (bbp) is incorporated as linkage and coordination site is designed and synthesized. Pd(II) ions are further immobilized in this MOP through the coordination interactions between Pd(II) ion and nitrogen atoms of bbp. The resulting material shows high stability and exhibits excellent heterogeneously catalytic activity for the Suzuki–Miyaura cross‐coupling reaction. Its high efficiency can be maintained after being reused for a number of cycles.

     

Synthesize,Characterization and Application of Phosphine‐free Polymer Supported Palladium Nanoparticles as Effective Catalyst in Suzuki‐Miyaura Cross‐coupling Reactions

Heterogeneous catalysts were developed by supporting palladium nanoparticles on modified cross‐linked polyacrylamide and successfully applied in Suzuki‐Miyaura cross‐coupling reactions. These catalysts are stable to air and moisture, and no sign of metal leaching was detected during the reactions as judged by elemental analysis of palladium by ICP‐OES technique and hot filtration test, which demonstrates the heterogeneous character of the catalysts. High yields of desired products were resulted by using these phosphine‐free catalysts at temperatures below 80 °C without aid of any additional ligands. The heat stability of the catalysts at the operating temperature was confirmed by thermogravimetric analysis (TGA). These catalysts are easy to use and cost effective. They can be recovered from reaction mixture by a simple filtration and reused in more successive reactions without significant loss in activity. The catalyst activity was restored by an ultrasonication program after deactivation in 10 cycles.     

Devising Boron Reagents for Orthogonal Functionalization through Suzuki–Miyaura Cross‐Coupling

Seeing the sites : The Suzuki–Miyaura reaction of substrates containing multiple coupling sites has been performed in a directed manner through the reactivity modulation of the boron moiety (see scheme). Several other strategies are also discussed.

     

Supramolecular photocatalyst of Palladium (II) Encapsulated within Dendrimer on TiO2 nanoparticles for Photo‐induced Suzuki‐Miyaura and Sonogashira Cross‐Coupling reactions

In this study, synthesis, characterization and catalytic performance of a novel supramolecular photocatalytic system including palladium (II) encapsulated within amine‐terminated poly (triazine‐triamine) dendrimer modified TiO₂ nanoparticles (Pd (II) [PTATAD] @ TiO₂) is presented. The obtained nanodendritic catalyst was characterized by FT‐IR, ICP‐AES, XPS, EDS, TEM, TGA and UV‐DRS. The as‐prepared nanodendritic catalyst was shown to be highly active, selective, and recyclable for the Suzuki–Miyaura and Sonogashira cross‐coupling of a wide range of aryl halides including electron‐rich and electron‐poor and even aryl chlorides, affording the corresponding biaryl compounds in good to excellent yields under visible light irradiation. This study shows that visible light irradiation can drive the cross‐coupling reactions on the Pd (II) [PTATAD] @ TiO₂ under mild reaction conditions (27–30 °C) and no additional additives such as cocatalysts or phosphine ligands. So, we propose that the improved photoactivity predominantly benefits from the synergistic effects of Pd (II) amine‐terminated poly (triazine‐triamine) dendrimer on TiO₂ nanoparticles that cause efficient separation and photogenerated electron–hole pairs and photoredox capability of nanocatalyst which all of these advantages due to the tuning of band gap of catalyst in the visible light region.     

Nanostructured Pyrophosphate Na2PdP2O7‐Catalyzed Suzuki‐Miyaura Cross‐Coupling Under Microwave Irradiation

Nanostructured palladium pyrophosphate (Na₂PdP₂O₇) catalyst was synthesized and well characterized by using different techniques (TGA, XRD, SEM, TEM....). This nanocatalyst exhibited excellent catalytic activity in the synthesis of biaryl compounds via Suzuki‐Miyaura cross‐coupling to produce their corresponding products in good to excellent yields under mild conditions. The catalyst is recyclable and was recycled for four runs for the reaction of 4‐bromoacetophenone with phenylboronic acid without appreciable loss of its catalytic activity.     

Suzuki–Miyaura coupling reactions of aryl chlorides catalyzed by a new nickel(II) σ‐aryl complex

A new nickel(II) σ‐aryl complex, trans‐chloro(9‐phenanthrenyl)bis(triphenylphosphine)nickel(II), was used as a precatalyst for the Suzuki–Miyaura coupling reactions of aryl chlorides. The catalytic conditions were optimized by investigating the cross‐coupling of p‐chloroanisole with phenylboronic acid. The results show that this complex is efficient for both electron‐rich and electron‐deficient aryl chlorides, though it gives better yields for activated arylboronic acids than deactivated ones. All isolated cross‐coupled biaryl products have been characterized by ¹H and ¹³C NMR, and their spectral data are consistent with those reported. Side products from the coupling of arylboronic acid with the precatalyst complex have also been isolated and characterized, which is helpful for understanding the coupling mechanism. Copyright © 2013 John Wiley & Sons, Ltd.     

Magnetite tethered mesoionic carbene‐palladium (II): An efficient and reusable nanomagnetic catalyst for Suzuki‐Miyaura and Mizoroki‐Heck cross‐coupling reactions in aqueous medium

In this paper, a highly active, air‐ and moisture‐stable and easily recoverable magnetic nanoparticles tethered mesoionic carbene palladium (II) complex (MNPs‐MIC‐Pd) as nanomagnetic catalyst was successfully synthesized by a simplistic multistep synthesis under aerobic conditions using commercially available inexpensive chemicals for the first time. The synthesized MNPs‐MIC‐Pd nanomagnetic catalyst was in‐depth characterized by numerous physicochemical techniques such as FT‐IR, ICP‐AES, FESEM, EDS, TEM, p‐XRD, XPS, TGA and BET surface area analysis. The prepared MNPs‐MIC‐Pd nanomagnetic catalyst was used to catalyze the Suzuki–Miyaura and Mizoroki–Heck cross‐coupling reactions and exhibited excellent catalytic activity for various substrates under mild reaction conditions. Moreover, MNPs‐MIC‐Pd nanomagnetic catalyst could be easily and rapidly recovered by applying an external magnet. The recovered MNPs‐MIC‐Pd nanomagnetic catalyst exhibited very good catalytic activity up to ten times in Suzuki–Miyaura and five times in Mizoroki–Heck cross‐coupling reactions without considerable loss of its catalytic activity. However, MNPs‐MIC‐Pd nanomagnetic catalyst shows notable advantages such as heterogeneous nature, efficient catalytic activity, mild reaction conditions, easy magnetic work up and recyclability.     

Organotrifluoroborates and Monocoordinated Palladium Complexes as Catalysts—A Perfect Combination for Suzuki–Miyaura Coupling

Monocoordinated palladium catalysts derived from sterically hindered, electron‐rich phosphines or N‐heterocyclic carbenes have revolutionized the Suzuki–Miyaura coupling reaction. The emergence of organotrifluoroborates has provided important new perspectives for the organoboron component of these reactions. In combination, these two components prove to be extraordinarily powerful partners for cross‐coupling reactions.     

Nanosilica‐anchored Pd(II)‐Schiff base complex as efficient heterogeneous catalyst for activation of aryl halides in Suzuki–Miyaura cross‐coupling reaction in water

A nanosilica (derived from rice husk)‐anchored Pd(II)–Schiff base complex has been synthesized and characterized. This immobilized complex has been found to be a very effective and recyclable heterogeneous catalyst for the Suzuki–Miyaura cross‐coupling reaction of various aryl halides with arylboronic acid in aqueous medium under mild conditions. The products were identified using ¹H NMR and mass spectral studies. This complex can be easily filtered out from the reaction medium and reused up to six times without significant loss of catalytic activity. Since the reaction proceeds under mild conditions in aqueous medium as well as the catalyst being recyclable, it provides an environmentally benign alternative route to the existing protocols for the Suzuki–Miyaura reaction.