Heck Reaction Of Aryl Halides Research Articles

Rh-Catalyzed Intramolecular Hydroarylation of Unactivated Alkenes via C–C Bond Activation

The transition-metal-catalyzed intramolecular hydroarylation of alkenes has been recognized as a straightforward approach for the construction of 3,3-disubstituted 2,3-dihydrobenzofurans. The reactions mainly rely on the reductive Heck reaction of aryl halides or the direct C–H bond activation of arenes bearing a directing group. This work realizes the Rh-catalyzed intramolecular hydroarylation of olefin-tethered benzocyclobutenols via C–C bond activation, which offers an alternative approach to 3,3-disubstituted 2,3-dihydrobenzofurans bearing a 4-β-keto moiety. The methodology features 100% atom economy and pH- and redox-neutral conditions, and is applicable to the late-stage functionalization of complex molecules. The asymmetric variant has also been achieved with excellent enantioselectivities.

Facile synthesis of a new covalent organic nanosheet (CON-KEY1) based on polyamide links as an effective heterogeneous catalyst in C-C cross coupling reactions.

C-C coupling reactions represent a fundamental synthetic methodology widely employed in academic and industrial settings. Herein, we present a report on developing and synthesizing a heterogeneous catalyst that is environmentally compatible and has recycling capabilities. Furthermore, the utilization of this catalyst for C-C coupling reactions was explored. A novel amide-based CON was prepared via the reaction of a novel [2,2'-bipyridine]-5,5'-diamine (BDA) and 1,3,5-tris(4-carboxyphenyl) (TCB). TCB was activated with carbonyl diimidazole (CDI) and then reacted with BDA to synthesize favorable CON (i.e., CON-KEY1). Finally, the CON synthesized was reacted with palladium chloride ions, and the palladium-containing organocatalytic complex was decorated with the abbreviated Pd/CON-KEY1. This new heterogeneous complex was fully characterized through the required techniques, including FT-IR, EDX, XRD, TEM, SEM, ICP, TGA-DTA, N2 isotherms, and elemental mapping analysis. Computer simulation results include a multi-sheet 2D framework proposed by CON-KEY1. As a result, palladium ions were found to be arranged between the layers and on the CON surface. This heterogeneous complex functioned as a catalyst precursor in both the Suzuki-Miyaura coupling reaction of aryl boronic acids with aryl halides and the Heck reaction of aryl halides with acrylate derivatives or styrene. The desired coupling products with various functional groups were successfully attained with excellent yields of up to 98%. Simple set-up, improved yields, short reaction times, non-toxic solvents, catalyst durability, and high turnover frequency are among the distinct advantages of this synthetic method. Some other outstanding features of this catalytic system include convenient separation of catalysts and products, high yields, almost complete conversion, high selectivity, and good turnover frequency (TOF). The results show that the highest product efficiency in the reaction was achieved in the shortest possible time using Pd/CON-KEY1. Theoretical studies demonstrated the precedence of the palladium complexation with nitrogen atoms of CON-KEY1 rather than oxygen ones. Natural Bond Orbital (NBO) analysis affirmed that the system with Pd-N bonds (Eg = 0.089 eV) is more reactive with high electron conductivity compared to the Pd-O system (Eg = 0.120 eV).

Total Synthesis of Resvebassianol A, a Metabolite of Resveratrol by Beauveria bassiana.

Resveratrol is a well-known dietary polyphenol because it has a variety of beneficial biological activities. The fungus Beauveria bassiana is one of the most frequently used microorganisms for the biotransformation of polyphenols. Recently, resvebassianol A (2), a glycosylated metabolite of resveratrol by B. bassiana, was isolated and structurally elucidated. It was demonstrated to exhibit antioxidant, regenerative, and anti-inflammatory activities with no cytotoxicity. Here, we report the first total synthesis of resvebassianol A, 4′-O-β-(4‴-O-methylglucopyranosyl)resveratrol (2), and its regiomer, 3-O-β-(4‴-O-methylglucopyranosyl)resveratrol (3). Key reactions include (i) the construction of a stilbene core via a novel Heck reaction of aryl halides and styrenes, and (ii) glycosylation with unnatural methylglucopyranosyl bromide. The glycosylation step was carefully optimized by varying the bases and solvents. Resveratrol metabolites 2 and 3 were obtained at 7.5% and 6.3% of the overall yield, respectively.

Magnetically recoverable nanostructured Pd complex of dendrimeric type ligand on the MCM-41: Preparation, characterization and catalytic activity in the Heck reaction

Abstract A palladium complex of a dendrimer type ligand of aminoethylacrylamide immobilized onto the mesoporous channels of MCM-41 with magnetic core was prepared and characterized using various techniques such as XRD, TEM, BET, FT-IR, TGA, and VSM. The prepared nanostructured material was found as a magnetically recoverable catalyst for Heck reaction of aryl halides and vinylic C–H. The catalyst is easily recoverable with an external magnet and is reusable with different leaching amounts depending to loading of Pd. A hot filtration test was also performed and gave evidence that Palladium in heterogeneous samples can dissolve and then redeposit on the surface of the support material.

Asymmetric Intermolecular Heck Reaction of Aryl Halides by Pd-histidine Organocatalysts

Extensive studies of asymmetric intermolecular Heck reaction are described and provide a deeper insight into histidine-catalyzed. In particular, aspects of enantio- as well as diastereoselectivity of these reactions are discussed. As the first report, we synthesized five histidine-based organocatalyts including histidine as a well-defined and biodegradable natural structure alone and in combination with 2,4,6-trichloro-1,3,5-triazine, benzene-1,3-diamine, dimethyl malonate and dimeric structure applied in the asymmetric intermolecular Heck reaction of aryl halides; their efficiency was compared to each other’s. These phosphine-free palladium catalysts were found as efficient catalytic system which provided the superior efficiency with excellent yields, regioselectivity and enantioselectivity. In these among, histidine with 2,4,6-trichloro-1,3,5-triazine which generate the star like molecule palladium catalyst gave the best activity in asymmetric intermolecular Heck reaction with excellent yields and good regio- and enantioselectivity under mild reaction conditions. The asymmetric intermolecular Heck reaction has been limited to aryl and vinyl triflates or aryl iodide in the rare reports of available Pd catalysts. Herein, we extend the reaction to aryl bromides. In addition, the scope of reaction was examined in two different techniques: conventional heating and microwave irradiation and compared. For the first time, microwave irradiation sintering is successfully used for this reaction. Comparison of catalytic activities of our catalyst (Pd/His) with literature examples confirmed our success.

Palladium nanoparticles immobilized on EDTA-modified Fe3O4@SiO2: a highly stable and efficient magnetically recoverable catalyst for the Heck–Mizoroki coupling reactions

Palladium nanoparticles supported on EDTA-modified Fe3O4@SiO2 NPs as an efficient and magnetically reusable nanocatalyst was applied for the Heck cross-coupling reactions. The catalyst was very effective for the Heck reaction of aryl halides (iodides, bromides, and chlorides) with alkenes and conversion was excellent in most cases with higher TOF (turn over frequency). Moreover, the catalyst could be recycled for eight runs without any significant loss of catalytic activity, showing its superiority over homogeneous catalysts for industrial and chemical applications. Also, the leaching of the catalyst has been examined by a hot filtration test and ICP analysis.

Bioinspired Palladium Nanoparticles Supported on Soil-Derived Humic Acid Coated Iron-Oxide Nanoparticles as Catalyst for C–C Cross-Coupling and Reduction Reactions

Pd nanoparticles supported on humic acid-coated nanoferrites as magnetically-recoverable catalyst was expediently prepared from inexpensive precursors and characterized by techniques such as SEM, TEM, XPS, FT-IR, XRD, ICP-AES, EDX. The as made catalyst displayed an admirable catalytic activity towards the Suzuki–Miyaura cross-coupling reaction of aryl halides (or) aryl diazonium salts with aryl boronic acid in non-toxic solvent EtOH/water under mild conditions. The same catalyst showed high efficiency for the Heck reaction of aryl halides with styrene was carried out with high efficiency offering good yields under ligand-free conditions. Additionally, the reduction of olefins using molecular hydrogen was also achieved using the same catalyst under ambient and base-free conditions affording the products in good to excellent yields. The magnetic activity of nano-Fe3O4 allowed the effortless recovery of the catalyst and demonstrated subsequent recyclability up to 5 cycles without a significant loss in the activity.

A Palladium NNC‐Pincer Complex as an Efficient Catalyst Precursor for the Mizoroki−Heck Reaction

AbstractThe Mizoroki−Heck reaction of aryl halides (iodides, bromides, or chlorides) with activated alkenes in the presence of a palladium NNC‐pincer complex at ppb to ppm loadings gave the corresponding internal alkenes in excellent yields. The total turnover number and turnover frequency reached up to 8.70×108 and 1.21×107 h−1 (3.36×103 s−1), respectively. The catalyst was applied in a ten‐gram‐scale synthesis of the UV‐B sunscreen agent octinoxate (2‐ethylhexyl 4‐methoxycinnamate). Reaction‐rate analyses, transmission electron microscopic examination of the reaction mixture, and poisoning tests suggested that a monomeric palladium species is the catalytically active species in the catalytic cycle.magnified image

Synthesis and structural characterization of well-defined bis(oxamato)palladate(II) precatalysts for Suzuki and Heck reactions

Abstract A family of tetra-n-butylammonium salts of bis(oxamato)palladate(II) complexes of formula (n-Bu4N)2[Pd(Lm)2]·pH2O [m = 1–9; L1 = N-phenyloxamate (pma) and p = 2 (1), L2 = N-2-methylphenyloxamate (2-Mepma) and p = 4 (2), L3 = N-4-methylphenyloxamate (4-Mepma) and p = 2 (3), L4 = N-2,3-dimethylphenyloxamate (2,3-Me2pma) and p = 3 (4), L5 = N-2,4-dimethylphenyloxamate (Me2pma) and p = 4 (5), L6 = N-2,5-dimethylphenyloxamate (2,5-Me2pma) and p = 7 (6), L7 = N-3,4-dimethylphenyloxamate (3,4-Me2pma) and p = 6 (7), L8 = N-3,5-dimethylphenyloxamate (3,5-Me2pma) and p = 5 (8)] have been prepared and characterized by spectroscopic methods. The crystal structure of 1 that has been solved by single crystal X-ray diffraction shares main structural features with that reported for (n-Bu4N)2[Pd(L9)2]·2CH3CONH2 [L9 = N-2,4,6-dimethylphenyloxamate (2,4,6-Me3pma) and CH3CONH2 = acetamide] (see F.R. Fortea-Perez et al. (2016)). Each palladium atom in 1 is four-coordinate with two oxygen and two nitrogen atoms from two fully deprotonated pma ligands building a centrosymmetric square-planar surrounding, the Pd N/Pd O bond lengths being 2.020(3)/2.003(2) A. The bis(oxamato)palladate(II) units in 1 are well separated from each other by the bulky organic cations, the resulting value of the shortest metal–metal separation being 9.56 A. This series of very stable, phosphine-free, complexes with well-defined structures were shown to efficiently catalyze the Heck reaction of aryl halides with olefins in DMF at 80 °C in 3 h, most likely involving Pd(II)/Pd(IV) species in the vinylation reaction of aryl halides, as well as the Suzuki coupling of aryl halides with arylboronic acids in the same solvent under similar conditions. The reaction conditions for both Heck and Suzuki couplings were optimized by varying the amount of the catalyst, and their scope was systematically studied by using different olefins and aryl halides. The influence of the number and positions of the methyl substituents from the phenyloxamate ligand on the catalytic activity is analyzed and discussed in the light of the results obtained.

Easily fabricated and recyclable Pd&Cu@Al catalyst for gram-scale phosphine-free Heck reactions with high TON

A unique Pd&Cu@Al catalyst was easily fabricated just by immersing commercial aluminum foil in a mixed xylene solution of PdCl2 and CuCl2. The catalyst fabrication process led to aluminum oxide coatings in situ, which supported the metal nanoparticles and enhanced their catalytic activities for the phosphine-free Heck reaction of aryl halides and styrenes with high turnover number (TON) up to 3.9×105. The reaction can be scaled up to at least 100mmol and has been applied in modification of drug Lapatinib’s intermediate with low metal residue. This novel catalyst is of good application potential in industrial production because it was extremely easy to be recycled, in regardless of the generation of the insoluble impurities or tars during the reaction processes.

ChemInform Abstract: NiCl2·6H2O: An Efficient Catalyst Precursor for Phosphine‐Free Heck and Sonogashira Cross‐Coupling Reactions.

AbstractAn efficient and simple protocol for the Heck reaction of aryl halides using NiCl2·6H2O as the pre‐catalyst is presented.

Jianrong (Steve) Zhou

Angewandte Chemie International EditionVolume 55, Issue 15 p. 4636-4636 Author ProfileFree Access Jianrong (Steve) Zhou First published: 03 December 2015 https://doi.org/10.1002/anie.201510761AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract “The worst advice I have ever given was ‘it won't work’. If I were not a scientist, I would be a historian ...” This and more about Jianrong (Steve) Zhou can be found on page 4636. 1 Table 1. Jianrong (Steve) Zhou Date of birth: September 12, 1975 Position: Assistant Professor, Nanyang Technological University, Singapore E-mail: jrzhou@ntu.edu.sg Homepage: http://www.spms.ntu.edu.sg/cbc/FacultyResearch/Individual%20Faculty/SZhou.html Education: 1988 BSc, National University of Singapore 2000 MSc with Prof. Teck-Peng Loh, National University of Singapore 2005 PhD with Prof. Gregory Fu, Massachusetts Institute of Technology 2005–2008 Postdoc with Prof. John Hartwig, Yale University and University of Illinois at Urbana–Champaign Awards: 2013 GSK Green and Sustainable Manufacturing Award Research: Transition metal catalysis and asymmetric catalysis for fundamental bond-forming reactions Hobbies: Reading, movies, and travel The worst advice I have ever given was “it won't work”. If I were not a scientist, I would be a historian. My favorite films of all time are The Godfather I—III. The most significant scientific advance of the last 100 years was the invention of NMR spectroscopy and X-ray crystallography. The biggest problem that scientists face is the energy crisis. There has not been a sustainable solution to date. When I'm frustrated, I read a book and go to sleep. Tomorrow will be a new day. I chose chemistry as a career because I was lucky to have excellent chemistry teachers in high school and university. My not-so-secret passion is to find good food in Singapore, which can be difficult. The most exciting thing about my research is to discover new reactions. My biggest motivation is to see co-workers grow intellectually and solve problems independently. I can never resist to share my new ideas with co-workers. My 5 top papers: References 1“A General Palladium-Catalyzed Method for Alkylation of Heteroarenes Using Secondary and Tertiary Alkyl Halides”: X. Wu, J. W. T. See, K. Xu, H. Hirao, J. Roger, J.-C. Hierso, J. Zhou, Angew. Chem. Int. Ed. 2014, 53, 13573; Angew. Chem. 2014, 126, 13791. (A good method for the introduction of alkyl groups to many electron-deficient heteroarenes.) 2“Nickel-Catalyzed Asymmetric Transfer Hydrogenation of Olefins for the Synthesis of α- and β-Amino Acids”: P. Yang, H. Xu, J. Zhou, Angew. Chem. Int. Ed. 2014, 53, 12210; Angew. Chem. 2014, 126, 12406. (Use of nickel catalysts in transfer hydrogenation with formic acid.) 3“Asymmetric Intermolecular Heck Reaction of Aryl Halides”: C. Wu, J. Zhou, J. Am. Chem. Soc. 2014, 136, 650. (Simple hydrogen-bond donors promoted the ionization of neutral arylpalladium halides.) 4“Intermolecular Mizoroki–Heck Reaction of Aliphatic Olefins with High Selectivity for Substitution at the Internal Position”: L. Qin, X. Ren, Y. Lu, Y. Li, J. Zhou, Angew. Chem. Int. Ed. 2012, 51, 5915; Angew. Chem. 2012, 124, 6017. (Regioselective Heck reaction of common aliphatic olefins using a designed bisphosphine, dnpf, which is now commercially available.) 5“Arene C−H⋅⋅⋅O Hydrogen Bonding in Palladium-Catalyzed Arylation and Vinylation of Lactones”: Z. Huang, Z. Chen, L. H. Lim, G. C. Phan Quang, H. Hirao, J. Zhou, Angew. Chem. Int. Ed. 2013, 52, 5807; Angew. Chem. 2013, 125, 5919. (Stereoselectivity was guided by weak attractive interactions between non-acidic C−H bonds and enolate oxygen atoms.) Volume55, Issue15April 4, 2016Pages 4636-4636 ReferencesRelatedInformation

Palladium‐Catalyzed Asymmetric Reductive Heck Reaction of Aryl Halides

AbstractAsymmetric reductive Heck reaction of aryl halides is realized in high stereoselectivity. Hydrogen‐bond donors, trialkylammonium salts in a glycol solvent, were used to promote halide dissociation from neutral arylpalladium complexes to access cationic, stereoselective pathways.

Palladium-catalyzed asymmetric reductive heck reaction of aryl halides.

Asymmetric reductive Heck reaction of aryl halides is realized in high stereoselectivity. Hydrogen-bond donors, trialkylammonium salts in a glycol solvent, were used to promote halide dissociation from neutral arylpalladium complexes to access cationic, stereoselective pathways.

Amine-based ionic liquids (R3N+PPh2) as a reusable reaction medium and Pd(II) ligand in Heck reactions of aryl halides with styrene and n-butyl acrylate

Amine-based ionic liquids (R3N+PPh2) are reported as an effective reusable medium, suitable Pd(II) ligand and also reducing agent for the Heck coupling reaction of aryl iodides and bromides with styrene and n-butyl acrylate. The ionic liquid, still containing its corresponding Pd(0) complex, was easily recovered and reused in several runs without losing its efficiency.

Palladium(II)-catalyzed Heck reaction of aryl halides and arylboronic acids with olefins under mild conditions

A series of general and selective Pd(II)-catalyzed Heck reactions were investigated under mild reaction conditions. The first protocol has been developed employing an imidazole-based secondary phosphine oxide (SPO) ligated palladium complex (6) as a precatalyst. The catalytic coupling of aryl halides and olefins led to the formation of the corresponding coupled products in excellent yields. A variety of substrates, both electron-rich and electron-poor olefins, were converted smoothly to the targeted products in high yields. Compared with the existing approaches employing SPO–Pd complexes in a Heck reaction, the current strategy features mild reaction conditions and broad substrate scope. Furthermore, we described the coupling of arylboronic acids with olefins, which were catalyzed by Pd(OAc)2 and employed N-bromosuccinimide as an additive under ambient conditions. The resulted biaryls have been obtained in moderate to good yields.

Preparation of Heterogeneous Palladium Catalysts Supported on Sporopollenin for Heck Coupling Reactions

The immobilized Schiff bases, S-[N-(2-aminoethyl)salicylal diimino] (1a), S-[N-(2-aminoethyl)cinnamaldiimino] (1b), S-[N-(2-aminoethyl)acetaldiimino] (1c), and their palladium(II) (2a–c) complexes, were synthesized onto a chemically modified sporopollenin with ethylenediamine. These complexes were investigated as catalysts in a Heck reaction of aryl halide with olefins. These immobilized palladium complexes is an efficient catalysts for Heck reaction of aryl halides with methyl and butyl acrylate.

Ethylenediamine-functionalized activated carbon anchored palladium complex: a recyclable catalyst for Heck reaction

Ethylenediamine-functionalized activated carbon anchored palladium catalyst was prepared via grafting ethylenediamine onto chemically modified activated carbon, followed by the reaction with palladium chloride and then the reduction with potassium borohydride. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy results indicated that palladium immobilized on the carrier via coordination bond in this catalyst. Transmission electron microscopy images showed that the supported palladium is in the form of near spherical particles smaller than 10 nm diameter and evenly dispersed on the surface of the carrier. This catalyst was applied for the Heck reaction of aryl halides with olefins. The influences of solvents, bases, reaction temperatures and times on catalytic property of the catalyst were investigated by using the coupling of iodobenzene and styrene as a probe reaction. By varying the combination of aryl halides and olefins, this catalyst showed effective catalytic activities to produce corresponding coupling products with moderate to excellent yields. Moreover, it can be recovered by simple filtration and reused several times without significant loss of activity and selectivity.

ChemInform Abstract: Remarkably Facile Heck Reactions in Aqueous Two‐Phase System Catalyzed by Reusable Pd/C under Ligand‐Free Conditions.

Abstract A fast and convenient Heck reaction was achieved catalyzed by Pd/C in aqueous two-phase system. The aqueous two-phase system has been shown to be a highly active solvent for Heck reactions of aryl halides even in the absence of organic ligands.

Remarkably Facile Heck Reactions in Aqueous Two-Phase System Catalyzed by Reusable Pd/C Under Ligand-Free Conditions

A fast and convenient Heck reaction was achieved catalyzed by Pd/C in aqueous two-phase system. The aqueous two-phase system has been shown to be a highly active solvent for Heck reactions of aryl halides even in the absence of organic ligands.