Showing papers on "Heck reaction published in 2017"
TL;DR: This work reports that the palladium-catalyzed Heck reaction proceeds smoothly at room temperature with a variety of tertiary, secondary, and primary alkyl bromides upon irradiation with blue light-emitting diodes in the presence of a dual phosphine ligand system.
Abstract: The palladium-catalyzed Mizoroki-Heck reaction is arguably one of the most significant carbon-carbon bond-construction reactions to be discovered in the last 50 years, with a tremendous number of applications in the production of chemicals. This Nobel-Prize-winning transformation has yet to overcome the obstacle of its general application in a range of alkyl electrophiles, especially tertiary alkyl halides that possess eliminable β-hydrogen atoms. Whereas most palladium-catalyzed cross-coupling reactions utilize the ground-state reactivity of palladium complexes under thermal conditions and generally apply a single ligand system, we report that the palladium-catalyzed Heck reaction proceeds smoothly at room temperature with a variety of tertiary, secondary, and primary alkyl bromides upon irradiation with blue light-emitting diodes in the presence of a dual phosphine ligand system. We rationalize that this unprecedented transformation is achieved by utilizing the photoexcited-state reactivity of the palladium complex to enhance oxidative addition and suppress undesired β-hydride elimination.
192 citations
TL;DR: The first visible light-induced Pd-catalyzed Heck reaction of α-heteroatom substituted alkyl iodides and -bromides with vinyl arenes/heteroarenes has been developed and enables synthesis of valuable functionalized allylic systems.
Abstract: The first visible light-induced Pd-catalyzed Heck reaction of α-heteroatom substituted alkyl iodides and -bromides with vinyl arenes/heteroarenes has been developed. This transformation efficiently proceeds at room temperature and enables synthesis of valuable functionalized allylic systems, such as allylic silanes, boronates, germanes, stannanes, pivalates, phosphonates, phthalimides, and tosylates from the corresponding α-substituted methyl iodides. Notably, synthesis of the latter substrates failed under existing thermally induced Pd-catalyzed conditions, which highlights the importance of visible light for this transformation.
146 citations
TL;DR: In this paper, a palladium nanoparticles (Pd NPs) loaded homochiral covalent organic framework using S-(+)-2-methylpiperazine and cyanuric chloride is presented.
Abstract: We herein report the fabrication of a palladium nanoparticles (Pd NPs) loaded homochiral covalent organic framework using S-(+)-2-methylpiperazine and cyanuric chloride (Pd@CCOF-MPC) (2) via a very facile chemical approach. The chiral COF support of 1 (CCOF-MPC) is synthesized by the combination of cyanuric chloride and S-(+)-2-methylpiperazine at 90 °C for 36 h, and the Pd NPs-loaded Pd@CCOF-MPC (2) is prepared via sequential solution impregnation and NaBH4 reduction at room temperature. 2, as a highly active reusable asymmetric heterogeneous composite catalyst, is able to effectively promote the Henry reaction and reductive Heck reaction in high yield with excellent stereoselectivity.
137 citations
TL;DR: A nickel-catalyzed asymmetric reductive Heck reaction of aryl chlorides has been developed that affords substituted indolines with high enantioselectivity.
Abstract: A nickel-catalyzed asymmetric reductive Heck reaction of aryl chlorides has been developed that affords substituted indolines with high enantioselectivity. Manganese powder is used as the terminal reductant with water as a proton source. Mechanistically, it is distinct from the palladium-catalyzed process in that the nickel-carbon bond is converted into a C-H bond to release the product through protonation instead of hydride donation followed by C-H reductive elimination on Pd.
124 citations
TL;DR: The Heck reaction is one of the most studied coupling reactions and is recognized with the Nobel Prize in Chemistry as discussed by the authors, and many articles, hundreds of reviews and a number of books have been published on it.
Abstract: The Heck reaction is one of the most studied coupling reactions and is recognized with the Nobel Prize in Chemistry. Thousands of articles, hundreds of reviews and a number of books have been published on this topic. All reviews are written exhaustively describing the various aspects of Heck reaction and refer to the work done hitherto. Looking at the quantum of the monographs published, and the reviews based on them, we found a necessity to summarize all reviews on Heck reaction about catalysts, ligands, suggested mechanisms, conditions, methodologies and the compounds formed via Heck reaction in one review and generate a resource of information. One can find almost all the catalysts used so far for Heck reaction in this review.
120 citations
TL;DR: In this paper, a detailed study involving 19 different Pd-NHC complexes with imidazolium, benzimidazolate, and triazolate ligands has been carried out and revealed a new mode of operation of metal NHC systems.
111 citations
TL;DR: In this paper, the type of reaction examined size and shape, stability, and recycling ability of silica-supported palladium nanoparticles, and the influence of different reaction parameters on carbon-carbon bond-forming reactions are discussed.
Abstract: Remarkable developments have been accomplished in silica-supported palladium nanoparticles (PdNPs)-mediated organic transformations for the generation of Suzuki (C–C), Heck (C═C), and Sonogashira (C≡C) coupling reactions in academic as well as industrial communities. Various synthetic methods were adopted to prepare highly dispersed PdNPs encapsulated within various forms of silica supports. The type of reaction examined size and shape, stability, and recycling ability of silica-supported PdNPs, and the influence of different reaction parameters on carbon–carbon bond-forming reactions are discussed. In these reactions, the silica-supported PdNPs exhibited superior performances compared to their unsupported colloidal metal nanoparticles (MNPs), revealing the advantages of designing nanocatalysts. Recent progress in the synthesis, catalytic results, stability, and recycling possibilities of silica-supported PdNPs are discussed, along with the prospective outlook of relevant research fields.
84 citations
TL;DR: A highly regio- and stereoselective cobalt catalyzed allylic selective dehydrogenative Heck reaction with internal aliphatic olefins was developed, thereby significantly expanding the scope of alkenylation chemistry.
Abstract: Unactivated acyclic internal aliphatic olefins are often found to be unreactive in conventional alkenylation reactions To address this problem, a cobalt catalyzed allylic selective dehydrogenative Heck reaction with internal aliphatic olefins has been developed The method is highly regio- and stereoselective, the conditions are mild and a wide variety of functional groups can be tolerated Remarkably, both internal and terminal aliphatic olefins can be employed, thereby significantly expanding the scope of alkenylation chemistry with aliphatic olefins
82 citations
TL;DR: A palladium-catalyzed reaction of γ,δ-unsaturated oxime esters with oxadiazoles afforded dihydropyrroles in good to excellent yields through an intramolecular iminopalladation/intermolecular direct heteroarene C-H alkylation cascade.
Abstract: A palladium-catalyzed reaction of γ,δ-unsaturated oxime esters with oxadiazoles afforded dihydropyrroles in good to excellent yields through an intramolecular iminopalladation/intermolecular direct heteroarene C-H alkylation cascade. This unprecedented iminoarylation of alkenes was subsequently realized in an enantioselective manner in the presence of a chiral bidentate phosphine ligand (Synphos).
79 citations
TL;DR: A series of pyridine-type ligands containing C≡C bonds were designed and synthesized for selective oxidative Heck reaction and used as a heterogeneous catalytic ligand for the PdII-catalyzed oxidative Heck Reaction with high linear selectivity.
Abstract: A series of pyridine-type ligands containing C≡C bonds were designed and synthesized for selective oxidative Heck reaction. These ligands were utilized as functional units and integrated into the skeleton of conjugated microporous polymers. 6,6′-diiodo-2,2′-bipyridine and 1,3,5-triethynylbenzene were polycondensed via Sonogashira cross-coupling strategy to afford CMP-1 material. The resultant CMP-1 was used as a heterogeneous catalytic ligand for the PdII-catalyzed oxidative Heck reaction with high linear selectivity. The linear selectivity of CMP-1 is about 30 times higher than that of bipyridine-based monomer ligand. This work opens a new front of using CMP as an intriguing platform for developing highly efficient catalysts in controlling the regioselectivity in organic reactions.
78 citations
TL;DR: The catalytic tests showed that the novel starch based palladium catalyst proved to be an economical and practical catalyst for the synthesis of biaryl compounds.
TL;DR: Iron-catalyzed methyl, ethyl and propyl Heck reactions were developed using readily availableAlkyl peroxides as alkyl sources to develop new reactions for high-performance liquid chromatography.
Abstract: Short alkyl chain Heck (type) reactions, especially methyl Heck reactions, are a difficult aspect of the alkyl Heck reaction. To provide a solution to this problem, iron-catalyzed methyl, ethyl and propyl Heck reactions were developed using readily available alkyl peroxides as alkyl sources. The reaction conditions were mild, clean, and easy to handle. No additive was needed, and no hazardous waste was generated. The products were obtained in up to 99% yield of one isomer for most situations. This reaction works for many types of olefin and tolerates a variety of functional groups. Several late-stage functionalizations of natural products and drug molecules were conducted to demonstrate the synthetic applications of this reaction.
TL;DR: These findings make the rGO@CoAl-LDH hybrid prepared by a facile and scalable synthesis route a universal green platform to support other noble or nonprecious metal NCs via lattice atomic-confined in situ reduction strategy to construct more desired heterogeneous catalysts.
Abstract: A series of novel nanosheet array-like catalysts Pdx/rGO@CoAl-LDH (x = 0.0098–1.9, refers to Pd loading in wt % on ICP, rGO: reduced graphene oxide, LDH: layered double hydroxide) were first prepared via a simple and green lattice atomic-confined in situ reduction of oxidative Pd precursors by the evenly atomic-dispersed reductive Co2+ sites on LDH layers of a nanohybrid rGO@CoAl-LDH with hexagonal LDH nanoplates (∼73 × 7 nm) interdigitated vertical to the surfaces of rGO layer in both sides, fabricated through a simple citric acid-assisted aqueous-phase coprecipitation method. The as-obtained Pd catalysts possess clean Pd nanoclusters (NCs) with tunable sizes in 1.3–1.8 nm on varied Pd loadings. All the Pdx/rGO@CoAl-LDH catalysts show excellent activities for the Heck reaction, and the Pd0.0098/rGO@CoAl-LDH with the ultrafine Pd NCs of 1.3 ± 0.2 nm yields a maximum turnover frequency of 160 000 h–1 over a heterogeneous catalyst so far. The excellent activities can be attributed to the ultrasmall Pd NCs w...
TL;DR: This work presents an intermolecular coupling reaction that unites organotriflates and aldehydes, and a Heck-type mechanism is postulated, wherein the π bond of the aldehyde takes the role of the olefin in the insertion/elimination steps.
Abstract: The use of transition metal catalysis to enable the coupling of readily available organic molecules has greatly enhanced the chemist's ability to access complex chemical structures. In this work, an intermolecular coupling reaction that unites organotriflates and aldehydes is presented. A unique catalyst system is identified to enable this reaction, featuring a Ni(0) precatalyst, a tridentate Triphos ligand, and a bulky amine base. This transformation provides access to a variety of ketone-containing products without the selectivity and reactivity-related challenges associated with more traditional Friedel-Crafts reactions. A Heck-type mechanism is postulated, wherein the pi-bond of the aldehyde takes the role of the olefin in the insertion/elimination steps.
TL;DR: In this paper, a new type of phosphorus-doped porous organic polymer (POP) has been readily synthesized through a Heck reaction, which could be used not only as a support but also a ligand for palladium nanoparticles.
Abstract: A new type of phosphorus-doped porous organic polymer (POP) has been readily synthesized through a Heck reaction, which could be used not only as a support but also a ligand for palladium nanoparticles. The dual-functional material supported palladium nanocatalyst was used for the efficient and chemoselective hydrogenation of varieties of nitroarenes and α,β-unsaturated compounds, as well as for the synthesis of indoles from 2-nitrophenylacetonitrile under 1 atm hydrogen in green solvents at room temperature. No obvious aggregation and loss of catalytic activity of the new nanocatalyst were observed after 10 runs in the reaction.
TL;DR: Palladium-catalyzed intramolecular dearomative reductive-Heck reaction of C2-substituted indoles is developed, which provides access to structurally diverse 3,2'-spiropyrrolidine oxindoles.
Abstract: Palladium-catalyzed intramolecular dearomative reductive-Heck reaction of C2-substituted indoles is developed, which provides access to structurally diverse 3,2′-spiropyrrolidine oxindoles. By changing the hydride source to AcONa base, direct C3-arylation products [2,3-b]quinolinones are achieved in good yields. The reaction of C2-substituted benzofuran is also realized, delivering the desired spiro-product.
TL;DR: In this paper, a practical Heck reaction between organoboronic acids and ethenesulfonyl fluoride (ESF) is developed, where Aryl and hetero-aryl-boronic acids react efficiently and stereoselectively with ESF in the presence of a catalytic amount of Pd(OAc)2 and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) or AgNO3 in AcOH to afford the corresponding E-isomer β-arylethen
Abstract: A practical oxidative Heck reaction between organoboronic acids and ethenesulfonyl fluoride (ESF) is developed. Aryl- and heteroaryl-boronic acids react efficiently and stereoselectively with ESF in the presence of a catalytic amount of Pd(OAc)2 and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) or AgNO3 in AcOH to afford the corresponding E-isomer β-arylethenesulfonyl fluoride products. The utility of this reaction is exemplified by an expanded scope of 47 examples including N-, O-, and S-containing heteroaromatics, demonstrated chemoselectivity over aryliodides, and gram-scale operation without the requirement for strict anhydrous or oxygen-free conditions. Furthermore, this procedure discriminates against the formation of arylboronic acid homo-coupling byproducts. In addition, the preparation the first aryl vinylsulfonate polymer, a material with functionalizable Michael acceptor sites, from a starting arylboronic acid is described.
TL;DR: BINAM-derived phosphoric acid catalysts were shown to prevent alkene isomerization in cyclopentene and cycloheptene starting materials and DFT(B3LYP-D3) computations revealed that increased product selectivity resulted from a chiral anion dependent lowering of the activation barrier for the desired pathway.
Abstract: A mild, asymmetric Heck-Matsuda reaction of five-, six- and seven-membered ring alkenes and aryl diazonium salts is presented. High yields and enantioselectivities were achieved using Pd0 and chiral anion co-catalysts, the latter functioning as a chiral anion phase-transfer (CAPT) reagent. For certain substrate classes, the chiral anion catalysts were modulated to minimize the formation of undesired by-products. More specifically, BINAM-derived phosphoric acid catalysts were shown to prevent alkene isomerization in cyclopentene and cycloheptene starting materials. DFT(B3LYP-D3) computations revealed that increased product selectivity resulted from a chiral anion dependent lowering of the activation barrier for the desired pathway.
TL;DR: In this work, it is proved that it is possible to tailor the PL properties of carborane-stilbene dyads by changing the Cc substituent and theCarborane isomer.
Abstract: Two novel styrene-containing meta-carborane derivatives substituted at the second carbon cluster atom (Cc) with either a methyl (Me) or a phenyl (Ph) group are introduced herein along with a new set of stilbene-containing ortho- (o-) and meta- (m-) carborane dyads. The latter set of compounds have been prepared from styrene-containing carborane derivatives via a Heck coupling reaction. High regioselectivity has been achieved for these compounds by using a combination of palladium complexes [Pd2(dba)3]/[Pd(t-Bu3P)2] as a catalytic system, yielding exclusively E isomers. All compounds have been fully characterised and the crystal structures of seven of them were analysed by X-ray diffraction. The absorption spectra of these compounds are similar to those of their respective fluorophore groups (styrene or stilbene), showing a very small influence of the substituent (Me or Ph) linked to the second Cc atom or the cluster isomer (o- or m-). On the other hand, fluorescence spectroscopy revealed high emission intensities for Me-o-carborane derivatives, whereas their Ph-o-carborane analogues evidenced an almost total lack of fluorescence, confirming the significant role of the substituent bound to the adjacent Cc in o-carboranes. In contrast, all the m-carborane derivatives display similar photoluminescence (PL) behavior regardless of the substituent attached to the second Cc, demonstrating its small influence on emission properties. Additionally, m-carborane derivatives are significantly more fluorescent than their o-counterparts, reaching quantum yield values as high as 30.2%. Regarding solid state emission, only stilbene-containing Ph-o-carborane derivatives, which showed very low fluorescence in solution, exhibited notable PL emission in films attributed to aggregation-induced emission. DFT calculations were performed to successfully complement the photoluminescence studies, supporting the experimentally observed photophysical behavior of the styrene and stilbene-containing carborane derivatives. In conclusion, in this work it is proved that it is possible to tailor the PL properties of carborane-stilbene dyads by changing the Cc substituent and the carborane isomer.
TL;DR: In this paper, a simple protocol for the phosphine-free C-C coupling reactions and synthesis of anilines in the presence of 2-aminobenzamide complex of palladium supported on Fe3O4 magnetic nanoparticles was reported.
Abstract: A simple, efficient and less expensive protocol for the phosphine-free C–C coupling reactions and synthesis of anilines in the presence of 2-aminobenzamide complex of palladium supported on Fe3O4 magnetic nanoparticles (Pd(0)-ABA-Fe3O4) has been reported. The Suzuki reaction was carried out in water or PEG using phenylboronic acid (PhB(OH)2) or sodium tetraphenyl borate (NaBPh4). Pd(0)-ABA-Fe3O4 has been found promising for Heck reaction of butyl acrylate, styrene or acrylonitrile with aryl halides (including Cl, Br and I). Also, Pd(0)-ABA-Fe3O4 has been found as efficient catalyst for the amination of aryl halides using aqueous ammonia. The products have been obtained in short reaction times and high yields. The catalyst was easily separated using an external magnet from the reaction mixture and reused for several runs without significant loss of its catalytic efficiency or palladium leaching. The leaching of catalyst has been examined by hot filtration and ICP-OES technique. The nanomagnetical catalyst was characterized by FTIR, TGA, XRD, VSM, TEM, SEM, EDS, DLS and ICP-OES techniques.
TL;DR: In this article, the authors focus on the mechanistic insights and complexity of the computational studies of Pd-catalyzed Suzuki, Heck, and Sonogashira carbon-carbon bond-forming reactions.
Abstract: This perspective focuses on the mechanistic insights and complexity, which are difficult to acquire from pure experimental techniques, of the computational studies of Pd-catalyzed Suzuki, Heck, and Sonogashira carbon–carbon bond-forming reactions. These reactions consist of three fundamental steps including oxidative addition (OA), transmetalation (TM), and reductive elimination (RE) for the generation of carbon–carbon bonds from the bond-forming reactions of aryl halides (R1X) and organometallic species (R2M). Computational studies of these coupling reactions allow us to understand specific reaction pathways in the analysis of OA (resolving the linkage between coordination number and selectivity in Suzuki reaction), TM (the function of the base in the Suzuki reaction and various mechanistic options in the Sonogashira reaction), and RE (way of efficient β-hydride elimination in the Heck reaction). In addition, the reaction pathways and complexities in the full catalytic cycle of each reaction along with t...
TL;DR: In this paper, a one-step synthesis of the anionic "ligandless" palladium complex [NBu4][Pd(DMSO)Cl3] together with its crystal structure is presented.
Abstract: Recent studies have shown that anionic palladium complexes are viable catalysts for a range of catalytic cross-coupling reactions. We present a one-step synthesis of the anionic “ligandless” palladium complex [NBu4][Pd(DMSO)Cl3] together with its crystal structure. This compound has been shown to be an active precatalyst in the Mizoroki–Heck reaction. Under Jeffery conditions, activated aryl chlorides can be coupled in yields of up to 94% without the need of an additional ligand. The presence of a small amount of water was necessary for product formation. An Amatore–Jutand-type catalytic cycle is consistent with the results presented herein. For comparison with the known mixed complex [(pym-Im-Me)2PdCl][Pd(DMSO)Cl3], the cationic complex [(pym-Im-Me)2PdCl]PF6 (pym = pyrimidyl, Im = imidazolin-2-ylidene) has been synthesized and characterized using standard techniques.
TL;DR: In this paper, a palladium-catalyzed enantioselective reductive Heck reaction of enones using monodentate phosphoramidite ligands is described.
Abstract: A palladium-catalyzed enantioselective reductive Heck reaction of enones using monodentate phosphoramidite ligands is described. TADDOL-based phosphoramidites with palladium(ll) acetate, and N-methyl dicyclohexylamine as reducing agent gives the reductive Heck product in high yields and enantioselectivities up to 90%. The solvent plays an important role and in diethyl carbonate the chemo and enantioselectivity appeared to be the highest.
TL;DR: In this article, the Pd-arginine complex on boehmite nanoparticles (Pd(0)-Arg-boehmite) was reported as a moisture and air-stable, heterogeneous, excellent and novel organometallic catalyst, which applied for the Suzuki and Heck cross coupling reactions through coupling of phenylboronic acid, 3,4-difluoro phenyl-boronic acids, sodium tetraphenyl borate, butyl acrylate, methyl acrylated, acrylonitrile and styrene with a wide range
Abstract: The direct supporting of Pd-arginine complex on boehmite nanoparticles (Pd(0)-Arg-boehmite) was reported as a moisture- and air-stable, heterogeneous, excellent and novel organometallic catalyst, which applied for the Suzuki and Heck cross coupling reactions through coupling of phenylboronic acid, 3,4-difluoro phenylboronic acid, sodium tetraphenyl borate, butyl acrylate, methyl acrylate, acrylonitrile and styrene with a wide range of aryl halide including Cl, Br and I. Pd(0)-Arg-boehmite was prepared for the first time via simple, environmental and inexpensive procedure in water and ethanol without inert atmosphere or high temperature using commercially available materials, and characterized by XRD, TGA, TEM, SEM, EDS and ICP-OES techniques. The leaching of palladium and heterogeneity test of this catalyst was studied by hot filtration and ICP-OES techniques; resulting we found that this catalyst was demonstrated remarkable and excellent recyclability. Boehmite nanoparticles were prepared by inexpensive procedure in water at room temperature and directly immobilized with a new type of Pd-arginine complex. After characterization of this catalyst, its application has been studied for the C–C coupling reactions.
TL;DR: A unique Pd & #38;Cu@Al catalyst was easily fabricated just by immersing commercial aluminum foil in a mixed xylene solution of PdCl2 and CuCl2, which supported the metal nanoparticles and enhanced their catalytic activities for the phosphine-free Heck reaction of aryl halides and styrenes up to 3.9 × 105.
Abstract: A unique Pd & #38;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 100 mmol and has been applied in modification of drug Lapatinibs 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.
TL;DR: This is the first example of a σ-alkylpalladium(ii) intermediate promoting the cyclization of alkynes containing a proximate nucleophilic center.
TL;DR: In this paper, the Heck and Suzuki cross-coupling reactions were performed using Pd-S-methylisothiourea on magnetic nanoparticles (Pd-SMU-MNPs) as an efficient and magnetically reusable nanocatalyst.
TL;DR: In this article, the use of palladium-vanillin-Schiff base complex immobilized on MCM-41 nanostructure as efficient catalyst for the Suzuki-Miyaura, Stille and Mizoroki-Heck reactions of several aryl halides under aerobic conditions was described.
Abstract: The present work describes the use of palladium-vanillin-Schiff-base complex immobilized on MCM-41 nanostructure as efficient catalyst for the Suzuki–Miyaura, Stille and Mizoroki–Heck reactions of several aryl halides under aerobic conditions. All the reactions were carried out in green solvents (H2O and PEG-400). The developed procedure results bring several benefits such as uses of inexpensive and non-toxic ligand (vanillin), easy catalyst/product separation and catalyst recycling. The catalyst can be reused at least for five consecutive cycles without a significant loss of its catalytic activity or metal leaching.
TL;DR: An asymmetric Heck annulation of propargylic acetates with several types of cyclic olefins affords highly strained cyclobutenes in high enantioselectivity.
Abstract: An asymmetric Heck annulation of propargylic acetates with several types of cyclic olefins affords highly strained cyclobutenes in high enantioselectivity
TL;DR: Evenly dispersed Pd nanoparticles are facilely and successfully deposited on N-doped carbon nanotubes (Pd/N-CNTs) by employing sodium dodecyl sulfate (SDS) as a salt and polyvinylpyrrolidone (PVP) as both a surface modifier and a stabilizing agent as discussed by the authors.