Showing papers on "Heck reaction published in 2015"
TL;DR: This tutorial review gives an overview of recent advances in radical alkenylation and its applications in direct olefinic C-H functionalization and radical addition to alkenes and following single-electron-transfer (SET) oxidation/elimination.
Abstract: Direct olefinic C–H functionalization represents the ideal way of introducing an alkenyl group into organic molecules. A well-known process is the Heck reaction, which involves alkene insertion and β-hydride elimination in the presence of a transition metal. However, the traditional Heck reaction mainly deals with the alkenylation of aryl or vinyl electrophiles. Recent developments have revealed that alkenylation can also be achieved through radical addition to alkenes and following single-electron-transfer (SET) oxidation/elimination. The radical alkenylation pathway allows alkenylation with a variety of carbon-centered radicals and even heteroatom-centered radicals. This tutorial review gives an overview of recent advances in this emerging field.
267 citations
TL;DR: This report reports the first Heck reaction of amides proceeding via highly chemoselective N-CO cleavage catalyzed by Pd(0) utilizing amide bond ground-state destabilization, which provides access to a myriad of metal-catalyzed transformations ofAmides via metal insertion/decarbonylation.
Abstract: Metal-catalyzed reactions of amides proceeding via metal insertion into the N-CO bond are severely underdeveloped due to resonance stabilization of the amide bond. Herein we report the first Heck reaction of amides proceeding via highly chemoselective N-CO cleavage catalyzed by Pd(0) utilizing amide bond ground-state destabilization. Conceptually, this transformation provides access to a myriad of metal-catalyzed transformations of amides via metal insertion/decarbonylation.
228 citations
TL;DR: In this paper, a facile and efficient one-step method for the synthesis of highly active, Pd/Fe3O4 nanoparticles supported on graphene nanosheets was reported.
Abstract: Herein, we report a facile and efficient one-step method for the synthesis of highly active, Pd/Fe3O4 nanoparticles supported on graphene nanosheets (Pd/Fe3O4/G) that exhibit excellent catalytic activity for Suzuki and Heck coupling reactions and that can be magnetically separated from the reaction mixture and recycled multiple times without loss of catalytic activity. The synthesis approach is based on the Microwave (MW)-assisted reduction of palladium and ferric nitrates in the presence of graphene oxide (GO) nanosheets using hydrazine hydrate as the reducing agent. The results provide a fundamental understanding of the system variables by comparing the catalytic activity and recyclability of four different catalysts with different properties. The most active and recyclable catalyst contains 7.6 wt% Pd nanoparticles with 4-6 nm diameters in Pd(0) oxidation state well-dispersed with 30 wt% Fe3O4 nanoparticles with 12–16 nm diameters on highly reduced GO containing a C/O ratio of 8.1. These combined properties produce remarkable catalytic activity for Suzuki cross coupling reactions under MW reaction conditions with an extremely high turnover number (TON) of 9250 and turn over frequency (TOF) of 111,000 h−1 at 80 °C. The magnetic properties imparted by the Fe3O4 component of the catalyst enables the catalyst to be easily isolated and recycled, thus greatly simplifying the ability to purify the reaction products and increasing the economic value of the catalyst. The utility of these magnetic catalysts towards Suzuki and Heck cross coupling reactions with a variety of functionalized substrates was also demonstrated.
151 citations
TL;DR: The green synthesis of palladium/CuO nanoparticles (Pd/ CuO NPs) using Theobroma cacao L. seeds extract and their catalytic activity for the reduction of 4-nitrophenol and Heck coupling reaction under aerobic conditions is reported.
128 citations
TL;DR: Diverse and controllable pathways induced by palladium-catalyzed intramolecular Heck reaction of N-vinylacetamides for the synthesis of nitrogen-containing products in reasonable to high yields via tuning the phosphine ligands and bases are reported.
Abstract: Diverse and controllable pathways induced by palladium-catalyzed intramolecular Heck reaction of N-vinylacetamides for the synthesis of nitrogen-containing products in reasonable to high yields via tuning the phosphine ligands and bases are reported. Domino reactions including unique β-N–Pd elimination, 1,4-Pd migration, or direct acyl C–H bond functionalization were found to be involved forming different products, respectively. Given the ability of using the same starting material to generate diverse products via completely different chemoselective processes, these current methodologies offer straightforward access to valuable nitrogen-containing products under mild reaction conditions as well as inspire the discovery of novel reactions.
128 citations
TL;DR: Hydrogen-bond donors, trialkylammonium salts in a glycol solvent, were used to promote halide dissociation from neutral arylpalladium complexes to access cationic, stereoselective pathways.
Abstract: 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.
121 citations
TL;DR: A highly enantioselective intermolecular Heck reaction of alkenyl triflates and acyclic primary or racemic secondary alkenols and tricyclic core structure, present in various natural products is reported.
Abstract: We report a highly enantioselective intermolecular Heck reaction of alkenyl triflates and acyclic primary or racemic secondary alkenols. The mild reaction conditions permit installation of a wide range of alkenyl groups at positions β, γ, or δ to a carbonyl group in high enantioselectivity. The success of this reaction is attributed to the use of electron-withdrawing alkenyl triflates, which offer selective β-hydride elimination followed by migration of the catalyst through the alkyl chain to give the alkenylated carbonyl products. The synthetic utility of the process is demonstrated by a two-step modification of a reaction product to yield a tricyclic core structure, present in various natural products.
107 citations
TL;DR: In this paper, the authors investigated the use of GVL in the palladium-catalyzed Heck reaction and accessed the clean synthesis of several small molecules, and optimized a GVL-based protocol to synthesize a polyphenylenevinylene (PPV) derivative in high yields and purity, and with very low Pd-content.
103 citations
TL;DR: A hybrid material of palladium supported on diaminoglyoxime-functionalized Fe3O4 was used as an effective and recyclable catalyst in Mizoroki-Heck coupling reactions.
Abstract: A hybrid material of palladium supported on diaminoglyoxime-functionalized Fe3O4 was used as an effective and recyclable catalyst in Mizoroki–Heck coupling reactions. The catalyst was very effective for the Mizoroki–Heck reaction of aryl halides with styrene and conversion was in most cases excellent. The yields of the products were in the range 75–98%. The catalyst showed good stability and could be recovered and reused for six reaction cycles without significant leaching and loss its catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd.
78 citations
TL;DR: In this article, a mesoporous cobalt oxide-carbon nanocomposites was applied to the water-mediated Suzuki coupling reaction of chlorobenzene and phenylboronic acid and exhibited a high yield of biphenyl (49%) under mild reaction conditions free of phase transfer agents and ligands.
Abstract: In this study, heterogeneous palladium catalysts supported on ordered mesoporous cobalt oxide–carbon nanocomposites were applied to the water-mediated Suzuki coupling reaction of chlorobenzene and phenylboronic acid and exhibited a high yield of biphenyl (49%) under mild reaction conditions free of phase-transfer agents and ligands. Product yields in the reaction of aryl chlorides containing electron-withdrawing groups attached to their benzene ring can reach approximately 90%. Thiol-functionalized mesoporous silica, which can trap soluble Pd species, was used to confirm the negligible leaching in solution and therefore heterogeneous reaction. This heterogeneous catalyst is stable, showing unobvious activity loss after 10 catalytic runs. Characterization by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray absorption fine structure analysis, and N2 sorption techniques revealed intercalated CoO nanoparticles inside a carbon matrix with uniform mesopore sizes (∼3 n...
66 citations
TL;DR: Pd(Xantphos)I2, which features a very large bite angle, has been found to facilitate the rapid carbonylation of azaarene-substituted allylamines into bioactive quinolizinones in good to excellent yields.
Abstract: A fundamentally novel approach to bioactive quinolizinones is based on the palladium-catalyzed intramolecular cyclocarbonylation of allylamines. [Pd(Xantphos)I2 ], which features a very large bite angle, has been found to facilitate the rapid carbonylation of azaarene-substituted allylamines into bioactive quinolizinones in good to excellent yields. This transformation represents the first dearomative carbonylation and is proposed to proceed by palladium-catalyzed CN bond activation, dearomatization, CO insertion, and a Heck reaction.
TL;DR: In this paper, a Pd-isatin Schiff base complex was synthesized and characterized by Fourier transform infrared, scanning electron microscopy and X-ray diffraction, thermogravimetric gravimetric analysis, inductively-coupled plasma, and Xray photoelectron spectroscopy.
TL;DR: In this article, the influence of the confinement of Pd nanoparticles in a functionalized silica support on the Heck and Suzuki reactions was studied, showing that ordered mesoporous materials enhance stability and particle growth is slowed down but not fully suppressed.
TL;DR: In this article, a single-site Pd(II) catalyst was developed, where 2,2′-bipyridine-grafted periodic mesoporous organosilica (PMO) was employed as the support of a Pd-II complex.
Abstract: The development of organometallic single-site catalysts (SSCs) has inspired the designs of new heterogeneous catalysts with high efficiency. Nevertheless, the application of SSCs in certain modern organic reactions, such as C–C bond formation reactions, has still been less investigated. In this study, a single-site Pd(II) catalyst was developed, where 2,2′-bipyridine-grafted periodic mesoporous organosilica (PMO) was employed as the support of a Pd(II) complex. The overall performance of the single-site Pd(II) catalyst in the oxidative Heck reaction was then investigated. The investigation results show that the catalyst displays over 99% selectivity for the product formation with high reaction yield. Kinetic profiles further confirm its high catalytic efficiency, showing that the rate constant is nearly 40 times higher than that for the free Pd(II) salt. X-ray absorption spectroscopy reveals that the catalyst has remarkable lifetime and recyclability.
TL;DR: In this paper, a polyaniline-anchored palladium catalyst was proposed for coupling reactions of aryl halides and shown to be effective in Mizoroki-Heck and Suzuki-Miyaura reactions.
Abstract: A polyaniline-anchored palladium catalyst was prepared and screened for coupling reactions of aryl halides. The robust and recyclable catalyst was effective in Mizoroki–Heck and Suzuki–Miyaura reactions of aryl bromides and aryl iodides. The catalyst system was further employed for one-pot Wittig–Heck and Wittig–Suzuki combinations to build conjugated compounds in good conversions. Copyright © 2014 John Wiley & Sons, Ltd.
TL;DR: In this paper, the incorporation of sulfonate into mesoporous SBA-15 molecular sieves as ligands for palladium ions was used for Heck arylation reaction of conjugate alkenes with aryl halides, to afford corresponding crosscoupling products under phosphine-free aerobic conditions with good to excellent yields.
Abstract: The incorporation of sulfonate into mesoporous SBA-15 molecular sieves as ligands for palladium ions was used. Then SBA-15/PrSO3Pd and SBA-15/PrSO3PdNP were prepared and applied for the Heck arylation reaction of conjugate alkenes with aryl halides, to afford corresponding cross-coupling products under phosphine-free aerobic conditions with good to excellent yields. These supported palladium pre-catalysts could be separated easily from reaction products and reused several times, showing superiority over homogeneous catalysts for industrial and chemical applications. Copyright © 2015 John Wiley & Sons, Ltd.
TL;DR: An unprecedented palladium-catalyzed oxidative annulation of acrylamides with benzyne precursors has been successfully developed using this mild "N-H activation/Heck reaction" method, which prepared a wide variety of quinolinones in one step with high efficiency.
Abstract: An unprecedented palladium-catalyzed oxidative annulation of acrylamides with benzyne precursors has been successfully developed. By using this mild “N–H activation/Heck reaction” method, a wide va...
TL;DR: In this paper, the authors proposed a plausible anionic Amatore-Jutand-type mechanism for the Heck reaction involving anionic (NHC)-palladium(0) catalytic species.
TL;DR: In this article, a simple, convenient and green protocol has been developed for the synthesis of cellulose supported Pd(0) nanoparticles (NPs) using hearth wood extract of Artocarpus lakoocha Roxb-as a bioreductant.
TL;DR: The Heck coupling reaction of vinyl-terminated double four-ring siloxane cages with aromatic bromide monomers was used to construct a class of luminescent nanoporous inorganic-organic hybrid polymers (PS-n) as mentioned in this paper.
TL;DR: In this paper, a novel, biodegradable and environmentally benign magnetic porous chitosan-thienyl imine palladium(II) complex, MPCS-TI/Pd, was prepared and characterized by FT-IR, SEM, TEM, EDX, XRD, BET, VSM and TG-DTA analysis.
Abstract: A novel, biodegradable and environmentally benign magnetic porous chitosan-thienyl imine palladium(II) complex, MPCS-TI/Pd, was prepared and characterized by FT-IR, SEM, TEM, EDX, XRD, BET, VSM and TG-DTA analysis. This complex, with high surface areas and low catalyst loading, was found to be a highly active and robust heterogeneous catalyst for the Mizoroki–Heck reaction of aryl bromides and chlorides with various terminal olefins in aqueous media in good to excellent yields. The catalyst was easily separated using an external magnet and the recovered catalyst was reused for seven cycles without significant loss of catalytic activity.
TL;DR: P palladium catalyst was applied to the coupling of CO2 with conjugated alkenes and it was reported the first catalyst based on palladium for the reaction ofCO2, alkene and a base to form sodium acrylate and derivatives.
TL;DR: A domino [Pd]-catalysis for the efficient synthesis of fluorenones is presented, where the usual water workup affords the fused tricyclic ketones (fluorenones) and this one-pot operation enabled the effective construction of two C-C to threeC-C bonds.
TL;DR: In this paper, a magnetically responsive polymer nanocomposite Fe3O4@poly(undecylenic acid-co-4-vinyl pyridine with sodium acrylate (SAA) was synthesized.
Abstract: A novel type of magnetically responsive polymer nanocomposite Fe3O4@poly(undecylenic acid-co-4-vinyl pyridine-co-sodium acrylate) (Fe3O4@PUVS) was synthesized by the free radical polymerization of 4-vinyl pyridine (4-VP) with sodium acrylate (SAA) and Fe3O4@undecylenic acid. Pd2+ was then immobilized on this magnetic nanocomposite to form the magnetic Fe3O4@PUVS-Pd catalyst. This catalyst exhibited excellent catalytic activity for the Heck and Suzuki coupling reactions in water, and could be simply separated by using a permanent magnet. The supported catalyst could be used consecutively for six runs without significant loss of catalytic activity.
TL;DR: A green method for the synthesis of gelatin/pectin stabilized palladium nano-particles has been described in this article, where the particles were prepared under green conditions without addition of any external reducing agent and ligand.
Abstract: A green method for the synthesis of gelatin/pectin stabilized palladium nano-particles has been described. These particles were prepared under green conditions without addition of any external reducing agent and ligand. All properties of the supported palladium particles on gelatin/pectin mixture were showed by UV–vis spectra and also by EDX, XRD, TEM and FESEM images. The synthesized palladium nanoparticles were studied in Mizoroki–Heck reaction between different aryl halides and n-butyl acrylate. The reaction was performed under solvent-free conditions and no complicated work up process was needed for the isolation of the nano-particles. Also the products were obtained in highly short reaction times with excellent yields.
TL;DR: In this article, the activity of Pd(II)-Schiff base complex molecules grafted on the surface of Fe3O4@SiO2 particles were investigated in the palladium-catalyzed coupling reactions of aryl halides with alkenes (Mizoroki-Heck reaction) and phenylboronic acids (Suzuki-Miyaura reaction) in the absence of phosphorous ligands.
Abstract: The activity of Pd(II)-Schiff base complex molecules grafted on the surface of Fe3O4@SiO2 particles were investigated in the palladium-catalyzed coupling reactions of aryl halides with alkenes (Mizoroki-Heck reaction) and phenylboronic acids (Suzuki-Miyaura reaction) in the absence of phosphorous ligands. This method shows notable advantages such as heterogeneous nature of the catalyst, excellent yields, short reaction times, easy preparation, simplicity of operation, and cleaner reaction profiles. The catalyst can be separated from the reaction mixture by applying a permanent magnet externally and can be reused for several times without significant loss of activity. Also, the amount of palladium leaching has been determined by ICP analysis.
TL;DR: A carbonylative Mizoroki-Heck reaction using alkyl iodides was achieved with a Pd/photoirradiation system using DBU as a base, giving α,β-unsaturated ketones via SET.
TL;DR: In this paper, the Heck reaction of methyl acrylate and styrene with a series of aryl iodides in CH3CN/H2O azeotrope as a green medium was optimized under flow conditions obtaining an extremely low waste production (E-factor) and allowing to isolate the final product with very low residual palladium content without any purification step.
Abstract: Palladium nanoparticles on layered potassium α-zirconium phosphate (PdNP/α-ZrPK) with high palladium loading (10.6 wt%) have been prepared and used as catalyst in low amount (0.1 mol% of Pd) in the Heck reaction of methyl acrylate and styrene with a series of aryl iodides in CH3CN/H2O azeotrope as a green medium. The procedure has been optimized under flow conditions obtaining an extremely low waste production (E-factor) and allowing to isolate the final product with very low residual palladium content without any purification step.
TL;DR: In this article, a series of glycosyl pyridyl-triazole@palladium nanoparticles (GPT-Pd) were synthesized by the reaction of azidoglycosides with 2-ethynylpyridine via click chemistry.