Showing papers on "Heck reaction published in 2020"
21 Feb 2020
TL;DR: Palladium has been the key element for several C-C bond-forming reactions, especially the Nobel-acclaimed Suzuki, Heck, and Sonogashira cross-coupling reactions, among others.
Abstract: Palladium (Pd) has been the key element for several C–C bond-forming reactions, especially the Nobel-acclaimed Suzuki, Heck, and Sonogashira cross-coupling reactions, among others. This review arti...
176 citations
TL;DR: In this paper, a new family of imidazolium-based ionic porous hybrid polymers (termed IM-iPHPs) with polyhedral oligomeric silsesquioxane (POSS)-derived silanols (Si OH) was constructed by the Heck reaction between newly-designed bromobenzene-bearing IM-IoS ionic monomers and octavinylsilsesquioxANE under solvothermal conditions.
101 citations
TL;DR: A practical silver-catalyzed decarboxylative allylation of α,α-difluoroarylacetic acids with allyl sulfones is described, which provides a variety of β,β -dIFluorinated alkenes in good yields and proceeds smoothly in water with good functional group tolerance.
Abstract: A practical silver-catalyzed decarboxylative allylation of α,α-difluoroarylacetic acids with allyl sulfones is described, which provides a variety of β,β-difluorinated alkenes in good yields. Notably, the reaction proceeds smoothly in water with good functional group tolerance. The practicality and synthetic value of this process was demonstrated by scaled-up experiment and elaboration of the products via reduction or Heck reaction. Primary mechanism investigations suggest that a radical process might be involved.
71 citations
TL;DR: An asymmetric palladium and copper co-catalyzed sequential Heck/Sonogashira reaction between o -iodoacrylanilides and terminal alkynes to synthesize chiral oxindoles was developed and can provide a general approach to access oxindole derivatives containing quaternary stereogenic centers including CF 3 -substituted ones.
Abstract: An asymmetric palladium and copper co-catalyzed Heck/Sonogashira reaction between o-iodoacrylanilides and terminal alkynes to synthesize chiral oxindoles was developed. In particular, a wide range of CF3 -substituted o-iodoacrylanilides reacted with terminal alkynes, affording the corresponding chiral oxindoles containing trifluoromethylated quaternary stereogenic centers in high yields with excellent enantioselectivities (94-98 % ee). This asymmetric Heck/Sonogashira reaction provides a general approach to access oxindole derivatives containing quaternary stereogenic centers including CF3 -substituted ones.
64 citations
TL;DR: The modularity and tunability of the QD core and surface make it a convenient and effective chromophore for this alternative mode of cooperative photocatalysis.
Abstract: This Article describes the design of a colloidal quantum dot (QD) photosensitizer for the Pd-photocatalyzed Heck coupling of styrene and iodocyclohexane to form 2-cyclohexylstyrene. In the presence...
59 citations
TL;DR: In this article, the authors summarized the progress in this field with respect to cross-electrophile couplings and reductive Heck reactions using vinyl electrophiles and concluded that the transition-metal-catalyzed reductive cross-coupling of vinyl Electrophiles has emerged as a promising tool to produce alkenes with improved flexibility, structural complexity, and functionality tolerance.
Abstract: The synthesis of alkenes (olefins) is a central subject in the synthetic community. The transition-metal-catalyzed reductive cross-coupling of vinyl electrophiles has emerged as a promising tool to produce alkenes with improved flexibility, structural complexity, and functionality tolerance. In this review, we summarized the progress in this field with respect to cross-electrophile couplings and reductive Heck reactions using vinyl electrophiles. 1 Introduction 2 Cross-Electrophile Coupling of Vinyl Electrophiles 3 Reductive Heck Reaction of Vinyl Electrophiles 4 Summary and Outlook
49 citations
46 citations
TL;DR: A transient directing group approach to reductive Heck hydroarylation of alkenyl benzaldehyde substrates that proceeds under mild conditions is reported and Computational studies reveal an unusual mode of enantioinduction by the remote chiral centre in the transient directs group.
Abstract: Metal-coordinating directing groups have seen extensive use in the field of transition-metal-catalyzed alkene functionalization; however, their waste-generating installation and removal steps limit the efficiency and practicality of reactions that rely on their use. Inspired by developments in asymmetric organocatalysis, where reactions rely on reversible covalent interactions between an organic substrate and a chiral mediator, we have developed a transient-directing-group approach to reductive Heck hydroarylation of alkenyl benzaldehyde substrates that proceeds under mild conditions. Highly stereoselective migratory insertion is facilitated by in situ formation of an imine from catalytic amounts of a commercially available amino acid additive. Computational studies reveal an unusual mode of enantioinduction by the remote chiral center in the transient directing group.
42 citations
TL;DR: It is demonstrated that a variety of homoallylic protected amines undergo an interrupted enantioselective relay Heck reaction to give enantioenriched allylic amine products and provides a roadmap for exploiting these processes in future reaction development.
Abstract: The formation of alkyl–palladium complexes via the nucleopalladation of alkenes is the entry point for a wide range of diverse reactions. One possibility is that the intermediate alkyl–Pd complexes...
41 citations
TL;DR: The combination of a nucleophilic aromatic substitution (SNAr) with the denitrative alkenylation produced a multifunctionalized arene in a one-pot operation.
32 citations
TL;DR: The present review gives a brief account of applications of the palladium-catalyzed cross-coupling reactions in comprehensive synthesis, viz., the Heck, Stille, Suzuki-Miyaura, Negishi, Sonogashira, Buchwald-Hartwig, Ullmann and the Oxidative, decarboxylative cross-Coupled reactions, with particular emphasis on the synthesis of heterocyclic compounds.
Abstract: Palladium-catalyzed cross-coupling reactions have gained a continuously growing interest of synthetic organic chemists. The present review gives a brief account of applications of the palladium-catalyzed cross-coupling reactions in comprehensive synthesis, viz., the Heck, Stille, Suzuki-Miyaura, Negishi, Sonogashira, Buchwald-Hartwig, Ullmann and the Oxidative, decarboxylative cross-coupling reactions, with particular emphasis on the synthesis of heterocyclic compounds.
TL;DR: A palladium-catalyzed Narasaka-Heck reaction by a domino cross-coupling reaction with aromatic alkenes under blue LED irradiation at room temperature was developed, enabling a broad range of oxime esters to undergo 5-exo cyclization and subsequent coupling with olefins.
TL;DR: A general intermolecular reductive Heck reaction of organohalides with both terminal and internal unactivated aliphatic alkenes has been first realized in high yield with complete anti-Markovnikov selectivity, demonstrating the wide synthetic utility of this scalable strategy.
TL;DR: In this article, the authors focused on the differentiation between homogeneous and heterogeneous reaction pathways and developed solid palladium catalysts for the Heck coupling reaction, which is generalization of the work of this article.
Abstract: Since the development of solid palladium catalysts for the Heck coupling reaction, many studies focused on the differentiation between homogeneous and heterogeneous reaction pathways. It is general...
TL;DR: A new domino Heck/disilylation reaction was reported in this article for indole-tethered 2-(2-halophenyl)-1H-indoles with hexamethyldisilane under palladium catalysis.
Abstract: The chemoselective reaction remains a tremendous but particularly fascinating challenge in organic synthesis. Herein, we report a new domino Heck/disilylation reaction of alkene-tethered 2-(2-halophenyl)-1H-indoles with hexamethyldisilane under palladium catalysis. This procedure involving the formation of one C–C bond and two C–Si bonds proceeds efficiently through two key steps of the chemoselective Heck reaction and C–H activation by overcoming undesirable C3–H bond activation on the indoles, thus generating various disilylated tetracyclic indolo[2,1-a]isoquinolines in moderate to excellent yields. Furthermore, borylated indolo[2,1-a]isoquinolines can be produced by a Heck/borylation cascade.
TL;DR: An outstanding heterogeneous catalyst was successfully prepared by immobilization of palladium nanoparticles (Pd NPs) with polymer containing 4′−(4−hydroxyphenyl) 2,2′:6′,2″−terpyridine (HPTPy) ligand as mentioned in this paper.
Abstract: An outstanding heterogeneous catalyst was successfully prepared by immobilization of palladium nanoparticles (Pd NPs) with polymer containing 4′‐(4‐hydroxyphenyl)‐2,2′:6′,2″‐terpyridine (HPTPy) ligand. The polymer cross‐linked with trimethylolpropane triacrylate (TMPTA) units was synthesized by polymerization of itaconic acid-HPTPy (ITC-HPTPy) monomer (so-called cross‐linked poly (ITC- HPTPy)). The cross‐linked poly (ITC-HPTPy) can stabilize the Pd NPs effectively against aggregation, thereby improving the catalytic efficiency of Pd NPs. The presence of Pd NPs on the polymer was confirmed by various physicochemical techniques. The resulting cross‐linked poly (ITC-HPTPy)-Pd was applied as a highly effective recyclable catalyst in Suzuki–Miyaura and Mizoroki–Heck coupling reactions under low Pd-loading conditions and straightforward methods, and provided the corresponding products with excellent yields (up to 98%), high catalytic activities (TOF up to 213 h−1). The catalyst can be separated from the reaction mixture by centrifugation and can be reused consecutive six times with slight reduction in catalytic activity. Pd NPs immobilized with polymer containing terpyridine ligand are highly active heterogeneous catalysts for Suzuki–Miyaura and Mizoroki–Heck coupling reactions.
TL;DR: A novel visible-light-induced palladium-catalyzed Heck reaction for bromine sugars and aryl olefins with high regio- and stereochemistry selectivity for the preparation of C-glycosyl styrene is described.
TL;DR: In this paper, a review of M-H reactions of internal olefins with arylor alkyl halides is presented, which is suitable for the reaction of a C(sp)-halide with a terminal olefin to produce a trans-1,2disubstituted olelin.
TL;DR: Asymmetric Heck/amination of nonconjugated cyclodienes proceeds to give substituted cyclohexenylamines in good enantioselectivity and exclusive trans configurations to improve stereoselective anti-attack of external amines.
Abstract: Substituted cyclohexylamines are becoming increasingly important in drug discovery. Asymmetric Heck insertion/amination of nonconjugated cyclodienes proceeds to give 5-aryl cyclohexenylamines with good enantioselectivity and exclusive trans configurations. Primary and secondary anilines, indoline, and benzylamines are suitable amines. The weakly donating diphosphite Kelliphite forms a deep unsymmetrical pocket, which is essential for stereoselective anti attack of amines.
TL;DR: A general intermolecular anti-Michael reductive Heck reaction of α,β-unsaturated esters with organobromides has been developed and preliminary mechanistic studies are consistent with the proposed mechanistic design.
Abstract: A general
intermolecular anti-Michael reductive
Heck reaction of α,β-unsaturated esters with organobromides
has been developed Most topical classes of aryl, heteroaryl, and
vinyl bromides were found to efficiently react with a variety of internal
conjugated alkenes This protocol set up a platform toward diverse
α-arylated 1,6-dicarbonyl frameworks found in natural products
and drugs, which are still highly challenging targets in traditional
α-arylation protocols because of competitive selectivity of
enolation A removable directing group, gram-scale reaction, and modification
of complex molecules have additionally demonstrated that the anti-Michael reductive Heck reaction is a powerful complementary
strategy to the classical α-arylation approaches Preliminary
mechanistic studies are consistent with our proposed mechanistic design
TL;DR: A miscellaneous oxindole synthesis bearing an all-carbon quaternary center enabled by Pd-catalyzed intramolecular cyclization followed by multiple intermolecular Heck reactions of both easily accessible alkene-tethered chlorides and olefins is reported.
23 Jun 2020
TL;DR: γ-Valerolactone (GVL) was proposed as an environmentally benign reaction medium for phosphine-free Pd-catalyzed homogeneous Heck coupling reaction of iodobenzene and styrene derivatives as discussed by the authors.
Abstract: γ-Valerolactone (GVL) was proposed as an environmentally benign reaction medium for phosphine-free Pd-catalyzed homogeneous Heck coupling reaction of iodobenzene and styrene derivatives. Detailed c...
TL;DR: In this paper, a novel triphenylamine-functionalized silsesquioxane monomer (OTS) is synthesized by Heck coupling reaction involving octavinylsilsesquioxanes and (4-bromophenyl)diphenylamines as the substrates, and a multifunctional hybrid porous polymer (HLPP-OTS) via Scholl coupling reaction in the presence of AlCl3.
TL;DR: A simple imine-based covalent organic framework (COF) as heterogeneous ligand for PdII-promoted Heck reaction is reported, opening a route for COF as an intriguing platform to control regioselectivity catalysis.
TL;DR: In this article, a green, facile and efficient water-assisted chemical vapor deposition (H2O-CVD) method was used to synthesize magnetic and hydroxylated carbon nanotubes (NiCNTs-OH) for the Heck reaction.
Abstract: Magnetic and hydroxylated carbon nanotubes (NiCNTs-OH) were synthesized in situ via a green, facile, and efficient water-assisted chemical vapor deposition (H2O-CVD) method. Pd nanoparticles (NPs) were then anchored to the surfaces of the NiCNTs-OH and the resulting Pd/NiCNTs-OH were studied for their catalytic efficiency in the Heck reaction. Transmission electron microscopy images show that the prepared Pd/NiCNTs-OH consist of a CNT-based framework with Pd NPs of 2–4 nm and Ni NPs encapsulated by the tubes. Vibrating sample magnetometer measurements reveal that the catalysts are easily recycled by magnetic separation. Raman spectroscopy, X-ray photoelectron spectroscopy, and density functional theory calculations suggest that defects and oxygen-containing groups are introduced by the H2O-CVD method, providing sufficient anchoring sites for Pd NP loading. Hence, the Pd/NiCNTs-OH exhibit excellent yields in the Heck reaction of various aryl iodides with methyl acrylate. This work thus demonstrates a green and facile method for the preparation of magnetic nano-catalysts that can be employed for various catalytic reactions.
TL;DR: This study has found that, in a reaction where the C–H activation step exhibits a different regio-preference from the subsequent functionalization step, a ligand-enabled switch of the regioselectivity-determining step could provide efficient regiocontrol.
Abstract: Efficient control of regioselectivity is a key concern in transition-metal-catalyzed direct C–H functionalization reactions. Various strategies for regiocontrol have been established by tuning the selectivity of the C–H activation step as a common mode. Herein, we present our study on an alternative mode of regiocontrol, in which the selectivity of the C–H activation step is no longer a key concern. We found that, in a reaction where the C–H activation step exhibits a different regio-preference from the subsequent functionalization step, a ligand-enabled switch of the regioselectivity-determining step could provide efficient regiocontrol. This mode has been exemplified by the Pd(II)-catalyzed aerobic oxidative Heck reaction of indoles, in which a ligand-controlled C3-/C2-selectivity was achieved for the first time by the development of sulfoxide-2-hydroxypyridine (SOHP) ligands.
TL;DR: In this paper, the final catalyst was characterized with FT-IR, nitrogen physisorption, thermogravimetry (TGA), scanning electron microscopy (SEM) combined with energy dispersive X-ray analysis (EDX), transmission electron microscope (TEM), vibrating sample magnetometry (VSM), wide-angle Xray diffraction spectroscopy (XRD) and Xray photoelectron spectroscope (XPS) and was then magnetically separated, washed, and reused 7 times without losing significantly catalytic activity.
Abstract: Magnetic particles were prepared by a hydrothermal method and then successively covered by Metal–Organic-Frameworks MIL-101-NH2 with a high surface area. This was followed by deposition of Pd(OAc)2 on Fe3O4–NH2@MIL-101-NH2 particles. The final catalyst was characterized with FT-IR, nitrogen physisorption, thermogravimetry (TGA), scanning electron microscopy (SEM) combined with energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), wide-angle X-ray diffraction spectroscopy (XRD) and X-ray photoelectron spectroscopy (XPS). The prepared magnetic catalyst was effectively used in the Heck coupling reaction in the presence of an inorganic base. The reaction parameters such as the base type, amounts of catalyst and solvents, temperature, and substrates ratios were optimized. The catalyst was then magnetically separated, washed, and reused 7 times without losing significantly catalytic activity.