Showing papers on "Heck reaction published in 1997"
432 citations
TL;DR: Cyclopalladated complexes of the general formula [Pd2(μ-L)2(PC)2] (L = bridging ligand, e.g. OAc, Cl, Br, I; PC = cyclometallated P donor) are highly efficient catalysts for the Heck vinylation of aryl halides.
Abstract: Cyclopalladated complexes of the general formula [Pd2(μ-L)2(PC)2] (L = bridging ligand, e.g. OAc, Cl, Br, I; PC = cyclometallated P donor, e.g. o-CH2C6H4P(o-Tol)2 or o-CH2C6H2(CH3)2-P(Mes)2) are highly efficient catalysts for the Heck vinylation of aryl halides. The isolated complexes are easily accessible from palladium(II) acetate by spontaneous metallation of ortho-methyl-substituted arylphosphines. They display improved activity and stability compared to conventional catalyst mixtures (e.g. [Pd(OAc)2] +nPPh3), and also exhibit a higher stability towards air than conventional Pd0-based systems (e.g. [Pd(PPh3)4]). Turnover numbers (TON) of up to 1000000 and turnover frequencies (TOF) in the range of 5000-20000 are achieved in catalytic coupling reactions of aryl bromides. Even technically interesting aryl chlorides undergo the Heck reaction (TON = 600-40000) if promoting salts are added to the catalyst ((NBu4)Br, LiBr). The new structural type for catalysts is compared to palladacycles formed in situ from mixtures of [Pd(OAc)2] + P(o-tolyl)3 and the established [Pd(OAc)2] + nPPh3 system. The scope of the new CC coupling catalysts is outlined for the vinylation of aryl halides by the use of different mono- and disubstituted olefins. Mechanistic consequences for the Heck reaction in general are discussed.
362 citations
TL;DR: In this article, a block copolymer stabilized palladium colloid was used for the Heck reaction, which was successfully applied for the Pd-catalyzed carbon−carbon coupling of aryl halides with alkenes.
Abstract: Colloidal dispersions of nanometer sized palladium colloids with very high stability were prepared in block copolymer micelles of polystyrene-b-poly-4-vinylpyridine and analyzed by electron microscopy and X-ray analysis. The resulting polymer/metal hybrids can easily be dissolved and handled in standard organic solvents such as toluene, tetrahydrofuran, and cyclohexane. They were successfully used for the Pd-catalyzed carbon−carbon coupling of aryl halides with alkenes (Heck reaction). Such block copolymer stabilized palladium colloids exhibit about the same reactivity as low molecular weight Pd complexes classically used for the Heck reaction, but show a much higher stability: in most reactions, the hybrids remain catalytically active even after 50000 turn-over cycles. Reaction rates were significantly controlled by the reactivity of the educts, but also respond to micelle architecture and dispersity of the palladium. Other advantages of the block copolymer stabilizer are that they are more simple and r...
330 citations
264 citations
226 citations
TL;DR: Palladium grafted mesoporous MCM-41 materials, prepared by vapor grafting, show remarkable activity in Heck carbon-carbon coupling reactions as discussed by the authors, demonstrating that the material can be used to construct mesopore MCM41 materials.
122 citations
114 citations
TL;DR: In this paper, the enantioselectivities arising from a Pd-catalyzed Heck reaction (>98% ee) and an allylic alkylation using a 3,5-di-tert-butyl-MeO−BIPHEP chiral auxiliary (1) are reported.
Abstract: The enantioselectivities arising from a Pd-catalyzed Heck reaction (>98% ee) and an allylic alkylation (>90% ee) using a 3,5-di-tert-butyl-MeO−BIPHEP chiral auxiliary (1) are reported. Higher ee's are observed with the 3,5-dialkyl substituents than with the unsubstituted parent MeO−BIPHEP. It is proposed that the observed dialkyl “meta-effect”, on enantioselectivity, is the combined result of a more rigid and slightly larger chiral pocket and that this effect will have some generality in homogeneous catalysis. Detailed NMR studies on the allyl complex [Pd(PhCHCHCHPh)(1)]PF6 (5), and the model hydrogenation catalyst [RuH(cymene)(1)]BF4 (6), reveal restricted rotation about several of the P−C(ipso) bonds of the phosphorus substituents containing the 3,5-di-tert-butyl groups. The X-ray structure of 6 reveals that the cymene ligand is not symmetrically bound to the Ru atom. This observation is interpreted as an expression of the chiral pocket of 1. MM3* calculations on 6 support the NMR findings and reproduce...
110 citations
90 citations
TL;DR: In this article, an amorphous carbon-activated palladium metallic clusters have been prepared at room temperature by ultrasound irradiation of an organometallic precursor, tris-μ-[dibenzylideneacetone]dipalladium [(φ-CHCH−CO−CHCH-φ)3Pd2] in mesitylene.
Abstract: Nanostructured particles of amorphous carbon-activated palladium metallic clusters have been prepared (in situ) at room temperature by ultrasound irradiation of an organometallic precursor, tris-μ-[dibenzylideneacetone]dipalladium [(φ-CHCH−CO−CHCH-φ)3Pd2] in mesitylene. Characterization by elemental analysis, transmission electron microscopy, differential scanning calorimetry, X-ray diffraction, X-ray photoelectron spectroscopy, and BET surface area measurements shows that the product powder consists of nanosize particles, agglomerated in clusters of approximately 800 A. Each particle is found to have a metallic core, covered by a carbonic shell that plays an important role in the stability of the nanoparticles. The catalytic activity in a Heck reaction, in the absence of phosphine ligands, has been demonstrated.
80 citations
TL;DR: The Heck reaction of trimethylsilylacetylene with N-t-Boc-4-iodo-L-phenylalanine methyl ester gives N-boc 4-ethynyl-L -phenylalane methyl esters (2) as discussed by the authors.
TL;DR: In this paper, the pentacyclic 5,11methanomorphanthridine Amaryllidaceae alkaloids (−)-montanine (1), (−)-coccinine (2), and (−)-pancracine (3) were achieved using an intramolecular concerted pericyclic allenylsilane imino ene cycloaddition as a key step.
Abstract: Enantioselective total syntheses of the pentacyclic 5,11-methanomorphanthridine Amaryllidaceae alkaloids (−)-montanine (1), (−)-coccinine (2), and (−)-pancracine (3) were accomplished using an intramolecular concerted pericyclic allenylsilane imino ene cycloaddition as a key step. These complex natural products were constructed starting from readily available enantiomerically pure epoxy alcohol 15 which was converted to allenylsilane aldehyde 28 via an efficient nine-step sequence. The imine generated from aldehyde 28 and iminophosphorane 47 underwent a stereospecific thermal imino ene reaction to afford key intermediate cis aminoalkyne 49. It was possible to transform this compound via Lindlar hydrogenation followed by an intramolecular Heck reaction to seven-membered ring tetracycle 51. This olefinic intermediate could be functionalized through its epoxide to yield α-hydroxymethyl intermediate 54, and then pentacyclic alcohol 64. Procedures were then developed to convert this material to the enantiomeri...
TL;DR: In this paper, a brief review of the palladium-catalyzed olefination and amination of aryl chlorides is presented, with special emphasis on the efficiency of known catalysts.
Abstract: In this paper we report a brief review of the palladium–catalyzed olefination and amination of aryl chlorides. Special emphasis is given on the efficiency of known catalysts. Best turnover numbers (TON up to 40,000) known to date for Heck reactions are displayed by palladacycle catalysts, e.g., 1 in the presence of salts as co–catalysts. Model studies show that the catalyst productivity is strongly influenced by the nature of the added salt. In addition, the ability of mixtures of Pd(OAc)2 and phosphines to catalyze the reaction of styrene with 1–chloro–4–trifluoromethylbenzene was studied dependent on the Pd:P ratio. It was found that apart from the palladacycle 1 a number of established phosphines permit efficient C–Cl activation. Amination of aryl chlorides is also possible in the presence of palladacycles as catalyst precursors. Crucial for the success of the C–N bond forming reaction is the use of potassium tert–butoxide as base and reaction temperatures > 120°C. Turnover numbers up to 900 and yields up to 80% have been obtained for the amination of 1–chloro–4–trifluoromethylbenzene.
TL;DR: In this article, solid phase intramolecular Heck coupling allows the synthesis of 2-oxindoles and additional diversity is introduced into the molecule by reductive alkylation prior to the Heck cyclisation and also by conjugate addition of a variety of nucleophiles onto the cyclised product prior to cleavage.
TL;DR: Chiral 2,2′-bis(diphenylarsino)-1,1′-binaphthyl (BINAs) was synthesized and found to be an effective ligand in an alkenyl iodide-using intramolecular asymmetric Heck reaction as discussed by the authors.
TL;DR: In this paper, the authors investigated the use of other metal catalysts for the Heck reaction based on the known mechanism of the Pd catalyzed vinylation reaction and reported the first use of these stable Ni(0) metal complexes, for the activation of aryl halides for reaction with olefins (Heck reaction) and alkynes.
TL;DR: In this paper, the synthesis of 1,2,3,4,11,11ahexahydrocyclopropa[c]naphtho[2,1−b]azepin-6-one (CNA), a seven-membered C-ring analog of the alkylation subunits of CC-1065 and the duocarmycins, is detailed.
Abstract: The synthesis of 1,2,3,4,11,11a-hexahydrocyclopropa[c]naphtho[2,1−b]azepin-6-one (CNA), a seven-membered C-ring analog of the alkylation subunits of CC-1065 and the duocarmycins, is detailed. The core structure of CNA was prepared through the implementation of an intramolecular Heck reaction for assemblage of the key tricyclic tetrahydronaphtho[2,1−b]azepine skeleton and a final Winstein Ar-3' spirocyclization for introduction of the reactive cyclopropane. A study of the solvolysis reactivity of N-BOC-CNA revealed that incorporation of the seven-membered fused C-ring system increased the reactivity 4750× compared to the corresponding five-membered C-ring analog. Solvolysis occurs with SN2 nucleophilic attack at the more substituted carbon of the activated cyclopropane to afford exclusively the abnormal ring expansion product in a reaction that was shown to proceed with complete inversion of configuration at the reaction center. Single crystal X-ray structure analyses of N-CO2Me-CNA (29) and CNA (11) and t...
TL;DR: A high molecular weight poly(2,5-dialkoxy-p-phenyleneethynylene) derivative has been prepared by the Heck reaction of 1,4-bis(2-ethylhexyloxy)-2-5-diiodobenzene and 1, 4-diethynyl-2, 5-dioctyloxybenzene.
Abstract: A high-molecular-weight poly(2,5-dialkoxy-p-phenyleneethynylene) derivative has been prepared by the Heck reaction of 1,4-bis(2-ethylhexyloxy)-2,5-diiodobenzene and 1,4-diethynyl-2,5-dioctyloxybenzene. The highly luminescent polymer exhibits excellent solubility and can readily be processed into high-optical-quality films. The weight-average molecular weight Mw was 240000 g · mol−1, with a polydispersity index of 2.9. Thermal analysis revealed a glass transition around 90°C, and an onset of chemical crosslinking at 130°C. The high Mw and the remarkable solubility enabled the preparation of liquid crystalline solutions of the new PPE.
TL;DR: In this article, the Heck reaction was applied to poly(p-phenylenevinylene) derivatives with long alkyl side chains and the 1H-NMR measurement showed that these polymers have well-defined primary structures without defects such as mislinkages.
TL;DR: In this paper, a novel intramolecular macrocyclization reaction on solid support using Heck reaction was achieved, where the Heck coupling of acrylic acid amide to 3-iodobenzylamine on solid-support proceeds smoothly to yield a cyclic tetrapeptide derivative containing a new 3-substituted cinnamic acid template and Arg-Gly-Asp sequence.
TL;DR: In this article, the development of the intermolecular and intramolecular asymmetric Heck reactions catalysed by palladium complexes of chiral diphosphine ligands, mainly (R)−BINAP, is reviewed.
Abstract: The development of the intermolecular and intramolecular asymmetric Heck reactions catalysed by palladium complexes of chiral diphosphine ligands, mainly (R)–BINAP, is reviewed. Recent developments using chiral phosphinamine ligands, including some preliminary results on the application of new diphenylphosphinopyrrolidine ligands to the intermolecular asymmetric Heck, are presented. These ligands show good regioselectivities but moderate enantioselectivities when compared to the phosphinooxazoline ligands. The latter class has extended the range of substrates to which the asymmetric Heck can be applied and exhibit better reactivities, regioselectivities and enantioselectivities when compared to (R)–BINAP. The exploitation of the intramolecular asymmetric Heck reaction in total synthesis is demonstrated through asymmetric approaches to a range of bioactive natural products. Some of the more recent mechanistic investigations of the Heck reaction are also discussed.
TL;DR: In this paper, a supported palladium complex on zirconium phosphite-phosphonate was made from triphenylphosphine phosphonic acid, which showed significant selectivity in the competitive Heck reaction between iodobenzene and different iodobenzoates.
TL;DR: Tetrahydro- and hexahydrobenzo[a]quinolizinones can be built up efficiently by means of a two step reaction sequence consisting of a tandem Mannich-Michael reaction and a Heck reaction as mentioned in this paper.
TL;DR: A convergent catalytic asymmetric synthesis of 4 which utilizes as key steps, two Heck reactions, a Sharpless asymmetric dihydroxylation reaction, and a Mitsunobu reaction.
Patent•
14 May 1997
TL;DR: In this article, a method for catalyzed organic reactions comprising a heating step with microwave energy was proposed, in which new carbon-carbon bonds were formed, and preferred reactions are the Heck, Stille and Suzuki reactions.
Abstract: The present invention relates to a method for organic reactions. More specifically, a method for palladium, except Pd/C, catalyzed organic reactions comprising a heating step with microwave energy. One type of organic reactions concerned are coupling reactions, in which new carbon-carbon bonds are formed. Preferred reactions are the Heck, Stille and Suzuki reactions. The method provides high yields in very short reaction times.
TL;DR: A study on the gegenion effect in Heck reaction of arenediazonium salts has given rise to arenediaonium perchlorates and fluorides as alternate Heck-substrates to the tetrafluoroborate salts as mentioned in this paper.
Book•
18 Feb 1997
TL;DR: In this article, the authors describe a series of reactions that are triggered by Palladium complexes: cross-coupling of Organometallics with RCOX Derivatives.
Abstract: Abbreviations. Introduction. Graphical Abstracts of Reaction Numbers (RXN). Reactions Catalyzed by Palladium Complexes: Cross-Coupling of Organometallics with RX Derivatives. Cross-Coupling of Organometallicswith RCOX Derivatives. Cross-Coupling of Siloxycyclopropanes with RX and RCOX Derivatives. Cross-Coupling of Terminal Alkynes with RX Derivatives. Intermolecular HECK Reaction. Intramolecular HECK Reaction. Intramolecular Coupling of Di(Vinyl Halides). Tandem HECK-Anion Capture Process of Alkenes, Alkyenes, Alkynes, Allenes and Dienes. Tandem HECK-Anion Capture Process of Norbonene and Related Compounds. Tandem Arylsulfonation-Cyclization Process. Tandem Cyclization-Anion Capture (-Carbonylation) Processof Alkenes and Alkynes. Tandem Cyclization-Anion Capture (-Carbonylation) Process of Ene-Vinyl, Ene-Aryl, and Ene-Alkyl Halides. Tandem Cyclization-Anion Capture Process of Yne-Vinyl and Yne-Aryl Halides. Hydroarylation and Hydrovinylation of Alkenes andAlkynes. Reduction of Alkenes. Semihydrogenation of Alkynes and 1,3-Dienes. Hydroboration, Hydrogennyladon, Hydrosilylation and Hydrostannation of Alkynes, Allenes, Dienes, and Enynes. Hydroselenation of Alkynes. 1,4-Disilyation of Conjugated Enones. Hydrocarboxylation, Hydrocarboalkoxylation and Hydrocarboamination of Alkenes and Alkynes. Tandem Carbonylation-Arylation with Alkynes. 1,2-Dimetallation of Alkynes and Alkenes and Related Reactions. 1,2-Dimetallation of Isonitriles. 1,2-Dimetallation of Allenes. Coupling of Aryl Derivatives with Alkenes Involving a Pd(II) Catalyst. Homocoupling of Aryl and Vinyl Derivatives. Codimerization of Alkynes. Codimerization of Terminal Alkynes with Allenes. Codimerization of Alkynes and Allyl Halides. Cyclopropanation of Alkenes and 1,3-Dienes by Diazomethane. Rearrangement of (-Hydroxy Diazo Compounds. Substitution, Addition, and Elimination on Pro-(-Allyl Substrates. [3,3]-Sigmatropic Rearrangement and [1,3]-Shift on Allylic Derivatives. 1,3-Diene Monoepoxide Rearrangement. Ring Extension of Cyclobutane Derivatives. [3+2], [3+4], [3+6], [1+2] Cycloadditions. Intramolecular Ene-Like Reactions. Cyclization of Hexatrienolate Derivatives. Amination or Amidation of Alkenes. Alkoxylation of Alkenes and Alkynes. Acetalization of Alkenes. Allylic Acyloxylation of Cycloalkenes. Tandem Acyloxylation-Cyclization of 1,5-Dienes. Tandem Acycloxychlorination-Cyclization of 1,6-Dienes. 1,4-Acycloxychlorination of 1,3-Dienes. 1,4-Diacyloxylation of 1,3-Dienes and Related Reactions. Intramolecular Amination, Alkoxylation of Acyloxylation of Alkynes. Tandem Intramolecular Amination, Alkoxylation, or Acyloxylation-Allylation of Alkynes and Allenes. Tandem Intramolecular Amination, Alkoxylation, or Acyloxylation-Carbonylation of Alkynes. Intramolecular Amination or Alkoxylation of Alkenes. Tandem Intramolecular Amination or Alkoxylation-Carbonylation of Alkenes and Allenes. Reductive Cyclization with Diynes and Enynes. Cycloisomerization of Diynes and Enynes. Cycloaddition of Aziridines with Carbodiimides. Telomerization of 1,3-Dienes with Nucleophiles. WACKER Process. Preparation of Ketones from Alcohols or Derivatives via a (-Hydride Elimination. Preparation of ((-Unsaturated Carbonyl Derivatives via a (-Hydride Elimination. Preparation of (-Diketones Derivatives via an Oxidative Rearrangement of a Propargyl Acetate. Carbonylation. Isomerization of Alkynes. Addition of Thiols to Alkynes. Preparation of Allylic Acetates from Alkynes by Tandem Redox-Addition. Tandem Cyclization-Capture Process of Enynes. Aldol-Like Condensation of Enol Esters with Aldehydes. Addition of Fluoroalkyl Iodides to Alkenes or Alkynes via a Pd(I) Species. Intermolecular Tandem Carbonylation-Coupling-Cyclization Process of Aryl Halides with Terminal Alkynes.Intramolecular Coupling of Aryl Halides with Arenes. Tandem Intramolecular Alkoxylation-Vinylation of Alkenes. Carbonylative [2+2] Cycloaddition. Dicarboalkoxylation of Alkenes. Addition of Pronucleophiles on 1,3-Dienes or Allenes. Tandem Cycloisomerization-Cycloaddition of Dienynes with 1,3-Dienes via Metallodienes. Acylcyanation of Terminal Alkynes. 1,4-Carbochlorination of 1,3-Dienes. Tandem Chlorination-Cyclization and Tandem Chlorination-Carbonylation-Cyclization of 1,6-Enynes. Intramolecular Cyclocarbonylation of Alkenes. Abbreviations and Symbols. Notes. Subject Index.