- Mechanochemical Oxidative Heck Coupling of Activated and Unactivated Alkenes: A Chemo-, Regio- and Stereo-Controlled Synthesis of Alkenylbenzenes
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In this work, we present an efficient mechanochemical strategy for chemo-, regio- and stereo-selective oxidative Heck coupling of readily accessible arylboron reagents/heteroaromatics with cyclic and acyclic olefins. Mono- and bis-arylation were achieved without the need of ligands, directing groups or prefunctionalized alkenes, and the reaction chemo-selectivity could be controlled by tuning of the oxidative system. This protocol offers the synthesis of alkenylbenzenes in broad substrate scope, satisfactory yields and excellent selectivity even in the gram scale. (Figure presented.).
- Yu, Jingbo,Shou, Haowen,Yu, Wangyang,Chen, Haodong,Su, Weike
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supporting information
p. 5133 - 5139
(2019/11/11)
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- Preparation method of inactive alkene aryl compound
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The invention discloses a preparation method of an inactive alkene aryl compound. The preparation method comprises steps as follows: arylboronic acid and inactive alkene are taken as raw materials andsubjected to an oxidization Heck reaction with a mechan
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Paragraph 0075; 0076
(2019/06/05)
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- N-Acylsaccharins as Amide-Based Arylating Reagents via Chemoselective N-C Cleavage: Pd-Catalyzed Decarbonylative Heck Reaction
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Palladium-catalyzed decarbonylative Heck reaction of amides by chemoselective N-C activation using N-acylsaccharins as coupling partners has been accomplished. These studies represent only the second example of amide-Heck reactions reported to date. A broad range of electronically diverse amide and olefin coupling partners is amenable to this transformation. Orthogonal site-selective Heck cross-couplings by C-Br/N-C cleavage and mechanistic studies are reported. This report introduces readily available, bench-stable, cheap, and benign N-acylsaccharins as aryl transfer reagents to access versatile aryl-metal intermediates.
- Liu, Chengwei,Meng, Guangrong,Szostak, Michal
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p. 12023 - 12030
(2016/12/09)
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- Ligand-Controlled Palladium-Catalyzed Alkoxycarbonylation of Allenes: Regioselective Synthesis of α,β- and β,γ-Unsaturated Esters
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The palladium-catalyzed regioselective alkoxycarbonylation of allenes with aliphatic alcohols allows to produce synthetically useful α,β- and β,γ-unsaturated esters in good yields. Efficient selectivity control is achieved in the presence of appropriate ligands. Using Xantphos as the ligand, β,γ-unsaturated esters are produced selectively in good yields. In contrast, the corresponding α,β-unsaturated esters are obtained with high regioselectivity in the presence of PPh2Py as the ligand. Preliminary mechanistic studies revealed that these two catalytic processes proceed by different reaction pathways. In addition, this novel protocol was successfully applied to convert an industrially available bulk chemical, 1,2-butadiene, into dimethyl adipate, which is a valuable feedstock for polymer and plasticizer syntheses, with high yield and TON (turnover number).
- Liu, Jie,Liu, Qiang,Franke, Robert,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 8556 - 8563
(2015/07/15)
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- General Olefin Synthesis by the Palladium-Catalyzed Heck Reaction of Amides: Sterically Controlled Chemoselective N-C Activation
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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 Pd0 utilizing amide bond ground-state destabilization. Conceptually, this transformation provides access to a myriad of metal-catalyzed transformations of amides via metal insertion/decarbonylation.
- Meng, Guangrong,Szostak, Michal
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supporting information
p. 14518 - 14522
(2016/01/25)
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- Heck reactions catalyzed by Pd(0)-PVP nanoparticles under conventional and microwave heating
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Pd(0) nanoparticles stabilized by polyvinylpyrrolidone (Pd-PVP) with a diameter of 3-6 nm in ethanol catalyzed Heck coupling of iodobenzene with different alkenes under microwave heating. Products were obtained in good yields (62-99%) and good selectivity to the E-isomers. Microwave heating proved to be superior to conventional heating, providing products in higher yields and selectivities in short times (12 min).
- Martins, Daniela De L.,Alvarez, Heiddy M.,Aguiar, Lúcia C.S.,Antunes, Octavio A.C.
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experimental part
p. 47 - 53
(2012/04/11)
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- Hydroxypropyl-a-cyclodextrin-capped palladium nanoparticles: active scaffolds for efficient carbon-carbon bond forming cross-couplings in water
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A new approach for the preparation of palladium nanoparticles in water from a renewable source, 2-hydroxypropyl-a-cyclodextrin (a-HPCD), which acts both as a reductant and capping agent, is presented. The palladium nanoparticles were characterized by using dynamic light scattering (DLS), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), which revealed the formation of spherical particles in the size range of 2-7 nm. Further analysis by Fourier-transform infrared spectroscopy (FT-IR) and 1H NMR did not show covalent bonds between cyclodextrins and palladium nanoparticles, suggesting that a-HPCD is only physically adsorbed on the nanoparticle surface, presumably through hydrophobic interactions which limit the mutual coalescence of nanoclusters. The catalytic activity was tested in Suzuki, Heck and Sonogashira reactions in neat water, providing good yields and selectivities of coupling products under very low Pd loadings (0.5-0.01 mol%). Remarkably, the nanocatalyst showed significant stability hence the aqueous phase remained active for four subsequent runs. The combination of a binding site for substrates (the HPCD cavity) and a reactive centre (Pd core) provides a potential to explore functional catalysis in aqueous medium.
- Senra, Jaqueline D.,Malta, Luiz Fernando B.,Da Costa, Marcelo E. H. M.,Michel, Ricardo C.,Aguiar, Lucia C. S.,Simas, Alessandro B. C.,Antunes
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supporting information; experimental part
p. 2411 - 2422
(2009/12/28)
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- General, Robust, and stereocomplementary preparation of α,β-disubstituted α,β-unsaturated esters
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An (E)- and (Z)-stereocomplementary preparative method for α,β-disubstituted α,β-unsaturated esters Is performed via three general and robust reaction sequences: (i) TI-Claisen condensation (formylation) of esters to give α-formyl esters (12 examples, 60-99%), (II) (E)- and (Z)-stereocomplementary enol ρ-toluenesulfonylation (tosylation) using TsCI-N-methylimidazole (NMI)-Et3N and LiOH (24 examples, 82-99%), and (iii) stereoretentive Suzuki-Miyaura cross-coupling (18 examples, 64-96%).
- Nakatsuji, Hidefumi,Nishikado, Hiroshi,Ueno, Kanako,Tanabe, Yoo
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experimental part
p. 4258 - 4261
(2009/12/28)
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- Palladium on calcium carbonate combined to 2-hydroxypropyl-α/β- cyclodextrins: A selective catalytic system for aqueous heck coupling and hydroarylation
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An efficient, selective and recoverable catalytic system for ligand-free aqueous Heck reactions using hydroxypropylated cyclodextrins (HPCDs) and palladium on calcium carbonate (Pd/CaCO3) is highlighted. Remarkably, stereo- and chemoselectivities could be tuned by the cavity size of cyclodextrins, exploiting the relevance of host-guest interactions. UVVis experiments have led to strong evidence concerning an interplay between Pd(II) and α-HPCD, possibly ascribed to a reduction/stabilization effect of CDs. Unexpectedly, hydroarylation was the favored pathway with acrylonitrile which provided access to 3-phenylpropionitrile derivatives without usual hydride donors. Finally, determination of soluble Pd(0/II) via AAS enabled the definition of a predominant homogeneous mechanism in which TONs over 5000 were observed.
- Senra, Jaqueline D.,Malta, Luiz Fernando B.,Souza, Andrea Luzia F.,Aguiar, Lucia C. S.,Antunesa
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supporting information; experimental part
p. 2551 - 2558
(2009/08/14)
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- Tandem oxidation of allylic and benzylic alcohols to esters catalyzed by N-heterocyclic carbenes
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(Chemical Equation Presented) N-Heterocyclic carbenes catalyze the oxidation of allylic, propargylic, and benzylic alcohols to esters with manganese(IV) oxide in excellent yields. A variety of ester derivatives can be synthesized, including protected carboxylates. This one-pot tandem oxidation represents the first organocatalytic oxidation of alcohols to esters. Saturated esters can also be accessed from aldehydes using this method. Through the utilization of a chiral catalyst, the acyl-heteroazolium intermediate becomes a chiral acylating agent, which can desymmetrize meso-1,2-diols.
- Maki, Brooks E.,Chan, Audrey,Phillips, Eric M.,Scheidt, Karl A.
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p. 371 - 374
(2007/10/03)
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- The design and synthesis of bis(thiourea) ligands and their application in Pd-catalyzed heck and suzuki reactions under aerobic conditions
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New, bulky N,N-disubstituted acyclic and cyclic bis(thiourea) ligands have been designed and synthesized. Their palladium(0) complexes are very stable and are active catalysts for Heck and Suzuki coupling reactions of aryl iodides and bromides under aerobic conditions. Good TONs and TOFs were achieved in the coupling reactions [for PhI, TONs up to 1000000 and TOFs up to 200000 (h -1); for activated aryl bromide, TONs up to 89000]. In addition, further studies were conducted to know more about the nature of these catalysts. The active catalyst was found to be the chelate complex containing the bis(thiourea) and Pd in a 1:1 ratio. However, unlike a monothiourea, further coordination can occur to give a coordinatively saturated complex when bis(thiourea) and Pd are combined in a 2:1 ratio; this complex is catalytically inactive in coupling reactions. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Chen, Wei,Li, Rui,Han, Bo,Li, Bang-Jing,Chen, Ying-Chun,Wu, Yong,Ding, Li-Sheng,Yang, Dan
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p. 1177 - 1184
(2007/10/03)
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- Coordination Chemistry and Mechanisms of Metal-Catalyzed C-C Coupling Reactions, Part 12. Nonaqueous Ionic Liquids: Superior Reaction Media for the Catalytic Heck-Vinylation of Chloroarenes
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Nonaqueous ionic liquids, that is molten salts, constitute an activating and stabilizing noninnocent solvent for the palladium-catalyzed Heck-vinylation of all types of aryl halides. Especially with chloroarenes an improved activity and stability of almost any known catalyst system is observed as compared to convetional, molecular solvents (e.g. dimethylformamide (DMF), dimethylacetamide (DMAc), N-methyl-2-pyrrolidinone (NMP), or dioxane). Thus, even catalytic amounts of ligand-free PdCl2 yield stilbene from technically interesting chlorobenzene and styrene in high yield (turnover number (TON) = 18) without the need for further promoting salt additives such as tetraphenylphosphonium chloride. The scope of the new reaction medium is outlined for the first time for the vinylation of various aryl halides using different mono- and disubstituted olefins as well as a variety of known palladium(0) and palladium(II) catalyst systems. Furthermore, a novel means of catalyst recycling is presented and its scope is evaluated.
- Boehm, Volker P. W.,Herrmann, Wolfgang A.
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p. 1017 - 1025
(2007/10/03)
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