- Palladium-Catalyzed meta-C-H Olefination of Arene-Tethered Diols Directed by Well-Designed Pyrimidine-Based Group
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The palladium-catalyzed meta-olefination of arene-tethered diols attached to a well-designed pyrimidine moiety is presented. Applications of the protocol are illustrated by the synthesis of various diol-based natural products, such as coumarins, phenylpropanoids, stilbenes, and chalcones. Advantages of this method are demonstrated through the easy removal of the template and a gram-scale olefination reaction. Finally, experimental verification, including 1H NMR, ESI-MS and IR, and DFT studies are undertaken to elucidate the mechanistic complexity.
- Fang, Siqiang,Wang, Xiaobing,Yin, Fucheng,Cai, Pei,Yang, Huali,Kong, Lingyi
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supporting information
(2019/03/19)
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- Evaluation of Potential Safety Hazards Associated with the Suzuki-Miyaura Cross-Coupling of Aryl Bromides with Vinylboron Species
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The potential safety hazards associated with the Suzuki-Miyaura cross-coupling of aryl bromides with vinylboron species were evaluated. In the Suzuki-Miyaura cross-coupling of 1-bromo-3-(trifluoromethyl)benzene with potassium vinyltrifluoroborate in the presence of potassium carbonate (K2CO3) in 9:1 dimethyl sulfoxide (DMSO)/water at 80 °C, the thermal profile revealed a significant exotherm upon the addition of catalytic 1,1′-bis(diphenylphosphino)ferrocene palladium(II) dichloride [Pd(dppf)Cl2]. Further investigations indicated that the exotherm was consistently higher and the reactions were faster in the studied aqueous systems compared to anhydrous conditions. Although under anhydrous conditions the exotherms were comparable among the studied cases, the rate of the exotherm was highly dependent on the choice of aryl electrophile, solvent, base, catalyst, as well as vinylboron species. In many of the studied cases the maximum temperature of a synthesis reaction (MTSR) was considerably higher than the boiling point of the solvent and/or the onset temperature of the DMSO decomposition, indicating that in the absence of active cooling the system could quickly exceed the boiling point of the solvent or trigger the decomposition of the reaction mixture to result in a runaway reaction.
- Yang, Qiang,Canturk, Belgin,Gray, Kaitlyn,McCusker, Elizabeth,Sheng, Min,Li, Fangzheng
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p. 351 - 359
(2018/03/22)
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- Regio- and chemoselective rearrangement of terminal epoxides into methyl alkyl and aryl ketones
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The development of the highly active pincer-type rhodium catalyst 2 for the nucleophilic Meinwald rearrangement of functionalised terminal epoxides into methyl ketones under mild conditions is presented. An excellent regio- and chemoselectivity is obtained for the first time for aryl oxiranes.
- Tian, Yingying,Jürgens, Eva,Kunz, Doris
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supporting information
p. 11340 - 11343
(2018/10/31)
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- Isomerizing ethenolysis as an efficient strategy for styrene synthesis
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A shrinking chain: A bimetallic system consisting of [{Pd(μ-Br)(tBu 3P)}2] and a ruthenium metathesis catalyst has been found to efficiently promote the cross-metathesis between substituted alkenes and ethylene, while continuously migrating the double bond along the alkenyl chain (see scheme). When alkenylarenes, such as the natural products eugenol, safrol, or estragol, were treated with this catalyst under an ethylene atmosphere, they were cleanly converted into the corresponding styrenes and propylene gas. Copyright
- Baader, Sabrina,Ohlmann, Dominik M.,Goossen, Lukas J.
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supporting information
p. 9807 - 9810
(2013/08/23)
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- Nickel-catalyzed heck-type reactions of benzyl chlorides and simple olefins
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Nickel-catalyzed intermolecular benzylation and heterobenzylation of unactivated alkenes to provide functionalized allylbenzene derivatives are described. A wide range of both the benzyl chloride and alkene coupling partners are tolerated. In contrast to analogous palladium-catalyzed variants of this process, all reactions described herein employ electronically unbiased aliphatic olefins (including ethylene), proceed at room temperature, and provide 1,1-disubstituted olefins over the more commonly observed 1,2-disubstituted olefins with very high selectivity.
- Matsubara, Ryosuke,Gutierrez, Alicia C.,Jamison, Timothy F.
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supporting information; experimental part
p. 19020 - 19023
(2011/12/21)
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- Process of heterocoupling by electrolytic microbattery, use of cobalt for implementing said coupling and composition for doing so
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This invention has as its object a process for preparation of vinyl aryl derivatives by an electrochemical path. This process is defined in that it consists in subjecting a composition that comprises a cobalt salt, an aromatic halide and a vinyl ester to the action of a metal that is at least as reducing as zinc. Application to organic synthesis.
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- New chemical cross-coupling between aryl halides and allylic acetates using a cobalt catalyst
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(Figure presented) The cobalt-catalyzed coupling reaction of aromatic halides and allylic acetates proceeds readily under mild conditions in the presence of the appropriate reducing agent to produce allylaromatic derivatives either in pure acetonitrile (aryl bromides) or in an acetonitrile/pyridine mixture (aryl chlorides).
- Gomes, Paulo,Gosmini, Corinne,Perichon, Jacques
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p. 1043 - 1045
(2007/10/03)
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- Cobalt-catalyzed direct electrochemical cross-coupling between aryl or heteroaryl halides and allylic acetates or carbonates
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The electroreduction of a mixture of functionalized aromatic or heteroaromatic bromides or chlorides and allylic compounds such as acetates or carbonates in an electrochemical cell fitted with a sacrificial iron anode affords, in the presence of cobalt halide associated with pyridine as ligand in acetonitrile or DMF, the corresponding coupling product in good yields.
- Gomes, Paulo,Gosmini, Corinne,Perichon, Jacques
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p. 1142 - 1145
(2007/10/03)
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- Nickel-catalyzed direct electrochemical cross-coupling between aryl halides and activated alkyl halides
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The electrochemical reduction of a mixture of aryl halides and activated alkyl halides in DMF in the presence of catalytic amount of NiBr2bipy leads to cross-coupling products in good to high yields. The method applies to the synthesis of α-aryl ketones, α-aryl esters, and allylated compounds from readily available organic halides. Optimization of the process has been obtained by slowly adding the most reactive organic halide (usually the activated alkyl halide) during the electrolysis which is best conducted at 70 °C when aryl bromides are involved.
- Durandetti, Muriel,Nedelec, Jean-Yves,Perichon, Jacques
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p. 1748 - 1755
(2007/10/03)
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- Syntheses of (S)-fenfluramine from (R) or (S)-1-propan-2-ol
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(R) and (S)-1-propan-2-ol 3 are useful intermediates in the synthesis of fenfluramine (S)-1.They can be obtained from optically active propylene oxide (R) or (S)-7.The alcohol (R)-3 was transformed in two steps into (S)-fenfluramine using the action of ethylamine on a sulfonate (R)-4.We describe a new one-pot synthesis for (S)-fenfluramine from the azide (S)-5, which was obtained from the alcohol (R)-3 in two steps.We also propose an original and rapid procedure to transform the alcohol (S)-3 into (S)-fenfluramine via the chloride (R)-14 and the azide (S)-5, without preliminary inversion of the alcohol.All of these reactions have been achieved without any loss of chirality.Keywords - 1-propan-2-ol / fenfluramine / asymmetric synthesis / chiral methyloxirane / nucleophilic substitution
- Goument, B.,Duhamel, L.,Mauge, R.
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p. 450 - 458
(2007/10/02)
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- Epoxides, amino alcohols, and aziridines as key intermediates in the asymmetric synthesis of (S)-fenfluramine
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The epoxides 3E, 3Z and 8 were obtained from the isomeric alkenes 2E, 2Z and 7.The epoxides were ring-opened by ethylamine in ethanol yielding mixtures of the amino alcohols 4E and 11E, 4T and 11T, and 9, respectively, which were transformed into the aziridines 5trans, 5cis and 12.The regiospecific Pd/C-catalyzed reduction of these aziridines gave fenfluramine 1.The three epoxides 3trans, 3cis and 8 were reduced regiospecifically into 1-propan-2-ol 6, a potent precursor to fenfluramine 1.The validity of our method for asymmettric synthesis has been demonstrated by a synthesis of (S)-fenfluramine 1 starting from the amino alcohol (S)-9.Keyword - fenfluramine / asymmetric synthesis / epoxide / amino alcohol / aziridine / regiospecific catalytic hydrogenation / 1-propan-2-ols
- Goument, B.,Duhamel, L.,Mauge, R.
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p. 459 - 466
(2007/10/02)
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