- C?C Bond Formation of Benzyl Alcohols and Alkynes Using a Catalytic Amount of KOtBu: Unusual Regioselectivity through a Radical Mechanism
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We report a C?C bond-forming reaction between benzyl alcohols and alkynes in the presence of a catalytic amount of KOtBu to form α-alkylated ketones in which the C=O group is located on the side derived from the alcohol. The reaction proceeds under thermal conditions (125 °C) and produces no waste, making the reaction highly atom efficient, environmentally benign, and sustainable. Based on our mechanistic investigations, we propose that the reaction proceeds through radical pathways.
- Kumar, Amit,Janes, Trevor,Chakraborty, Subrata,Daw, Prosenjit,von Wolff, Niklas,Carmieli, Raanan,Diskin-Posner, Yael,Milstein, David
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supporting information
p. 3373 - 3377
(2019/02/14)
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- Synthesis of Aryl Alkynes via Copper Catalyzed Decarboxylative Alkynylation of 2-Nitrobenzoic Acids
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An efficient protocol for the synthesis of internal aryl alkynes was achieved via Cu-catalyzed decarboxylative cross-coupling reactions, and to the best of our knowledge, this is the first example of a Cu-catalyzed decarboxylative alkynylation of benzoic acids with terminal alkynes. This approach utilizes simple Cu salt as catalyst and O2, an abundant, clean, and green material, as the oxidant. The reaction tolerates various functional groups, and a variety of internal aryl alkynes were synthesized in 46-83% yields.
- Yu, Yongqi,Chen, Xiang,Wu, Qianlong,Liu, Da,Hu, Liang,Yu, Lin,Tan, Ze,Gui, Qingwen,Zhu, Gangguo
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supporting information
p. 8556 - 8566
(2018/06/29)
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- Room-Temperature Alkynylation of Phosphine Oxides with Copper Acetylides: Practical Synthesis of Alkynylphosphine Oxides
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An efficient procedure for the synthesis of alkynylphosphine oxides based on the oxidative alkynylation of secondary phosphine oxides with copper acetylides was developed. Activation with molecular oxygen in the presence of either a mixture of 1,2-dimethylimidazole and triethylamine or N-methylimidazole alone enabled the formal umpolung of the poorly nucleophilic copper acetylides, which were coupled with phosphine oxides under remarkably mild conditions. Notable features of this procedure are the availability of the starting materials, its user-friendliness, and its mild conditions, which allow the synthesis of complex alkynylphosphine oxides.
- Gérard, Phidéline,Veillard, Romain,Alayrac, Carole,Gaumont, Annie-Claude,Evano, Gwilherm
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p. 633 - 638
(2017/01/18)
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- Mesoporous Copper/Manganese Oxide Catalyzed Coupling of Alkynes: Evidence for Synergistic Cooperative Catalysis
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Copper oxide supported on mesoporous manganese oxide (meso Cu/MnOx) was synthesized by an inverse micelle templated evaporation induced self-assembly procedure. Controlled aggregation of nanoparticles and a monomodal size distribution of mesopores with tunable structural properties were observed. The material possessed superior catalytic activity in the aerobic oxidative coupling of terminal alkynes. Excellent conversion (>99% in most cases) and selectivity were observed in both homocoupling and cross-coupling of alkynes using the optimized reaction conditions. Use of air as the sole oxidant, avoidance of any kind of additives, ease of product separation, great functional group tolerability, wide synthetic scope, and superior reusability (up to eighth cycle) are the notable features of our catalytic protocol. While the reaction mechanism was elucidated, a synergistic cooperative effect between the copper and manganese has been established, which is responsible for the superior catalytic activity. The labile lattice oxygen of the meso Cu/MnOx played a vital role in deprotonation of the alkyne proton, as supported by TPD and TGA studies. Moreover, for the first time, we designed model complexes for the active sites of the catalyst by DFT calculations and provided a qualitative description of the coupling mechanism, which supports the experimental findings.
- Biswas, Sourav,Mullick, Kankana,Chen, Sheng-Yu,Kriz, David A.,Shakil, Md,Kuo, Chung-Hao,Angeles-Boza, Alfredo M.,Rossi, Angelo R.,Suib, Steven L.
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p. 5069 - 5080
(2016/08/18)
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- Copper(II)-Promoted, One-Pot Conversion of 1-Alkynes with Anhydrides or Primary Amines to the Respective 2,5-Disubstituted Furans or Pyrroles under Microwave Irradiation Conditions
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Furans and pyrroles are prepared from 1-alkynes by using a Cu(II)-promoted, one-pot, microwave irradiation method. Glaser coupling of 1-alkynes and cyclization of the resulting 1,3-diyne in the presence of an anhydride or a primary amine results in the formation of the respective 2,5-diaryl- or 2,5-dialkyl-substituted furans and pyrroles.
- Lee, Hyejeong,Yi, Yeonhui,Jun, Chul-Ho
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p. 3485 - 3490
(2016/01/25)
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- Aqueous Sonogashira coupling of aryl halides with 1-alkynes under mild conditions: Use of surfactants in cross-coupling reactions
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Aqueous Sonogashira coupling between lipophilic terminal alkynes and aryl bromides or iodides gave moderate to high yields at 40°C using readily available and inexpensive surfactants (2.0 w/v% in water) such as SDS and CTAB. The catalyst precursor was 2 m
- Roberts, Gina M.,Lu, Wenya,Woo, L. Keith
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p. 18960 - 18971
(2015/06/01)
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- A mild CuI-catalyzed Glaser-type homo-coupling reaction using α,α-dibromo-β-dicarbonyl compounds as oxidants
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Exploration of α,α-dibromo-β-dicarbonyl compounds as novel organic oxidants for the mild Cu(I)-catalyzed Glaser-type homo-coupling reaction has been achieved, which provides an alternatively efficient pathway for the construction of 1,3-conjugated structures. In addition, the mechanism of this reaction was investigated.
- Fan, Xiaohui,Li, Na,Shen, Tong,Cui, Xiao-Meng,Lv, Hao,Zhu, Hong-Bo,Guan, Yong-Hong
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supporting information
p. 256 - 261
(2014/01/06)
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- Unsymmetrical coupling of 1-chloroalkynes and terminal alkynes under experimental Sonogashira conditions
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The coupling of a 1-chloroalkyne and a terminal alkyne to furnish a 1,3-butadiyne under experimental Sonogashira conditions is investigated. Through competition experiments, it is found that 1-chloroalkynes provide cross-coupling products as efficiently (or slightly better) in comparison with iodobenzenes, and almost as effectively as vinyl bromides. Yet, in regard to the degree of conversion into various products, chloroalkynes are the most reactive of all the substrates examined under the explored conditions. Optimized conditions for this cross-coupling reaction are presented. Georg Thieme Verlag Stuttgart New York.
- Christensen, Mikkel Andreas,Rimmen, Morten,Nielsen, Mogens Brondsted
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supporting information
p. 2715 - 2719
(2014/01/06)
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- Unprecedented synthesis of alkynylphosphine-boranes through room-temperature oxidative alkynylation
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An original and user-friendly synthesis of alkynylphosphine-boranes, useful building blocks in organic synthesis, based on an oxidative P-alkynylation reaction with readily available copper acetylides is reported. The ability of a secondary phosphine protected with a borane to undergo oxidative coupling without oxidation of the P-moiety is demonstrated for the first time. The reaction, which proceeds at room temperature, is applicable to the preparation of enantioenriched and structurally complex alkynylphosphine-boranes.
- Jouvin, Kevin,Veillard, Romain,Theunissen, Cedric,Alayrac, Carole,Gaumont, Annie-Claude,Evano, Gwilherm
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p. 4592 - 4595
(2013/09/24)
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- Copper-catalyzed synthesis of 2,4-disubstituted allenoates from α-diazoesters
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Chemical equations presented. A Cu-catalyzed method for coupling α-substituted-α-diazoesters with terminal alkynes to give substituted allenoates is described. Key to the development of a selective method was the recognition that an adventitous base catalyzes the isomerization to form the allenoate product. A plausible mechanism is proposed, based in part on evidence against a mechanism that involves a Cu(I)-acetylide as a low-valent intermediate.
- Hassink, Matthew,Liu, Xiaozhong,Fox, Joseph M.
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scheme or table
p. 2388 - 2391
(2011/06/25)
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- Transition-metal-free homocoupling of 1-haloalkynes: A facile synthesis of symmetrical 1,3-diynes
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Symmetrical 1,3-diyne compounds can be easily synthesized via a transition-metal-free homocoupling reaction of 1-haloalkynes without base and oxidant. The method shows excellent functional group compatibility and high yields.
- Chen, Zhengwang,Jiang, Huanfeng,Wang, Azhong,Yang, Shaorong
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supporting information; experimental part
p. 6700 - 6703
(2010/12/19)
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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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experimental part
p. 2411 - 2422
(2009/12/28)
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- Palladium-catalyzed homocoupling reaction of 1-iodoalkynes: A simple and efficient synthesis of symmetrical 1,3-diynes
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This paper describes a highly efficient synthetic method of symmetrical 1,3-diynes from 1-iodoalkynes in the presence of 4 mol % Pd(PPh 3)4 in DMF at room temperature under a nitrogen atmosphere without any use of additives and other metals.
- Damle, Subhash V.,Seomoon, Dong,Lee, Phil Ho
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p. 7085 - 7087
(2007/10/03)
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- Oxovanadium(V)-induced oxidation of alkenylzirconocenes for facile inter- and intramolecular coupling
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The oxidation reaction of (E)-1-alkenylchlorozirconocenes with an oxovanadium(V) compound at room temperature led to intermolecular homocoupling, giving the corresponding (E,E)-dienes stereoselectively. (E)-1-Alkenyl-1-alkynylzirconocenes underwent the oxovanadium(V)-induced intramolecular cross-coupling of organic substituents on zirconium, leading to the stereoselective formation of the (E)-enynes.
- Ishikawa, Takuji,Ogawa, Akiya,Hirao, Toshikazu
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- Platinum Complex Catalyzed Carbonylation of Organic Iodides: Effective Carbonylation of Organic Iodides Having β-Hydrogens on Saturated sp3 Carbons
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Dichlorobis(triphenylphosphine)platinum(II) is an effective catalyst precursor for the carbonylation of organic iodides having β-hydrogens on saturated sp3 carbons.The carbonylation under carbon monoxide pressure in the presence of alcohol gives esters, and aldehydes are obtained by the reaction under carbon monoxide and hydrogen pressure.Thus, 1-iodohexane is carbonylated to methyl heptanoate in 79percent yield in the presence of methanol at 120 deg C under 70 kg cm-2 of initial carbon monoxide pressure.Heptanal is formed in 86percent yield from 1-iodohexane at 120 deg Cunder carbon monoxide (50 kg cm-2) and hydrogen (50 kg cm-2).Alkenyl und alkynyl iodides are also smoothly carbonylated in the presence of alcohol into the corresponding esters without reduction of unsaturated bonds.
- Takeuchi, Ryo,Tsuji, Yasushi,Fujita, Masayuki,Kondo, Teruyuki,Watanabe, Yoshihisa
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p. 1831 - 1836
(2007/10/02)
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- Palladium(II) Chloride Catalyzed Carbonylation of Organic Tellurides with Carbon Monoxide
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Various organic tellurides react with carbon monoxide (1 atm) at room temperature in methanol in the presence of PdCl2 and Et3N to afford the corresponding methyl carboxylates in good to excellent yields.The reaction is catalytic in PdCl2 when a suitable reoxidant such as CuCl2, CuCl/O2, FeCl3 or Ce(NH4)2(NO3)6 is present.The combination of this carbonylation with phenyltellurenylation of arylacetylenes and propargylic alcohols makes it possible to prepare ring-substituted cis-methyl cinnamates and Δα,β-butenolides, respectively.Both monomeric and dimeric palladium complexes, (Ph2Te)2PdCl2 and 2, react readily with CO to give a high yield of methyl benzoate.The key step of the present carbonylation is proposed to be the migration of an organic moiety from Te to Pd (transmetalation) in organic telluride-PdCl2 complexes, presumably formed in situ, to afford organopalladium compounds.
- Ohe, Kouichi,Takahashi, Hidetaka,Uemura, Sakae,Sugita, Nobuyuki
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p. 4859 - 4863
(2007/10/02)
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