- Lewis acid activation of molybdenum nitrides for alkyne metathesis
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The substantial kinetic barrier to molybdenum nitride-alkyne metathesis is facilitated by precomplexation of the borane Lewis acid B(C6F 5)3, providing convenient access to metathesis-active molybdenum alkylidynes. Spectroscopic and X-ray structural analysis suggest MoN bond weakening upon borane complexation.
- Finke, Aaron D.,Moore, Jeffrey S.
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- Impact of Ligands and Metals on the Formation of Metallacyclic Intermediates and a Nontraditional Mechanism for Group VI Alkyne Metathesis Catalysts
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The intermediacy of metallacyclobutadienes as part of a [2 + 2]/retro-[2 + 2] cycloaddition-based mechanism is a well-established paradigm in alkyne metathesis with alternative species viewed as off-cycle decomposition products that interfere with efficient product formation. Recent work has shown that the exclusive intermediate isolated from a siloxide podand-supported molybdenum-based catalyst was not the expected metallacyclobutadiene but instead a dynamic metallatetrahedrane. Despite their paucity in the chemical literature, theoretical work has shown these species to be thermodynamically more stable as well as having modest barriers for cycloaddition. Consequentially, we report the synthesis of a library of group VI alkylidynes as well as the roles metal identity, ligand flexibility, secondary coordination sphere, and substrate identity all have on isolable intermediates. Furthermore, we report the disparities in catalyst competency as a function of ligand sterics and metal choice. Dispersion-corrected DFT calculations are used to shed light on the mechanism and role of ligand and metal on the intermediacy of metallacyclobutadiene and metallatetrahedrane as well as their implications to alkyne metathesis.
- Thompson, Richard R.,Rotella, Madeline E.,Zhou, Xin,Fronczek, Frank R.,Gutierrez, Osvaldo,Lee, Semin
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- Synthesis of symmetrical diarylalkynes by double stille coupling of bis(tributylstannyl)acetylene
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Treatment of bis(tributylstannyl)acetylene with two equivalents of an aryl iodide in the presence of tetrakis(triphenylphosphine)palladium (0) affords good yields of the symmetrical diarylalkyne. This approach provides a convenient and safe alternative to
- Cummins, Clark H.
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- 183W NMR Spectroscopy Guides the Search for Tungsten Alkylidyne Catalysts for Alkyne Metathesis
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Triarylsilanolates are privileged ancillary ligands for molybdenum alkylidyne catalysts for alkyne metathesis but lead to disappointing results and poor stability in the tungsten series. 1H,183W heteronuclear multiple bond correlation spectroscopy, exploiting a favorable 5J-coupling between the 183W center and the peripheral protons on the alkylidyne cap, revealed that these ligands upregulate the Lewis acidity to an extent that the tungstenacyclobutadiene formed in the initial [2+2] cycloaddition step is over-stabilized and the catalytic turnover brought to a halt. Guided by the 183W NMR shifts as a proxy for the Lewis acidity of the central atom and by an accompanying chemical shift tensor analysis of the alkylidyne unit, the ligand design was revisited and a more strongly π-donating all-alkoxide ligand prepared. The new expanded chelate complex has a tempered Lewis acidity and outperforms the classical Schrock catalyst, carrying monodentate tert-butoxy ligands, in terms of rate and functional-group compatibility.
- Copéret, Christophe,Fürstner, Alois,Gordon, Christopher P.,Hillenbrand, Julius,Leutzsch, Markus
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- Stabilizing Pentacene by Cyclopentannulation
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A new class of stabilized pentacene derivatives with externally fused five-membered rings are prepared by means of a key palladium-catalyzed cyclopentannulation step. The target compounds are synthesized by chemical manipulation of a partially saturated 6,13-dibromopentacene precursor that can be fully aromatized in a final step through a DDQ-mediated dehydrogenation reaction (DDQ=2,3-dichloro-5,6-dicyano-1,4-benzoquinone). The new 1,2,8,9-tetraaryldicyclopenta[fg,qr]pentacene derivatives have narrow energy gaps of circa 1.2 eV and behave as strong electron acceptors with lowest unoccupied molecular orbital energies between -3.81 and -3.90 eV. Photodegradation studies reveal the new compounds are more photostable than 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene). Five in a row: A palladium-catalyzed cyclopentannulation followed by a DDQ-mediated dehydrogenation converts a partially hydrogenated pentacene precursor into stabilized pentacenes. These pentacene derivatives are excellent electron acceptors and have small energy gaps. DDQ=2,3-dichloro-5,6-dicyano-1,4-benzoquinone.
- Bheemireddy, Sambasiva R.,Ubaldo, Pamela C.,Rose, Peter W.,Finke, Aaron D.,Zhuang, Junpeng,Wang, Lichang,Plunkett, Kyle N.
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- Hexaphenylbenzene as a rigid template for the straightforward syntheses of "star-shaped" glycodendrimers
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Original glycodendrimers emanating from propargylated hexaphenylbenzene cores and containing up to 54 peripheral sugar ligands have been synthesized by Cu(I)-catalyzed [1,3]-dipolar cycloadditions using both convergent and divergent approaches.
- Chabre, Yoann M.,Brisebois, Patrick P.,Abbassi, Leila,Kerr, Sheena C.,Fahy, John V.,Marcotte, Isabelle,Roy, Rene
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- Synthesis of symmetrical diarylalkyne from palladium-catalyzed decarboxylative couplings of propiolic acid and aryl bromides under water
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Symmetric diarylalkynes were obtained from the decarboxylative coupling reactions of aryl bromides and propiolic acid in water solvent condition. In the presence of phase transfer surfactant C18H37N(CH 3)3Cl, the catalytic system of both Pd(PPh 3)2Cl2/dppb and Pd(TPPMS)2Cl 2/TPPMS afforded the desired coupled products in good yields.
- Park, Kyungho,Bae, Goun,Park, Ahbyeol,Kim, Yong,Choe, Jaehoon,Song, Kwang Ho,Lee, Sunwoo
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- Reaction of elemental phosphorus with α-methylstyrenes: One-pot synthesis of secondary and tertiary phosphines, prospective bulky ligands for Pd(II) catalysts
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α-Methylstyrene and 4-chloro-α-methylstyrene react readily with elemental (red) phosphorus under microwave-irradiation in the superbase KOH/DMSO suspension to afford, depending on the reactant ratio and reaction time, either corresponding bis(2-arylpropyl
- Artem'ev, Alexander V.,Malysheva, Svetlana F.,Gusarova, Nina K.,Belogorlova, Nataliya A.,Sukhov, Boris G.,Sutyrina, Anastasiya O.,Matveeva, Elena A.,Vasilevsky, Sergey F.,Govdi, Anastasiya I.,Gatilov, Yuriy V.,Albanov, Alexander I.,Trofimov, Boris A.
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- The use of calcium carbide in one-pot synthesis of symmetric diaryl ethynes
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An efficient Pd-catalyzed copper and amine free coupling reaction of acetylene and aryl bromides was achieved with calcium carbide as an acetylene source, using inorganic base and easily prepared, air-stable aminophosphine ligand in common organic solvents, providing symmetric diaryl ethynes in one-pot with yields ranged from moderate to excellent. The Royal Society of Chemistry 2006.
- Zhang, Weiwei,Wu, Huayue,Liu, Zhiqing,Zhong, Ping,Zhang, Lin,Huang, Xiaobo,Cheng, Jiang
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- Rhodium-catalyzed asymmetric synthesis of silicon-stereogenic dibenzosiloles by enantioselective[2+2+2] cycloaddition
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A rhodium-catalyzed asymmetric synthesis of silicon-stereogenic dibenzosiloles has been developed through a [2+2+2] cycloaddition of silicon-containing prochiral triynes with internal alkynes. High yields and enantioselectivities have been achieved by emp
- Shintani, Ryo,Takagi, Chihiro,Ito, Tomoaki,Naito, Masanobu,Nozaki, Kyoko
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- Ruthenium(II)-Catalyzed Synthesis of Indolo[2,1-a]isoquinolines through Double Oxidative Annulation Reaction of Phenyl Isocyanates with Di(hetero)aryl Alkynes
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Indole-containing polycyclic hetero aromatic compounds are synthesized by multistep process, which have wide application in biological activities and organic semi-conductor materials. Herein we report the one-pot method for the synthesis of polysubstituted indolo[2,1-a]isoquinolines by Ru(II) catalyzed double aryl/hetero aryl C(sp2)?H activation through in-situ installed carbamide of phenyl isocyanate and di(hetero)aryl substituted alkynes in the presence of Cu(OAc)2.H2O as an oxidant and CsOAc as an additive at 120 °C for 3 h in good to excellent yields. (Figure presented.).
- Kumar, Amrendra,Kant, Ruchir,Tadigoppula, Narender
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- Nickel-Catalyzed Decarbonylative Cycloaddition of Benzofuran-2,3-diones with Alkynes to Flavones
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Using dppe as the ligand, the Nickel-catalyzed decarbonylative cycloaddition of benzofuran-2,3-diones with alkynes was established, and a variety of functional flavones were synthesized in 65–99% yields. Terminal alkynes with substituted phenyl groups and internal alkynes such as aryl acyl acetylenes and diphenylacetylenes are suitable for this reaction. The effects of bases on the reactions of different types of alkyne substrates were also investigated and discussed. (Figure presented.).
- Zhang, Yu-Yang,Li, Han,Jiang, Xiaoding,Subba Reddy, Chitreddy V,Liang, Hao,Zhang, Yaqi,Cao, Rihui,Sun, Raymond Wai-Yin,Tse, Man Kin,Qiu, Liqin
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supporting information
p. 525 - 530
(2021/12/22)
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- Mechanochemical Synthesis of Diarylethynes from Aryl Iodides and CaC 2
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A mechanochemical synthesis of diarylethynes from aryl iodides and calcium carbide as acetylene source is reported. The reaction is catalyzed by a palladium catalyst in the presence of copper salt, base, and ethanol as liquid assisting grinding (LAG) additive. Various aryl and heteroaryl iodides have been converted in up to excellent yields.
- Bolm, Carsten,Van Bonn, Pit
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supporting information
(2022/02/25)
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- Evidence of a Photoinduced Electron-Transfer Mechanism in the Fluorescence Self-quenching of 2,5-Substituted Selenophenes Prepared through in Situ Reduction of Elemental Selenium in Superbasic Media
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A series of new 2,5-disubstituted selenophene derivatives are described from elemental selenium and 1,3-diynes in superbasic media. The activation of elemental selenium in a KOH/DMSO system allows cyclization with conjugated diynes at room temperature. The cyclization reaction is extended to a broad range of functional groups, for which photophysics were experimentally and theoretically investigated. The selenophene derivatives present absorption maxima in the UV-A region and fluorescence emission in the violet-to-blue region. Fluorescence decay profiles were obtained showing a monoexponential decay with fast fluorescence lifetimes (~0.118 ns), as predicted by the Strickler-Berg relations. In general, in both investigations, no dependence on the solvent polarity on the absorption and emission maxima location was observed. On the other hand, solvents and substituents are shown to play a role in the fluorescence quantum yield values. In addition, a fluorescence self-quenching behavior could be observed, related to a photoinduced electron-transfer mechanism. Theoretical calculations performed at the MP2/ADC(2)/cc-pVDZ level of theory were performed in order to investigate the photophysical features of this series of selenophene derivatives.
- De Salles, Helena Domingues,Coelho, Felipe Lange,Paix?o, Douglas Bernardo,Barboza, Cristina Aparecida,Da Silveira Rampon, Daniel,Rodembusch, Fabiano Severo,Schneider, Paulo Henrique
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p. 10140 - 10153
(2021/07/31)
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- Iodonium Cation-Pool Electrolysis for the Three-Component Synthesis of 1,3-Oxazoles
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The synthesis of 1,3-oxazoles from symmetrical and unsymmetrical alkynes was realized by an iodonium cation-pool electrolysis of I2 in acetonitrile with a well-defined water content. Mechanistic investigations suggest that the alkyne reacts with the acetonitrile-stabilized I+ ions, followed by a Ritter-type reaction of the solvent to a nitrilium ion, which is then attacked by water. The ring closure to the 1,3-oxazoles released molecular iodine, which was visible by the naked eye. Also, some unsymmetrical internal alkynes were tested and a regioselective formation of a single isomer was determined by two-dimensional NMR experiments.
- Sattler, Lars E.,Hilt, Gerhard
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supporting information
p. 605 - 608
(2020/12/07)
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- Rh(iii)-Catalyzed three-component cascade annulation to produce theN-oxopropyl chain of isoquinolone derivatives
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Developing powerful methods to introduce versatile functional groups at theN-substituents of isoquinolone scaffolds is still a great challenge. Herein, we report a novel three-component cascade annulation reaction to efficiently construct theN-oxopropyl chain of isoquinolone derivativesviarhodium(iii)-catalyzed C-H activation/cyclization/nucleophilic attack, with oxazoles used both as the directing group and potential functionalized reagents.
- He, Yuan,Liao, Xian-Zhang,Dong, Lin,Chen, Fen-Er
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supporting information
p. 561 - 567
(2021/02/06)
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- Nickel-Catalyzed One-Pot Carbonylative Synthesis of 2-Mono- And 2,3-Disubstituted Thiochromenones from 2-Bromobenzenesulfonyl Chlorides and Alkynes
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A nickel-catalyzed one-pot carbonylation reaction of 2-bromobenzenesulfonyl chlorides with alkynes for the synthesis of thiochromenones has been established. Both terminal and internal alkynes were suitable substrates in this carbonylative transformation, and a broad range of 2-mono- and 2,3-disubstituted thiochromenone products were obtained in moderate to good yields with quite high functional group compatibility. Notably, this procedure presents the first example of nickel-catalyzed carbonylative synthesis of thiochromenones with 2-bromobenzenesulfonyl chlorides as a promising sulfur precursor.
- Wang, Wei,Bao, Zhi-Peng,Qi, Xinxin,Wu, Xiao-Feng
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supporting information
p. 6589 - 6593
(2021/08/30)
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- Palladium-Catalyzed Cascade Dearomative Spirocyclization and C?H Annulation of Aromatic Halides with Alkynes
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Described herein is a palladium-catalyzed intermolecular dearomative annulation of aryl halides with alkynes, which provides a rapid approach to a class of structurally unique spiroembedded polycyclic aromatic compounds. The cascade process is accomplished by a sequential alkyne migratory insertion, Heck-type dearomatization, and C-H bond annulation. Further optoelectronic study indicated this fused spirocyclic scaffold could be a potential host material for OLEDs, as exemplified by a fabricated red PhOLED device with a maximum external quantum efficiency of 23.0%.
- Liao, Xingrong,Zhou, Fulin,Bin, Zhengyang,Yang, Yudong,You, Jingsong
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supporting information
p. 5203 - 5207
(2021/07/19)
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- Fritsch-Buttenberg-Wiechell rearrangement of magnesium alkylidene carbenoids leading to the formation of alkynes
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A series of 1-heteroatom-substituted vinyl p-tolyl sulfoxides were prepared and treated with organometallic reagents to evaluate which combination of sulfoxides and organometallic reagents yielded alkynes the most efficiently. The use of 1-chlorovinyl p-tolyl sulfoxide and isopropylmagnesium chloride was optimal for this purpose. A variety of 1-chlorovinyl p-tolyl sulfoxides were prepared from carbonyl compounds and chloromethyl p-tolyl sulfoxide and were converted into alkynes via the sulfoxide/magnesium exchange reaction and subsequent Fritsch-Buttenberg-Wiechell (FBW) rearrangement of the resulting magnesium alkylidene carbenoids. The mechanism of the FBW rearrangement of magnesium alkylidene carbenoids was studied by using13C-labeled sulfoxides and by using DFT calculations.
- Ando, Akane,Imafuji, Aki,Kimura, Tsutomu,Sekiguchi, Koto
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p. 1352 - 1359
(2021/06/06)
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- Synthesis of Diarylethynes from Aryldiazonium Salts by Using Calcium Carbide as an Alkyne Source in a Deep Eutectic Solvent
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An efficient method for the synthesis of diarylethynes from aryldiazonium salts by using calcium carbide as an alkyne source at room temperature in a deep eutectic solvent is described. The salient features of this protocol are an inexpensive and easy-to-handle alkyne source, a nonvolatile and recyclable solvent, mild conditions, and a simple workup procedure.
- Ma, Xiaolong,Li, Zheng
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supporting information
p. 631 - 635
(2020/12/28)
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- Rhodium-Catalyzed Regioselective Hydroformylation of Alkynes to α,β-Unsaturated Aldehydes Using Formic Acid
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A rhodium-catalyzed hydroformylation of alkynes with formic acid was developed. The method provides α,β-unsaturated aldehydes in high yield and E-selectivity without the need to handle toxic CO gas.
- Fan, Chao,Hou, Jing,Chen, Yu-Jia,Ding, Kui-Ling,Zhou, Qi-Lin
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supporting information
p. 2074 - 2077
(2021/04/05)
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- Magnetic chitosan-functionalized cobalt-NHC: Synthesis, characterization and catalytic activity toward Suzuki and Sonogashira cross-coupling reactions of aryl chlorides
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Aryl chlorides are one of the most stable and available electrophiles, however, their coupling with nucleophiles remains a challenge in organic synthesis. Herein, we prepared a Cobalt-NHC (N-Heterocyclic carbene) complex anchored on magnetic chitosan nanoparticles and assayed its catalytic activity for the reactions of substituted phenylboronic acid and also phenlacetylene with derivatives of aryl chlorides. These reactions are of great importance since they are employed for the synthesis of unsymmetrical diarylethynes and biphenyls, which belong to a prime class of building blocks. The synthesized nanocatalyst was found to be highly efficient in Suzuki and Sonogashira coupling in terms of their activity and recyclability in polyethylene glycol (PEG) as a green reaction media under conditions of temperatures (70 and 100 °C) and Co loading (3 and 6 mol%). To the best of our knowledge, this is the first attempt of using cobalt-NHC complex for catalyzing the abovementioned reactions. Moreover, replacing the earth-abundant Cobalt-based catalyst as an alternative to high cost palladium make this approach promising from sustainable chemistry view.
- Hajipour, Abdol R.,Malek, Shaghayegh Sadeghi
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- Synthesis of Bidentate Nitrogen Ligands by Rh-Catalyzed C-H Annulation and Their Application to Pd-Catalyzed Aerobic C-H Alkenylation
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A new class of bidentate ligands was prepared by a modular approach involving Rh-catalyzed C-H annulation reactions. The resulting conformationally constrained ligands enabled the Pd-catalyzed C-H alkenylation at electron-rich and sterically less hindered positions of electron-rich arenes while promoting the facile oxidation of Pd(0) intermediates by oxygen. This newly introduced ligand class is complementary to the ligands developed for Pd-catalyzed oxidative reactions and may find broad application in transition-metal-catalyzed reactions.
- Kim, Hyun Tae,Kang, Eunsu,Kim, Minkyu,Joo, Jung Min
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p. 3657 - 3662
(2021/05/10)
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- Synthesis and Photophysical Study of Heteropolycyclic and Carbazole Motif: Nickel-Catalyzed Chelate-Assisted Cascade C-H Activations/Annulations
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Herein, nickel-catalyzed synthesis of polyarylcarbazole through sequential C-H bond activations has been described. Regioselective indole C2/C3 functionalization has been achieved in the presence of indole C7-H, which is quite challenging. In addition, this approach also gives easy access to building a heteropolycyclic motif through C6/C7 C-H functionalization of indoline. This methodology is not limited to aromatic internal alkynes as coupling partners; aliphatic alkynes have also shown good tolerance. Notably, during the optimization the catalytic enhancement with sodium iodide as an additive has been observed. We have also studied the photophysical properties of these highly conjugated molecules.
- Prusty, Namrata,Banjare, Shyam Kumar,Mohanty, Smruti Ranjan,Nanda, Tanmayee,Yadav, Komal,Ravikumar, Ponneri C.
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supporting information
p. 9041 - 9046
(2021/11/30)
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- Rhodium-Catalyzed Spiro Indenyl Benzoxazine Synthesis via C-H Activation/Annulation of 3-Aryl-2H-Benzo[b][1,4]oxazines and Alkynes
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The rhodium (III)-catalyzed annulation of 3-Aryl-2H-Benzo[b][1,4]oxazines with alkynes via C–H activation has been developed. This reaction afforded a series of spiro indenyl benzoxazine in high yields under mild reaction condition with good functional group tolerance.
- Tan, Heng,Laishram, Ronibala Devi,Zhang, Xuexin,Shi, Guangrui,Li, Kangkui,Chen, Jingchao
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supporting information
p. 4542 - 4546
(2020/07/04)
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- Phosphorus(III)-Mediated, Tandem Deoxygenative Geminal Chlorofluorination of 1,2-Diketones
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Tetrasubstituted carbon containing two different halogen substituents was constructed in a single-step operation by utilizing the carbene-like reactivity of dioxaphospholene through the tandem reaction of electrophilic and nucleophilic halogenating reagents. It was crucial to devise non-dealkylatable phosphoramidite, which enabled the efficient formation of geminal chlorofluorides from various 1,2-diketones with (PhSO2)2NF and n-Bu4NCl. In addition, selective functionalization of the chlorine substituent was demonstrated, and the absence of halogen scrambling was confirmed.
- Choi, Garam,Chung, Won-Jin,Hwang, Sunjoo,Jang, Hanna,Kim, Ha Eun
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supporting information
p. 4190 - 4195
(2020/06/27)
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- Fluorine-induced emission enhancement of tolanesviaformation of tight molecular aggregates
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Fluorinated tolanes were found to show aggregation-induced emission characteristics and significantly enhanced photoluminescence efficiencies in molecular aggregates when compared with non-fluorinated tolanes. The fluorine atoms play important roles in th
- Konno, Tsutomu,Morita, Masato,Yamada, Shigeyuki
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supporting information
p. 6704 - 6708
(2020/05/16)
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- Preparation of dendritic carboranyl glycoconjugates as potential anticancer therapeutics
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A series of carborane-appended glycoconjugates containing three and six glucose and galactose moieties have been synthesizedviaCu(i)-catalyzed azide-alkyne [3 + 2] click cycloaddition reaction. The carboranyl glycoconjugates containing three glucose and g
- Beriha, Swaraj Kumar,Dash, Barada P.,Jena, Bibhuti Bhusan,Mahanta, Chandra Sekhara,Nayak, Bismita,Satapathy, Rashmirekha,Swain, Biswa Ranjan
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p. 34764 - 34774
(2020/10/13)
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- A novel approach for rhodium(iii)-catalyzed C-H functionalization of 2,2′-bipyridine derivatives with alkynes: A significant substituent effect
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We described a novel approach for the C-H functionalization of 2,2′-bipyridine derivatives with alkynes. DFT calculations and experimental data showed a significant substituent effect at the 6-position of 2,2′-bipyridine, which weakened the adjacent N-Rh bond and provided the possibility of subsequent rollover cyclometalation, C-H activation, and functionalization.
- Wu, Shaonan,Wang, Zhuo,Bao, Yinwei,Chen, Chen,Liu, Kun,Zhu, Bolin
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supporting information
p. 4408 - 4411
(2020/05/05)
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- Synthesis of Phenanthrenes via Palladium-Catalyzed Three-Component Domino Reaction of Aryl Iodides, Internal Alkynes, and o-Bromobenzoic Acids
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A new palladium-catalyzed domino alkyne insertion/C-H activation/decarboxylation sequence has been developed, which provides an efficient approach for synthesizing a variety of functionalized phenanthrenes in moderate to good yields. The method shows broad substrate scope and good functional group tolerance by employing readily available materials, including aryl iodides, internal alkynes, and o-bromobenzoic acids, as three-component coupling partners.
- Deng, Guobo,Liang, Yun,Luo, Xiai,Yang, Xiumei,Yang, Yuan,Yang, Yuzhong,Zhou, Liwei
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supporting information
p. 1223 - 1230
(2020/04/15)
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- Method for preparing aryl internal alkyne compound through light-mediated copper catalysis
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The invention relates to a method for preparing an aryl internal alkyne compound through light-mediated copper catalysis, and belongs to the field of organic chemistry. An aryl sulfide salt and a terminal alkyne are used as raw materials, a + 1 valent copper salt is used as a catalyst, potassium carbonate is used as alkali, reaction is performed in solvents such as DMSO to obtain the aryl internalalkyne compound, and the yield is 50%-86%. According to the synthetic method, the raw materials are easy to obtain, the reaction conditions are mild, a simple, convenient, green and efficient synthetic route of the internal alkyne compound is provided, and an effective method for introducing alkynyl into aromatic ring-containing drug molecules is provided.
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Paragraph 0031-0033; 0037-0039
(2020/09/09)
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- "canopy Catalysts" for Alkyne Metathesis: Molybdenum Alkylidyne Complexes with a Tripodal Ligand Framework
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A new family of structurally well-defined molybdenum alkylidyne catalysts for alkyne metathesis, which is distinguished by a tripodal trisilanolate ligand architecture, is presented. Complexes of type 1 combine the virtues of previous generations of silanolate-based catalysts with a significantly improved functional group tolerance. They are easy to prepare on scale; the modularity of the ligand synthesis allows the steric and electronic properties to be fine-tuned and hence the application profile of the catalysts to be optimized. This opportunity is manifested in the development of catalyst 1f, which is as reactive as the best ancestors but exhibits an unrivaled scope. The new catalysts work well in the presence of unprotected alcohols and various other protic groups. The chelate effect entails even a certain stability toward water, which marks a big leap forward in metal alkylidyne chemistry in general. At the same time, they tolerate many donor sites, including basic nitrogen and numerous heterocycles. This aspect is substantiated by applications to polyfunctional (natural) products. A combined spectroscopic, crystallographic, and computational study provides insights into structure and electronic character of complexes of type 1. Particularly informative are a density functional theory (DFT)-based chemical shift tensor analysis of the alkylidyne carbon atom and 95Mo NMR spectroscopy; this analytical tool had been rarely used in organometallic chemistry before but turns out to be a sensitive probe that deserves more attention. The data show that the podand ligands render a Mo-alkylidyne a priori more electrophilic than analogous monodentate triarylsilanols; proper ligand tuning, however, allows the Lewis acidity as well as the steric demand about the central atom to be adjusted to the point that excellent performance of the catalyst is ensured.
- Copéret, Christophe,Fürstner, Alois,Gordon, Christopher P.,Hillenbrand, Julius,Leutzsch, Markus,N?thling, Nils,Wille, Christian,Yiannakas, Ektoras
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supporting information
p. 11279 - 11294
(2020/07/13)
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- Robust Alkyne Metathesis Catalyzed by Air Stable d2Re(V) Alkylidyne Complexes
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We report in this communication the first example of catalytic alkyne metathesis reactions mediated by well-defined non-d0 alkylidyne complexes. The air-stable d2 Re(V) alkylidyne complex Re4, bearing two PO-chelating ligands and a labile pyridine ligand, could catalyze homometathesis of internal alkynes with a broad substrate scope, including alcohols, amines, and even carboxylic acids. The catalyst can tolerate heating, air, and moisture in both solid and solution states, and the catalytic metathesis reactions could proceed normally in wet solvents.
- Cui, Mingxu,Bai, Wei,Sung, Herman H. Y.,Williams, Ian D.,Jia, Guochen
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supporting information
p. 13339 - 13344
(2020/09/03)
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- Photoinduced copper-catalyzed site-selective C(sp2)-C(sp) cross-coupling via aryl sulfonium salts
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The classical Sonogashira reaction of aryl electrophiles in the presence of Pd catalysts has been well established as a potent method for arylalkyne synthesis. However, the site-selective C(sp2)-C(sp) cross-coupling strategy using a non-noble-metal catalyst is rare. An efficient alternative approach for the synthesis of arylalkynes via a Cu-catalyzed Sonogashira-type reaction promoted by visible light is described. This method enables site-selective alkynylation from aryl sulfonium salts derived from diverse arenes to a set of arylalkynes with high selectivity and high functional-group compatibility. Moreover, rapid alkynylation of drug molecules is demonstrated.
- Liang, Lei,Niu, Hong-Ying,Li, Ren-Long,Wang, Yao-Fei,Yan, Jin-Kai,Li, Chang-Gong,Guo, Hai-Ming
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supporting information
p. 6842 - 6846
(2020/09/15)
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- Iridium-Catalyzed Hydrochlorination and Hydrobromination of Alkynes by Shuttle Catalysis
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Described herein are two different methods for the synthesis of vinyl halides by a shuttle catalysis based iridium-catalyzed transfer hydrohalogenation of unactivated alkynes. The use of 4-chlorobutan-2-one or tert-butyl halide as donors of hydrogen halides allows this transformation in the absence of corrosive reagents, such as hydrogen halides or acid chlorides, thus largely improving the functional-group tolerance and safety profile of these reactions compared to the state-of-the-art. This method has granted access to alkenyl halide compounds containing acid-sensitive groups, such as tertiary alcohols, silyl ethers, and acetals. The synthetic value of those methodologies has been demonstrated by gram-scale synthesis where low catalyst loading was achieved.
- Yu, Peng,Bismuto, Alessandro,Morandi, Bill
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supporting information
p. 2904 - 2910
(2020/01/25)
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- Stereodivergent Synthesis of Alkenylpyridines via Pd/Cu Catalyzed C-H Alkenylation of Pyridinium Salts with Alkynes
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The first Pd/Cu catalyzed selective C2-alkenylation of pyridines with internal alkynes has been developed via the pyridinium salt activation strategy. Importantly, the configuration of the product alkenylpyridines could be tuned by the choice of the proper N-alkyl group of the pyridinium salts, thus allowing for both the Z- and E-alkenylpyridines synthesized with good regio- and stereoselectivity. A plausible mechanism was proposed based on the Hammett study and KIE experiment.
- Chen, Hua,Haiyan, Fu,Jiang, Weidong,Li, Ruixiang,Li, Shun,Li, Wenjing,Tang, Juan,Xu, Bin,Yuan, Maolin,Zheng, Xueli
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supporting information
p. 7814 - 7819
(2020/11/03)
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- Sodium-metal-promoted reductive 1,2-syn-diboration of alkynes with reduction-resistant trimethoxyborane
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Reductive 1,2-diboration of alkynes has been accomplished by means of sodium dispersion in the presence of trimethoxyborane as a reduction-resistant boron electrophile. Two boron moieties can be introduced onto alkynes with excellent syn selectivity to afford the corresponding (Z)-1,2-diborylalkenes. Bis(borate) species generated in situ can be involved in one-pot Suzuki-Miyaura arylation, formal arylboration of alkynes thus being executed.
- Fukazawa, Mizuki,Ito, Shiori,Nogi, Keisuke,Takahashi, Fumiya,Yorimitsu, Hideki
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p. 1171 - 1179
(2020/10/18)
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- Nickel-Catalyzed Allylmethylation of Alkynes with Allylic Alcohols and AlMe3: Facile Access to Skipped Dienes and Trienes
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We present herein an unprecedented allylative dicarbofunctionalization of alkynes with allylic alcohols. This simple catalytic procedure utilizes commercially available Ni(COD)2, triphenylphosphine, and inexpensive reagents, and delivers valuable skipped dienes and trienes with an all-carbon tetrasubstituted alkene unit in a highly stereoselective fashion. Preliminary mechanistic studies support the reaction pathway of allylnickelation followed by transmetalation in this dicarbofunctionalization of alkynes.
- Li, Jincan,Li, Wanfang,Yu, Shun,Zhao, Yu
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supporting information
p. 14404 - 14408
(2020/07/04)
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- Asymmetric Dearomatization of Indole by Palladium/PC-Phos-Catalyzed Dynamic Kinetic Transformation
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A palladium-catalyzed intermolecular dynamic kinetic asymmetric dearomatization of 3-arylindoles with internal alkynes was developed with the use of achiral Xantphos and chiral sulfinamide phosphine ligand (PC-Phos) as the co-ligands. This method could deliver various spiro[indene-1,3′-indole] compounds in good yields (up to 95 % yield) with up to 98 % ee. The salient features of the transformation include the use of readily available substrates, ease of scale-up and the versatile functionalization of the products. The mechanistic experiments gave some insights on active intermediates.
- Cheng, Jie,Chu, Haoke,Guo, Yin-Long,Yang, Junfeng,Zhang, Junliang
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supporting information
p. 21991 - 21996
(2020/10/02)
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- Pd-Catalyzed decarboxylative alkynylation of alkynyl carboxylic acids with arylsulfonyl hydrazides via a desulfinative process
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In the presence of a Pd(ii)/P-ligand catalytic system, decarboxylative alkynylation of alkynyl carboxylic acids and arylsulfonyl hydrazides by desulfinative coupling could provide aryl alkynes in satisfactory yields by either judiciously selecting palladium catalysts or modulating phosphine ligands under mild conditions. The reported coupling reactions are very practical as they do not require the protection of inert gas or oxygen and are tolerant to many functional groups.
- Chang, Sheng,Liu, Ying,Yin, Shu Zhu,Dong, Lin Lin,Wang, Jian Feng
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p. 5357 - 5362
(2019/04/04)
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- Visible Light-Catalyzed Decarboxylative Alkynylation of Arenediazonium Salts with Alkynyl Carboxylic Acids: Direct Access to Aryl Alkynes by Organic Photoredox Catalysis
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A convenient method mediated by photoredox catalysis is developed for the direct construction of aryl alkynes. Readily available aromatic diazonium salts have been utilized as the aryl radical source to couple alkynyl carboxylic acids to feature the decarboxylative arylation. A wide range of substrates are amenable to this protocol with broad functional group tolerance, and diversely-functionalized aryl alkynes could be synthesized under mild, neutral and transition metal-free reaction conditions using visible light irradiation. Alongside synthetic sustainability associated with the photocatalytic and transition metal-free operation, another key point of this method is that the organic dye catalyst acts as an excited-state reductant, thus establishing the quenching cycle for radical addition and decarboxylative elimination. (Figure presented.).
- Yang, Liangfeng,Li, Haifeng,Du, Yijun,Cheng, Kai,Qi, Chenze
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p. 5030 - 5041
(2019/11/03)
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- Preparation and catalytic properties of the triphenylarsine and triphenylstibine-stabilized tri-heteroleptic NHC–Pd?allyl complexes
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A series of triphenylarsine and triphenylstibine-stabilized tri-heteroleptic NHC–Pd?allyl complexes were synthesized and characterized. The solid-state structures of the complexes shown mononuclear carbene palladium complexes, in which, each palladium cen
- Yang, Jin
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- Insights on bimetallic micellar nanocatalysis for buchwald-hartwig aminations
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A nanocatalyst for micellar Buchwald-Hartwig aminations is developed, thoroughly characterized, and applied on a variety of substrates. The catalyst is stable under ambient conditions for at least six months. The catalyst retained its activity after several cycles, and its structure remained intact as confirmed by NMR spectroscopy. Association of Pd nanoparticles with Cu by a phosphine ligand is revealed by 31P NMR spectroscopy, and their linkage with the activated carbon surface is revealed by XAS analysis. Control NMR experiments revealed the binding of the ligand with both Cu and Pd, and all phosphine molecules are under the same environment. In addition to NMR and XAS analysis, the catalyst is characterized by SEM, HRTEM, XPS, and TGA. Reactions are highly reproducible at variable scales. Environmentally benign, proline-based amphiphile PS-750-M is critical for catalytic activity, which is achieved under mild conditions in water as the reaction medium. The inherent sustainability of these conditions coupled with a low E factor achievable through robust recycling of catalyst and reaction medium demonstrates the significant utility of this technology.
- Ansari, Tharique N.,Taussat, Armand,Clark, Adam H.,Nachtegaal, Maarten,Plummer, Scott,Gallou, Fabrice,Handa, Sachin
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p. 10389 - 10397
(2019/10/14)
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- Rate Enhancement in CAN-Promoted Pd(PPh3)2Cl2-Catalyzed Oxidative Cyclization: Synthesis of 2-Ketofuran-4-carboxylate Esters
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Stoichiometric ceric ammonium nitrate (CAN) and a catalytic amount of Pd(PPh3)2Cl2 (5 mol %) can rapidly produce multisubstituted 2-ketofuran-4-carboxylate esters from 2-propargylic 1,3-ketoesters via oxidative O-cyclization reaction. Pd(PPh3)2Cl2 was found to be the crucial catalyst as its inclusion greatly enhanced the rate of the reaction and cleanly afforded the products within minutes. Over 30 substrates were successfully converted to the desired compounds in mostly moderate to good yields.
- Ruengsangtongkul, Sureeporn,Chaisan, Nattawadee,Thongsornkleeb, Charnsak,Tummatorn, Jumreang,Ruchirawat, Somsak
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supporting information
p. 2514 - 2517
(2019/04/30)
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- Palladium-Catalyzed Benzofulvenation of o-Arylanilines through C?H Bond Activation by Using Two Diarylacetylenes as an Implicit Benzofulvene
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We report the first example of Pd(II)-catalyzed highly step- and atom-economical benzofulvenation through free amine-directed ortho C?H bond activation of o-arylanilines. This paper presents a novel, simple, and efficient approach for the synthesis of benzofulvene derivatives from o-arylaniline substrates through C?H bond activation with two diarylacetylenes as an implicit benzofulvene unit. The reactivity of synthesized benzofulvenes toward oxidation was investigated, and they were shown to transform into phenanthridines, oxabenzofulvenes, and fluorescent polycyclics. (Figure presented.).
- Raju, Selvam,Hsiao, Huan-Chang,Thirupathi, Selvakumar,Chen, Pei-Ling,Chuang, Shih-Ching
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supporting information
p. 683 - 689
(2019/01/04)
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- Sequentially Pd/Cu-Catalyzed Alkynylation-Oxidation Synthesis of 1,2-Diketones and Consecutive One-Pot Generation of Quinoxalines
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We report a simple and efficient one-pot synthesis of 1,2-diketones by concatenation of two Pd/Cu-catalyzed processes: Pd0/CuI-catalyzed Sonogashira coupling of terminal alkynes with aryl (pseudo)halides furnishes internal alkynes, which are directly transformed by PdII/CuII-catalyzed Wacker-type oxidation with DMSO and oxygen as dual oxidants to furnish 1,2-diketones. With this efficient, catalyst economical process, various aryl iodides and triflates are efficiently transformed in high yields into symmetrically and unsymmetrically substituted 1,2-diketones with various functional groups. This process can be readily extended to a consecutive one-pot synthesis of quinoxalines in a diversity-oriented fashion.
- Niesobski, Patrik,Martínez, Ivette Santana,Kustosz, Sebastian,Müller, Thomas J. J.
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supporting information
p. 5214 - 5218
(2019/07/31)
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- Palladium-Catalyzed Annulation of Aryltriazoles and Arylisoxazoles with Alkynes
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We developed herein a palladium-catalyzed annulation of aryltriazoles and arylisoxazoles with internal alkynes via C?H bond activation process. 4,5-disubstituted-3H-naphtho[1,2-d][1,2,3]triazoles and 4,5-disubstituted-naphtho[2,1-d]isoxazoles could be afforded in good yields, respectively. The starting materials are readily available and the scope and applications of this transformation were explored. The reaction offers a practical approach to naphthalene fused heterocycles. (Figure presented.).
- Yuan, Hairui,Wang, Min,Xu, Zhenghu,Gao, Hongyin
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supporting information
p. 4386 - 4392
(2019/08/12)
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- Rhodium(iii)-catalyzed unreactive C(sp3)-H alkenylation of N-alkyl-1H-pyrazoles with alkynes
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The first example of pyrazole-directed rhodium(iii)-catalyzed unreactive C(sp3)-H alkenylation with alkynes has been described, which showed a relatively broad substrate scope with good functional group compatibility. Moreover, we demonstrated that the transitive coordinating center pyrazole could be easily removed under mild conditions.
- Li, Tongyu,Liu, Chang,Wu, Shaonan,Chen, Chen C.,Zhu, Bolin
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supporting information
p. 7679 - 7683
(2019/08/30)
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- Electrochemistry-Enabled Ir-Catalyzed Vinylic C-H Functionalization
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Synergistic use of electrochemistry and organometallic catalysis has emerged as a powerful tool for site-selective C-H functionalization, yet this type of transformation has thus far mainly been limited to arene C-H functionalization. Herein, we report the development of electrochemical vinylic C-H functionalization of acrylic acids with alkynes. In this reaction an iridium catalyst enables C-H/O-H functionalization for alkyne annulation, affording α-pyrones with good to excellent yields in an undivided cell. Preliminary mechanistic studies show that anodic oxidation is crucial for releasing the product and regeneration of an Ir(III) intermediate from a diene-Ir(I) complex, which is a coordinatively saturated, 18-electron complex. Importantly, common chemical oxidants such as Ag(I) or Cu(II) did not give significant amounts of the desired product in the absence of electrical current under otherwise identical conditions.
- Yang, Qi-Liang,Xing, Yi-Kang,Wang, Xiang-Yang,Ma, Hong-Xing,Weng, Xin-Jun,Yang, Xiang,Guo, Hai-Ming,Mei, Tian-Sheng
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supporting information
p. 18970 - 18976
(2019/12/04)
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- A palladium catalyzed aryl alkyne preparation method
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The invention discloses a palladium catalyzed aryl alkyne of the preparation method, comprises the following steps: in the catalyst, under the action of the ligand and alkali, substituted with aryl sulfonyl chloride alkynoic occurs in the organic solvent escapes suosuo the coupling reaction, after the reaction is finished after treatment to obtain the aryl alkyne. Used in the preparation method of the cheap raw material, the reaction and simple post treatment operation, at the same time, the reaction less side reaction, high yield of the product.
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-
Paragraph 0034; 0035; 0036
(2019/05/21)
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- The Direct Conversion of α-Hydroxyketones to Alkynes
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Alkynes are highly important functional groups in organic chemistry, both as part of target structures and as versatile synthetic intermediates. In this study, a protocol for the direct conversion of α-hydroxyketones to alkynes is reported. In combination with the variety of synthetic methods that generate the required starting materials by forming the central C-C bond, it enables a highly versatile fragment coupling approach toward alkynes. A broad scope for this novel transformation is shown alongside mechanistic insights. Furthermore, the utility of our protocol is demonstrated through its application in concert with varied α-hydroxyketone syntheses, giving access to a broad spectrum of alkynes.
- Ghiringhelli, Francesca,Nattmann, Lukas,Bognar, Sabine,Van Gemmeren, Manuel
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p. 983 - 993
(2019/01/24)
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- LiHMDS-Promoted Palladium-Catalyzed Sonogashira Cross-Coupling of Aryl Fluorides with Terminal Alkynes
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A highly efficient Pd-catalyzed Sonogashira coupling of various aryl fluorides with terminal alkynes in the presence of LiHMDS was developed. Both unreactive electron-rich fluoroarenes and electron-poor fluoroarenes proceeded smoothly and afforded the cor
- He, Jingjing,Yang, Kang,Zhao, Jianhong,Cao, Song
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supporting information
p. 9714 - 9718
(2019/11/28)
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- Rh(III)-Catalyzed [5 + 2] Oxidative Annulation of Cyclic Arylguanidines and Alkynes to 1,3-Benzodiazepines. A Striking Mechanistic Proposal from DFT
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A novel and mild Rh(III)-catalyzed [5 + 2] oxidative annulation between cyclic arylguanidines and alkynes efficiently affords 1,3-benzodiazepines (pentacyclic guanidines). The use of O2 as the sole oxidant in place of commonly used metal oxidants such as AgOAc clearly improves the efficiency of the oxidative annulation process. The mechanism of the cycloaddition most likely involves the formation of an eight-membered rhodacycle. DFT calculations support a striking mechanistic proposal for the [5 + 2] oxidative annulation.
- Martínez-Yá?ez, Nuria,Suárez, Jaime,Cajaraville, Ana,Varela, Jesús A.,Saá, Carlos
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supporting information
p. 1779 - 1783
(2019/03/29)
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- A novel zinc-catalyzed Suzuki-type cross-coupling reaction of aryl boronic acids with alkynyl bromides
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A novel Suzuki-type cross-coupling reaction of organoboron reagents with alkynyl bromides has been developed in the presence of catalytic Et2Zn/DMEDA system. The reaction afforded a variety of internal alkynes in moderate to excellent yields under mild reaction conditions without the formation of any homo-coupling products. The resulting internal alkynes have valuable applications in pharmaceutical and industrial areas. The use of relatively non-toxic zinc, chelating amine ligand and low reaction temperature make this protocol an alternative for the synthesis of internal alkynes. The scope and limitations of this protocol are also investigated.
- Keerthi Krishnan,Saranya, Salim,Rohit,Anilkumar, Gopinathan
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p. 266 - 271
(2019/03/26)
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- Molybdenum Alkylidyne Complexes with Tripodal Silanolate Ligands: The Next Generation of Alkyne Metathesis Catalysts
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A new type of molybdenum alkylidyne catalysts for alkyne metathesis is described, which is distinguished by an unconventional podand topology. These structurally well-defined complexes are easy to make on scale and proved to be tolerant toward numerous functional groups; even certain protic substituents were found to be compatible. The new catalysts were characterized by X-ray crystallography and by spectroscopic means, including 95Mo NMR.
- Hillenbrand, Julius,Leutzsch, Markus,Fürstner, Alois
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supporting information
p. 15690 - 15696
(2019/10/28)
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- Diborative Reduction of Alkynes to 1,2-Diboryl-1,2-Dimetalloalkanes: Its Application for the Synthesis of Diverse 1,2-Bis(boronate)s
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Reduction of alkynes with alkali metals in the presence of B2pin2 results in diboration of alkynes. Distinct from conventional dissolving metal hydrogenations, two carbon-boron bonds and also two carbon-alkali metal bonds can be constructed in one operation to form 1,2-diboryl-1,2-dimetalloalkanes. The 1,2-diboryl-1,2-dimetalloalkanes generated are readily convertible to a wide range of vicinal bis(boronate)s. In particular, oxidation of the 1,2-dianionic species provides (E)-1,2-diborylalkenes, unique anti-selective diboration of alkynes being thus executed.
- Takahashi, Fumiya,Nogi, Keisuke,Sasamori, Takahiro,Yorimitsu, Hideki
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supporting information
p. 4739 - 4744
(2019/06/27)
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- Copper-Catalyzed Twofold Silylmetalation of Alkynes
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The first twofold silylmetalation across a C≡C triple bond was achieved. In the presence of a catalytic amount of copper cyanide, diarylacetylenes were converted into 1,2-dimetalated 1,2-disilyl-1,2-diarylethanes on treatment with silylpotassium species generated in situ from disilane and t -BuOK. The dimetalated species were subsequently protonated to yield a series of 1,2-disilyl-1,2-diarylethanes.
- Shimokawa, Jun,Yamagishi, Hiroki,Yorimitsu, Hideki
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supporting information
p. 1551 - 1554
(2019/08/07)
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- Porous organic polymer supported rhodium as a heterogeneous catalyst for hydroformylation of alkynes to α,β-unsaturated aldehydes
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A new porous organic polymer supported rhodium catalyst (Rh/POL-BINAPa&PPh3) has been developed for the hydroformylation of various alkynes to afford the corresponding α,β-unsaturated aldehydes with high chem- and stereoselectivity, excellent catalytic activity and good reusability (10 cycles). The heterogeneous catalyst exhibited more catalytic activity than the comparable homogeneous Rh/BINAPa/PPh3 system.
- Liang, Zuyu,Chen, Jianbin,Chen, Xin,Zhang, Kai,Lv, Jinhe,Zhao, Haowen,Zhang, Guoying,Xie, Congxia,Zong, Lingbo,Jia, Xiaofei
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supporting information
p. 13721 - 13724
(2019/11/19)
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