- Kinetic Analysis of Domino Catalysis: A Case Study on Gold-Catalyzed Arylation
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Domino catalysis is a well-explored route to increasing the efficiency of multistep reactions. However, the kinetic features required for efficient turnover of a process where multiple transformations are effected by a single catalytic mechanism have not been explored in any detail. The kinetics of a nominally simple two-stage domino catalytic reaction have been analyzed by way of a gold-catalyzed coupling of two electron-deficient arylsilanes to generate an arylated fluorene. A combination of in situ interleaved 1H and 19F NMR spectroscopic kinetic measurements, kinetic simulations, and variations in substitution reveal how the catalyst partitioning between the two different cycles impacts both the rate and the selectivity of the process. The insight enables identification that sequential catalyst speciation and accumulation of the domino intermediate are general kinetic criteria for efficient domino catalysis.
- Ball, Liam T.,Corrie, Tom J. A.,Cresswell, Alexander J.,Lloyd-Jones, Guy C.
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- Palladium-Catalyzed Coupling of Biphenyl-2-yl Trifluoromethanesulfonates with Dibromomethane to Access Fluorenes
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A facile and efficient method has been developed for the synthesis of fluorenes by Pd-catalyzed C-H alkylation of biphenyl-2-yl trifluoromethanesulfonates. The trifluoromethanesulfonates are more readily available and more environmentally benign than biphenyl iodides, and are advantageous substrates for traceless directing-groupassisted C-H activation. The reaction generates C,C-palladacycles as the key intermediates that form two C(sp2)-C(sp3) bonds through reaction with CH2Br2. The reaction tolerates various functional groups, permitting easy access to a range of fluorene derivatives.
- Pan, Shulei,Zhang, Yanghui,Zhu, Qiongqiong
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- Solid-state construction of zigzag periphery: Via intramolecular C-H insertion induced by alumina-mediated C-F activation
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Caryl-F bond activation has become an important and quickly developing method for construction of carbon-based materials. We report that alumina-mediated C-F bond activation (AmCFA) enables construction of PAHs with zigzag periphery. This method includes
- Akhmetov, Vladimir,Amsharov, Konstantin,F?rtsch, Andreas,Feofanov, Mikhail
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p. 12325 - 12328
(2021/11/30)
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- Palladium-catalyzed synthesis of fluorenes by intramolecular c(sp 2)-h activation at room temperature
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The synthesis of fluorenes by intramolecular Pd-catalyzed C(sp 2)-H activation of 2-arylbenzyl chlorides was conducted at room temperature by using commercially available triphenylphosphine and pivalic acid as ligands. The desired reactions proceeded efficiently at room temperature, and various substrates were converted into the corresponding fluorene derivatives in excellent yields.
- Fujihara, Tetsuaki,Tanji, Yutaka,Tsuji, Yasushi
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supporting information
p. 805 - 808
(2020/05/19)
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- Palladium-Catalyzed Formal [4 + 1] Annulation via Metal Carbene Migratory Insertion and C(sp2)-H Bond Functionalization
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A highly efficient and operationally simple palladium-catalyzed formal [4 + 1] annulation reaction has been developed. The reaction is featured by the formation of two different C-C bonds on a carbenic center. It represents a concise method for the synthesis of a wide range of polycyclic aromatic hydrocarbons (PAHs) and 1H-indenes with easily available (trimethylsilyl)diazomethane as the carbene source. Metal carbene migratory insertion and C(sp2)-H bond activation are proposed as the key steps in this transformation. The reaction further demonstrates the versatility of the carbene-based coupling in combination with various transition-metal-catalyzed transformations.
- Xu, Shuai,Chen, Ri,Fu, Zihao,Zhou, Qi,Zhang, Yan,Wang, Jianbo
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p. 1993 - 1997
(2017/08/14)
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- Au-catalyzed biaryl coupling to generate 5- to 9-membered rings: Turnover-limiting reductive elimination versus π-complexation
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The intramolecular gold-catalyzed arylation of arenes by aryl-trimethylsilanes has been investigated from both mechanistic and preparative aspects. The reaction generates 5- to 9-membered rings, and of the 44 examples studied, 10 include a heteroatom (N, O). Tethering of the arene to the arylsilane provides not only a tool to probe the impact of the conformational flexibility of Ar-Au-Ar intermediates, via systematic modulation of the length of aryl-aryl linkage, but also the ability to arylate neutral and electron-poor arenes-substrates that do not react at all in the intermolecular process. Rendering the arylation intramolecular also results in phenomenologically simpler reaction kinetics, and overall these features have facilitated a detailed study of linear free energy relationships, kinetic isotope effects, and the first quantitative experimental data on the effects of aryl electron demand and conformational freedom on the rate of reductive elimination from diaryl-gold(III) species. The turnover-limiting step for the formation of a series of fluorene derivatives is sensitive to the reactivity of the arene and changes from reductive elimination to π-complexation for arenes bearing strongly electron-withdrawing substituents (σ > 0.43). Reductive elimination is accelerated by electron-donating substituents (ρ = -2.0) on one or both rings, with the individual σ-values being additive in nature. Longer and more flexible tethers between the two aryl rings result in faster reductive elimination from Ar-Au(X)-Ar and lead to the π-complexation of the arene by Ar-AuX2 becoming the turnover-limiting step.
- Corrie, Tom J. A.,Ball, Liam T.,Russell, Christopher A.,Lloyd-Jones, Guy C.
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supporting information
p. 245 - 254
(2017/05/29)
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- Au-Catalyzed Biaryl Coupling to Generate 5- To 9-Membered Rings: Turnover-Limiting Reductive Elimination versus ?-Complexation
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The intramolecular gold-catalyzed arylation of arenes by aryl-trimethylsilanes has been investigated from both mechanistic and preparative aspects. The reaction generates 5- to 9-membered rings, and of the 44 examples studied, 10 include a heteroatom (N, O). Tethering of the arene to the arylsilane provides not only a tool to probe the impact of the conformational flexibility of Ar-Au-Ar intermediates, via systematic modulation of the length of aryl-aryl linkage, but also the ability to arylate neutral and electron-poor arenes - substrates that do not react at all in the intermolecular process. Rendering the arylation intramolecular also results in phenomenologically simpler reaction kinetics, and overall these features have facilitated a detailed study of linear free energy relationships, kinetic isotope effects, and the first quantitative experimental data on the effects of aryl electron demand and conformational freedom on the rate of reductive elimination from diaryl-gold(III) species. The turnover-limiting step for the formation of a series of fluorene derivatives is sensitive to the reactivity of the arene and changes from reductive elimination to ?-complexation for arenes bearing strongly electron-withdrawing substituents (σ > 0.43). Reductive elimination is accelerated by electron-donating substituents (ρ = -2.0) on one or both rings, with the individual σ-values being additive in nature. Longer and more flexible tethers between the two aryl rings result in faster reductive elimination from Ar-Au(X)-Ar and lead to the ?-complexation of the arene by Ar-AuX2 becoming the turnover-limiting step.
- Ball, Liam T.,Corrie, Tom J. A.,Lloyd-Jones, Guy C.,Russell, Christopher A.
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supporting information
p. 245 - 254
(2021/09/04)
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- Efficient palladium-catalyzed C(sp2)-H activation towards the synthesis of fluorenes
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A facile protocol for the synthesis of fluorene derivatives has been developed through palladium-catalyzed cyclization of 2′-halo-diarylmethanes via activation of arylic C-H bonds. The reactions occurred smoothly and allowed both electron-rich and electron-deficient substrates to convert into their corresponding fluorenes in good to excellent yields. Studies revealed that this Pd-catalyzed cyclization was also available for the substrates of 2′-chloro-diarylmethanes and no catalyst poisoning occurred for 2′-iodo-diphenylmethane.
- Song, Juan,Li, Yali,Sun, Wei,Yi, Chenglong,Wu, Hao,Wang, Haotian,Ding, Keran,Xiao, Kang,Liu, Chao
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p. 9030 - 9033
(2016/11/11)
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- Synthesis of Fluorenes Starting from 2-Iodobiphenyls and CH2Br2 through Palladium-Catalyzed Dual C-C Bond Formation
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A facile and efficient approach is developed for the synthesis of fluorene and its derivatives starting from 2-iodobiphenyls and CH2Br2. A range of fluorene derivatives can be synthesized under relatively mild conditions. The reaction proceeds via a tandem palladium-catalyzed dual C-C bond formation sequence through the key dibenzopalladacyclopentadiene intermediates, which are obtained from 2-iodobiphenyls through palladium-catalyzed C-H activation.
- Shi, Guangfa,Chen, Dushen,Jiang, Hang,Zhang, Yu,Zhang, Yanghui
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p. 2958 - 2961
(2016/07/06)
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- Pd(0)-Catalyzed Cross-Coupling of 1,1-Diboronates with 2,2′-Dibromobiphenyls: Synthesis of 9H-Fluorenes
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An efficient and mild synthesis of 9H-fluorene derivatives through a Pd(0)-catalyzed cross-coupling reaction of 1,1-diboronates with 2,2′-dibromobiphenyls has been developed. This reaction features high yields, operational simplicity, and mild reaction conditions, thus providing an excellent alternative to published methods for 9H-fluorene synthesis.
- Xu, Shuai,Shangguan, Xianghang,Li, Huan,Zhang, Yan,Wang, Jianbo
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p. 7779 - 7784
(2015/08/18)
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- Gold(I) carbenes by retro-buchner reaction: Generation and fate
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The fate of the aryl gold(I) carbenes generated by retro-Buchner reaction of ortho-substituted 7-aryl-1,3,5-cycloheptatrienes is dependent on the constitution of the ortho substituent. Indenes and fluorenes are obtained by intramolecular reaction of highly electrophilic gold(I) carbenes with alkenes and arenes. According to density functional theory calculations, the gold-catalyzed retro-Buchner process occurs stepwise, although the two carbon-carbon cleavages occur on a rather flat potential energy surface.
- Wang, Yahui,McGonigal, Paul R.,Herle, Bart,Besora, Maria,Echavarren, Antonio M.
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supporting information
p. 801 - 809
(2014/02/14)
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- Br?nsted acid-mediated intramolecular cyclization of biaryl triazenes for the synthesis of fluorenes and 9,10-dihydro-phenanthrenes
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The efficient synthesis of fluorenes from biaryl triazenes is successfully developed. Up to 27 examples of biaryl triazenes are converted into their corresponding fluorene derivatives in the presence of CF3COOH (4.0 equiv). Mechanism research i
- Xu, Lijun,Yang, Weijun,Zhang, Lili,Miao, Maozhong,Yang, Zhigen,Xu, Xin,Ren, Hongjun
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p. 9206 - 9221
(2015/01/08)
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- Highly efficient and versatile synthesis of polyarylfluorenes via Pd-catalyzed C-H bond activation
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A facile protocol for the Pd-catalyzed preparative synthesis of fluorene derivatives has been developed. While a wide range of fluorenes were easily obtained with high efficiency and selectivity under mild conditions, excellent functional group tolerance
- Hwang, Seung Jun,Kim, Hyun Jin,Chang, Sukbok
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supporting information; experimental part
p. 4588 - 4591
(2009/12/09)
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- Mild chlorination of aromatic compounds with tin(IV) chloride and lead tetraacetate
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SnCl4/Pb(OAc)4 acts as a safe source of Cl2 for the chlorination of aromatic compounds. A variety of aromatic compounds are effectively chlorinated with SnCl4/Pb(OAc)4 under mild conditions. The mixture is a selective chlorinating agent, particularly with polyalkylbenzenes, polycyclic aromatic compounds and anisoles.
- Muathen, Hussni A.
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p. 8863 - 8866
(2007/10/03)
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- The Decomposition of Arenediazonium Tetrafluoroborates with Halo- and Azidotrimethylsilanes in Nonaqueous Solvents
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The reaction of arenediazonium tetrafluoroborates with chlorotrimethylsilane in a tetrahydrofuran/N,N-dimethylformamide (DMF) (5v/3v) solution afforded the protodediazotization products in high yields.The reactions of the diazonium salts with halotrimethylsilanes in DMF were found to give the corresponding haloarenes.Among the halodediazotization reactions, the iododediazotization with iodotrimethylsilane proceeded smoothly at room temperature to give the iodoarenes in excellent yields.In a similar manner, a variety of azidoarenes were obtained in cosistently high yields by the treatment of arenediazonium tetrafluoroborates with azidotrimethylsilane in a DMF solution.
- Keumi, Takashi,Umeda, Toshiaki,Inoue, Yoshinori,Kitajima, Hidehiko
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