- 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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supporting information
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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- Dual Gold Catalysis: Synthesis of Fluorene Derivatives from Diynes
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1,5-Diyne systems bearing one terminal and one benzyl- or allyl-substituted alkyne attached to an aromatic backbone were converted in the presence of a gold catalyst. In a dual gold-catalyzed process, gold vinylidenes are formed that selectively undergo formal CH insertion into the C(sp2)–H bond of the offered unsaturated systems. If H atoms are present in the propargylic position, a subsequent isomerization to the aromatic system takes place leading to 9H-fluorene and 11H-benzo[b]fluorene derivatives as final products. In the case of a quaternary carbon in the propargylic position no further aromatization is observed and 10H-benzo[b]fluorene derivatives are obtained in high yield. (Figure presented.).
- Bucher, Janina,Wurm, Thomas,Taschinski, Svenja,Sachs, Eleni,Ascough, David,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
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supporting information
p. 225 - 233
(2017/02/05)
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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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- Halogen-Adjusted Chemoselective Synthesis of Fluorene Derivatives with Position-Controlled Substituents
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Fluorenes have been synthesized through an efficient novel Pd-catalyzed tandem cross-coupling reaction; these substrates are fascinating building blocks found in organic photoelectric materials. The position of the substituent on fluorenes could be conveniently tuned by changing the halogen in the ortho-halobenzyl bromide substrates when coupled with various arylboronic acids. This newly developed synthetic approach could achieve the potential diversity in fluorene-based molecular architectures.
- Song, Juan,Sun, Wei,Li, Yali,Wei, Fuliang,Liu, Chao,Qian, Yan,Chen, Shufen
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supporting information
p. 211 - 215
(2016/03/01)
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- Palladium-Catalyzed Reaction of Haloarenes with Diarylethynes: Synthesis, Structural Analysis, and Properties of Methylene-Bridged Arenes
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Fluorenes and methylene-bridged polyarenes were easily and efficiently synthesized from haloarenes (or aryl triflates) and diarylethynes by a one-pot, two-step procedure. This protocol involves the palladium-catalyzed cycloisomerization and a subsequent base-mediated retro-aldol condensation. A major advantage is that the starting materials need not have ortho functional groups to complete the annulation. The backbone of the designed products was enlarged using dihaloarenes, highly π-conjugated haloarenes, or diarylalkynes. The mechanism of the formation of benzo[a]fluorene was investigated. The bowl-shaped structure of methylene-bridged indenocorannulene was verified by X-ray crystallography. The photophysical and electrochemical properties of the products thus prepared were investigated.
- Lee, Che-Wei,Liu, En-Chih,Wu, Yao-Ting
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p. 10446 - 10456
(2015/11/18)
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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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- Rhodium- and iridium-catalyzed dehydrogenative cyclization through double C-H bond cleavages to produce fluorene derivatives
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The rhodium-catalyzed cyclization of a series of 2,2-diarylalkanoic acids in the presence of copper acetate as an oxidant smoothly proceeded through double C-H bond cleavages and subsequent decarboxylation to produce the corresponding fluorene derivatives. The direct cyclization of triarylmethanols also took place efficiently by using an iridium catalyst in place of the rhodium, while the hydroxy function was still intact.
- Itoh, Masaki,Hirano, Koji,Satoh, Tetsuya,Shibata, Yu,Tanaka, Ken,Miura, Masahiro
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p. 1365 - 1370
(2013/03/28)
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- Synthesis of methylene-bridge polyarenes through palladium-catalyzed activation of benzylic carbon-hydrogen bond
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In the presence of palladium(II) acetate [Pd(OAc)2] and an N-heterocyclic carbene (NHC) ligand, fluorene derivatives can be generated in good to excellent yields from 2-halo-2′-methylbiaryls through the benzylic C-H bond activation (14 examples; 81-97% yields). The scope and limitations of this protocol have been examined. A wide range of functional groups, such as alkyl, alkoxy, ester, nitrile, and others, is able to tolerate the reaction conditions herein. The cyclization of an isotope-labelled biphenyl gave the corresponding product with a primary kinetic isotope effect (k H/kD=4.8:1), which indicates that the rate-determining step of this reaction is the activation of the benzylic C-H bond. Moreover, indenofluorenes were also accessed in excellent results from terphenyls (3 examples; 91-92% yields). The cascade reaction of 2,6-dichloro-2′- methylbiphenyl with diphenylacetylene produced 8,9-diphenyl-4H-cyclopenta[def] phenanthrene in 60% yield through the activation of an aryl and a benzylic C-H bond. Copyright
- Hsiao, Chien-Chi,Lin, Yi-Kuan,Liu, Chia-Ju,Wu, Tsun-Cheng,Wu, Yao-Ting
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experimental part
p. 3267 - 3274
(2011/02/23)
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- Synthesis of fluorene and indenofluorene compounds: Tandem palladium-catalyzed suzuki cross-coupling and cyclization
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Figure Presented "Fluor" it: Palladium-catalyzed tandem reactions, in which C(sp3)-H bond activation is the key step (see scheme; DMA = dimethylacetamide), lead to substituted fluorenes and indenofluorenes through annulation in high yield and i
- Liu, Tao-Ping,Xing, Chun-Hui,Hu, Qiao-Sheng
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supporting information; experimental part
p. 2909 - 2912
(2010/08/04)
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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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- MATERIAL FOR ORGANIC LIGHT-EMITTING ELEMENT AND ORGANIC LIGHT-EMITTING ELEMENT INCLUDING THE SAME
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A fluorene compound and an organic light-emitting element including the fluorene compound are provided. The fluorene compound is represented by the following general formula [1], and the fluorene compound is a material for an organic light-emitting element. A steric hindrance group is introduced directly on a fluorene ring in the fluorene compound.
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Page/Page column 24
(2008/12/08)
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- Low-valent niobium-mediated double activation of C-F/C-H bonds: Fluorene synthesis from o-arylated α,α,α-trifluorotoluene derivatives
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By the treatment of 0.3 molar amount of NbCl5 and LiAlH4, o-arylated α,α,α-trifluorotoluenes afforded fluorene derivatives in good yields. C-F bonds of the CF3 group and the neighboring ortho C-H bond were doubly activated to give the coupling products. Copyright
- Fuchibe, Kohei,Akiyama, Takahiko
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p. 1434 - 1435
(2007/10/03)
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- An N.M.R. Investigation of the Mills-Nixon Effect
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The 4J coupling constant, previously established as a probe of bond order, was used to examine the bond orders in a series of ortho-bridged compounds: benzocyclopropene, 1,2-dihydrobenzocyclobutene, indan and tetralin.No evidence for sterically induced bond fixation (i.e. the Mills-Nixon effect) was found, but some evidence for electronic distortion in the corresponding benzylic ketones was observed.The experimental results are in accord with SCF/MO calculations.
- Collins, Michael J.,Gready, Jill E.,Sternhell, Sever,Tansey, Charles W.
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p. 1547 - 1557
(2007/10/02)
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