- Palladium-catalyzed benzylic C(sp3)–H arylation of o-alkylbenzaldehydes
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The palladium-catalyzed benzylic C(sp3)–H arylation of o-alkylbenzaldehyde derivatives was achieved utilizing 2-dimethylaminoethylamine as a novel transient directing group. The γ-C(sp3)–H arylation reaction efficiently afforded a variety of arylated o-alkylbenzaldehydes and polycyclic aromatic hydrocarbons (PAHs) in one pot, exhibiting high functional group tolerance with broad substrate scope. The aliphatic diamine auxiliary represents a simple, inexpensive, readily available, and removable directing group for C–H activation. The resultant o-benzylbenzaldehyde products could be diversely transformed into potentially important synthetic intermediates under mild conditions.
- Lei, Lan,Wu, Ping,Liu, Zhuqing,Lou, Jiang
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supporting information
(2021/02/16)
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- Semicarbazide: A Transient Directing Group for C(sp3)?H Arylation of 2-Methylbenzaldehydes
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Semicarbazide as an effective transient directing group for C(sp3)?H arylation of 2-methylbenzaldehydes is described. Various substituted 2-benzylbenzaldehydes are efficiently synthesized by this strategy. The salient features of this protocol are the use of inexpensive transient directing group, wide scope of substrates with good functional group compatibility, up to 98% yield, and applicability to gram scale. (Figure presented.).
- Wen, Fei,Li, Zheng
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supporting information
p. 133 - 138
(2019/11/28)
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- Cascade reaction for the synthesis of polycyclic aromatic hydrocarbons via transient directing group strategy
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A Pd(II)-catalyzed cascade synthesis of diverse polycyclic aromatic hydrocarbons via transient directing group strategy has been developed, involving the consecutive arylation, cyclization and aromatization. The efficiency and practicality were demonstrated by wide substrate range, concise synthetic pathway and mild reaction conditions. The subsequent transformations of the benz[a]anthracene core accessed natural bioactive PAH molecules.
- Wang, Ziqi,Dong, Wendan,Sun, Bing,Yu, Qinqin,Zhang, Fang-Lin
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supporting information
p. 4031 - 4041
(2019/07/03)
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- Modular Design of Fluorescent Dibenzo- and Naphtho-Fluoranthenes: Structural Rearrangements and Electronic Properties
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A library of 12 dibenzo- and naphtho-fluoranthene polycyclic aromatic hydrocarbons (PAHs) with MW = 302 (C24H14) was synthesized via a Pd-catalyzed fluoranthene ring-closing reaction. By understanding the various modes by which the palladium migrates during the transformation, structural rearrangements were bypassed, obtaining pure PAHs in high yields. Spectroscopic and electrochemical characterization demonstrated the profound diversity in the electronic structures between isomers. Highlighting the significant differences in emission of visible light, this library of PAHs will enable their standardization for toxicological assessment and potential use as optoelectronic materials.
- Mohammad-Pour, Gavin S.,Ly, Richard T.,Fairchild, David C.,Burnstine-Townley, Alex,Vazquez-Molina, Demetrius A.,Trieu, Khang D.,Campiglia, Andres D.,Harper, James K.,Uribe-Romo, Fernando J.
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supporting information
p. 8036 - 8053
(2018/05/31)
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- Oxygen- and sulfur-bridged bianthracene V-shaped organic semiconductors
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Highly π-electron conjugated backbones are of great interest for applications to organic electronic devices, e.g., organic field-effect transistors and organic photovoltaics. A series of oxygen- and sulfur-bridged bianthracene V-shaped π-electronic cores are facilely synthesized. Both V-shaped molecules possess bent structures induced by the intermolecular interaction in a herringbone-packing manner. A theoretical calculation study reveals that the driving force of the bent structures originates from the strong dispersion energy. Also, the bent conformation plays a vital role in the formation of a dense packing structure, resulting in an attractive intermolecular overlap. An examination of the charge transport demonstrates that the hole mobility is up to 2.0 sq cm/Vs. Sulfur-bridged V-shaped π-electronic cores are more suitable for two-dimensional carrier-transport than oxygen-bridged analogs.
- Mitsui, Chikahiko,Yamagishi, Masakazu,Shikata, Ryoji,Ishii, Hiroyuki,Matsushita, Takeshi,Nakahara, Katsumasa,Yano, Masafumi,Sato, Hiroyasu,Yamano, Akihito,Takeya, Jun,Okamoto, Toshihiro
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p. 931 - 938
(2017/08/08)
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- Indium-catalyzed construction of polycyclic aromatic hydrocarbon skeletons via dehydration
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Polycyclic aromatic compounds can be synthesized from 2-benzylic- or 2-allylbenzaldehydes using a catalytic amount of In(III) or Re(I) complexes. By using this method, polycyclic aza-aromatic compounds can also be prepared efficiently. In these reactions, only water is formed as a side product.
- Kuninobu, Yoichiro,Tatsuzaki, Tomohiro,Matsuki, Takashi,Takai, Kazuhiko
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experimental part
p. 7005 - 7009
(2011/10/09)
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- Efficient synthesis of 9-tosylaminofluorene derivatives by boron trifluoride etherate-catalyzed aza-friedel-crafts reaction of in situ generated N-tosylbenzaldimines
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An efficient and expeditious boron trifluoride etherate (BF 3·Et2O) catalyzed one-pot reaction for the synthesis of N-tosyl-9-aminofluorenes and anthracene derivatives from in situ generated N-tosylbenzaldimines via an aza-Friedal-Crafts reaction has been developed. The catalytic reaction shows high substrate tolerance with excellent yields.
- Yu, Xufen,Lu, Xiyan
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scheme or table
p. 569 - 574
(2011/04/23)
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- A versatile synthesis of annulated carbazole analogs involving a domino reaction of bromomethylindoles with arenes/heteroarenes
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A ZnBr2-mediated arylation of aryl/heteroaryl methyl bromides with arenes at 80°C led to the formation of arylated products, which underwent subsequent 1,5-sigmatropic rearrangement followed by electrocyclization and aromatiza tion with loss of a diethylmalonate unit to afford the corresponding annulated products.
- Dhayalan, Vasudevan,Clement, J. Arul,Jagan, Radhakrishnan,Mohanakrishnan, Arasambattu K.
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experimental part
p. 531 - 546
(2009/09/06)
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- A New Convenient Synthesis of Alkoxyanthracenes from Alkoxy-9,10- anthraquinones
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Methoxy-9,10-anthraquinones with mono-, di- and tetraether groups at different positions 1a-h can be directly reduced to the corresponding methoxyanthracenes 3a-h in moderate to good yields by zinc in refluxing acetic acid. Under similar conditions, ethyl 1′-anthracenoxyacetate (3i) with the ester group unaffected and 1,8-oxybis(ethyleneoxyethyleneoxy)anthracene (5) were also conveniently synthesized in 65 and 70% yields, respectively.
- Lu, Lingang,Chen, Qiyin,Zhu, Xiaozhang,Chen, Chuanfeng
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p. 2464 - 2466
(2007/10/03)
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- Electron and oxygen transfer in polyoxometalate, H5PV2Mo10O40, catalyzed oxidation of aromatic and alkyl aromatic compounds: Evidence for aerobic Mars-van Krevelen-type reactions in the liquid homogeneous phase
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The mechanism of aerobic oxidation of aromatic and alkyl aromatic compounds using anthracene and xanthene, respectively, as a model compound was investigated using a phosphovanadomolybdate polyoxometalate, H5PV2Mo10O40, as catalyst under mild, liquid-phase conditions: The polyoxometalate is a soluble analogue of insoluble mixed-metal oxides often used for high-temperature gas-phase heterogeneous oxidation which proceed by a Mars-van Krevelen mechanism. The general purpose of the present investigation was to prove that a Mars-van Krevelen mechanism is possible also in liquid-phase, homogeneous oxidation reactions. First, the oxygen transfer from H5PV2Mo10O40 to the hydrocarbons was studied using various techniques to show that commonly observed liquid-phase oxidation mechanisms, autoxidation, and oxidative nucleophilic substitution were not occurring in this case. Techniques used included (a) use of 18O-labeled molecular oxygen, polyoxometalate, and water; (b) carrying out reactions under anaerobic conditions; (c) performing the reaction with an alternative nucleophile (acetate) or under anhydrous conditions; and (d) determination of the reaction stoichiometry. All of the experiments pointed against autoxidation and oxidative nucleophilic substitution and toward a Mars-van Krevelen mechanism. Second, the mode of activation of the hydrocarbon was determined to be by electron transfer, as opposed to hydrogen atom transfer from the hydrocarbon to the polyoxometalate. Kinetic studies showed that an outer-sphere electron transfer was probable with formation of a donor-acceptor complex. Further studies enabled the isolation and observation of intermediates by ESR and NMR spectroscopy. For anthracene, the immediate result of electron transfer, that is formation of an anthracene radical cation and reduced polyoxometalate, was observed by ESR spectroscopy. The ESR spectrum, together with kinetics experiments, including kinetic isotope experiments and 1H NMR, support a Mars-van Krevelen mechanism in which the rate-determining step is the oxygen-transfer reaction between the polyoxometalate and the intermediate radical cation. Anthraquinone is the only observable reaction product. For xanthene, the radical cation could not be observed. Instead, the initial radical cation undergoes fast additional proton and electron transfer (or hydrogen atom transfer) to yield a stable benzylic cation observable by 1H NMR. Again, kinetics experiments support the notion of an oxygen-transfer rate-determining step between the xanthenyl cation and the polyoxometalate, with formation of xanthen-9-one as the only product. Schemes summarizing the proposed reaction mechanisms are presented.
- Khenkin,Weiner,Wang,Neumann
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p. 8531 - 8542
(2007/10/03)
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- An Efficient Reduction of Anthrones to Anthracenes
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An efficient and general means of reducing anthrones to anthracenes has been developed.The procedure, which uses NaBH4 as the reducing agent in a mixed solvent system of diglyme/methanol, produced anthracenes in essentially quantitative yield from a variety of anthrones.
- Marquardt, Donald J.,McCormick, Frankie A.
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p. 1131 - 1134
(2007/10/02)
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- Thermally reversible organic solvent gels
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Stable, thermally reversible gels of organic solvents and a gelling agent having the formula wherein R1 is an anthracene analogue or substituted anthracene analogue, n is zero or a whole number from 2 to 20, and R2 is cholesteryl and cholestanyl or a derivative of cholesteryl or cholestanyl, processes for producing same, and novel anthracene analogue cholesteryl and cholestanyl esters and derivatives.
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- Process for the selective production of dihydroxybenzenes
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The known nuclear hydroxylation of phenol or substituted phenols or phenol ethers with organic solutions of hydrogen peroxide in the presence of a catalyst is carried out in improved manner by employing both (1) a special, practically water free solution of hydrogen peroxide in an organic solvent which forms an azeotrope with water, which azeotrope boils below the boiling point of hydrogen peroxide, and (2) selenium dioxide as a catalyst. Through this, the nuclear hydroxylation is substantially simpler than previously. Besides, for the first time, it is possible to control the ortho to para ratio or the two ortho ratios to each other.
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- Benzannelated 9-Hydroxyphenalenones
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The preparation and characterization of the two title compounds (6-hydroxybenzanthracen-7-one (2) and 3-hydroxybenzanthracen-4-one (3) or their proton tautomers), and an isomer (8-hydroxybenzanthracen-7-one (4)), are reported.The electronic spectra of (2) and (3) suggest that annelation of 9-hydroxyphenalenone (1) produces substantial shifts in the energies and intensities of the transitions, but does not fundamentally alter the underlying character of the chromophore.
- Haddon, R. C.
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p. 1733 - 1738
(2007/10/02)
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