- A Convenient Route to Heteronaphthacenes
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Heteronaphthacenes 1 were prepared in two steps from 1,3-dihydrobenzo[c]thiophene 2,2-dioxide (4) and dienophiles 2 via convenient high-temperature Diels-Alder reactions.
- Markgraf, J. Hodge,Patterson, Daniel E.
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- Facile Construction of Furanoacenes by a Three-Step Sequence Going through Disilyl-exo-cyclic Dienes
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Facile synthesis of various benzonaphthofurans was achieved by intramolecular hydroarylation of 1,4-disilyl-2-aryloxy-1,3-enynes followed by cycloaddition with arynes or alkenes and finally desilylaromatization. The three-step transformation can be operated sequentially in one-pot, providing with a range of furanoacenes easily and highly effectively.
- Minami, Yasunori,Furuya, Yuki,Hiyama, Tamejiro
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- Pd-Catalyzed Denitrative Intramolecular C-H Arylation
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A Pd-catalyzed intramolecular C-H arylation of nitroarenes has been developed. Nitroarenes bearing tethered aryl groups at the ortho-position can be readily prepared in one step from 2-halonitroarenes by a nucleophilic aromatic substitution (SNAr). Under Pd/BrettPhos catalysis, activations of the C-NO2 bond as well as the C-H bond on arenes generated the corresponding biaryl linkage in moderate to excellent yields.
- Asahara, Kitty K.,Okita, Toshimasa,Saito, Ami N.,Muto, Kei,Nakao, Yoshiaki,Yamaguchi, Junichiro
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supporting information
p. 4721 - 4724
(2019/06/17)
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- Microwave-Promoted Pd-Catalyzed Synthesis of Dibenzofurans from Ortho-Arylphenols
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ortho-Aryl phenols, synthesized via protecting group free Suzuki–Miyaura coupling of ortho-halophenols and arene boronic acids, undergo a cyclization to dibenzofurans via oxidative C–H activation. The reaction proceeds under microwave irradiation in short reaction times using catalytic amounts of Pd(OAc)2 without additional ligands.
- Schmidt, Bernd,Riemer, Martin
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p. 1287 - 1297
(2017/03/27)
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- Synthesis of fused dibenzofuran derivatives via palladium-catalyzed domino C-C bond formation and iron-catalyzed cycloisomerization/aromatization
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A range of tetracyclic dibenzofuran derivatives bearing a variety of functional groups was readily synthesized via a two-stage domino strategy starting from propargyl ethers of 2-halo phenol derivatives. The first stage in the strategy involves Pd(0)-catalyzed domino intramolecular carbopalladation/Suzuki coupling via 5-exo-dig cyclization onto the alkyne, leading to 3-methylene-2,3-dihydrobenzofuran derivatives. In the second stage of the domino strategy, an iron(III)-catalyzed cycloisomerization and aromatization reaction produces tetracyclic benzofuran derivatives. This two-step sequence provides efficient access to diversely substituted polycyclic dibenzofuran derivatives in high yields and in an atom-efficient and environmentally friendly manner. Moreover, this strategy was also successfully used for the synthesis of a naturally occurring tetracyclic dibenzofuran, β-brazan.
- Paul, Kartick,Jalal, Swapnadeep,Kundal, Sandip,Jana, Umasish
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p. 1164 - 1174
(2016/02/19)
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- OXYGEN-CONTAINING FUSED RING AMINE COMPOUND, SULPHUR-CONTAINING FUSED RING AMINE COMPOUND, AND ORGANIC ELECTROLUMINESCENT ELEMENT
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A fused amine compound including a furan ring or a thiophene ring and an organic electroluminescence device employing the amine compound. The organic electroluminescence device includes a cathode, an anode, and one or more organic thin film layers which are disposed between the cathode and the anode. The organic thin film layers include a light emitting layer and at least one layer of the organic thin film layers includes at least one amine compound.
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Paragraph 0443; 0448-0449
(2016/12/01)
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- Experimental NMR and DFT studies of persistent carbocations derived from hetero-polycyclic aromatic hydrocarbons containing oxygen atom: Dibenzo[b,d]furan, Benzo[b]naphtho[1,2-d]furan, Benzo[b]naphtho[2,3-d]furan, Benzo[b]naphtho[2,1-d]furan, and Dinaphtho[2,1-b: 1′,2′-d]furan
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Persistent protonation carbocations generated from hetero-PAHs containing oxygen atoms in their aromatic rings, dibenzo[b,d]furan (5), benzo[b]naphtho[1,2-d]furan (6), benzo[b]naphtho[2,3-d]furan (7), benzo[b]naphtho[2,1-d]furan (8), and dinaphtho[2,1-b: 1′,2′-d]furan (9), were directly observed by NMR measurements in superacid. Compound 5 was protonated mainly at C(2) in FSO3H-SbF5 (1: 1) or (4: 1)/SO2ClF, and 6, 8, and 9 were protonated exclusively at C(5) in CF3SO3H or FSO3H/SO2ClF, whereas 7 was protonated at C(6) and C(11) to give two species in FSO3H/SO2ClF. Surprisingly, compound 5 resists protonation in FSO3H/SO2ClF to show NMR spectra corresponding to that of the intact material. Positive charge delocalization mapping for carbocations based on experimental Δδ13C values indicates limited delocalization in these systems. The chemical shifts and charge delocalization modes derived by DFT calculations agreed with the experimental results.
- Okazaki, Takao,Nakagawa, Madoka,Kitagawa, Toshikazu,Laali, Kenneth K.
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p. 1235 - 1244
(2015/02/18)
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- Lewis acid/Broensted acid mediated benz-annulation of thiophenes and electron-rich arenes
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A facile preparation of benz-annulated heterocycles were achieved at rt involving a Lewis acid/Broensted acid mediated annulation of heterocycles using 2,5-dimethoxytetrahydrofuran as a four-carbon synthon. The benz-/naphth-annulation was found to be successful with electron-rich arenes as well.
- Rafiq, Settu Muhamad,Sivasakthikumaran, Ramakrishnan,Mohanakrishnan, Arasambattu K.
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supporting information
p. 2720 - 2723
(2014/06/09)
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- Nickel-catalyzed intramolecular C-H arylation using aryl pivalates as electrophiles
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This paper describes a method for nickel catalyzed intramolecular C-H arylation using aryl pivalates as electrophiles. The transformation is efficient for the synthesis of diverse electronically and sterically differentiated dibenzofurans. Additionally, the method could be expanded toward the synthesis of carbazoles. Preliminary mechanistic studies of the transformation are also described.
- Wang, Jiayi,Ferguson, Devin M.,Kalyani, Dipannita
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p. 5780 - 5790
(2013/07/19)
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- Efficient synthesis of dibenzoxaborininols from diaryl ethers and their application to dibenzofuran synthesis
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A convenient and efficient method for the borylation of diaryl ethers leading to dibenzoxaborininols and the synthesis of dibenzofuran derivatives has been developed. The borylation involves the sequential three-step process: lithiation, borylation and hydrolysis. The synthesized dibenzoxaborininols could be readily transformed into dibenzofuran derivatives in good to excellent yields under palladium catalysis in the presence of iodine, and this is the first example for the formation of an aryl C-C bond from diarylborinic acids. Copyright
- Niu, Liting,Yang, Haijun,Jiang, Yuyang,Fu, Hua
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p. 3625 - 3632
(2014/01/06)
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- Rhodium-catalyzed decarbonylative C-H arylation of 2-aryloxybenzoic acids leading to dibenzofuran derivatives
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Rhodium-catalyzed intramolecular C-H arylation of 2-aryloxybenzoic acids proceeded accompanied by decarbonylation to give dibenzofuran derivatives in high yields. The present reaction is widely applicable to substrates bearing various functionalities.
- Maetani, Shinji,Fukuyama, Takahide,Ryu, Ilhyong
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supporting information
p. 2754 - 2757
(2013/07/19)
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- Palladium-catalyzed intramolecular C-H arylation of arenes using tosylates and mesylates as electrophiles
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This paper describes a method for the palladium catalyzed intramolecular C-H arylation using tosylates and mesylates as electrophiles. The transformation is efficient for the synthesis of various heterocyclic motifs including furans, carbazoles, indoles, and lactams. Additionally, a protocol for the one-pot sequential tosylation/arylation of phenol derivatives is presented.
- Nervig, Christine S.,Waller, Peter J.,Kalyani, Dipannita
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p. 4838 - 4841,4
(2020/09/16)
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- Oxidative cyclization of 2-arylphenols to dibenzofurans under Pd(II)/peroxybenzoate catalysis
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2-Arylphenols undergo intramolecular C-H bond activation/C-O bond formation to afford dibenzofuran derivatives under palladium catalysis in the presence of tert-butyl peroxybenzoate as an oxidant. Kinetic isotope effect experiments indicated that C-H bond cleavage is the rate-limiting step of the reaction.
- Wei, Ye,Yoshikai, Naohiko
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supporting information; experimental part
p. 5504 - 5507
(2011/12/05)
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- Lewis acid mediated one-pot synthesis of aryl/heteroaryl-fused carbazoles involving a cascade Friedel-Crafts alkylation/electrocyclization/aromatization reaction sequence
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A Lewis-acid-mediated domino reaction of 2/3-(bromomethyl)indoles with arenes/heteroarenes led to the formation of the corresponding annulated carbazoles. This three-step one-pot transformation proceeds by sequential Lewis acid catalysed Friedel-Crafts alkylation, electrocyclization and aromatization reactions. The strategy is highly efficient for the assembly of complex aryl/heteroaryl-fused carbazoles.
- Sureshbabu, Radhakrishnan,Saravanan, Velu,Dhayalan, Vasudevan,Mohanakrishnan, Arasambattu K.
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p. 922 - 935
(2011/04/22)
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- Formation of dibenzofurans by flash vacuum pyrolysis of aryl 2-(allyloxy)benzoates and related reactions
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Flash vacuum pyrolysis (FVP) of aryl 2-(allyloxy)benzoates 5 and of the corresponding aryl 2-(allylthio)benzoates 6 at 650°C, gives dibenzofurans 19 and dibenzothiophenes 20, respectively. The mechanism involves generation of phenoxyl (or thiophenoxyl) radicals by homolysis of the O-allyl (or S-allyl) bond, followed by ipso attack at the ester group, loss of CO2 and cyclisation of the resulting aryl radical. Synthetically, the procedure works well for p-substituted substrates, which lead to 2-substituted dibenzofurans 19b-f (73-90%) and dibenzothiophenes 20b-c (90-94%). Little selectivity is shown in the cyclisation of m-substituted substrates and competing interactions of the radical with the substituent - and ipso-attack - complicate the pyrolyses of o-substituted substrates. FVP of related radical precursors including 2-(allyloxy)phenyl benzoates 43 gave no dibenzofurans, whereas 2-(allyloxy-5-methyl)azobenzene 44 gave a much reduced yield. No carbazoles were obtained by FVP of 4-methylphenyl 2-(allylamino)benzoate 42.
- Black, Michael,Cadogan,McNab, Hamish
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experimental part
p. 2961 - 2967
(2010/09/06)
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- New '2-phenylnaphthalene'-mediated synthesis of benzo[b]naphtho[2,3-d] furan-6,11-diones and 6-oxa-benzo[a]anthracene-5,7,12-triones: First total synthesis of 6-oxa-benzo[a]anthracen-5-ones
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We describe here a novel synthesis of benzo[b]naphtho[2,3-d]furan-6,11- diones based on the heteroannulation of 2-(2-bromophenyl)-3-hydroxy-1,4- naphthoquinones. The naphthoquinones were prepared from 3-(2-bromophenyl) naphthalen-2-ols, which were obtained by intramolecular aldol condensation of 2-[3-(2-bromophenyl)-2-oxo-propyl]benzaldehydes. Alternatively, benzo[b]naphtho[2,3-d]furan-6,11-diones were obtained more directly and efficiently by cyclization of 3-(2-bromophenyl)naphthalen-2-ols to benzo[b]naphtho[2,3-d]furans and oxidation of the resulting compounds. Furthermore, the first 6-oxabenzo[a]anthracen-5-one described was similarly obtained from 2-[3-(2-formylphenyl)-2-oxopropyl]benzoic acid and oxidized to 6-oxa-benzo[a]anthracene-5,7,12-trione.
- Martínez, Ana,Fernández, Marcos,Estévez, Juan C.,Estévez, Ramón J.,Castedo, Luis
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p. 1353 - 1362
(2007/10/03)
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- Synthesis of polycyclic xanthenes and furans via palladium-catalyzed cyclization of polycyclic aryltriflate esters
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Palladium-catalyzed cyclization of polycyclic aromatic o-(arylmethyl)phenol triflate esters takes place with unexpected sulfur-oxygen bond cleavage to furnish polycyclic xanthenes. These are the first examples of Pd-catalyzed cross-coupling of aryl triflate esters with arenes to form diaryl ethers. In contrast, analogous palladium-catalyzed cyclization of polycyclic o-(aryloxy)phenol triflate esters proceeds via a mechanism that involves conventional carbon-oxygen bond cleavage to furnish diaryl furans.
- Wang, Ji-Quan,Harvey, Ronald G
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p. 5927 - 5931
(2007/10/03)
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- Evolution of products in the combustion of scrap tires in a horizontal, laboratory scale reactor
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A horizontal laboratory reactor was used to study the evolution of byproducts from the combustion of scrap tires at five nominal temperatures (ranging from 650 to 1050 °C) and different oxygen:sample ratios A model was used to calculate the bulk air ratio (λ), and the oxygen consumption was discussed considering this ratio λ. More than 100 volatile and semivolatile compounds were identified and quantified by gas chromatography mass spectrometry, plotting their yields vs the bulk air ratio and temperature. Five different behaviors considering the bulk air ratio and the temperature were identified.
- Fullana,Font,Conesa,Blasco
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p. 2092 - 2099
(2007/10/03)
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- 1,2- and 1,4-naphthoquinones: General synthesis of benzo[b]naphtho [2,3- d]furan-6,11-diones
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A new general synthesis of benzo[b]naphtho[2,3-d]furan-6,11-diones starting from readily available 2-(2'-oxo-3'-phenylpropyl)benzaldehydes is described. (C) 2000 Elsevier Science Ltd.
- Martínez, Ana,Estévez, Juan C.,Estévez, Ramón J.,Castedo, Luis
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p. 2365 - 2367
(2007/10/03)
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- A Short Synthesis of Dibenzofurans and Dibenzothiophenes
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An afficient synthesis of dibenzofurans and dibenzothiophenes from aryl salicylates is described, which involves a novel rearrangement-extrusion-cyclisation sequence of o-substituted phenoxyl and thiophenoxyl radicals.
- Black, Michael,Cadogan, J. I. G.,McNab, Hamish
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p. 395 - 396
(2007/10/02)
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