- Quinoline Ligands Improve the Classic Direct C?H Functionalisation/Intramolecular Cyclisation of Diaryl Ethers to Dibenzofurans
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The C?H functionalisation approach to the synthesis of dibenzofurans is hampered by a number of problems. Herein we describe the evolution of a cheap, bench stable quinoline ligand, which obviates most of the current limitations and allows for a high yielding synthesis of a range of valuable dibenzofurans. Dibenzofurans are important motifs in natural products and compounds with wide biological activity.
- Mackey, Katrina,Jones, David J.,Pardo, Leticia M.,McGlacken, Gerard P.
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p. 495 - 498
(2021/01/12)
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- Synthesis of Dibenzofurans by Cu-Catalyzed Deborylative Ring Contraction of Dibenzoxaborins
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An efficient transformation of dibenzoxaborins to dibenzofurans by deborylative ring contraction was achieved under mild conditions using a copper catalyst. The method showed a broad substrate scope enabling the preparation of various dibenzofurans, including those bearing a functional group. The ready availability of various dibenzoxaborins enhances the utility of this method, as demonstrated by the regiodivergent synthesis of dibenzofurans.
- Sumida, Yuto,Harada, Ryu,Sumida, Tomoe,Johmoto, Kohei,Uekusa, Hidehiro,Hosoya, Takamitsu
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supporting information
p. 6687 - 6691
(2020/09/02)
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- Efficient photocaging of a tight-binding bisubstrate inhibitor of cAMP-dependent protein kinase
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Photocaging of a tight-binding bisubstrate inhibitor of cAMP-dependent protein kinase (PKA) with a nitrodibenzofuran-based group fully abolished its inhibitory potency. The affinity difference between the photocaged and the active inhibitor was over 5 orders of magnitude. The photocaged inhibitor disrupted the PKA holoenzyme in cell lysates upon photolysis under a 398 nm LED.
- S?rmus, Tanel,Lavogina, Darja,Enkvist, Erki,Uri, Asko,Viht, Kaido
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supporting information
p. 11147 - 11150
(2019/09/20)
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- Photoinduced Synthesis of Dibenzofurans: Intramolecular and Intermolecular Comparative Methodologies
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The SRN1 reaction has been used as a powerful tool for the synthesis of heterocycles, and only a few studies about photoinduced intramolecular cyclization to generate a new C-O bond by a radical pathway have been reported. This work introduces two strategies for the synthesis of substituted dibenzofurans by electron transfer (eT) reactions. The first one is a three-step process that comprises bromination of o-arylphenols, Suzuki-Miyaura cross-coupling and photoinduced cyclization in order to obtain the above-mentioned products. The second one is a metal-free procedure and does not require any photocatalyst. Different solvents were tested, and the yields ranged from low to moderate. A comparison was established between both methodologies, showing that the second one is the most suitable for the synthesis of dibenzofurans.
- Camargo Solórzano, Patricia,Brigante, Federico,Pierini, Adriana B.,Jimenez, Liliana B.
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p. 7867 - 7877
(2018/06/11)
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- Organic electroluminescent material using quinolyl dibenzo substituent as ligand, and uses thereof
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The invention relates to a compound using quinolyl dibenzo substituent as a ligand, and uses thereof, wherein the compound has a structure represented by a formula I. According to the present invention, the compound has advantages of good thermal stability, high light-emitting efficiency, long service life and the like, can be used in organic light-emitting devices, can be particularly used as thered light-emitting dopant, and can be used in AMOLED industry.
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Paragraph 0066; 0067; 0068
(2018/05/16)
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- Visible-Light-Promoted Synthesis of Dibenzofuran Derivatives
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Dibenzofurans are naturally occurring molecules that have received considerable attention for a variety of practical applications, such as in pharmaceuticals and electronic materials. Herein, an efficient and eco-friendly method for the synthesis of dibenzofuran derivatives via intramolecular C-O bond formation, which involves the in situ production of a diazonium salt, is described. The transformation requires a diazotizing agent and is promoted by the use of an organic photosensitizer under visible-light irradiation.
- Cho, Ji Young,Roh, Geum-Bee,Cho, Eun Jin
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p. 805 - 811
(2018/01/28)
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- Palladium-catalyzed intra-and intermolecular C-H arylation using mesylates: Synthetic scope and mechanistic studies
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This paper describes the development of Pd-catalyzed inter-and intramolecular direct arylation using mesylates. Furthermore, a sequential mesylation/arylation protocol using phenols as substrates is described. These transformations are general with respect to the electronics of the C-H substrates and allow for the synthesis of diverse heterocyclic motifs in good yields. Both arenes and heteroarenes efficiently participate in these reactions. Preliminary mechanistic studies are presented for both inter-and intramolecular arylations.
- Ferguson, Devin M.,Rudolph, Stacey R.,Kalyani, Dipannita
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p. 2395 - 2401
(2014/07/21)
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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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- 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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- 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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- 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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supporting information
p. 4838 - 4841,4
(2020/09/16)
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- Synthesis of dibenzofurans by palladium-catalysed tandem denitrification/C-H activation
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A palladium-catalysed method for intramolecular cyclisation of ortho-diazonium salts of diaryl ethers to give dibenzofurans is described. The protocol uses 3 mol% palladium acetate as the catalyst in refluxing ethanol in the absence of base. Georg Thieme Verlag Stuttgart · New York.
- Du, Zhenting,Zhou, Jing,Si, Changmei,Ma, Weili
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scheme or table
p. 3023 - 3025
(2012/01/05)
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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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- Diels-Alder reactions of nitrobenzofurans: A simple dibenzofuran Synthesis. Theoretical studies using DFT methods
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2- and 3-nitrobenzofurans are studied in polar thermal Diels-Alder reactions with normal electron demand using several structurally different dienes. A very strong electron-acceptor group, such as the nitro group, pushes the dienophilic character of these heterocyclic compounds. Since this substituent is easily extruded under thermal conditions, this reaction sequence becomes a simple method for the preparation of families of organic compounds with heteroatom rings. Part of this work is specifically concerned with theoretical studies using DFT methods. The global and local electrophilicity and nucleophilicity indices were calculated for the dienophiles and dienes used in this study. When 2-nitrobenzofuran and 3-nitrobenzofuran were reacted with isoprene, 1-trimethylsilyloxy-1,3-butadiene and Danishesfky's diene, under different thermal reaction conditions they showed their dienophilic character taking part in normal-demand polar DA cycloaddition reactions.
- Della Rosa, Claudia D.,Sanchez, Juan P.,Kneeteman, María N.,Mancini, Pedro M.E.
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scheme or table
p. 2316 - 2319
(2011/05/09)
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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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- Synthesis of carbazoles and dibenzofurans via cross-coupling of o-iodoanilines and o-iodophenols with silylaryl triflates and subsequent Pd-catalyzed cyclization
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An efficient route to a variety of carbazoles and dibenzofurans has been developed. It involves the reaction of o-iodoanilines or o-iodophenols with silylaryl triflates in the presence of CsF to afford the N- or O-arylated products, which are subsequently cyclized using a Pd catalyst to carbazoles and dibenzofurans in good to excellent yields. By using this methodology, the carbazole alkaloid, mukonine has been synthesized in 76% overall yield in three steps.
- Liu, Zhijian,Larock, Richard C.
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p. 347 - 355
(2007/10/03)
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- SYNTHESIS OF NITRODIBENZYLFURAN CHROMOPHORE FOR PHOTODEPROTECTION OF ORGANIC MOLECULES
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Inventors have developed a chromophore (nitrodibenzylfuranyl, or NBDF) for ultra efficient uncaging of a caged substrate (e.g., an organic molecule such as, for example, an amino acid, a biological molecules, such as, for example, second messengers inside cells). Photolysis of a NBDF derivative of EGTA (i.e. caged calcium) is about 50 times more efficient than others calcium cages (the quantum yield of photolysis is 0.6 and the extinction coefficient is 18,400. NDBF-EGTA has a 2-photon cross section of about 0.3-0.6 GM).
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Page/Page column 26-27
(2008/06/13)
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- A study of the gas-phase interconversion of 1-(2-aryloxyphenyl)-alkaniminyl and 2-(aryliminomethyl)phenoxyl radicals
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Flash vacuum pyrolysis of the allyl ethers 9-11 and of the oxime ethers 15-17 at 650°C (5 × 10-2-5 × 10-3 Torr) generates 2-(aryliminomethyl)phenoxyl radicals 4 and 1-(2-aryloxyphenyl)alkaniminyl radicals 5 respectively which can interconvert via a spirodienyl radical leading to common products which are generally isolated in low to moderate yield. The iminyls 5 normally undergo β-cleavage leading to nitriles (e.g. 21) and/or to benzofurans (e.g. 22) after cyclisation. The phenoxyls 4 show more complex behaviour dominated by hydrogen abstraction processes leading to products such as phenols (e.g. 32), the indole 27 or phenanthridines 34 and 35.
- Black, Michael,Cadogan,Leardini, Rino,McNab, Hamish,McDougald, Graham,Nanni, Daniele,Reed, David,Zompatori, Alberto
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p. 1825 - 1832
(2007/10/03)
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- An improved synthesis of dibenzofurans by a free-radical cyclization
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Reaction conditions for the formation of dibenzofurans from diazotized o-(aryloxy)anilines have been examined. Several promoters (hydroquinone, SnCl2, NaI, CuSO4, FeSO4, etc.) have been discovered; these act as electron donors and promote a free-radical mechanism. The best of these is FeSO4 which shortens the reaction time from hours to minutes and contributes to high yields (77-83%). We have been able to transform the cyclization to a reliable and convenient synthesis.
- Wassmundt,Pedemonte
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p. 4991 - 4994
(2007/10/03)
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- Gas phase generation and cyclisation reactions of some o-substituted phenyl radicals
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Flash vacuum pyrolysis of the allyl esters 2 (X=O, S, CH2, CO) at 900°C (10-2 Torr) gives dibenzofurans, dibenzothiophenes, fluorenes, and fluorenones respectively as the major products. The mechanism involves the phenyl radical intermediates 1 which equilibrate by intramolecular hydrogen transfer via six-membered transition states, prior to cyclisation.
- Cadogan,Hutchison,McNab
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p. 7747 - 7762
(2007/10/02)
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- Gas-phase Reactions of 2-Benzyl- and 2-Benzoyl-phenoxyl Radicals, and of 2-Phenoxybenzyl Radicals: Examples of New Hydrogen-transfer Processes
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Generation of the 2-benzylphenoxyl radical 23 or the 2-phenoxybenzyl radical 24 by flash vacuum pyrolysis of the ethers 8 or 9, or the oxalate 19, respectively, leads to fluoren-1-ol 22 together with 2-benzylphenol 7 and a low yield of xanthene 21.Pyrolysis of the para-substituted derivatives 11 and 20 gives an analogous distribution of products, including two isomeric methylxanthenes 28 and 29 formed via the spirodienyl 27.The reactions of the corresponding 2-benzoylphenoxyl radicals give information on the mechanism of these processes.Thus the formation of the fluorenones 37 and 43 provides evidence for the hydrogen-abstraction mechanism (Scheme 4) of fluorene formation.Secondly, a detailed study of the ratios of xanthones 41 and 42 under a variety of pyrolysis conditions suggests that such 6-membered-ring products are formed by sigmatropic shifts in the spirodienyl, rather than direct cyclisation of the phenoxyl or benzoyl radicals.
- Cadogan, J. I. G.,Hutchison, H. Susan,McNab, Hamish
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p. 385 - 393
(2007/10/02)
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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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- EFFECT OF RING SIZE ON PHOTOREACTIVITY OF MEDIUM AND LARGE RING ESTERS.
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Photochemical studies on 7,8,12,14,16 and 20 membered cyclic esters have been carried out in benzene and methanol.Decarboxylation and solvolysis ascribable to β- and α-scission respectively are observed in case of seven and eight membered cyclic esters.Larger rings do not undergo these photoreactions thus demonsrating effect of ring size on photoreactivity.
- Kulkarni, V. S.,Kulkarni, N. N.,Lele, S. R.,Hosangadi, B. D.
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p. 6169 - 6174
(2007/10/02)
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