- A simple Hückel model-driven strategy to overcome electronic barriers to retro-Brook silylation relevant to aryne and bisaryne precursor synthesis
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ortho-Silylaryl triflate precursors (oSATs) have been responsible for many recent advances in aryne chemistry and are most commonly accessed from the corresponding 2-bromophenol. A retro-BrookO- toC-silyl transfer is a key step in this synthesis but not all aromatic species are amenable to the transformation, with no functionalized bisbenzyneoSATs reported. Simple Hückel models are presented which show that the calculated aromaticity at the brominated position is an accurate predictor of successful retro-Brook reaction, validated synthetically by a new success and a predicted failure. From this, the synthesis of a novel difunctionalized bisaryne precursor has been tested, requiring different approaches to install the twoC-silyl groups. The first successful use of a disubstitutedo-silylaryl sulfonate bisbenzyne precursor in Diels-Alder reactions is then shown.
- Neal, Edward A.,Werling,Jones, Christopher R.
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supporting information
p. 1663 - 1666
(2021/02/26)
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- Preparation method of 9-hydroxyphenanthrene
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The invention discloses a preparation method of 9-hydroxyphenanthrene, the preparation method comprises the following steps: taking a phenanthrene solution as a raw material, carrying out bromination, methoxylation and demethylation reaction to obtain the 9-hydroxyphenanthrene. The preparation method has the advantages of low preparation cost, high preparation efficiency, environmental friendliness, greatly improved product yield and high quality of the prepared product, is suitable for industrial production, and can be used for large-scale industrial preparation of 9-hydroxyphenanthrene and derivatives thereof.
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Paragraph 0045-0046; 0049-0050
(2021/08/07)
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- Chiral Ligand-Mediated Nucleophilic Aromatic Substitution of Naphthoic Acids: A Fast and Efficient Access to Axially Chiral Biaryls
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A transition metal-free synthesis of enantioenriched biaryls from aryllithium species has been developed. This approach relies on atropoenantioselective nucleophilic aromatic substitution (SNAr) reaction of unprotected naphthoic acids. The ability of a diverse set of chiral ligands to mediate this transformation has been investigated. 1,2-diether ligands outperform their diamine counterparts and the best enantiocontrol was obtained with readily accessible enantiopure trans-1,2-dimethoxycyclohexane. This SNAr reaction offers an efficient and rapid access to enantioenriched binaphthalenes, phenylnaphthalene, and phenanthrylnaphthalenes (up to 94:6 er).
- Nguyen, Thi Thanh Thuy,Guyon, Hélène,Nguyen, Kim Phi Phung,Boussonnière, Anne,Mortier, Jacques,Castanet, Anne-Sophie
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supporting information
p. 3829 - 3833
(2020/05/25)
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- Regioselective arene homologation through rhenium-catalyzed deoxygenative aromatization of 7-oxabicyclo[2.2.1]hepta-2,5-dienes
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Combined use of oxorhenium catalysts with triphenyl phosphite as an oxygen acceptor allowed efficient deoxygenative aromatization of oxabicyclic dienes. The reaction proceeded under neutral conditions and was compatible with various functional groups. Combining this deoxygenation with regioselective bromination and trapping of the generated aryne with furan resulted in benzannulative π-extension at the periphery of the PAHs. This enabled direct use of unfunctionalized PAHs for extension of π-conjugation. Iteration of the transformations increased the number of fused-benzene rings one at a time, which has the potential to alter the properties of PAHs by fine-tuning the degree of π-conjugation, shape, and edge topology.
- Murai, Masahito,Ogita, Takuya,Takai, Kazuhiko
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p. 2332 - 2335
(2019/02/27)
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- Preparation method of 9-bromophenanthrene
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The invention discloses a preparation method of 9-bromophenanthrene shown as in formula (II) that is shown in the description. The preparation method is characterized by including the steps of using phenanthrene shown in formula (I) that is shown in the description as a raw material, adding KBr bromination reagent, adding bromination reagent ZnAl-BrO3-LDHs into acetic acid and water mixed solvent, reacting at 20-70 DEG C for 2-5 hours to obtain reacted liquid that is post-treated to obtain the 9-bromophenanthrene shown as in the formula (II); the mas ratio of the phenanthrene shown as in the formula (I) to the KBr and ZnAlBrO3-LDHs is 1:0.9:0.6; the preparation method has the advantages that the preparation process is convenient, the reaction conditions are mild, low environmental pollution is caused, the requirements for equipment are low, bromine utilization rate is high, and the reaction time is short.
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Paragraph 0018; 0019; 0021-0024; 0025-0028
(2017/09/19)
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- The synthesis of polyarene-modified 5-phenyl-2,2'-bipyridines via the methodology and aza-Diels-Alder reaction
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Nucleophilic substitution of hydrogen () in 6-phenyl-3-(2-pyridyl)-1,2,4- triazine under the action of lithium derivatives of polynuclear arenes followed by aza-Diels-Alder reaction with norbornadiene or morpholinocyclopentene gives the novel polyarenemodified photoluminescent 5-phenyl-2,2'-bipyridine ligands.
- Kovalev, Igor S.,Kopchuk, Dmitry S.,Khasanov, Albert F.,Zyryanov, Grigory V.,Rusinov, Vladimir L.,Chupakhin, Oleg N.
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p. 117 - 118
(2014/04/17)
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- Dinuclear Pd(i) complexes - Solely precatalysts? Demonstration of direct reactivity of a Pd(i) dimer with an aryl iodide
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This report provides experimental, computational and spectroscopic data in support of the direct reactivity of a Pd(i) dimer with an aryl iodide, resulting in Br/I halogen exchange between the complex and the aryl iodide. The reactivity could not be achieved through analogous Pd(0) conditions, demonstrating the distinct reactivities at such multiple Pd-sites. Computational studies support that the direct oxidative addition to ArI by the dinuclear metal complex is energetically feasible.
- Bonney, Karl J.,Proutiere, Fabien,Schoenebeck, Franziska
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p. 4434 - 4439
(2013/11/19)
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- Nucleophilic substitution of hydrogen in naphthalene by chloride (Cl -) in ionic liquids
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Nucleophilic aromatic substitution of hydrogen in non-activated aromatic ring, a very rare phenomenon in organic chemistry, is found in ionic liquids containing Cl- as anion under mild reaction conditions. The reaction may be carried out by the addition of the halogen-bonding adduct (Br 2Cl-) as nucleophile to aromatic ring carbon atom, leading to the formation of the nucleophilic substitution product.
- Shi, Shen Yi,Kong, Ai Guo,Zhao, Xin Hua,Ding, Han Ming,Yang, Fan,Shan, Yong Kui
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experimental part
p. 147 - 150
(2012/01/03)
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- Stereoselective bromination reactions using tridecylmethylphosphonium tribromide in a "stacked" reactor
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(Chemical Equation Presented) A new reagent, tridecylmethylphosphonium tribromide, and new procedures for bromination reactions of unsaturated substrates (including one that allows several substrates to be reacted in sequence) are described. The procedures exploit the diffusion of components and the densities and immiscibilities of layers, including a fluorous "spacer" layer, within a reaction vessel. The stereoselectivities achieved in the reactions are superior in some cases to those found with other brominating reagents.
- Ma, Kefeng,Li, Shaw,Weiss, Richard G.
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supporting information; experimental part
p. 4155 - 4158
(2009/06/06)
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- A new method for the oxybromination of aromatic compounds with copper(II)bromide and potassium dichromate
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A new and mild method for oxybromination of aromatic compounds with CuBr2 and K2Cr2O7 in HOAC is reported. Copyright Taylor & Francis Inc.
- Badri, Rashid,Shushizadeh, Mohammad Reza
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p. 533 - 536
(2007/10/03)
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- Sonogashira coupling using bulky palladium-phenanthryl imidazolium carbene catalysis
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(Matrix presented) Bulky phenanthracenyl imidazolium-derived carbene ligands were investigated for copper-free Sonogashira coupling with terminal acetylenes. Aryl bromides and iodides gave coupled products in excellent yields from the Pd(PPh3)2Cl2 complex with potassium t-butoxide and 18-crown-6 in THF. A remarkable dependence on the size of the ligand was found. The highest yields were obtained with the bulky 2,9-dicyclohexyl-10-phenanthryl ligand 5.
- Ma, Yudao,Song, Chun,Jiang, Wei,Wu, Quansheng,Wang, Yong,Liu, Xueying,Andrus, Merritt B.
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p. 3317 - 3319
(2007/10/03)
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- Oxidative halogenation of aromatic compounds with metal halides and sodium bismuthate
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A new mild and efficient method for aromatic halogenation with a wide variety of halides in the presence of sodium bismuthate NaBO3 in AcOH is reported. Metal halides of groups Ia, IIa, IIIa, IVa, Va, and the first row of transition elements are suitable for this method.
- Muathen, Hussni A.
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p. 164 - 168
(2007/10/03)
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- Photochemical reactions of hydroarenes with N-bromosuccinimide
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The photochemical reactions of 1,2,3,4-tetrahydronaphthalene (THN), 9,10-dihydrophenanthrene (DHP), 9,10-dihydroanthracene (DHA), and acenaphthene (AN) with N-bromosuccinimide (NBS) were investigated under N2 atmosphere at room temperature. The results show that the relative reactivities of the hydroarenes toward a photochemical reaction with NBS are THN DHP AN DHA, which is consistent with the stabilities of the radicals produced by benzylic hydrogen abstraction from the hydroarenes. Photochemical reactions of THN and DHP mainly afforded dehydrogenated products, while the photobrominations of the dehydrogenated products from AN and DHA with NBS proceeded readily.
- Zong, Zhi-Min,Zhang, Wei-Hong,Jiang, Qun,Lu, Jin,Wei, Xian-Yong
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p. 769 - 771
(2007/10/03)
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- An environmentally benign synthesis of organic ammonium tribromides (OATB) and bromination of selected organic substrates by tetrabutylammonium tribromide (TBATB)
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Stable crystalline organic ammonium tribromides (OATB), like Me4NBr3, Et4NBr3, Bu4NBr3, cetyltrimethylammonium tribromide, PyHBr3, can be readily synthesised from the reaction of the corresponding bromides with V2O5 and aqueous H2O2. Typically, TBATB, Bu4NBr3, brominates a variety of organic substrates rather easily under mild conditions. An activated aromatic ring is selectively brominated in the presence of an olefinic double bond.
- Chaudhuri, Mihir K.,Khan, Abu T.,Patel, Bhisma K.,Dey, Deepa,Kharmawophlang, Wancydora,Lakshmiprabha,Mandal, Gagan C.
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p. 8163 - 8166
(2007/10/03)
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- Halogenation Using N-Halogenocompounds. II. Acid Catalyzed Bromination of Aromatic Compounds with 1,3-Dibromo-5,5-dimethylhydantoin
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Ring bromination of aromatic compounds using 1,3-dibromo-5,5-dimethylhydantoin in dichloromethane is promoted by the addition of strong acids.Both organic and inorganic acids whose pKa values are lower than -2 showed the promoting effect.This acid-catalyzed bromination is both practical and effective, even for aromatics having electron-withdrawing substituents.
- Eguchi, Hisao,Kawaguchi, Hideichiro,Yoshinaga, Sachiyo,Nishida, Akiko,Nishiguchi, Takeshi,Fujisaki, Shizuo
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p. 1918 - 1921
(2007/10/02)
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- Mimicking the vanadium bromoperoxidases reactions: Mild and selective bromination of arenes and alkenes in a two-phase system
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Vanadium bromoperoxidases catalyze the oxidation of bromide ion by hydrogen peroxide to a bromine-equivalent intermediate. This, in turn, brominates organic molecules. The hypothesis is made that the former reaction takes place in the hydrophilic portion of the enzyme whereas the latter proceeds in a hydrophobic one in which the brominating intermediate is rapidly transferred. We have reproduced such situation by employing a two-phase (H2O/CHCl3) system. In the aqueous acid phase H2O2 and catalytic amounts of NH4VO3 are present, together with KBr. The substrates, i.e. aromatic hydrocarbons and alkenes are dissolved in CHCl3. The bromination proceeds smoothly with stirring, at 25°C, providing high yields of the corresponding brominated products.
- Conte,Di Furia,Moro
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p. 7429 - 7432
(2007/10/02)
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