- Corey-Chaykovsky Cyclopropanation of Nitronaphthalenes: Access to Benzonorcaradienes and Related Systems
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Nitronaphthalene derivatives react as Michael acceptors in the Corey-Chaykovsky reaction with alkyl phenyl selenones and alkyl diphenyl sulfonium salts. Mechanistic studies reveal that sterically demanding substituents at the carbanionic center favor formation of cyclopropanes and suppress competitive β-elimination to the alkylated products. The transformation, demonstrated also on heterocyclic nitroquinoline and nitroindazolines, is an example of transition metal-free dearomatization method.
- Antoniak, Damian,Barbasiewicz, Micha?
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p. 9320 - 9325
(2019/11/19)
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- Regioselective Functionalization of 9,9-Dimethyl-9-silafluorenes by Borylation, Bromination, and Nitration
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Despite the utility of 9-silafluorenes as functional materials and as building blocks, methods for efficient functionalization of their backbone are rare, probably because of the presence of easily cleavable C-Si bonds. Although controlling the regioselectivity of iridium-catalyzed direct borylation of C-H bonds is difficult, we found that bromination and nitration of 2-methoxy-9-silafluorene under mild conditions occurred predominantly at the electron-rich position. The resulting product having methoxy and bromo groups can be utilized as a building block for the synthesis of unsymmetrically substituted 9-silafluorene-containing ?-conjugated molecules.
- Murai, Masahito,Nishinaka, Naoki,Kimura, Mizuki,Takai, Kazuhiko
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p. 5667 - 5676
(2019/05/10)
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- Regioselective Functionalization of 9,9-Dimethyl-9-silafluorenes by Borylation, Bromination, and Nitration
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Despite the utility of 9-silafluorenes as functional materials and as building blocks, methods for efficient functionalization of their backbone are rare, probably because of the presence of easily cleavable C-Si bonds. Although controlling the regioselectivity of iridium-catalyzed direct borylation of C-H bonds is difficult, we found that bromination and nitration of 2-methoxy-9-silafluorene under mild conditions occurred predominantly at the electron-rich position. The resulting product having methoxy and bromo groups can be utilized as a building block for the synthesis of unsymmetrically substituted 9-silafluorene-containing π-conjugated molecules.
- Murai, Masahito,Nishinaka, Naoki,Kimura, Mizuki,Takai, Kazuhiko
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- Direct nitration method of electron-enriched aromatic hydrocarbons
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The invention discloses a direct nitration method of electron-enriched aromatic hydrocarbons, and belongs to the field of organic synthesis. The direct nitration method is a novel green free radical nitration method; aromatic hydrocarbons are taken as raw materials, acetonitrile, dichloromethane, chloroform, or acetone is taken as a reaction solvent, at room temperature conditions, the raw materials and green nitration reagent tert-butyl nitrite (TBN) are subjected to free radical nitration so as to obtain nitro-aromatic compounds. According to the direct nitration method, no metal is adoptedin reaction, tert-butyl nitrite is directly adopted in nitration reaction. Electron-donating groups such as OMe are introduced, the electron density of aromatic compounds is increased, the nitration reaction possibility is increased. The using amount of tert-butyl nitrite is reduced; only a product and tert-butyl alcohol are generated, environment pollution is reduced. The direct nitration methodis promising in application prospect in the field of nitro-aromatic compound synthesis, green nitration is realized, and a novel idea is provided for large-scale industrialized nitro-aromatic compoundproduction.
- -
-
Paragraph 0084-0086
(2018/10/02)
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- A Facile Synthesis of Benzo[h]quinolines via Silica-TsOH-P2O5 Promoted Condensation of 1-Naphthylamines with 1,3-Diketones under Solvent Free Conditions
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A facile synthesis of benzo[h]quinolines has been developed via improved Combes reaction. A combination of silica gel, p-toluenesulfonic acid and phosphorus pentoxide was utilized to promote the condensation of 1-naphthylamines with 1,3-diketones under solvent free conditions. In this case, silica gel was used as reaction media, p-toluenesulfonic acid and phosphorus pentoxide were acted as catalyst and dehydrating agent, respectively.
- Zhu, Chuanlei,Guo, Ruiqiang,Sheng, Zhe,Li, Yanzhe,Chu, Changhu
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supporting information
p. 1595 - 1600
(2017/10/06)
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- The relevance of Ki calculation for bi-substrate enzymes illustrated by kinetic evaluation of a novel lysine (K) acetyltransferase 8 inhibitor
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Histone acetyltransferases (HATs) are important mediators of epigenetic post-translational modifications of histones that play important roles in health and disease. A disturbance of these modifications can result in disease states, such as cancer or inflammatory diseases. Inhibitors of HATs (HATi) such as lysine (K) acetyltransferase 8 (KAT8), could be used to study the epigenetic processes in diseases related to these enzymes or to investigate HATs as therapeutic targets. However, the development of HATi is challenged by the difficulties in kinetic characterization of HAT enzymes and their inhibitors to enable calculation of a reproducible inhibitory potency. In this study, a fragment screening approach was used, enabling identification of 4-amino-1-naphthol, which potently inhibited KAT8. The inhibitor was investigated for enzyme inhibition using kinetic and calorimetric binding studies. This allowed for calculation of the Ki values for both the free enzyme as well as the acetylated intermediate. Importantly, it revealed a striking difference in binding affinity between the acetylated enzyme and the free enzyme, which could not be revealed by the IC50 value. This shows that kinetic characterization of inhibitors and calculation of Ki values is crucial for determining the binding constants of HAT inhibitors. We anticipate that more comprehensive characterization of enzyme inhibition, as described here, is needed to advance the field of HAT inhibitors.
- Wapenaar, Hannah,van den Bosch, Thea,Leus, Niek G.J.,van der Wouden, Petra E.,Eleftheriadis, Nikolaos,Hermans, Jos,Hailu, Gebremedhin Solomon,Rotili, Dante,Mai, Antonello,D?mling, Alexander,Bischoff, Rainer,Haisma, Hidde J.,Dekker, Frank J.
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supporting information
p. 480 - 486
(2017/05/22)
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- Nitrogen Dioxide Catalyzed Oxidative Thiocyanation of Arenes with Ambient Air as the Terminal Oxidant
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NO2 is an effective catalyst for the oxidative thiocyanation of arenes. This unique catalyst is inexpensive and separated easily from the final products because of its low boiling point. The mild reaction conditions allow a series of arenes and thiophenes to be thiocyanated smoothly in moderate to high yields. A preliminary mechanistic investigation suggests that the present reaction may proceed through a radical pathway.
- Ren, Yun-Lai,Wang, Wenhui,Zhao, Bo,Tian, Xinzhe,Zhao, Shuang,Wang, Jianji,Li, Fuwei
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p. 3361 - 3366
(2016/11/16)
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- Oxidative dimerization of 4-methoxynaphthylamines in the presence of semiconductors
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Three types of 4-methoxynaphthylamines 4a-c were oxidized by treatment with metal oxides under molecular oxygen (O2). 4-Methoxy-1-naphthylamine 4a and 4,6-dimethoxy-1-naphthylamine 4b, on treatment with TiO2 under O2, gave mainly 2-amino-1,4-naphthoquinone derivatives 5a and 5b, respectively whereas 4,8-dimethoxy-1-naphthylamine 4c afforded an unique carbazole 6c as the major product.
- Takeya, Tetsuya,Takahashi, Yosuke,Okamoto, Iwao,Tamura, Osamu
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experimental part
p. 1479 - 1488
(2010/10/20)
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- Aromatic nitration in liquid Ag0.51K0.42Na 0.07NO3
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(Figure Presented) Aromatic molecules have a strong affinity for silver(I) and dissolve to a limited extent in Ag0.51K0.42Na 0.07NO3, a low-melting eutectic mixture of silver, potassium, and sodium nitrates. Aromatic nitration in this inorganic ionic liquid leads to products which arise from nonelectrophilic substitution pathways.
- Mascal, Mark,Yin, Lunxiang,Edwards, Ross,Jarosh, Michael
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p. 6148 - 6151
(2008/12/22)
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- Nitration of some aromatic compounds by sodium nitrate in the presence of benzyltriphenylphosphonium peroxodisulfate
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A simple, mild, and regioselective method for the nitration of some aromatic compounds using sodium nitrate in the presence of benzyltriphenylphosphonium peroxodisulfate in acetonitrile as solvent is reported. Mild reaction conditions and good to excellent yields of the products are the noteworthy advantages of the method. Copyright Taylor & Francis Group, LLC.
- Tajik, Hassan,Zolfigol, Mohammad Ali,Albadi, Jalal,Eslami, Ramin
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p. 2771 - 2776
(2008/02/12)
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- Direct and regioselective iodination and bromination of benzene, naphthalene and other activated aromatic compounds using iodine and bromine
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Direct and regioselective iodination and bromination of benzene, naphthalene and other activated aromatic compounds with iodine and bromine or their sodium salts proceed well in the presence of Fe(NO3) 3·1.5N2O4/charcoal in CH 2Cl2 at room temperature.
- Firouzabadi,Iranpoor,Shiri
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p. 8781 - 8785
(2007/10/03)
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- Direct methoxylation of nitroarenes and nitroazaarenes with alkaline methoxides via nucleophilic displacement of an aromatic hydrogen atom
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Treatment of 1,3-dinitrobenzene and 5-substituted derivatives with excess potassium or sodium methoxide in 1,3-dimethylimidazolidin-2-one (DMI) at room temperature results in the displacement of an aromatic hydrogen at the 4-position by methoxide, affording 2,4-dinitroanisole and its 6-substituted derivatives, respectively, in low to moderate yield. In contrast, an equimolar reaction under similar conditions leads to the replacement of the nitro group in preference to the ring hydrogen. The reaction does not take place with lithium methoxide as a base. Mono- and dinitronaphthalenes and nitroquinolines undergo similar displacement of a hydrogen atom at the position ortho or para to the nitro group, giving the corresponding methoxy derivatives in moderate yield. A slow addition of the nitro compound to a large excess of potassium methoxide under an oxygen atmosphere has been found to enhance the conversion and improve the product yield. On the basis of the product distribution as well as the kinetic isotope effect kH/kD = 2.1, direct displacement of a ring hydrogen atom by methoxide ion has been interpreted in terms of the rate-determining release of an ipso-hydrogen atom as a proton from the initially formed Meisenheimer adduct.
- Kawakami, Takehiko,Suzuki, Hitomi
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p. 1259 - 1264
(2007/10/03)
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- Improved nitrations using metal nitrate-sulfuric acid systems
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Procedures for efficient mono- and di-nitration of aromatic substrates have been developed using ceric ammonium nitrate suspended in dichloromethane in the presence of 2 equiv. of sulfuric acid. By suspending the sulfuric acid on silica gel following nitration, products are easily isolated by filtration and evaporation of solvent. In these nitrations ceric ammonium nitrate can be replaced by other metal nitrates, for example potassium- or tetrabutylammonium-nitrate. In contrast the nitration of naphthalene by ceric ammonium nitrate in the presence of methanol and sulfuric acid affords a mixture of 1,4- and 1,2-methoxynitronaphthalenes, but these nitrations cannot be achieved using potassium or tetrabutylammonium nitrate. The mechanism of this nitration/oxidation is discussed. (C) 2000 Elsevier Science Ltd.
- Mellor, John M.,Mittoo, Stifun,Parkes, Rachel,Millar, Ross W.
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p. 8019 - 8024
(2007/10/03)
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- Synthesis of 1-alkoxy-4-nitronaphthalenes in a novel nitration of naphthalene
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A new nitration of naphthalene affords as major products 1,4-disubstituted naphthalenes and as minor products 12-disubstituted naphthalenes. By use of eerie ammonium nitrate suspended on silica gel, or in homogeneous solution, nitration of naphthalene in the presence of alcohols, sodium- or tetrabutyl ammonium- nitrite and acid gives alkoxynitronaphthalenes. A preparation of 1-nitroaaphthalene is described under heterogeneous conditions.
- Mellor, John M.,Parkes, Rachel,Millar, Ross W.
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p. 8739 - 8742
(2007/10/03)
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- Thermal and photochemical decomposition pathways of trinitromethylarenes. part II. The effects of ethanol on the photolysis reactions of some alkoxy- and dialkoxyarenes in the presence of tetranitromethane. enhancement of adduct and trinitromethyl substitution product formation
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The photolysis of the charge transfer (CT) complex of tetranitromethane with 1-methoxynaphthalene, 1,4-dimethoxybenzene, 1,2-dimethoxybenzene, 1,2-methylenedioxybenzene or 2-methylanisole is reported for dichloromethane, acetonitrile, dichloromethane-ethanol and acetonitrile-ethanol solvent systems. The effects of adding ethanol (8% v/v ? 1.4 mol dm-3) to dichloromethane or acetonitrile as reaction solvents include: (i) the stabilization of alkoxytrinitro-methylarenes, thus reducing their normal tendency for decomposition according to ArC (NO2)3→ArCOOH→ArNO2, (ii) a reduction in the nucleophilicity of trinitromethanide ion, and (iii) changes in the regioselectivity of trinitromethanide ion attack on the radical cations of alkoxyaromatic compounds away from attack ipso to the alkoxy substituent. Adducts are also stabilized, as shown by the photolysis of the CT complex of 1,4-dimethoxybenzene-tetranitromethane in dichloromethane-ethanol (8% v/v) which gives the epimeric 1,4-dimethoxy-3-nitro-6-trinitromethylcyclohexa-1,4-dienes and 1,4-dimethoxy-2-trinitromethylbenzene, in addition to 1,4-dimethoxy-2-nitrobenzene. The adducts are detected also among the products of photolysis reactions in neat dichloromethane or acetonitrile. Acta Chemica Scandinavica 1997.
- Butts, Craig P.,Eberson, Lennart,Hartshorn, Michael P.,Persson, Ola
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p. 718 - 732
(2007/10/03)
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- Thermal and photochemical decomposition pathways of trinitromethylarenes. Part I. The conversion of ArC(NO2)3 to ArNO2 - A rationalization of apparent solvent effects
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The thermal and photochemical decomposition of trinitromethylarenes in an inert solvent (dichloromethane or acetonitrile) has been investigated, using 1-methoxy-4-trinitromethylnaphthalene (2) and 2-trinitromethyl-4-chloroanisole (6) as representatives of reactive and unreactive ArC(NO2)3, respectively. Compound 2 underwent slow thermal decomposition in both solvents to give 4-methoxy-1-naphthoic acid (3) and 1-methoxy-4-nitronaphthalene (5). The reaction was speeded up by additives, such as 1-methoxynaphthalene or nitrous acid. The decomposition of 2 was strongly accelerated by irradiation with light of λ>430 nm. Both the thermal and photochemical processes were faster in acetonitrile than in dichloromethane. Spin trapping experiments resulted in the trapping of ArCOO· radicals, in both the thermal and photochemical reactions, indicating that the decomposition reaction is at least partially of radical nature. The acid 3 was shown to undergo fast thermal nitrodecarboxylation by treatment with NO2 in dichloromethane. Compound 6 exhibited similar behaviour, except that the rates were much slower, less than 100 times slower than those of 2. The mechanism suggested involves an initial nitro→nitrito rearrangement of ArC(NO2)3, followed by homolytic decomposition of the nitritodinitromethylarene formed. The finding that trinitromethylarenes have differing stabilities, depending on the nature of the ring substituent (s) and/or the solvents used, offers a reasonable explanation for the chemoselectivity of tetranitromethane-ArH photolyses. Acta Chemica Scandinavica 1996.
- Eberson, Lennart,Hartshorn, Michael P.,Radner,Svensson, Jan Olof
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p. 885 - 898
(2007/10/03)
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- Nachweis und Reaktionen von photolytisch aus aromatischen Verbindungen and Tetranitromethan in 1,1,1,3,3,3-Hexafluor-2-propanol bei Raumtemperatur hergestellten Radikalkationen
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Keywords: Hexafuorpropanol, Nitroverbindungen, Photochemie, Radikalkationen, Tetranitromethan
- Eberson, Lennart,Hartshorn, Michael P.,Persson, Ola
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p. 2417 - 2418
(2007/10/03)
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- Photochemical Nitration by Tetranitromethane. Part XXII. Adducts as Precursors of Nitro Substitution Products from the Photolysis of 1-Methoxynaphthalene-Tetranitromethane, Dehydrodimer Formation and the Regiochemistry of Trinitromethanide Ion Attack on the Radical Cation of ...
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The photolysis of 1-methoxynaphthalene with tetranitromethane in dichloromethane at 20 deg C gives mainly 1-methoxy-4-nitronaphthalene (2) and 1-methoxy-4-trinitromethylnaphthalene (5), together with smaller amounts of 1-methoxy-2-nitronaphthalene (1) and the two adducts, 4-methoxy-r-1-nitro-t-2-trinitromethyl-1,2-dihydronaphthalene (6) and 4-methoxy-r-2-nitro-t-1-trinitromethyl-1,2-dihydronaphthalene (7).Photolysis in the presence of trifluoroacetic acid under otherwise identical conditions gives initially exclusively 4,4'-dimethoxy-1,1'-binaphthalene (10) as the product, trinitromethanide ion being eliminated as a reactant by protonation to give nitroform.EPR spectral and cyclic voltammetric data indicate that the radical cation 10 is present in this reaction.Evidence is presented that, in the absence of trifluoroacetic acid, the reaction products 1, 2 and 5 all arise by decomposition of highly labile nitro-trinitromethyl or nitrito-trinitromethyl adducts 11, 12 and 14.The regiochemistry of attack of trinitromethanide ion on the radical cation of 1-methoxynaphthalene is discussed, and it is proposed that this step is reversible, the regiochemistry of attack being determined by the relative energies of the carbon radicals formed in the process.X-Ray crystal structures are reported for 1-methoxy-4-trinitromethylnaphthalene (5) and 4,4'-dimethoxy-1,1'-binaphthalene (10).
- Butts, Craig P.,Eberson, Lennart,Hartshorn, Michael P.,Persson, Ola,Robinson, Ward T.
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p. 253 - 264
(2007/10/02)
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- Light-initiated and thermal nitration reactions during photolysis of naphthalene/tetranitromethane or 1-methoxynaphthalene/tetranitromethane in dichloromethane
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The photolysis of naphthalene or 1-methoxynaphthalene together with tetranitromethane in dichloromethane, using light with a cutoff at λ 2-promoted nitration (α/β ratio ca. 20). The adducts are formed by photochemical excitation of the CT complex between naphthalene and tetranitromethane, resulting in formation of the triad [ArH?+ NO2 (NO2)3C-] from which the observed chemistry develops by attack of trinitromethanide upon the radical cation. For 1-methoxynaphthalene, a representative of more highly reactive aromatics, the reaction is again photochemically initiated and again adducts seem to be responsible for the further development of thermal nitration reactions, apart from the NO2-induced reaction. Elimination of HNO2 from one of the 1,4-adducts induces a novel HNO2/tetranitromethane-dependent nitration process, shown separately to operate in the dark on reactive substrates. The aryltrinitromethane formed in this step is "hydrolyzed" to the corresponding carboxylic acid, 4-methoxy-1-naphthoic acid, under the anhydrous conditions prevailing during photolysis. Nitrous acid is a likely candidate as the proton source for this reaction. With an alcohol present, moderate yields (up to ≈50%) of alkyl 4-methoxy-1-naphthoates are obtained. From other adducts, nitro compounds are formed by elimination of nitroform. Trinitromethanide ion was shown to possess greatly differing reactivity (ratio >103) toward a model radical cation, tris(4-bromophenyl)aminium ion, in dichloromethane and acetonitrile, respectively.
- Eberson, Lennart,Radner, Finn
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p. 5825 - 5834
(2007/10/02)
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- Regioselective Functionalization of Alkyl Aryl Ethers
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A new procedure for regioselective functionalization of sensitive alkyl aryl ethers has been proposed as an alternative to picrate and sulphonamide derivatives.The procedure is based upon their reaction with cerium(IV) ammonium nitrate (CAN) and gives good yields of nitro substituted ethers, affording one pot synthesis of hitherto unknown 1-isopropoxy-4-nitronaphthalene, 1-butoxy-4-nitronaphthalene, 2-isopropoxy-6-nitronaphthalene and 2-butoxy-6-nitronaphthalene.A plausible mechanism has been suggested.
- Chawla, H. Mohindra,Pathak, Manisha
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p. 1092 - 1093
(2007/10/02)
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- Oxidative Derivatisation of Aromatic Ethers
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Reaction of cerium(IV) ammonium nitrate with some naphthyl ethers has been studied as a substitute to traditionally used hydrolytic cleavage method for their identification.One-pot, one-step synthesis of 2,2'-dinitro-1,1'-diethoxy-4,4'-bisnaphthalene; 2,2'-diethoxy-8-nitro-4,4'-bisnaphthalene; 1,8-dinitro-2-methoxynaphthalene; 2-methoxy-8-nitronaphthalene; 1-methoxy-4-nitronaphthalene; 1-ethoxy-4-nitronaphthalene; 4-nitro-1-naphthylbenzoate; 2-methoxy-6-nitronaphthalene; 1-nitro-2-naphthylbenzoate are described.
- Chawla, H. Mohindra,Mittal, Ram S.
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p. 539 - 542
(2007/10/02)
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