- Heck- And Suzuki-coupling approaches to novel hydroquinone inhibitors of calcium ATPase
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In this study, we explored Heck- and Suzuki-coupling methodology to modify the template 2,5-di-tert-butylhydroquinone (BHQ, 2), an inhibitor of the enzyme sarco/endoplasmic reticulum calcium ATPase (SERCA). We found that by utilizing Suzuki coupling, we c
- Kempton, Robert J.,Kidd-Kautz, Taylor A.,Laurenceau, Soizic,Paula, Stefan
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supporting information
p. 971 - 975
(2019/06/08)
-
- Photocatalytic Oxidative Iodination of Electron-Rich Arenes
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A visible-light-mediated oxidative iodination of electron-rich arenes has been developed. 2.5 mol% of unsubstituted anthraquinone as photocatalyst were used in combination with elementary iodine, trifluoroacetic acid and oxygen as the terminal oxidant. The iodination proceeds upon irradiation in non- or weakly-electron donating solvents (DCM, DCE and benzene) wherein a spectral window in strongly coloured iodine solutions can be observed at around 400 nm. The method provides good to excellent yields (up to 98%) and shows excellent regioselectivity and good functional group tolerance (triple bonds, ketone, ester, amide). Moreover, the photo-iodination was also upscaled to a 5 mmol scale (1.1 g). Mechanistic investigations by intermediate trapping and competition experiments indicate a photocatalytic arene oxidation and the subsequent reaction with iodine as a likely mechanistic pathway. (Figure presented.).
- Narobe, Rok,Düsel, Simon J. S.,Iskra, Jernej,K?nig, Burkhard
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supporting information
p. 3998 - 4004
(2019/07/17)
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- One-pot ortho-amination of aryl C-H bonds using consecutive iron and copper catalysis
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A one-pot approach for ortho-coupling of arenes with non-actived N-nucleophiles has been developed using sequential iron and copper catalysis. Regioselective ortho-activation of anisoles, anilines and phenols was achieved through iron(iii) triflimide catalysed iodination, followed by a copper(i)-catalysed, ligand-assisted coupling reaction with N-heterocycle, amide and sulfonamide-based nucleophiles. The synthetic utility of this one-pot, two-step method for the direct amination of ortho-aryl C-H bonds was demonstrated with the late-stage functionalisation of 3,4-dihydroquinolin-2-ones. This allowed the preparation of a TRIM24 bromodomain inhibitor and a series of novel analogues.
- Henry, Martyn C.,McGrory, Rochelle,Faggyas, Réka J.,Mostafa, Mohamed A. B.,Sutherland, Andrew
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p. 4629 - 4639
(2019/05/17)
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- N-Iodosuccinimide (NIS) in Direct Aromatic Iodination
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N-Iodosuccinimide (NIS) in pure trifluoroacetic acid (TFA) offers a time-efficient and general method for the iodination of a wide range of mono- and disubstituted benzenes at room temperature, as demonstrated in this paper. The starting materials were generally converted into mono-iodinated products in less than 16 hours at room temperature, without byproducts. A few deactivated substrates needed addition of sulfuric acid to increase the reaction rate. Another exception was methoxybenzenes that preferentially were iodinated by NIS in acetonitrile with only catalytic amounts of TFA.
- Bergstr?m, Maria,Suresh, Ganji,Naidu, Veluru Ramesh,Unelius, C. Rikard
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p. 3234 - 3239
(2017/06/21)
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- Rapid aerobic iodination of arenes mediated by hypervalent iodine in fluorinated solvents
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Arenes are rapidly converted to the corresponding iodides by aerobic oxidative iodination at room temperature by treatment with iodine and catalytic quantities of nitrous acid in a fluorinated solvent. Dichloroiodic acid is proposed as the actual iodination reagent.
- Iskra, Jernej,Murphree, S. Shaun
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supporting information
p. 645 - 648
(2017/01/28)
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- Transition-Metal-Free Decarboxylative Iodination: New Routes for Decarboxylative Oxidative Cross-Couplings
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Constructing products of high synthetic value from inexpensive and abundant starting materials is of great importance. Aryl iodides are essential building blocks for the synthesis of functional molecules, and efficient methods for their synthesis from chemical feedstocks are highly sought after. Here we report a low-cost decarboxylative iodination that occurs simply from readily available benzoic acids and I2. The reaction is scalable and the scope and robustness of the reaction is thoroughly examined. Mechanistic studies suggest that this reaction does not proceed via a radical mechanism, which is in contrast to classical Hunsdiecker-type decarboxylative halogenations. In addition, DFT studies allow comparisons to be made between our procedure and current transition-metal-catalyzed decarboxylations. The utility of this procedure is demonstrated in its application to oxidative cross-couplings of aromatics via decarboxylative/C-H or double decarboxylative activations that use I2 as the terminal oxidant. This strategy allows the preparation of biaryls previously inaccessible via decarboxylative methods and holds other advantages over existing decarboxylative oxidative couplings, as stoichiometric transition metals are avoided.
- Perry, Gregory J. P.,Quibell, Jacob M.,Panigrahi, Adyasha,Larrosa, Igor
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supporting information
p. 11527 - 11536
(2017/08/30)
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- High-capacity organic cathode active materials of 2,2′-bis-p-benzoquinone derivatives for rechargeable batteries
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Rechargeable batteries using organic cathode materials are expected to afford high mass energy densities since these materials can undergo multiple electron redox reactions per molecule. Although the batteries using benzoquinone (BQ) derivatives as organic cathode active materials exhibited high theoretical capacity, their practical capacities and cycle retention were far from satisfactory. To overcome these problems, dimeric BQ derivatives based on the 2,2′-bis-p-benzoquinone (BBQ) framework were synthesized, and the charge-discharge behaviour of the prepared cells using BBQs as the cathode active materials was investigated. BBQ-based cells exhibited excellent performance compared to those based on BQ monomers. For example, the BBQ cell afforded a high initial capacity of 358 A h kg-1 (more than twice that of current lithium-ion batteries that use LiCoO2 as the cathode active material) and a high cycle retention of 198 A h kg-1 at 50 cycles. Electrochemical measurements and density functional theory (DFT) calculations indicated that three electron-redox reactions generally occur in BBQ derivatives, although (OMe)2-BBQ appeared to undergo a four-electron redox reaction.
- Yokoji, Takato,Kameyama, Yuki,Maruyama, Norihiko,Matsubara, Hiroshi
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supporting information
p. 5457 - 5466
(2016/05/24)
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- C-substituted, 1H-azoles for amphoteric, solvent-less proton conductivity
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Disclosed herein are the compounds shown below. Also disclosed are methods of making the compounds. R1=—O—; R2=any alkyl chain; R3=—CH3, —CN, —COOCH3, -tetrazole, -imidazole, or -triazole; R4=—H or —R5; R5=—H, -halogen, —C≡CH, or —C≡C—; n is a positive integer; and m is a positive integer.
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- Triflic acid mediated cascade cyclization of aryldiynes for the synthesis of indeno[1,2-c]chromenes: Application to dye-sensitized solar cells
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A new triflic acid (TfOH)-mediated cascade cyclization of ortho-anisole-substituted aryldiynes is described for the construction of indeno[1,2-c]chromenes. The cascade cyclization proceeds through an unusual TfOH-induced alkyne-alkyne cyclization followed by nucleophilic attack of the methoxy group on the benzylidene cation, which is completely different to the cyclization of ortho-aniline- or ortho-thioanisole-substituted aryldiynes. A new class of organic dyes with the indeno[1,2-c]chromene framework as both donor and π-linker were synthesized. These compounds exhibit high photovoltaic performances in dyesensitized solar cells (DSCs).
- Jiang, Hua,Ferrara, Giovanni,Zhang, Xuan,Oniwa, Kazuaki,Islam, Ashraful,Han, Liyuan,Sun, Ying-Ji,Bao, Ming,Asao, Naoki,Yamamoto, Yoshinori,Jin, Tienan
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supporting information
p. 4065 - 4070
(2015/10/19)
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- C-SUBSTITUTED, 1H-AZOLES FOR AMPHOTERIC, SOLVENT-LESS PROTON CONDUCTIVITY
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Disclosed herein are the compounds shown below. Also disclosed are methods of making the compounds. R1=—O—; R2=any alkyl chain; R3=—CH3, —CN, —COOCH3, -tetrazole, -imidazole, or -triazole; R4=—H or —R5; R5=—H, -halogen, —C≡CH, or —C≡C—; n is a positive integer; and m is a positive integer.
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Page/Page column
(2014/02/16)
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- Computed CH acidity of biaryl compounds and their deprotonative metalation by using a mixed lithium/Zinc-TMP base
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With the aim of synthesizing biaryl compounds, several aromatic iodides were prepared by the deprotonative metalation of methoxybenzenes, 3-substituted naphthalenes, isoquinoline, and methoxypyridines by using a mixed lithium/zinc-TMP (TMP=2,2,6,6-tetramethylpiperidino) base and subsequent iodolysis. The halides thus obtained, as well as commercial compounds, were cross-coupled under palladium catalysis (e.g., Suzuki coupling with 2,4-dimethoxy-5-pyrimidylboronic acid) to afford various representative biaryl compounds. Deprotometalation of the latter compounds was performed by using the lithium/zinc-TMP base and evaluated by subsequent iodolysis. The outcome of these reactions has been discussed in light of the CH acidities of these substrates, as determined in THF solution by using the DFT B3LYP method. Except for in the presence of decidedly lower pKa values, the regioselectivities of the deprotometalation reactions tend to be governed by nearby coordinating atoms rather than by site acidities. In particular, azine and diazine nitrogen atoms have been shown to be efficient in inducing the reactions with the lithium/zinc-TMP base at adjacent sites (e.g., by using 1-(2-methoxyphenyl)isoquinoline, 4-(2,5-dimethoxyphenyl)-3-methoxypyridine, or 5-(2,5-dimethoxyphenyl)-2,4-dimethoxypyrimidine as the substrate), a behavior that has already been observed upon treatment with lithium amides under kinetic conditions. Finally, the iodinated biaryl derivatives were involved in palladium-catalyzed reactions. Copyright
- Kadiyala, Raghu Ram,Tilly, David,Nagaradja, Elisabeth,Roisnel, Thierry,Matulis, Vadim E.,Ivashkevich, Oleg A.,Halauko, Yury S.,Chevallier, Floris,Gros, Philippe C.,Mongin, Florence
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supporting information
p. 7944 - 7960
(2013/07/05)
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- Potassium 4-iodylbenzenesulfonate: Preparation, structure, and application as a reagent for oxidative iodination of arenes
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A new hypervalent iodine(V) compound, potassium 4-iodylbenzenesulfonate, was prepared by the oxidation of 4-iodobenzensulfonic acid with Oxone in water. This potassium salt can be further converted into 4-iodylbenzenesulfonic acid by treatment with the acidic form of Amberlyst 15 in water. A single-crystal X-ray structure of potassium 4-iodylbenzenesulfonate revealed the presence of polymeric chains in the solid state due to a combination of numerous intra- and intermolecular interactions. Potassium 4-iodylbenzenesulfonate will likely find many practical applications as a thermally stable and water-soluble hypervalent iodine-based oxidant, particularly useful as a reagent for oxidative iodination of aromatic substrates. This reagent can be effectively recovered from the reaction mixture (92 % recovery) by treatment of the aqueous layer with Oxone at 60°C for 2 h, followed by filtration of the precipitate. A new hypervalent iodine(V) compound, potassium 4-iodylbenzenesulfonate, was prepared by oxidation of 4-iodobenzenesulfonic acid with Oxone in water. This new reagent promises many practical applications as a thermally stable, water-soluble and recyclable hypervalent iodine oxidant, particularly useful for oxidative iodination of aromatic substrates.
- Yusubov, Mekhman S.,Yusubova, Roza Y.,Nemykin, Victor N.,Maskaev, Andrey V.,Geraskina, Margarita R.,Kirschning, Andreas,Zhdankin, Viktor V.
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p. 5935 - 5942,8
(2020/09/02)
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- Deprotonative metalation of aromatic compounds by using an amino-based lithium cuprate
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Deprotonative cupration of aromatic compounds by using amino-based lithium cuprates was optimized with 2,4-dimethoxypyrimidine and 2-methoxypyridine as the substrates and benzoyl chloride as the electrophile. [(tmp)2CuLi] (+2 LiCl) (tmp=2,2,6,6-tetramethylpiperidino) was identified as the best reagent and its use was extended to anisole, 1,4-dimethoxybenzene, other substituted pyridines, furan, thiophene and derivatives, and N-Boc-indole (Boc=tert-butyloxycarbonyl). Of the electrophiles employed to attempt the interception of the generated aryl cuprates, aroyl chlorides, iodomethane, and diphenyl disulfide efficiently reacted. In addition, different oxidative agents were identified to afford symmetrical biaryls. Finally, palladium-catalyzed coupling with aryl halides was optimized and allowed the synthesis of different aryl derivatives in medium to good yields.
- Nguyen, Tan Tai,Marquise, Nada,Chevallier, Floris,Mongin, Florence
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experimental part
p. 10405 - 10416
(2011/10/12)
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- Deprotonative metalation of substituted aromatics using mixed lithium-cobalt combinations
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The deprotonation of anisole was attempted using different homo- and heteroleptic TMP/Bu mixed lithium-cobalt combinations. Using iodine to intercept the metalated anisole, an optimization of the reaction conditions showed that in THF at room temperature 2 equiv of base were required to suppress the formation of the corresponding 2,2′-dimer. The origin of the dimer was not identified, but its formation was favored with allyl bromide as electrophile. The metalated anisole was efficiently trapped using iodine, anisaldehyde, and chlorodiphenylphosphine, and moderately employing benzophenone, and benzoyl chloride. 1,2-, 1,3-, and 1,4-dimethoxybenzene were similarly converted regioselectively to the corresponding iodides. It was observed that 2-methoxy- and 2,6-dimethoxypyridine were more prone to dimerization than the corresponding benzenes when treated similarly. Involving ethyl benzoate in the metalation-iodination sequence showed that the method was not suitable to functionalize substrates bearing reactive functions.
- Dayaker, Gandrath,Chevallier, Floris,Gros, Philippe C.,Mongin, Florence
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experimental part
p. 8904 - 8910
(2011/01/04)
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- Ortho-directed functionalization of arenes using magnesate bases
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Ortho-directed functionalisation of arenes using lithium alkylmagnesate bases were achieved, demonstrating the potential use of arylmagnesates as suitable arylanions, without a further transmetallation step, for challenging functionalizations such as fluorination, hydroxylation, arylation, vinylation and alkylation through epoxide ring-opening.
- Bellamy, Estelle,Bayh, Omar,Hoarau, Christophe,Trecourt, Francois,Queguiner, Guy,Marsais, Francis
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supporting information; experimental part
p. 7043 - 7045
(2010/11/02)
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- New Gilman-type lithium cuprate from a copper(II) salt: synthesis and deprotonative cupration of aromatics
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Deprotonative cupration of aromatics including heterocycles (anisole, 1,4-dimethoxybenzene, thiophene, furan, 2-fluoropyridine, 2-chloropyridine, 2-bromopyridine, and 2,4-dimethoxypyrimidine) was realized in tetrahydrofuran at room temperature using the Gilman-type amido-cuprate (TMP)2CuLi in situ prepared from CuCl2·TMEDA through successive addition of 1 equiv of butyllithium and 2 equiv of LiTMP. The intermediate lithium (hetero)arylcuprates were evidenced by trapping with iodine, allyl bromide, methyl iodide, and benzoyl chlorides, the latter giving the best results. Symmetrical dimers were also prepared from lithium azine and diazine cuprates using nitrobenzene as an oxidative agent.
- Nguyen, Tan Tai,Chevallier, Floris,Jouikov, Viatcheslav,Mongin, Florence
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experimental part
p. 6787 - 6790
(2010/04/29)
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- How the π conjugation length affects the fluorescence emission efficiency
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How the π conjugation length affects the fluorescence emission efficiency is elucidated by examination of the theoretical and experimental relationship between absolute quantum yield (Φf) and magnitude (Aπ) of the π conjugation lengt
- Yamaguchi, Yoshihiro,Matsubara, Yoshio,Ochi, Takanori,Wakamiya, Tateaki,Yoshida, Zen-Ichi
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supporting information; experimental part
p. 13867 - 13869
(2009/02/07)
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- Iodination of organic compounds with elemental iodine in the presence of hydrogen peroxide in ionic liquid media
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Iodo-transformations using the reagent system I2/H 2O2 were studied in the water miscible ionic liquid (IL) 1-butyl-3-methyl imidazolium tetrafluoroborate (bmimBF4) and in water immiscible IL, 1-butyl-3-methyl i
- Pavlinac, Jasminka,Laali, Kenneth K.,Zupan, Marko,Stavber, Stojan
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experimental part
p. 946 - 955
(2009/04/05)
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- Practical electrochemical iodination of aromatic compounds
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A practical method for electrochemical iodination of aromatic compounds was developed. The method involves the generation of I+ by electrochemical oxidation of I2 in CH3CN using H 2SO4 as supporting electrolyte followed by the reaction with aromatic compounds. The para/ortho selectivity for the reaction of mono-substituted benzenes was significantly improved using dimethoxyethane as cosolvent in the second step. The reaction with highly reactive aromatic compounds led to the formation of significant amounts of diiodo compounds in a macrobatch reactor. This problem was solved by fast 1:1 mixing of I+ with an aromatic compound using a microflow system consisting of a T-shaped micromixer and a microtube reactor.
- Kataoka, Kazuhide,Hagiwara, Yuji,Midorikawa, Koji,Suga, Seiji,Yoshida, Jun-Ichi
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p. 1130 - 1136
(2013/01/03)
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- PROCESS FOR PRODUCING AROMATIC IODINE COMPOUND
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A process for producing an aromatic iodine compound. It has advantages of ease of handling and high safety. By the process, the reaction product having an excellent colour tone can be produced in a high yield. The process for aromatic iodine compound production is characterized by introducing an aromatic compound and an active iodizing agent into a flow-through type reactor equipped with a high-speed mixer to continuously replace hydrogen atoms of the aromatic nucleus of the aromatic compound with iodine atoms.
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- Rigid molecular architectures that comprise a 1,3,5-trisubstituted benzene core and three oligoaryleneethynylene arms: Light-emitting characteristics and π conjugation between the arms
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In view of increasing interest in light-emitting materials, we have investigated the light-emitting characteristics and occurrence of conjugation between arms of star-shaped rigid molecules that comprise a 1,3,5-triethynylbenzene core and methoxy group-su
- Yamaguchi, Yoshihiro,Ochi, Takanori,Miyamura, Satoshi,Tanaka, Takahiro,Kobayashi, Shigeya,Wakamiya, Tateaki,Matsubara, Yoshio,Yoshida, Zen-Ichi
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p. 4504 - 4505
(2007/10/03)
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- Grindstone chemistry: (Diacetoxyiodo)benzene-mediated oxidative nuclear halogenation of arenes using NaCl, NaBr or I2
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A technique of "Grindstone chemistry" is applied to the solvent-free halogenation of arenes with NaCl, NaBr or I2 using (diacetoxyiodo)benzene as the oxidant. Improved yields and higher purities of the products are observed compared with those from established methods.
- Karade,Tiwari,Huple,Siddiqui
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p. 366 - 368
(2007/10/03)
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- 'Green' iodination of dimethoxy- and trimethoxy-substituted aromatic compounds using an iodine-hydrogen peroxide combination in water
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Mild iodination using iodine and a 30% solution of hydrogen peroxide as oxidant was performed in water. The method proved to be efficient and selective for the introduction of iodine into dimethoxybenzenes, trimethoxybenzenes, and dimethoxy- and trimethox
- Pavlinac, Jasminka,Zupan, Marko,Stavber, Stojan
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p. 2603 - 2607
(2008/02/04)
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- Effect of water on the functionalization of substituted anisoles with iodine in the presence of F-TEDA-BF4 or hydrogen peroxide
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Water was found to be a convenient reaction medium for functionalization of substituted anisoles using iodine in the presence of Selectfluor F-TEDA-BF 4 or hydrogen peroxide as mediators and oxidizers. Two types of functionalization were observ
- Pavlinac, Jasminka,Zupan, Marko,Stavber, Stojan
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p. 1027 - 1032
(2007/10/03)
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- Selective monoiodination of aromatic compounds with electrochemically generated I+ using micromixing
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Selective monoiodination of aromatic compounds such as dimethoxybenzene has been successfully achieved with I+, which is generated by anodic oxidation of I2 in acetonitrile, using micromixing. The Royal Society of Chemistry 2006.
- Midorikawa, Koji,Suga, Seiji,Yoshida, Jun-Ichi
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p. 3794 - 3796
(2007/10/03)
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- PROCESS FOR PRODUCING AROMATIC IODINE COMPOUND
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A process for producing an aromatic iodine compound. It has advantages of ease of handling and high safety. By the process, the reaction product having an excellent color tone can be produced in a high yield. The process for aromatic iodine compound production is characterized by introducing an aromatic compound and an active iodizing agent into a flow-through type reactor equipped with a high-speed mixer to continuously replace hydrogen atoms of the aromatic nucleus of the aromatic compound with iodine atoms.
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Page/Page column 17-18; 24
(2008/06/13)
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- Light-emitting efficiency tuning of rod-shaped π conjugated systems by donor and acceptor groups
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In view of the increasing importance of highly efficient light-emitting materials in chemistry, biological science, and materials science, we investigated the light-emitting efficiency tuning of rod-shaped oligo(p-phenylene ethynylene)s (OPEs, trimeric to pentameric systems) by donor and acceptor groups, so that they emit the very intense fluorescence (Φf ≈ 1.0, log ε ≈ 5) at 460 nm as the desired wavelength region. This goal was achieved by side modification by MeO (donor) groups and end modification by a CN-substituted benzene ring or CF3-substituted pyridine ring (acceptor) of tetrameric p-phenylene ethynylene rod-shaped molecules (Φf = 0.96, λem = 458 nm, log ε = 4.96 for the former and Φf = 0.99, λem = 459 nm, log ε = 4.92 for the latter). The high Φf values for 11 and 12 are interpreted in terms of kr (radiative rate constant) and kd (radiationless rate constant). The linear relationship with a positive slope between Φf and the Hammett σ constant was found for the first time. It is found that kd rather than kr varies with σp-X. The photophysical properties (Φf, λem, λabs, log ε) were not so altered with the solvent polarity, which could be explained by the dipole moments in the excited and ground states. The results would be valuable for the molecular design of highly efficient light-emitting materials. Copyright
- Yamaguchi, Yoshihiro,Tanaka, Takahiro,Kobayashi, Shigeya,Wakamiya, Tateaki,Matsubara, Yoshio,Yoshida, Zen-Ichi
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p. 9332 - 9333
(2007/10/03)
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- Banana-shaped oligo(aryleneethynylene)s: Synthesis and light-emitting characteristics
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(Chemical Equation Presented) Pick of the bunch: Banana-shaped molecules 1 and 2 containing dimethoxybenzene and pyridine units are highly efficient emitters of violet light despite the interruption of the π conjugation because of meta substitution. The c
- Yamaguchi, Yoshihiro,Kobayashi, Shigeya,Wakamiya, Tateaki,Matsubara, Yoshio,Yoshida, Zen-Ichi
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p. 7040 - 7044
(2007/10/03)
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- Practical and regioselective halogenations of aromatic compounds using tetrabutylammonium peroxydisulfate
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The halogenated aromatic compounds have been important intermediates for various synthetic methods. Electron-rich aromatic compounds were easily iodinated using tetrabutylammonium peroxydisulfate (1) and iodine in mild conditions with excellent yields. Bromination was achieved using 1 and bromine, and regioselective bromination of highly activated aromatic compounds was also achieved using 1 and lithium bromide in mild conditions with excellent yields. Copyright Taylor & Francis Inc.
- Min, Young Park,Seung, Gak Yang,Kim, Yong Hae
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p. 1235 - 1240
(2007/10/03)
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- Amplified quenching in metal-organic conjugated polymers
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The luminescence from conjugated polyelectrolytes that contain pendant metal complex units is quenched very efficiently by oppositely charged electron acceptors.
- Liu, Yao,Jiang, Shujun,Schanze, Kirk S.
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p. 650 - 651
(2007/10/03)
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- A new, environment friendly protocol for iodination of electron-rich aromatic compounds
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A new environment friendly procedure for effective aromatic iodination is presented. A mixture of potassium iodide and potassium iodate is used in the presence of an acid for in situ iodination of aromatic compounds.
- Adimurthy, Subbarayappa,Ramachandraiah, Gadde,Ghosh, Pushpito K.,Bedekar, Ashutosh V.
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p. 5099 - 5101
(2007/10/03)
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- An Efficient, Catalytic, Aerobic, Oxidative Iodination of Arenes Using the H5PV2Mo10O40 Polyoxometalate as Catalyst
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Iodination of arenes was carried out by reacting 1 equiv of arene substrate with 0.5 equiv of iodine under an oxygen atmosphere with H 5PV2Mo10O40 as oxidation catalyst. The synthesis is an inherently waste-free method for the preparation of iodoarenes.
- Branytska, Olena V.,Neumann, Ronny
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p. 9510 - 9512
(2007/10/03)
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- A facile synthesis of 1,4-dialkoxy-2,5-diiodobenzenes: reaction of dialkoxybenzenes with iodine monochloride in alcoholic solvents
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A facile synthesis of 1,4-dialkoxy-2,5-diiodobenzenes via diiodination of the corresponding dialkoxybenzenes with iodine monochloride has been developed. Employment of ah alcoholic solvent as a reaction medium is crucial for attaining a high yield; the reaction in a nonalcoholic solvent usually resulted in a poor yield. The diiodobenzene derivatives are useful intermediates in the synthesis of such advanced materiais as soluble phenylenevinylene polymers anal dialkoxy derivatives of 7,7,8,8-tetracyanoquinodimethane.
- Wariishi, Koji,Morishima, Sin-Ichi,Inagaki, Yoshio
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- Iodination of activated arenes using silfen: An improved protocol
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A simple and direct method for the iodination of activated arenes, using molecular iodine and silfen (silica supported ferric nitrate nonahydrate) as an oxidant, is presented. The reactions are performed at 20°C in dichloromethane. The method provides an easy access to the corresponding iodinated products in good yields. The observed orientation effects are in agreement with those based on general aromatic electrophilic substitution theory.
- Tilve, Rutuja D.,Alexander, Varughese M.,Khadilkar, Bhushan M.
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p. 9457 - 9459
(2007/10/03)
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- Aromatic iodination: A new investigation on the nature of the mechanism
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Following a suggestion by the late Lennart Eberson, we have employed the ICl-HFP (HFP being hexafluoropropan-2-ol) system in iodination reactions, and found unambiguous evidence for the occurrence of an ET-mechanism of halogenation. The evidence is based on the use of 'intelligent' substrates, which make it possible to fix the boundaries between the occurrence of an ET-mechanism and of a conventional polar mechanism. In an 'intelligent' substrate, in fact, the nature of the product(s) changes significantly depending on the operating mechanism. The ICl-HFP combination is instrumental to the onset of a one-electron oxidation with electron-rich substrates, followed by halogenation. The most prominent example is that of the electron-rich substrate durene (1,2,4,5-tetramethylbenzene, DUR), when compared to mesitylene (1,3,5-trimethylbenzene, MES): with a 'conventional' iodination system (i.e., I2/ Ag+) and in common solvents, where the polar mechanism holds, durene is less reactive (kMES/kDUR = 46 ± 3), but becomes more reactive (kMES/kDUR = 0.23) in HFP with ICl, where the ET-mechanism takes over. Other substrates also support the onset of ET-pathways in HFP. Finally, a preliminary survey of a biohalogenation reaction induced by laccase indicates the modest occurrence of a polar process of iodination with a few substrates.
- Fabbrini, Maura,Galli, Carlo,Gentili, Patrizia,Macchitella, Daniele,Petride, Horia
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p. 1516 - 1521
(2007/10/03)
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- A practical iodination of aromatic compounds using tetrabutylammonium peroxydisulfate and iodine
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A variety of aromatic compounds substituted with an electron donating group such as methoxy, hydroxy, or amino group, were regioselectively iodinated with iodine in the presence of tetrabutylammonium peroxydisulfate under mild conditions in excellent yields.
- Yang, Seung Gak,Kim, Yong Hae
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p. 6051 - 6054
(2007/10/03)
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- Radical cation mechanism of aromatic halogenation by halogens or iodine chloride in 1,1,1,3,3,3-hexafluoropropan-2-ol
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The reaction between aromatic compounds ArH and halogenating agents, viz. iodine chloride, chlorine, bromine, iodine, N-bromosuccinimide and N-chlorosuccinimide, in 1,1,1,3,3,3-hexafluoropropan-2-ol (HFP) has been investigated. EPR spectroscopy established that these reagents produced persistent radical cations ArH.+ from ArH with Erev(ArH.+/ArH) up to 1.6, 1.3, 1.4, 1.1, 1.5 and 1.2 V vs. Ag/AgCl, respectively. Cyclic voltammetry of the halogenating species shows that no effect of complexation with halide ion is observed in HFP, as expected from its capacity to drastically attenuate nucleophilic reactivity, and that the cathodic peak potentials Epc (referenced to the internal ferricinium/ferrocene redox couple) are significantly or remarkably higher in HFP than in acetonitrile. For N-bromosuccinimide, the difference amounts to almost 1 V. The persistency of the radical cations in HFP is such that the kinetics of reactions between a halogenating agent, such as iodine chloride or bromine, and ArH, such as 1,4-dimethoxybenzene [Erev(ArH.+/ArH) = 1.50 V vs. Ag/AgCl] or 1,4-dimethoxy-2,3-dimethylbenzene [Erev(ArH.+/ArH) = 1.16 V], have been studied at room temperature over periods of hours. The initial concentration of the radical cation corresponds to yields in the range of 40-100%, depending on the reaction conditions. It is thus possible to establish that the radical cation decays via two pathways, one being the well known oxidative substitution reaction with halide ion. The second mechanism involves halogen atom transfer from the halogenating agent (Cl atom from ICl, Br atom from bromine). In the case of the radical cation of 1,4-dimethoxy-2,3-dimethylbenzene reacting with bromide ion or bromine, the latter reaction is >102 times faster.
- Eberson, Lennart,Hartshorn, Michael P.,Radner, Finn,Persson, Ola
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- Mild and regiospecific nuclear iodination of methoxybenzenes and naphthalenes with N-iodosuccinimide in acetonitrile
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A wide range of methoxy substituted benzenes and naphthalenes were regiospecifically iodinated at para position with N-iodosuccinimide in acetonitrile under mild conditions in excellent yields. Methylanisoles afforded only nuclear iodination products.
- Carreno, M. Carmen,Garcia Ruano, Jose L.,Sanz, Gema,Toledo, Miguel A.,Urbano, Antonio
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p. 4081 - 4084
(2007/10/03)
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- Iodination of alkyl aryl ethers by mercury(II) oxide-iodine reagent in dichloromethane
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A convenient method for selective mono- and diiodination of alkyl aryl ethers by mercury(II) oxide-iodine reagent in dichloromethane is reported.
- Orito,Hatakeyama,Takeo,Suginome
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p. 1273 - 1277
(2007/10/02)
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- Cation Radicals as Intermediates in Aromatic Halogenation with Iodine Monochloride: Solvent and Salt Effects on the Competition between Chlorination and Iodination
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Three distinct classes of substitutional reactivity can be discerned in the halogenation of a series of methyl-substituted methoxybenzenes (ArH) with iodine monochloride (ICl), namely, exclusive iodination, exclusive chlorination, and mixed iodination/chlorination.Spectral studies establish the prior formation of the charge-transfer complex which suffers electron transfer to afford the reactive triad .+,I.,Cl(-)> according to Scheme 1.Separate reactivity studies show that chlorination and iodination can result from the quenching of the aromatic cation radical by chloride and iodine (atom), respectively.Iodination versus chlorination thus represents the competition between radical-pair and ion-pair collapse from the reactive triad, and it is predictably modulated by solvent polarity and added salt.
- Hubig, S. M.,Jung, W.,Kochi, J. K.
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p. 6233 - 6244
(2007/10/02)
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- Preparation of 7-oxaaporphine derivatives and evaluation of their dopaminergic activity
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A series of 7-oxaaporphine derivatives was prepared. The compounds were evaluated as dopaminergic agents. None of them showed either affinity for dopamine receptors or activity in vivo in the climbing behavior (mice) and turning behavior (6-hydroxydopamin
- Banzatti,Carfagna,Commisso,Heidempergher,Pegrassi,Melloni
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p. 1466 - 1471
(2007/10/02)
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- Mercury in Organic Chemistry. 26. Synthesis of Heterocycles via Intramolecular Solvomercuration of Aryl Acetylenes
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A number of ortho substituted aryl acetylenes, o-CH3XC6H4YCCR (X=O, S, CO2; Y=-, CO), have been observed to undergo facile intramolecular solvomercuration with mercuric acetate in acetic acid to afford the corresponding benzofuran, benzothiophene, isocoumarin, and chromone organomercuric chlorides, after aqueous sodium chloride workup.The aryl acetylenes m-XC6H4YCH2CCR (X=H, Y=O, R=CH3; X=CH3O, Y=CH2, R=n-C3H7) undergo similar cyclizations to yield mercurated 2H-1-benzopyrans and 1,2-dihydronaphthalenes.The mercuration and subsequent carbonylation of o-R1OC6H4CCR2 1=Si(t-Bu)Me2, R2=CH3; R1=CH3, R2=o-C6H4OCH3> has provided a new approach to the coumarin and coumestan ring systems.
- Larock, Richard C.,Harrison, L. Wayne
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p. 4218 - 4227
(2007/10/02)
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- Synthesis of Substituted Phenazines from Benzofurazanoxid and Hydroquinones
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The sterical course of the formation of substituted phenazines from benzofurazanoxid and hydroquinone derivatives was investigated.The additional functional group of the hydroquinone determines the substitution pattern and the product ratio of the phenazines formed. - Key words: Phenazine, Synthese, Hydrochinone
- Roemer, A.,Sammet, M.
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p. 866 - 872
(2007/10/02)
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