- Enthalpies of combustion of phenazine N-oxide, phenazine, benzofuroxan, and benzofurazan: the dissociation enthalpies of the (N-O) bonds
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The standard (p0 = 0.1 MPa) molar enthalpies of combustion at 298.15 K were measured by static-bomb calorimetry and the standard molar enthalpies of sublimation at 298.15 K were measured by microcalorimetry for phenazine, benzofurazon, and their corresponding N-oxides: From the standard molar enthalpies of formation of the gaseous compounds, the molar dissociation enthalpies of the (N-O) bonds were derived: D(N-O)/(kJ*mol-1): phenazine N-oxide, 280.7 +/- 5.6; benzofuroxan, 250.9 +/- 3.0.
- Leitao, M. Luisa P.,Pilcher, G.,Acree, W. E.,Zvaigzne, Anita I.,Tucker, Sheryl A.,et al.
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Read Online
- Solvent Dependent Bergman Cyclization of 2,3-Diethynylquinoxaline
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Kinetics of thermocyclization of 2,3-diethynylquinoxaline have been studied in various solvents. The cyclization rates observed were surprisingly solvent dependent. The half-lives varied from 361 in CH3CN to 16 min in THF. The half-life data show a good correlation with the solvents' spectroscopic ET(30) values and dielectric constants.
- Kim, Chang-Sik,Russell, K. C.
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Read Online
- Enhanced catalytic activity in organic solvents using molecularly dispersed haemoglobin-polymer surfactant constructs
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The surface of haemoglobin (Hb) is chemically modified to produce molecular dispersions of discrete core-shell Hb-polymer surfactant bionanoconjugates in water and organic solvents. The hybrid nanoconstructs exhibit peroxidase-like catalytic activity with enhanced turnover rates compared with native Hb in water. The Royal Society of Chemistry 2013.
- Zhang, Yixiong,Patil, Avinash J.,Perriman, Adam W.,Mann, Stephen
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Read Online
- One-pot production of phenazine from lignin-derived catechol
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Upgrading lignin-derived monomeric products is crucial in bio-refineries to effectively utilize lignin. Herein, we report a simple strategy to convert catechol to phenazine, a useful N-heterocycle three-aromatic-ring compound, whose current synthetic procedure is complex via a petroleum-derived feedstock. The reaction uses catechol as the sole carbon source and aqueous ammonia as reaction media and a nitrogen source. Without additional solvents, phenazine was obtained in 67% yield in the form of high purity crystals (>97%) over a Pd/C catalyst after a one-pot-two-stage reaction. When cyclohexane was used as a co-solvent in the first step, a higher yield (81%) and purity (>99%) were achieved. Mechanistic investigations involving control experiments and an isotope labeling study reveal that hydrogenation, amination, coupling and dehydrogenation reactions are the key steps leading to phenazine formation. The conversion of other lignin-derived catechols highlights that the protocol is extendable to produce substituted phenazines.
- He, Zhimin,Qi, Wei,Ren, Tianyu,Yan, Ning
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p. 1224 - 1230
(2022/02/17)
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- An umpolung strategy for rapid access to thermally activated delayed fluorescence (TADF) materials based on phenazine
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Herein, Ag(I)-promoted regioselective intramolecular radical nucleophilic addition/rearrangement of 2-aryl diazaboroles has been accomplished for the first time to construct phenazine structures. This protocol is an umpolung strategy based on the classical electrophilic mechanism, and therefore, a reversed regioselectivity was observed, which provides an opportunity to prepare sterically hindered phenazines. The resulting thermally activated delayed fluorescence (TADF) materials based on phenazine exhibit emission bands from green to red with high quantum yields and moderate fluorescence lifetimes as solid films.
- Cheng, Hu,Guo, Qiang,Lan, Jingbo,Ran, Chunhao,Wu, Di,Zhang, Huaxing
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supporting information
p. 1581 - 1584
(2022/02/10)
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- The silver-mediated annulation of arylcarbamic acids and nitrosoarenes toward phenazines
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A silver-mediated annulation between arylcarbamic acids and nitrosoarenes was developed, leading to phenazines in moderate to good yields with complexity and diversity. This procedure proceeded with the sequential ortho[sbnd] C[sbnd]H functionalization of arylcarbamic acids, insertion to nitroso group and decarboxylative annulation.
- Chen, Fan,Cheng, Jiang,Qian, Peng-Cheng,Wang, Lu
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- Decarboxylation of Aromatic Carboxylic Acids by the Prenylated-FMN-dependent Enzyme Phenazine-1-carboxylic Acid Decarboxylase
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Phenazine-1-carboxylic acid decarboxylase (PhdA) is a member of the expanding class of prenylated-FMN-dependent (prFMN) decarboxylase enzymes. These enzymes have attracted interest for their ability to catalyze (de)carboxylation reactions on aromatic rings and conjugated double bonds. Here we describe a method to reconstitute PhdA with prFMN that produces an active and stable form of the holo-enzyme that does not require prereduction with dithionite for activity. We establish that oxidized phenazine-1-carboxylate (PCA) is the substrate for decarboxylation, withkcat= 2.6 s-1andKM= 53 μM. PhdA also catalyzes the much slower exchange of solvent deuterium into the product, phenazine, with an apparent turnover number of 0.8 min-1. The enzyme was found to catalyze the decarboxylation of a broad range of polyaromatic carboxylic acids, including anthracene-1-carboxylic acid. Previously described prFMN-dependent aromatic (de)carboxylases have utilized electron-rich phenolic or heterocyclic molecules as substrates. PhdA extends the substrate range of prFMN-dependent (de)carboxylases to electron-poor and unfunctionalized aromatic systems, suggesting that it may prove a useful catalyst for the regioselective (de)carboxylation of otherwise unreactive aromatic molecules.
- Datar, Prathamesh M.,Marsh, E. Neil G.
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p. 11723 - 11732
(2021/09/28)
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- K2S2O8activation by glucose at room temperature for the synthesis and functionalization of heterocycles in water
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While persulfate activation at room temperature using glucose has primarily been focused on kinetic studies of the sulfate radical anion, the utilization of this protocol in organic synthesis is rarely demonstrated. We reinvestigated selected K2S2O8-mediated known organic reactions that invariably require higher temperatures and an organic solvent. A diverse, mild functionalization and synthesis of heterocycles using the inexpensive oxidant K2S2O8 in water at room temperature is reported, demonstrating the sustainability and broad scope of the method. Unlike traditional methods used for persulfate activation, the current method uses naturally abundant glucose as a K2S2O8 activator, avoiding the use of higher temperature, UV light, transition metals or bases.
- Hunjan, Mandeep Kaur,Laha, Joydev K.
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p. 8437 - 8440
(2021/09/02)
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- PHENAZINE-BASED COMPOUNDS AND USE THEREOF AS REDOX FLOW BATTERY ELECTROLYTE
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The present invention relates to novel phenazine-based compounds of formula (l)(a) and (l)(b) and compositions comprising the same and their use as redox flow battery electrolytes.(l)(a), (l)(b)
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Page/Page column 68
(2021/08/27)
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- Synthesis of phenazines from ortho-bromo azo compounds via sequential Buchwald-Hartwig amination under micellar conditions and acid promoted cyclization
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Non-symmetric phenazines were synthesized via the Buchwald-Hartwig amination of ortho-bromoazobenzenes with anilines under micellar conditions, using the commercially available surfactant Kolliphor EL in water, followed by an acid-promoted 6π-electrocyclization-aromatization process. Two different synthetic pathways to obtain the ortho-bromo azo intermediates were explored, namely the palladium catalysed selective ortho bromination of azobenzenes and the diazo coupling of ortho-bromo diazonium salts with N,N-dimethylaniline, imidazole, phenol, sodium methanesulfinate and ethyl chloroformate.
- Yousif, Dawod,Monti, Mauro,Papagni, Antonio,Vaghi, Luca
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supporting information
(2020/10/19)
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- Aerobic Dehydrogenation of N-Heterocycles with Grubbs Catalyst: Its Application to Assisted-Tandem Catalysis to Construct N-Containing Fused Heteroarenes
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An aerobic dehydrogenation of nitrogen-containing heterocycles catalyzed by Grubbs catalyst is developed. The reaction is applicable to various nitrogen-containing heterocycles. The exceptionally high functional group compatibility of this method was confirmed by the oxidation of an unprotected dihydroindolactam V to indolactam V. Furthermore, by taking advantage of the oxygen-mediated structural change of the Grubbs catalyst, we integrated ring-closing metathesis and subsequent aerobic dehydrogenation to develop the novel assisted-tandem catalysis using molecular oxygen as a chemical trigger. The utility of the assisted-tandem catalysis was demonstrated by the concise synthesis of N-containing fused heteroarenes including a natural antibiotic, pyocyanine.
- Kawauchi, Daichi,Noda, Kenta,Komatsu, Yoshiyuki,Yoshida, Kei,Ueda, Hirofumi,Tokuyama, Hidetoshi
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p. 15793 - 15798
(2020/10/12)
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- The development of a Cu(I)/pyrazolylpyridineamine catalyst system for the hydroxylation of aryl halides
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A catalyst system comprising of pyrazolylpyridineamine/Cu(I)/CsOH is reported. for the hydroxylation of aryl iodides and bromides with moderate to outstanding yields, without the use of an inert atmosphere. A comprehensive parameter optimisation study established optimum component concentrations: [Cu(MeCN)4]BF4 and 2-(1H-pyrazol-1-yl)-N-(pyridine-2-ylmethyl)ethan-1-amine (L01) (2 mol %), substrate (1 mmol), CsOH (4 mmol) and DMSO:H2O (1:1, 3 mL). Monitoring substrate conversion as a function of time revealed an induction period of 90 min, which could be eliminated through the initial in situ formation of the proposed [(L01)Cu-OH] intermediate. Eliminating the induction period resulted in complete conversion within one hour, with turnover numbers exceeding that of the benchmark catalyst system operating at an optimal catalyst loading of 0.05 mol %.
- Marais, Lindie,Vosloo, Hermanus C.M.,Swarts, Andrew J.
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- REDOX-ACTIVE COMPOUNDS AND USES THEREOF
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The present invention relates to novel I ign in-derived compounds and compositions comprising the same and their use as redox flow battery electrolytes. The invention further provides a method for preparing said compounds and compositions as well as a redox flow battery comprising said compounds and compositions. Additionally, an assembly for carrying out the inventive method is provided.
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Page/Page column 162
(2020/03/05)
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- Rhodium-Catalyzed Reaction of Azobenzenes and Nitrosoarenes toward Phenazines
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A rhodium-catalyzed annulative reaction between azobenzenes and nitrosoarenes has been developed, leading to a series of phenazines in moderate to good yields. This procedure proceeds with sequential chelation-assisted addition of aryl C-H to nitrosoarenes and ring closure by electrophilic attack of azo group to aryl. During this transformation, the azo group served as not only a traceless directing group but also a building block in the final products.
- Xiao, Yan,Wu, Xiaopeng,Wang, Hepan,Sun, Song,Yu, Jin-Tao,Cheng, Jiang
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supporting information
p. 2565 - 2568
(2019/04/30)
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- A Simple and Efficient Flow Preparation of Pyocyanin a Virulence Factor of Pseudomonas aeruginosa
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The synthesis of the naturally occurring toxin pyocyanin has been realized in a short 4 step sequence. The key photochemical reaction and isolation of the final product have been facilitated by the use of flow chemistry techniques and immobilised reagents. Using these procedures gram quantities of pyocyanin were easily prepared in high yield and purity.
- Mortzfeld, Frederik B.,Pietruszka, J?rg,Baxendale, Ian R.
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p. 5424 - 5433
(2019/06/13)
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- Direct Synthesis of Diphenylamines from Phenols and Ammonium Formate Catalyzed by Palladium
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Arylamines are commercially and synthetically useful compounds with a wide variety of applications. Their preparation has been traditionally achieved using metal-catalyzed C?N coupling reactions with aryl halides. In this work, 17 different diarylamines are prepared from phenols by using ammonium formate as the aminating reagent. Phenolic compounds are more desirable feedstocks, owing to their availability from lignin, making them valuable biorenewable alternatives to aryl halides. Ammonium formate is found to be a convenient surrogate for ammonia and a useful aminating reagent for phenols. Diarylamine products are obtained in good to excellent yields while only water and CO2 are generated as byproducts of the transformation.
- Dominguez-Huerta, Alejandra,Perepichka, Inna,Li, Chao-Jun
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p. 2999 - 3002
(2019/06/13)
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- One-pot cascade syntheses of microporous and mesoporous pyrazine-linked covalent organic frameworks as Lewis-acid catalysts
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Covalent organic frameworks (COFs) are crystalline porous solids with broad potential applications. So far, the successful construction of COFs has been limited to a few condensation reactions, and nearly all COFs were obtained by single-step synthesis based on predesigned linkers. Here, we report a general strategy in view of a one-pot cascade reaction to prepare both microporous and mesoporous fully π-conjugated pyrazine-linked COF materials (PZ-COFs). The obtained PZ-COFs show high chemical stability, large specific surface areas and promising H2, CH4 and CO2 uptake capacities. Furthermore, we demonstrate that manganese(ii)-incorporated PZ-COFs can act as excellent Lewis-acid catalysts for the cyanosilylation of aromatic aldehydes. This study not only provides a facile method to synthesize COFs required for multistep reactions but also expands the applications of COFs as promising catalysts.
- Ma, Yunchao,Liu, Xiaozhou,Guan, Xinyu,Li, Hui,Yusran, Yusran,Xue, Ming,Fang, Qianrong,Yan, Yushan,Qiu, Shilun,Valtchev, Valentin
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supporting information
p. 7352 - 7357
(2019/06/06)
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- Hydrogen on Cobalt Phosphide
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Cobalt phosphide (CoP) is one of the most promising earth-abundant replacements for noble metal catalysts for the hydrogen evolution reaction (HER). Critical to HER is the binding of H atoms. While theoretical studies have computed preferred sites and energetics of hydrogen bound to transition metal phosphide surfaces, direct experimental studies are scarce. Herein, we describe measurements of stoichiometry and thermochemistry for hydrogen bound to CoP. We studied both mesoscale CoP particles, exhibiting phosphide surfaces after an acidic pretreatment, and colloidal CoP nanoparticles. Treatment with H2 introduced large amounts of reactive hydrogen to CoP, ca. 0.2 H per CoP unit, and on the order of one H per Co or P surface atom. This was quantified using alkyne hydrogenation and H-atom transfer reactions with phenoxy radicals. Reactive H atoms were even present on the as-prepared materials. On the basis of the reactivity of CoP with various molecular hydrogen donating and accepting reagents, the distribution of binding free energies for H atoms on CoP was estimated to be roughly 51-66 kcal mol-1 (δG°H 0 to -0.7 eV vs H2). Operando X-ray absorption spectroscopy gave preliminary indications about the structure of hydrogenated CoP, showing a slight lattice expansion and no significant change of the effective nuclear charge of Co under H2-flow. These results provide a new picture of catalytically active CoP, with a substantial amount of reactive H atoms. This is likely of fundamental relevance for its catalytic and electrocatalytic properties. Additionally, the approach developed here provides a roadmap to examine hydrogen on other materials.
- Delley, Murielle F.,Wu, Zishan,Mundy, M. Elizabeth,Ung, David,Cossairt, Brandi M.,Wang, Hailiang,Mayer, James M.
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supporting information
p. 15390 - 15402
(2019/11/02)
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- An Improved Rapid and Mild Deoxygenation of Amine N-oxides
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An improved mild and selective method for the deoxygenation of a variety of amine N-oxides has been carried out in the presence of silica gel under mild conditions at room temperature to afford corresponding amines in relatively good yields without purification. The reaction is tolerant of a variety of functional groups such as hydroxyl, ester, acid, carbonyl, and cyano groups, as well as halogens. This method would be of great utility to synthesize various pyridines and amines easily.
- Rajesh
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p. 486 - 491
(2017/12/29)
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- Sulfur-Promoted Aminative Aromatization of 1,2,3,4-Tetrahydrophenazines with Amines: Flexible Access to 1-Aminophenazines
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Elemental sulfur was found to be an excellent reagent for promoting the aminative aromatization of 1,2,3,4-tetrahydrophenazines with amines to provide a wide range of functionalized 1-aminophenazines. (Figure presented.).
- Nguyen, Thanh Binh,Retailleau, Pascal
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p. 2389 - 2393
(2018/05/07)
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- Super electron donor-mediated reductive transformation of nitrobenzenes: A novel strategy to synthesize azobenzenes and phenazines
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The transformation of nitrobenzenes into azobenzenes by pyridine-derived super electron donor 2 is described. This method provides an efficient synthesis of azobenzenes because of not requiring the use of expensive transition-metals, toxic or flammable reagents, or harsh conditions. Moreover, when using 2-fluoronitrobenzenes as substrates, phenazines were found to be obtained. The process affords a novel synthesis of phenazines.
- Nozawa-Kumada, Kanako,Abe, Erina,Ito, Shungo,Shigeno, Masanori,Kondo, Yoshinori
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supporting information
p. 3095 - 3098
(2018/05/22)
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- Elemental Sulfur as Reaction Medium for the Synthesis of Fused Nitrogen Heterocycles by Oxidative Coupling between Cycloalkanones and Nitrogen Nucleophiles
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Molten elemental sulfur was found to be an excellent reaction medium for oxidative coupling between bis-aza nucleophiles and cycloalkanones to the fused diaza heterocycles. No extensive aromatization was observed when cyclohexanone was used. These reaction conditions tolerate a wide range of functional groups and are applicable to oxidation sensitive o-phenylenediamines. (Figure presented.).
- Nguyen, Thanh Binh,Retailleau, Pascal
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supporting information
p. 3843 - 3847
(2017/11/15)
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- A under the microwave radiation in the aqueous phase catalytic synthesis of phenazine compounds
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The invention discloses a method for catalytically synthesizing phenazine compounds in a water phase under microwave radiation, which comprises the following steps: adding a catalytic amount of catalyst ferric chloride or nickelous chloride, a cocatalyst lithium proline, a substrate substituted 2-haloaniline, a phase-transfer catalyst 4-butyl ammonium chloride, 4-butyl ammonium bisulfate or 4-butyl ammonium bromide, an inorganic alkali or organic alkali and water into a reaction vessel, putting into a microwave reaction instrument, reacting at certain temperature under certain power for some time, concentrating under reduced pressure, and purifying the product by column chromatography. The method for preparing phenazine compounds is friendly to the environment, simple to operate and high in efficiency. Compared with the prior art, the method has the advantages of obviously higher reaction speed than conventional heating, mild reaction conditions, high yield, high safety, low cost and environment friendliness, and is simple to operate.
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Paragraph 0054; 0067
(2017/10/06)
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- Transition-Metal-Free Poly(thiazolium) Iodide/1,8-Diazabicyclo[5.4.0]undec-7-ene/Phenazine-Catalyzed Esterification of Aldehydes with Alcohols
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Poly(3,4-dimethyl-5-vinylthiazolium) iodide was used as a polymer precatalyst in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and phenazine for the oxidative esterification of aldehydes with alcohols. Selective functionalization of OH groups was achieved in the presence of NH2 groups. The poly(thiazolium) iodide/DBU/phenazine system exhibited excellent catalytic activity and could be reused five times without loss of activity.
- Chun, Supill,Chung, Young Keun
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supporting information
p. 3787 - 3790
(2017/07/26)
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- Synchronous double C-N bond formation via C-H activation for a novel synthetic route to phenazine
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A novel synthetic strategy for phenazine formation is reported following self-coupling of anilines by Pd-Ag binary nanocluster-catalysed synchronous double C-N bond formation via non-radical mode of ortho-aryl C-H activation.
- Seth, Kapileswar,Raha Roy, Sudipta,Chakraborti, Asit K.
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supporting information
p. 922 - 925
(2016/01/16)
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- The palladium and copper contrast: A twist to products of different chemotypes and altered mechanistic pathways
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A novel contrast in palladium and copper catalysis is revealed to form products of different chemotypes resulting in a phenazine to azoarene twist through an altered mechanistic pathway (from non-radical C-H activation mode of C-N coupling to radical N-N coupling) during the oxidative self-coupling of anilines catalysed by Pd-Ag and Cu-Ag nanoclusters.
- Seth, Kapileswar,Roy, Sudipta Raha,Kumar, Asim,Chakraborti, Asit K.
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p. 2892 - 2896
(2016/05/24)
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- Facile Rearrangement of the 6,11-Diphenyldibenzo[b,f][1,4]diazocine Skeleton into a Substituted 2-(2-Aminophenyl)-1,3-diphenylisoindole via Anomalous Carbolithiation or Hydrolithiation: Corroboration of Operative SET Processes
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The starting 6,11-diphenyldibenzo[b,f][1,4]diazocine has been individually treated with R-Li reagents in THF, where R = AlH4, PhCH2, Ph2CH, Ph3C, CH3, CH3(CH2)3, C6H5 or Ph-C≡C, to learn whether an expected 1,2- or 1,4-addition would cleanly occur. Contrary to such an assumption based on nucleophilic attack, this [1,4]diazocine with PhCH2Li yielded only the enantiomers of (4b,11R)-11-benzyl-4b,11-diphenyl-4b,11-dihydro-5H-benzo[4,5]imidazo[2,1-a]isoindole; with Ph2CHLi yielded 2-[1-(4-benzhydrylphenyl)-phenyl-2H-isoindol-2-yl]analine; and with LiAlH4 2-(2-aminophenyl)-1,3-diphenylisoindole. Finally, individual reactions of the [1,4]diazocine with CH3Li, nBuLi or PhLi gave 4-5 inseparable products, instead of any simple 1,2 or 1,4 adduct. The anomalous carbolithiations and hydrolithiation observed are irreconcilable with a nucleophilic mechanism but in excellent accord with a SET radical-anion pathway.
- Eisch, John J.,Liu, Wei,Zhu, Lisheng,Rheingold, Arnold L.
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p. 7384 - 7394
(2015/11/25)
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- Palladium-catalyzed α-arylation of enones in the synthesis of 2-alkenylindoles and carbazoles
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A new unified strategy has been developed for the synthesis of substituted 2-alkenylindoles and carbazoles. The strategy uses palladium-catalyzed α-arylation of TES-enol ethers of enones as the key step. The method is highly regioselective, provides good yields, and is expected to have wide application.
- Kale, Ajit Prabhakar,Kumar, Gangam Srikanth,Mangadan, Arun Raj Kizhakkayil,Kapur, Manmohan
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p. 1324 - 1327
(2015/03/14)
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- Copper-catalyzed oxygen atom transfer of N-oxides leading to a facile deoxygenation procedure applicable to both heterocyclic and amine N-oxides
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Deoxygenation of various types of N-oxides including both heterocyclic and alkyl(aryl)amine derivatives has successfully been developed by the copper-catalyzed oxygen atom transfer using diazo compounds as the oxygen acceptor. The reaction proceeds smoothly over a broad range of substrates with excellent functional group tolerance under mild conditions. This journal is
- Jeong, Jisu,Lee, Donggun,Chang, Sukbok
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supporting information
p. 7035 - 7038
(2015/04/22)
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- Facile Redox Interconversion of 6,11-Diphenyldibenzo[b,f][1,4]diazocine and 2-(2-Aminophenyl)-1,3-diphenylisoindole: Reversible SET Ring Contraction and Expansion Processes
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In our continuing attempts to convert tub-shaped dibenzo[1,4]diazocines or dibenzo[1,5]diazocines into necessarily planar Hückel aromatic ten-π-electron dianions or dihydro derivatives of the central diazocine ring, we have added requisite electrons by Na or Li metal in THF. Subsequent hydrolysis yielded no evidence for the formation of such Hückel aromatic products but in each case a profound rearrangement of the tricyclic diazocine had instead occurred. In the present study we have attempted to form the unknown aromatic 6,11-diphenyldibenzo[b,f][5,12]-dihydro[1,4]diazocine at 25°C by such a straightforward addition of two electrons to 6,11-diphenyldibenzo[b,f][1,4]diazocine. We were encouraged by the prior reduction of the unsubstituted [1,4]diazocine to 1,4-dihydro-[1,4]diazocine, which by X-ray and 1H NMR evidence displays aromatic-like properties. However, this diphenyldibenzo[1,4]-diazocine upon reduction underwent instead an unusual, serendipitous rearrangement to yield quantitatively 2-(2-aminophenyl)-1,3-diphenylisoindole. Then in a purposive search for other reductants capable of reductively rearranging this [1,4]diazocine to its corresponding isoindole, we discovered three other reductants, namely o-diaminobenzene, titanium(II) salts, and concentrated aqueous hydriodic acid with visible light. Conversely, again in a serendipitous observation, it was found that O2 in CHCl3 with visible light could readily convert the isoindole in an oxidative rearrangement back into the [1,4]diazocine. A purposive method for achieving this oxidative rearrangement was then found to be treatment with DDQ. General mechanistic pathways are proposed via SET intermediates for both redox interconversions.
- Eisch, John J.,Liu, Wei,Zhu, Lisheng,Rheingold, Arnold L.
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p. 7489 - 7498
(2016/02/20)
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- Transition-metal-free tandem oxidative removal of benzylic methylene group by C-C and C-N bond cleavage followed by intramolecular new aryl C-N bond formation under radical conditions
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A novel tandem oxidative conversion of 10,11-dihydro-5H-dibenzo[b,e][1,4]diazepines to phenazines has been achieved under transition-metal-free, mild conditions using K2S2O8 or DDQ as the oxidizing agent. The transformation proceeds through oxidative removal of a benzylic methylene group by C-C and C-N bond cleavage followed by a new aryl C-N bond formation under radical conditions.
- Laha, Joydev K.,Tummalapalli, K. S. Satyanarayana,Gupta, Ankur
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supporting information
p. 4392 - 4395
(2015/01/08)
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- Water at elevated temperatures (WET): Reactant, catalyst, and solvent in the selective hydrolysis of protecting groups
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Water at elevated temperatures (WET) can act simultaneously as reactant, solvent, and catalyst in reaction processes. WET has been successfully employed in the removal of protecting groups alleviating the need for added strong acids/bases, subsequent neutralization and waste salt elimination. The protocols for the water-mediated removal of several common protecting groups such as tert-butyl carbamates (N-Boc) from 125 to 150 °C, acetamide (N-Ac) at 275 °C and acetate esters (O-Ac) at 250 °C are reported for different model aryl compounds. In addition, high yields and selective deprotection of one protecting group in the presence of another by simply tuning the temperature is demonstrated. In order to gain further insights into reaction processes, the aqueous solubilities of several of the reactants, the kinetics and mechanisms associated with some of these reactions are also discussed. the Partner Organisations 2014.
- Medina-Ramos, Wilmarie,Mojica, Mike A.,Cope, Elizabeth D.,Hart, Ryan J.,Pollet, Pamela,Eckert, Charles A.,Liotta, Charles L.
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p. 2147 - 2155
(2014/04/17)
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- Palladium-catalyzed domino double n-arylations (inter- and intramolecular) of 1,2-diamino(hetero)arenes with o,o-dihalo(hetero)arenes for the synthesis of phenazines and pyridoquinoxalines
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Domino reactions for the synthesis of phenazines have been developed that start from 1,2-diaminoarenes and 1,2-dihaloarenes and proceed through palladium-catalyzed double N-arylations (inter- and intramolecular) followed by an in situ oxidation. A variety of functional groups, which include base-sensitive groups, were well tolerated under the optimized reaction conditions to afford phenazines in good to excellent yields. The protocol was extended to the synthesis of pyridoquinoxalines by employing either o-phenylenediamines and 2,3-dihalopyridines or 1,2-diaminopyridines and 1,2-dihaloarenes. Domino reactions for the synthesis of phenazines have been developed that start from 1,2-diaminoarenes and 1,2-dihaloarenes and proceed through palladium-catalyzed double N-arylations (inter- and intramolecular) followed by an in situ oxidation. The protocol was extended to the synthesis of pyridoquinoxalines. Copyright
- Laha, Joydev K.,Tummalapalli, K.S. Satyanarayana,Gupta, Ankur
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p. 8330 - 8335
(2014/01/06)
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- Synthesis of phenazines by Cu-catalyzed homocoupling of 2-halogen anilines in water
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Phenazines are synthesized by Cu-catalyzed homocoupling of 2-iodoanilines or 2-bromoanilines in water in moderate to excellent yields up to 85%.
- Yu, Lintao,Zhou, Xiangge,Wu, Di,Xiang, Haifeng
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supporting information; experimental part
p. 75 - 78
(2012/04/17)
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- Synthesis of 2-arylbenzoxazoles from flash vacuum pyrolysis of 2-methoxy-N-(arenylidene)anilines
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Flash vacuum pyrolysis of 2-methoxy-N-(arenylidene)anilines 2a-g at 700 °C and 1 × 10-2 Torr gave the corresponding 2-arylbenzoxazoles 1a-g.
- Chou, Chin-Hsing,Hsueh, Yu-Tan,Wang, Bo-Chi
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experimental part
p. 301 - 305
(2011/10/18)
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- Microwave-assisted Cadogan reaction for the synthesis of 2-aryl-2H-indazoles, 2-aryl-1H-benzimidazoles, 2-carbonylindoles, carbazole, and phenazine
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(Chemical Equation Presented) The Cadogan reaction, a widely accepted route for the synthesis of nitrogen containing heterocycles, is modified by using microwave radiation as the source of heat instead of the conventional heating by reflux in a nitrogen atmosphere for several hours. Appropriate starting materials were mixed with triethyl phosphite or triphenylphosphine and irradiated with microwaves for several minutes at a specific power to give the desired products. The indazoles were prepared by irradiating N-(2-nitrobenzylidene) anilines with triethyl phosphite at 200 W for 12-14 min to give 85-92% product yields. Irradiation of the mixture of N-benzylidene-2-nitroanilines and triphenylphosphine at 200 W for 3-5 min yielded 93-96% of the benzimidazoles. The carbonylindoles were obtained in 61-68% yields by irradiating 2-nitrochalcone or alkyl 2-nitrocinnamates and triphenylphosphine with microwaves at 80-200 W for 8-11 min. The mixture of 2-nitrobiphenyl and triphenylphosphine yielded 96% of carbazole when irradiated with microwaves at 200 W for 2 min while 75% of phenazine was obtained by irradiating the mixture of 2-nitrodiphenylamine and triphenylphosphine with microwaves at 200 W for 3.5 min. These results show that microwave-assisted Cadogan reactions gave better product yields at shorter reaction times.
- Creencia, Evelyn Cuevas,Kosaka, Masahiro,Muramatsu, Toshikatsu,Kobayashi, Masashi,Iizuka, Tomohiro,Horaguchi, Takaaki
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scheme or table
p. 1309 - 1317
(2010/03/23)
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- Thermal reactions of N-Alkyl-2-benzylaniline and N-Alkyl-N′-phenyl-o- phenylenediamine: An unusual route to 2-phenylindole and 2-phenylbenzimidazole
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(Chemical Equation Presented) Thermal cyclization reactions of N-alkyl-2-benzylaniline 1a-d and N-alkyl-N′-phenyl-o-phenylenediamine 2a-b were carried out expecting to get seven-membered heterocyclic compounds. However, the results show that aside from th
- Creencia, Evelyn Cuevas,Taguchi, Kei,Horaguchi, Takaaki
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p. 837 - 843
(2008/09/21)
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- METHOD FOR PREPARING 4-AMINODIPHENYLAMINE
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The present invention relates to a method for preparing 4-aminodiphenylamine comprising the steps of reacting carbanilide and nitrobenzene in an adequate solvent in the presence of an appropriate organic base or a mixture of an organic base and an inorganic base and subsequently reducing the reaction product, or a 4-aminodiphenylamine intermediate, without separation from the reaction mixture, in the presence of an appropriate catalyst and hydrogen gas. Because the method of the present invention uses carbanilide as starting material, which reacts directly with nitrobenzene with high reactivity and selectivity, generation of by-products such as phenazine and 2-nitrodiphenylamine can be reduced and the 4-aminodiphenylamine intermediate can be prepared with good selectivity and production yield. Also, because a recyclable organic base is used, amount of wasted material can be minimized and 4-aminodiphenylamine, or the final product, can be prepared efficiently, without the separation of 4-aminodiphenylamine intermediate for the subsequent reduction process. In addition, in comparison with conventional preparation methods of 4-aminodiphenylamine, generation of harmful wastes can be significantly reduced and environment-damaging corrosive materials are not generated.
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Page/Page column 8-9
(2008/06/13)
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- METHOD FOR PREPARING 4-AMINODIPHENYLAMINE
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4-aminodiphenylamine is prepared by reacting carbanilide and nitrobenzene in an adequate solvent, which may be nitrobenzene, in the presence of an appropriate organic base, which may be tetramethylammonium hydroxide, alone or in mixture with an inorganic base and subsequently reducing the reaction product in the presence of an appropriate catalyst and hydrogen gas. The subsequent reduction may be carried out on the reaction mixture before the reaction mixture is subjected to separation.
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Page/Page column 4-5
(2008/06/13)
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- Process for preparing 4-aminodiphenylamine
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The present invention discloses a process for preparing 4-aminodiphenylamine, which process uses nitrobenzene and aniline as raw materials, a complex base catalyst as condensation catalyst and a powdery composite catalyst as hydrogenation catalyst, and comprises five process stages: condensation; separation I; hydrogenation; separation II; and refining. The process can be continuously carried out. By selecting a complex base catalyst to catalyze the condensation reaction and separating it prior to the hydrogenation, the problem that the complex base catalysts thermally decompose in the hydrogenation reaction is avoided, the selectable range of hydrogenation catalysts is largely enlarged so that it is possible to select cheaper hydrogenation catalyst, and the selection of production process and equipment is easier and further industrialization is easier. The complex base catalysts used in the present invention are inexpensive and have higher catalytic activity. The process can be carried out at mild conditions and can adapt to broad range of water content, by-product is less and conversion and selectivity are higher. The operational strength is low, no corrosive liquid is produced, and environment pollution is reduced. The purity of 4-aminodiphenylamine prepared can exceed 99 wt.-%, and the yield in the industrial production process can be over 95%.
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Page/Page column 9-10
(2008/06/13)
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- THE METHOD FOR PREPARING 4-NITRODIPHENYLAMINE AND 4-NITROSODIPHENYLAMINE FROM CARBANILIDE
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This invention relates to a process for preparing 4-nitrodiphenylamine and 4-nitrosodiphenylamine to be used for 4-aminodiphenylamine as an intermediate of antiozonant, wherein carbanilide is reacted with nitrobenzene in the presence of an appropriate base, while simultaneously adding aniline to the mixture so as to regenerate some amounts of carbanilide as a starting material. According to this invention, 4-nitrodiphenylamine and 4-nitrosodiphenylamine can be prepared in a higher selectivity and conversion rate via a continuous reaction by recycling carbanilide, a starting material, while adding a certain amount of aniline during the process. Further, the amount of waste water can be significantly reduced compared to the conventional method without any corrosive materials harmful to the environment.
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- Process for preparing 4-aminodiphenylamine intermediates
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The invention is directed to a method of producing one or more 4-aminodiphenylamine intermediates comprising the steps: a. bringing an aniline or aniline derivative and nitrobenzene into reactive contact; and b. reacting the aniline and nitrobenzene in a confined zone at a suitable time and temperature, in the presence of a mixture comprising a strong organic base, or equivalent thereof, and an oxidant comprising hydrogen peroxide in an amount of from about 0.01 to about 0.60 moles of hydrogen peroxide to moles of nitrobenzene.
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- Synthesis of Carbazole, Acridine, Phenazine, 4H-Benzo[def]carbazole and Their Derivatives by Thermal Cyclization Reaction of Aromatic Amines
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A variety of nitrogen-containing heterocycles were synthesized by passing vapors of aromatic amines over calcium oxide at 450-650 °C under nitrogen carrier gas. Reaction of 2-aminobiphenyl 3a at 560 °C gave carbazole 4 in 80% yield. Reaction of 2,2′-diaminobiphenyl 3b afforded a mixture of carbazole 4 and 4-aminocarbozole 6b. In the case of 2-amino-2′ -nitrobiphenyl 3c, benzo[c]cinnoline 7 was obtained along with carbazole 4. Reaction of 2-amino-2′-methoxybiphenyl 3d gave four products of carbazole 4, 4-hydroxycarbazole 6e, phenanthridine 8 and dibenzofuran 9. Reaction of 2-aminodiphenylmethane 5a afforded acridine 10. In the case of 2-aminobenzophenone 5b, acridone 11 was obtained as a major product. Reaction of 2-aminobenzhydrol 5c gave acridine 10. When 2-aminodiphenylamine 5d was reacted, phenazine 12 was obtained in good yield. In contrast, reaction of 2-aminodiphenyl ether 5e produced only 2-hydroxydiphenylamine 13. Reaction of 4-aminophenanthrene 14 produced 4H-benzo[def]carbazole 15 in 61% yield.
- Horaguchi, Takaaki,Oyanagi, Takako,Creencia, Evelyn Cuevas,Tanemura, Kiyoshi,Suzuki, Tsuneo
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- An Efficient Deoxgenation of Heteroaromatic N-Oxides Using Zinc Dust/Ammonium Formate Reagent System
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Heteroaromatic N-oxides were readily and selectively deoxygenated to the corresponding bases with zinc/ammonium formate reagent system.
- Balicki, Roman,Cybulski, Marcin,Maciejewski, Grzegorz
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p. 4137 - 4141
(2007/10/03)
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- Benzo[A] [phenazin-11-carboxamide derivatives and their use as joint inhibitors of topomerase I and II
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A compound which is a benzo[a]phenazine-11-carboxamide derivative of formula (I) wherein each of R1 to R4, which are the same or different, is selected from hydrogen, halogen, hydroxyl, C1-C6 alkoxy which is unsubstituted or substituted, heteroaryloxy, C1-C6 alkyl which is unsubstituted or substituted, nitro, cyano, azido, amidoxime, CO2R10, CON(R12)2, OCON(R12), SR10, SOR11, SO2(R11), SO2N(R12)2, N(R12)2, NR10SO2R11, N(SO2R11)2NR10(CH2)nCN, NR10COR11, OCOR11 or COR10; each of R5 to R7, which are the same or different, is selected from hydrogen, halogen, hydroxy, C1-C6 alkoxy, C1-C6 alkyl, SR10 and N(R12)2; Q is C1-C6 alkylene which is unsubstituted or substituted by (i) C1-C6 alkyl which is unsubstituted or substituted, (ii) hydroxy, provided that the hydroxy group is not, to either of the N atoms adjacent to Q in formula (I), (iii) CO2R10, or (iv) CON(R12); R1 and R9, which are the same or different, are each hydrogen or C1-C6 alkyl, or R8 and R9 together with the nitrogen atom to which they are attached form a saturated 5- or 6-membered N-containing heterocyclic ring which may include one additional heteroatom selected from O, N and S, or one of R8 and R9 is an alkylene chain optionally interrupted by O, N or S, which is attached to a carbon atom on the alkylene chain represented by Q to complete a saturated 5- or 6-membered N-containing heterocyclic ring as defined above; or a pharmaceutically acceptable salt thereof; with the proviso that at least one R1 to R4 is other than hydrogen. These compounds are inhibitors of topoisomerase I and/or topoisomerase II and can be used to treat tumours, including tumours which express MDR.
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- Method of preparation of 4-aminodiphenylamine
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A method of preparing 4-aminodiphylamine through an intermediate preparation of 4-nitrodiphenylamine and/or 4-nitrosodiphenylamine and/or their salts by reaction of aniline with nitobenzene in a liquid medium at a temperature of 50 to 130° C., under normal or reduced pressure, in an inert atmosphere or in the presence of air oxygen, with subsequent hydrogenation of an intermediate of 4-nitrodiphenylamine and/or nitrosodiphenylamine and side products, and by isolation of 4-aminodiphenylamine and the side products of unconverted raw materials.
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Page column 10
(2008/06/13)
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- A mild deoxygenation of heteroaromatic N-oxides by formamidinesulfinic acid
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Various heteroaromatic N-oxides were efficiently deoxygenated to the corresponding bases under mild conditions using formamidinesulfinic acid (thiourea S,S-dioxide).
- Balicki, Roman,Chmielowiec, Urszula
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p. 1105 - 1107
(2007/10/03)
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- Hydrobromic acid-dimethyl sulfoxide reagent for dealkylation of 5,10-dialkyl-5,10-dihydrophenazines: Synthesis of 10-alkyl- 2(10H)-phenazinones
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By the reaction of 5,10-dialkyl-substituted 5,10- dihydrophenazine with hydrobromic acid in dimethyl sulfoxide at 90-110°, 10-alkyl-2(10H)-phenazinone was obtained as a major product. Brominated dihydrophenazine was isolated in the case of 1,6-dichloro-5,10-dimethyl-5,10-dihydrophenazine.
- Sugimoto, Akira,Yoshino, Yasuyuki,Watanabe, Ryo,Mizuno, Kazuhiko,Uehara, Kaku
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p. 1057 - 1064
(2007/10/03)
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- One-step synthesis of dialkynyl-1,2-diones and their conversion to fused pyrazines bearing enediyne units
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A convenient procedure for the preparation of symmetrically end-protected dialkynyl-1,2-diones 3 from lithium acetylides and oxalyl chloride in the presence of CuBr and LiBr is described. The condensation of 3 with various aromatic and heteroaromatic 1,2-diamines leads to pyrazine-based α-dialkynylated heterocycles. The enediyne substructure of diethynylquinoxaline can be thermally rearranged in a Bergman cyclization reaction.
- Faust, Ruediger,Weber, Christian,Fiandanese, Vito,Marchese, Giuseppe,Punzi, Angela
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p. 14655 - 14670
(2007/10/03)
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- Investigation of the direct and indirect reduction processes of some disulfides by electrochemical means
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The free energy relationship for the reaction between aromatic radical anions A.- having about the same intrinsic barrier and three disulfides RSSR (diphenyl disulfide, dimethyl disulfide and di-tert-butyl disulfide) in N,N-dimethylformamide has been obtained. For each RSSR second-order rate constants were measured electrochemically in the interval 10-3-105 M-1 s-1 by changing the nature of A.- and thereby the driving force. In the case of diphenyl disulfide the standard potential ERSSR/RSSR.-? and the self-exchange reorganization energy λ(0) of the RSSR/RSSR.- couple could be extracted from the free energy relationship to values of -1.4 (±0.1) V vs. SCE and 65 kcal mol-1, respectively. This knowledge may be combined with the kinetic features of the heterogeneous reduction process of diphenyl disulfide to obtain, among other parameters, the standard heterogeneous rate constant. The cleavage rate constant kc of the corresponding radical anion was estimated from kinetic measurements to be about 5 × 108 s-1. No such information was accessible for the aliphatic disulfides due to a high self-exchange energy of the RSSR/RSSR.- couple but still a maximum value of kc could be determined at 2x108 s-1. The minimum values of ERSSR/RSSR.-? and λ(0) were estimated to be -1.9 V vs. SCE and 75 kcal mol-1 and -2.2 V vs. SCE and 75 kcal mol-1 for dimethyl disulfide and di-tert-butyl disulfide, respectively. ? Acta Chemica Scandinavica 1997.
- Bo Christensen, Torben,Daasbjerg, Kim
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p. 307 - 317
(2007/10/03)
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- Oxidation of fluoroanilines to fluoroazobenzenes with potassium ferricyanide and KOH
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The oxidation of several fluoroanilines to fluoroazobenzenes with potassium ferricyanide and KOH in a solvent mixture of ethanol/water is described.
- Leyva, Elisa,Monreal, Elena,Medina, Concepcion,Leyva, Socorro
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p. 7847 - 7848
(2007/10/03)
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