- Cobalt-Catalyzed Deoxygenative Hydroboration of Nitro Compounds and Applications to One-Pot Synthesis of Aldimines and Amides
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The commercially available and bench-stable Co(acac)2 ligated with bis[(2-diphenylphosphino)phenyl] ether (dpephos) was employed for selective room temperature hydroboration of nitro compounds with HBPin (TOF up to 4615 h?1), tolerating halide, hydroxy, amino, ether, ester, lactone, amide and heteroaromatic functionalities. These reactions offered a direct access to a variety of N-borylamines RN(H)BPin, which were in situ treated with aldehydes and carboxylic acids to produce a series of aldimines and secondary carboxamides without the need for dehydrating and/or coupling reagents. Combination of these transformations in a sequential one-pot manner allowed for direct and selective synthesis of aldimines and secondary carboxamides from readily available and inexpensive nitro compounds.
- Gudun, Kristina A.,Hayrapetyan, Davit,Khalimon, Andrey Y.,Segizbayev, Medet,Slamova, Ainur,Zakarina, Raikhan
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- Manganese Catalyzed Hydrogenation of Azo (N=N) Bonds to Amines
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We report the first example of homogeneously catalyzed hydrogenation of the N=N bond of azo compounds using a complex of an earth-abundant-metal. The hydrogenation reaction is catalyzed by a manganese pincer complex, proceeds under mild conditions, and yields amines, which makes this methodology a sustainable alternative route for the conversion of azo compounds. A plausible mechanism involving metal-ligand cooperation and hydrazine intermediacy is proposed based on mechanistic studies. (Figure presented.).
- Ben-David, Yehoshoa,Das, Uttam Kumar,Diskin-Posner, Yael,Kar, Sayan,Milstein, David
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p. 3744 - 3749
(2021/07/09)
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- Synthesis of Azobenzene Dyes Mediated by CotA Laccase
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An eco-friendly protocol for the synthesis of azobenzene dyes by oxidative coupling of primary aromatic amines is reported. As efficient biocatalytic systems, CotA laccase and CotA laccase/ABTS (2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)) enable the oxidation of various substituted anilines, in aqueous medium, ambient atmosphere and under mild reaction conditions of pH and temperature. A series of azobenzene dyes were prepared in good to excellent yields in an one-pot reaction. A mechanistic proposal for the formation of the azo derivatives is presented. Our strategy offers an alternative approach for the direct synthesis of azobenzene dyes, avoiding the harsh conditions generally required for most of the traditional synthetic methods.
- Sousa, Ana Catarina,Baptista, Sara R.,Martins, Lígia O.,Robalo, M. Paula
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p. 187 - 193
(2018/12/04)
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- Catalytic Azoarene Synthesis from Aryl Azides Enabled by a Dinuclear Ni Complex
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Azoarenes are valuable chromophores that have been extensively incorporated as photoswitchable elements in molecular machines and biologically active compounds. Here, we report a catalytic nitrene dimerization reaction that provides access to structurally and electronically diverse azoarenes. The reaction utilizes aryl azides as nitrene precursors and generates only gaseous N2 as a byproduct. By circumventing the use of a stoichiometric redox reagent, a broad range of organic functional groups are tolerated, and common byproducts of current methods are avoided. A catalyst featuring a Ni - Ni bond is found to be uniquely effective relative to those containing only a single Ni center. The mechanistic origins of this nuclearity effect are described.
- Powers, Ian G.,Andjaba, John M.,Luo, Xuyi,Mei, Jianguo,Uyeda, Christopher
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p. 4110 - 4118
(2018/03/29)
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- Convenient Electrocatalytic Synthesis of Azobenzenes from Nitroaromatic Derivatives Using SmI2
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The synthesis of azobenzenes has been a long-standing challenge. Their current preparation at a preparative or industrial scale requires stoichiometric amounts of environmentally unfriendly reactants. Herein, we demonstrate that the catalytic use of electrogenerated samarium diiodide (SmI2) could promote, in one-step synthesis, the reduction of nitrobenzenes into azobenzenes in high yields under mild reaction conditions. This catalytic procedure contains many elements satisfying a sustainable chemical process for the preparation of one of the most widely wanted family of chemical compounds. The easy synthetic procedure, and the absence of precious metals, bases, and nonhazardous substances, already makes our catalytic procedure a serious alternative to currently available methods. This is a promising method for the efficient synthesis of both symmetrical and asymmetrical azo compounds with a high functional group tolerance.
- Zhang, Yu-Feng,Mellah, Mohamed
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p. 8480 - 8486
(2017/12/08)
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- Mesoporous manganese oxide catalyzed aerobic oxidative coupling of anilines to aromatic azo compounds
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Herein we introduce an environmentally friendly approach to the synthesis of symmetrical and asymmetrical aromatic azo compounds by using air as the sole oxidant under mild reaction conditions in the presence of cost-effective and reusable mesoporous manganese oxide materials.
- Dutta, Biswanath,Biswas, Sourav,Sharma, Vinit,Savage, Nancy Ortins,Alpay, S. Pamir,Suib, Steven L.
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supporting information
p. 2171 - 2175
(2016/02/18)
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- Formal [4+2] cycloaddition of 3-ethoxycyclobutanones with azo compounds
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Azobenzenes reacted with 3-ethoxycyclobutanoes to give 2,3-dihydro-pyridazin-4(1H)-ones by using EtAlCl2as a Lewis acid. Thus, ring cleavage of 3-ethoxycyclobutanones took place to form a zwitterionic intermediate by activation with EtAlCl2, and intermolecular formal [4+2] cycloaddition of the zwitterionic intermediate proceeded with azobenzenes to give 2,3-dihydro-pyridazin-4(1H)-ones after elimination of ethanol. Regioselectivity for cycloaddition of unsymmetrical azobenzenes, ring contraction and chemoselective reduction of 2,3-dihydro-pyridazin-4(1H)-ones, and [4+2] cycloaddition to 4-phenyl-1,2,4-triazolin-3,5-dione are also described.
- Shima, Yusuke,Matsuo, Jun-ichi
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supporting information
p. 4066 - 4069
(2016/08/18)
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- Solution photochemistry of [ p -(Dimethylamino)phenyl]pentazole (DMAPP) at 193 and 300 nm
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The photochemistry of [p-(dimethylamino)phenyl]pentazole (DMAPP) at 193 nm and in the near UV is reported, with emphasis on the nature of the final stable products. The (dimethylamino)phenyl azide (DMAPA) is found as a major product in MeCN, but not in dichloromethane (DCM). (In this paper the acronyms DMAPP and DMAPA refer to the para isomers.) The photochemistry of DMAPA is also explored for comparison. The data obtained in MeCN solutions are consistent with the initial formation of the corresponding nitrene, but in DCM, different products are found, on the basis of NMR data. In the case of high reactant concentration in DCM (10-2 M), quantitative conversion of DMAPP and DMAPA is observed, indicating a high quantum yield. In contrast, MeCN solutions react much more slowly. A radical-type chain reaction mechanism is proposed to account for this observation. At high dilution, DMAPP is completely converted to products in both solvents. Possible mechanisms accounting for these results are discussed.
- Bazanov,Haas
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p. 2661 - 2671
(2015/03/30)
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- Thermal stability of p-dimethylaminophenylpentazole
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The thermal stability of p-dimethylaminophenylpentazole (1) in the solid phase has been thoroughly investigated. The decomposition process of 1 has been verified by a combination of differential scanning calorimetry (DSC), thin-layer chromatography (TLC), temperature-programmed FTIR, and Raman spectroscopy. FTIR and Raman spectra were also calculated to corroborate the results. It was found that 1 could be handled below 20 °C without any obvious deterioration, but it decomposed sharply at 56 °C. The calculated FTIR and Raman vibrational frequencies were in accord with the experimental values.
- Yang, Yu-Zhang,Li, Yu-Chuan,Zhang, Ru-Bo,Sun, Cheng-Hui,Pang, Si-Ping
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p. 57629 - 57634
(2015/02/05)
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- One-pot preparation of azobenzenes from nitrobenzenes by the combination of an indium-catalyzed reductive coupling and a subsequent oxidation
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We demonstrated how a reduction step with a reducing system comprised of In(OTf)3 and Et3SiH and a subsequent oxidation that occurred under an ambient (oxygen) atmosphere allowed the highly selective and catalytic conversion of aromatic nitro compounds into symmetrical or unsymmetrical azobenzene derivatives. This catalytic system displayed a tolerance for the functional groups on a benzene ring: an alkyl group, a halogen, an acetyl group, an ester, a nitrile group, an acetyl group, an ester moiety, and a sulfonamide group.
- Sakai, Norio,Asama, Shun,Anai, Satsuki,Konakahara, Takeo
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p. 2027 - 2033
(2014/03/21)
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- Ruthenium nanoparticle-catalyzed, controlled and chemoselective hydrogenation of nitroarenes using ethanol as a hydrogen source
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This communication describes a ruthenium nanoparticle-catalyzed reduction of nitroarenes giving azoxyarenes, azoarenes, or anilines in good to excellent yields using ethanol as a hydrogen source. Copyright
- Kim, Ju Hyun,Park, Ji Hoon,Chung, Young Keun,Park, Kang Hyun
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supporting information
p. 2412 - 2418
(2012/11/07)
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- Highly efficient synthesis of aromatic azos catalyzed by unsupported ultra-thin Pt nanowires
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Aromatic azos were synthesized using unsupported ultra-thin platinum nanowires as catalysts under mild reaction conditions and the reaction mechanism was proposed.
- Hu, Lei,Cao, Xueqin,Chen, Liang,Zheng, Junwei,Lu, Jianmei,Sun, Xuhui,Gu, Hongwei
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supporting information; experimental part
p. 3445 - 3447
(2012/05/20)
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- A highly active nano-palladium catalyst for the preparation of aromatic azos under mild conditions
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A worm-like Pd nanocatalyst has been prepared and used in the preparation of azo compounds from nitroaromatics under mild reaction conditions. This highly dispersible nano-Pd catalyst shows high activity toward the synthesis of both symmetric aromatic azo compounds and a range of asymmetric aromatic azo compounds.
- Hu, Lei,Cao, Xueqing,Shi, Linyan,Qi, Fenqiang,Guo, Zhiqiang,Lu, Jianmei,Gu, Hongwei
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supporting information; experimental part
p. 5640 - 5643
(2011/12/04)
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- PREPARATION OF AZO COMPOUNDS WITH SOLID CATALYSTS
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The present invention refers to a procedure for preparing azo compounds comprising a reaction between at least: one amine or polyamine, molecular oxygen, a catalyst comprising at least one support selected from at least a metal oxide of one of the elements of the groups 3, 4, 5, 6, 8, 9, 11 and 13, silica, an anionic laminar compound of hydrotalcite type or its derivatives, active carbon or an organic polymer. In addition, said catalyst may contain nanoparticles of gold.
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Page/Page column 7
(2011/06/23)
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- Chemoselective reductive coupling of nitroarenes with magnesium in methanol via single electron transfer
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A chemoselective reductive coupling of nitroarenes using magnesium in methanol has been reported at ambient temperature. While the cyano, formyl, methoxycarbonyl, methyl, methoxy, phenyl, amino, and chloro groups are unaffected, iodo and bromo groups undergo dehalogenation but in a slower reaction than the coupling of nitro group. The coupling is believed to be proceeding via SET from Mg to nitroarenes.
- Khurana, Jitender M.,Ray, Abhijit
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p. 407 - 410
(2007/10/03)
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- THE DIANIONS OF AROMATIC NITRO COMPOUNDS IN AZO COUPLING REACTIONS
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With arenediazonium fluoroborates the dianions of o- and p-dinitrobenzenes and 1,8-dinitronaphthalene give nitroazo compounds.A competing reaction is the oxidation of the dianions by the diazonium cations, the degree of which increases with increase in the dissociating character of the solvent and the electron-withdrawing characteristics of the substituent in the arenediazonium ion.The structure of one of the products of this reaction i.e., 1-nitro-8-(4-methoxyphenylazo)naphthalene, was confirmed by x-ray crystallographic analysis.
- Todres, Z. V.,Ovsepyan G. Ts.,Kosnikov, A. Yu.,Lindeman, S. V.,Struchkov, Yu. T.
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p. 522 - 527
(2007/10/02)
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- ELECTRICAL CONDUCTIVITY IN TCNQ SALTS OF BIS(4-DIMETHYLAMINOPHENYLIMINO) SULFUR AND ITS STRUCTURAL ANALOGUES.
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Four compounds, N,N,N prime ,N prime -tetramethyl-p-phenylene diamine, N,N,N prime ,N prime -tetramethyl-benzidine, 4,4 prime -bis(dimethylamino)azobenzene and bis(4-dimethylaminophenylimino)sulfur (BAPIS) were examined electrochemically and spectroscopically. Each was shown to be a fairly good donor forming in its first oxidation state a radical-cation. The latter two materials surprisingly exhibited only single one-electron oxidations. Conformational flexibility about the -NSN- unit was studied by NMR spectroscopy and ab initio molecular orbital theory. The experimental DELTA G* for a cis-trans to trans-cis interconversion in BAPIS was found to be 11. 9 kcal/mole. The four donors all form 1:1 adducts with TCNQ. The compaction resistances of the complexes have been measured as a function of temperature. Of the four, (BAPIS)(TCNQ) appears to be a one-dimensional material. The other three complexes behave as typical mixed stack organic semiconductors.
- Kaplan,Haddon,Raghavachari,Menezes,Schilling,Hauser,Marshall
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- STUDIES ON ORGANOPHOSPHORUS COMPOUNDS XXXII Reactions of 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide with compounds containing the N=O function
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Reactions of 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide, 1, with a series of substrates having a semipolar bond have been studied.C-Nitroso compounds react to give azoxy compounds or azo compounds, whereas N,N-dimethyl-p-nitrosoaniline furnishes p-dimethylamino-N-thiosulfinyl-aniline, 6, and benzofurazan-1-oxide produces 2,1,3-benzothiadiazole.N-nitroso compounds react with 1 to give phosphorous heterocycles in which the N-nitroso function is destroyed.Elimination of HNO from certain N-nitroso compounds has also been observed.Nitrones and N-oxides react with 1 to form the corresponding deoxygenated products.In the case of quinoline-N-oxide, small amounts of quinoline-2-thione could be isolated in addition to the deoxygenated product.Mechanistic considerations are presented.
- Jorgensen, K. A.,Shabana, R.,Scheibye, S.,Lawesson, S.-O.
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p. 247 - 254
(2007/10/02)
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- Thermal Decomposition of Aromatic Azides. Formation of Phenazines and Related Compounds
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The decomposition of some aromatic azides yielding significant amounts of phenazines, and thereby constituting a potential synthetic procedure, is reported.
- Nay, Barry,Scriven, Eric F. V.,Suschitzky, Hans,Thomas, Desmond R.
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p. 611 - 613
(2007/10/02)
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