1215-42-5

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• Efficient Solar-Driven Hydrogen Transfer by Bismuth-Based Photocatalyst with Engineered Basic Sites
• Photocatalytic organic conversions involving a hydrogen transfer (HT) step have attracted much attention, but the efficiency and selectivity under visible light irradiation still needs to be significantly enhanced. Here we have developed a noble metal-free, basic-site engineered bismuth oxybromide [Bi24O31Br10(OH)] that can accelerate the photocatalytic HT step in both reduction and oxidation reactions, i.e., nitrobenzene to azo/azoxybenzene, quinones to quinols, thiones to thiols, and alcohols to ketones under visible light irradiation and ambient conditions. Remarkably, quantum efficiencies of 42% and 32% for the nitrobenzene reduction can be reached under 410 and 450 nm irradiation, respectively. The Bi24O31Br10(OH) photocatalyst also exhibits excellent performance in up-scaling and stability under visible light and even solar irradiation, revealing economic potential for industrial applications.
• Dai, Yitao,Li, Chao,Shen, Yanbin,Zhu, Shujie,Hvid, Mathias S.,Wu, Lai-Chin,Skibsted, J?rgen,Li, Yongwang,Niemantsverdriet, J. W. Hans,Besenbacher, Flemming,Lock, Nina,Su, Ren

• p. 16711 - 16719

  (2018)
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• Selective oxidation of primary substituted aromatic amines to azoxy products using lacunary catalyses
• Some of the substituted anilines were selectively converted in to the corresponding azoxy and azobenzenes by oxidation with 30% aqueous hydrogen peroxide. The reactions were catalyzed by various heteropolyoxometalates, at boiling point of the used solvent
• Nezhadali,Akbarpour

• p. 43 - 46

  (2010)
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• Cadmium chloride-zinc catalysed selective reduction of nitro aromatics to azoxy compounds
• Treatment of aromatic nitro compounds with cadmium chloride-metallic zinc combination systems has been shown to display a good reaction selectivity in the formation of symmetrical azoxy compounds in high yields.
• Baruah, Bipul,Boruah, Anima,Prajapati, Dipak,Sandhu, Jagir S.

• p. 351 - 352

  (1996)
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• Zr(OH)4-Catalyzed Controllable Selective Oxidation of Anilines to Azoxybenzenes, Azobenzenes and Nitrosobenzenes
• The selective oxidation of aniline to metastable and valuable azoxybenzene, azobenzene or nitrosobenzene has important practical significance in organic synthesis. However, uncontrollable selectivity and laborious synthesis of the expensive required catalysts severely hinders the uptake of these reactions in industrial settings. Herein, we have pioneered the discovery of Zr(OH)4 as an efficient heterogeneous catalyst capable of the selective oxidation of aniline, using either peroxide or O2 as oxidant, to selectively obtain various azoxybenzenes, symmetric/unsymmetric azobenzenes, as well as nitrosobenzenes, by simply regulating the reaction solvent, without the need for additives. Mechanistic experiments and DFT calculations demonstrate that the activation of H2O2 and O2 is primarily achieved by the bridging hydroxyl and terminal hydroxyl groups of Zr(OH)4, respectively. The present work provides an economical and environmentally friendly strategy for the selective oxidation of aniline in industrial applications.
• Long, Yu,Luo, Nan,Ma, Jiantai,Qin, Jiaheng,Sun, Fangkun,Wang, Wei David,Zhou, Pan-Pan
• supporting information

  (2021/12/09)
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• Convergent Paired Electrochemical Synthesis of Azoxy and Azo Compounds: An Insight into the Reaction Mechanism
• A convergent paired electrochemical method was developed for the synthesis of azoxy and azo compounds starting from the corresponding nitroarenes. We propose a unique mechanism for electrosynthesis of azoxy and azo compounds. We find that both anodic and cathodic reactions are responsible for the synthesis of these compounds. The synthesis of azoxy and azo derivatives have been successfully performed in an undivided cell, using carbon rod electrodes, by constant current electrolysis at room temperature.
• Sadatnabi, Ali,Mohamadighader, Niloofar,Nematollahi, Davood
• supporting information

  p. 6488 - 6493

  (2021/08/23)
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• Continuous Flow Synthesis of Azoxybenzenes by Reductive Dimerization of Nitrosobenzenes with Gel-Bound Catalysts
• In the search for a new synthetic pathway for azoxybenzenes with different substitution patterns, an approach using a microfluidic reactor with gel-bound proline organocatalysts under continuous flow is presented. Herein the formation of differently substituted azoxybezenes by reductive dimerization of nitrosobenzenes within minutes at mild conditions in good to almost quantitative yields is described. The conversion within the microfluidic reactor is analyzed and used for optimizing and validating different parameters. The effects of the different functionalities on conversion, yield, and reaction times are analyzed in detail by NMR. The applicability of this reductive dimerization is demonstrated for a wide range of differently substituted nitrosobenzenes. The effects of these different functionalities on the structure of the obtained azoxyarenes are analyzed in detail by NMR and single-crystal X-ray diffraction. Based on these results, the turnover number and the turnover frequency were determined.
• Schmiegel, Carsten J.,Berg, Patrik,Obst, Franziska,Schoch, Roland,Appelhans, Dietmar,Kuckling, Dirk

• p. 1628 - 1636

  (2021/03/15)
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• SO2F2-mediated oxidation of primary and tertiary amines with 30% aqueous H2O2 solution
• A highly efficient and selective oxidation of primary and tertiary amines employing SO2F2/H2O2/base system was described. Anilines were converted to the corresponding azoxybenzenes, while primary benzylamines were transformed into nitriles and secondary benzylamines were rearranged to amides. For tertiary amine substrates quinolines, isoquinolines and pyridines, their oxidation products were the corresponding N-oxides. The reaction conditions are very mild and just involve SO2F2, amines, 30% aqueous H2O2 solution, and inorganic base at room temperature. One unique advantage is that this oxidation system is just composed of inexpensive inorganic compounds without the use of any metal and organic compounds.
• Liao, Xudong,Zhou, Yi,Ai, Chengmei,Ye, Cuijiao,Chen, Guanghui,Yan, Zhaohua,Lin, Sen
• supporting information

  (2021/11/01)
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• Selective Oxidation of Anilines to Azobenzenes and Azoxybenzenes by a Molecular Mo Oxide Catalyst
• Aromatic azo compounds, which play an important role in pharmaceutical and industrial applications, still face great challenges in synthesis. Herein, we report a molybdenum oxide compound, [N(C4H9)4]2[Mo6O19] (1), catalyzed selective oxidation of anilines with hydrogen peroxide as green oxidant. The oxidation of anilines can be realized in a fully selectively fashion to afford various symmetric/asymmetric azobenzene and azoxybenzene compounds, respectively, by changing additive and solvent, avoiding the use of stoichiometric metal oxidants. Preliminary mechanistic investigations suggest the intermediacy of highly active reactive and elusive Mo imido complexes.
• Han, Sheng,Cheng, Ying,Liu, Shanshan,Tao, Chaofu,Wang, Aiping,Wei, Wanguo,Yu, Han,Wei, Yongge
• supporting information

  p. 6382 - 6385

  (2021/02/09)
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• Shape-dependent reactivity and chemoselectivity of nanogold towards nitrophenol reduction in water
• Although the catalytic activity of nano-gold surfaces for the reduction of nitro compounds has been known, the effect of their shape has been rarely evaluated. Here, the synthesis, characterization, and application of both gold nanoworms (GNW) and gold nanospheres (GNS) are described. Both GNW and GNS were characterized using SEM, TEM, UV–Vis, FTIR, and XPS spectroscopy. The catalytic efficiency of GNW with an average dimensions of 2 × 250 nm (D × L) towards the hydrogenation of nitrophenol, a pollutant present in industrial wastewater, is higher (TOF 3675 h?1) than that of spherical GNS (10 ± 1 nm), for which TOF is 1838 h?1 in water using NaBH4 as the reductant. The selectivity of 4-aminophenol is 100% for both GNS and GNW.
• Aziz, Md Abdul,Nafiu, Sodiq Adeyeye,Shaikh, M. Nasiruzzaman

• (2020/07/08)
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• Palladium Nanoparticles on Silica Nanospheres for Switchable Reductive Coupling of Nitroarenes
• Abstract: In this study, we synthesized a robust and sustainable Pd/SiO2 nanospheres catalyst. Further, its catalytic activity was demonstrated for the direct reductive coupling of nitroarenes under mild conditions. While the reaction with Pd nanoparticles on other supporting materials such as modified carbon materials and TiO2, under similar conditions, resulted formation of amines exclusively. Therefore, it was confirmed that the SiO2 was found to be the best supporting material towards the selective reductive coupling of nitroarenes. Also, the catalyst could be recycled up to five cycles with a marginal loss of product yield ( 2% yield). Graphic Abstract: [Figure not available: see fulltext.].
• Lakshminarayana, Bhairi,Manna, Arun Kumar,Satyanarayana,Subrahmanyam, Ch.

• p. 2309 - 2321

  (2020/02/18)
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• Tandem selective reduction of nitroarenes catalyzed by palladium nanoclusters
• We report a catalytic tandem reduction of nitroarenes by sodium borohydride (NaBH4) in aqueous solution under ambient conditions, which can selectively produce five categories of nitrogen-containing compounds: anilines, N-aryl hydroxylamines, azoxy-, azo- and hydrazo-compounds. The catalyst is in situ-generated ultrasmall palladium nanoclusters (Pd NCs, diameter of 1.3 ± 0.3 nm) from the reduction of Pd(OAc)2 by NaBH4. These highly active Pd NCs are stabilized by surface-coordinated nitroarenes, which inhibit the further growth and aggregation of Pd NCs. By controlling the concentration of Pd(OAc)2 (0.1-0.5 mol% of nitroarene) and NaBH4, the water/ethanol solvent ratio and the tandem reaction sequence, each of the five categories of N-containing compounds can be obtained with excellent yields (up to 98%) in less than 30 min at room temperature. This tunable catalytic tandem reaction works efficiently with a broad range of nitroarene substrates and offers a green and sustainable method for the rapid and large-scale production of valuable N-containing chemicals.
• Yan, Ziqiang,Xie, Xiaoyu,Song, Qun,Ma, Fulei,Sui, Xinyu,Huo, Ziyu,Ma, Mingming
• supporting information

  p. 1301 - 1307

  (2020/03/11)
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• Au@zirconium-phosphonate nanoparticles as an effective catalytic system for the chemoselective and switchable reduction of nitroarenes
• In the present paper, a novel inorganic-organic layered material, a zirconium phosphate aminoethyl phosphonate, ZP(AEP), bearing aminoethyl groups on the layer surface, was used to immobilize AuNPs by a two-step procedure. The gold-based catalyst, Au1@ZP(AEP), containing 1 wt% Au, was characterized in terms of physico-chemical properties and TEM analysis revealed that the AuNPs have a spherical shape and an average size of 7.8 (±2.4) nm. Au1@ZP(AEP) proved its high efficiency for the chemoselective reduction of nitroarenes under mild conditions. Both batch and flow condition protocols have been defined. The catalytic system has been proven to be able to easily switch chemoselectivity allowing the control of the reduction of a series of nitroaromatics towards their corresponding azoxyarenes (2a-k) or anilines (2a-l) in 96% EtOH or abs EtOH, respectively, by using NaBH4 as a reducing agent, in good to excellent yields. Recovery and reuse of the catalytic system has been investigated proving the benefits of the flow approach.
• Ferlin, Francesco,Cappelletti, Matteo,Vivani, Riccardo,Pica, Monica,Piermatti, Oriana,Vaccaro, Luigi
• supporting information

  p. 614 - 626

  (2019/02/13)
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• Method for synthesizing oxidized azo compound through selective oxidation of aromatic amine
• The invention discloses a method for synthesizing an oxidized azo compound through selective oxidation of an aromatic amine, wherein an aromatic amine is used as a raw material, hydrogen peroxide is used as an oxidizing agent, a titanium-silicon molecular sieve or a metal modified titanium-silicon molecular sieve is used as a catalyst, and the aromatic amine is subjected to selective catalytic oxidation to prepare the corresponding oxidized azobenzene compound. According to the present invention, the method has advantages of environmental protection, good selectivity, high product yield, easyseparation and recycling of the catalyst, simple instrument required by the reaction, and easy operation.
• -
• Paragraph 0027-0051; 0052-0055

  (2019/02/13)
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• Nb2O5 supported on mixed oxides catalyzed oxidative and photochemical conversion of anilines to azoxybenzenes
• The synthesis of novel supported niobium oxide catalysts and their application for aniline conversion to azoxybenzenes is described. The catalysts were successfully prepared by thermal decomposition of layered double hydroxides (LDHs), containing M2+ (M = Mg2+ and/or Zn2+) and Al3+ as layer cations, followed by niobium oxide incorporation employing the wetness impregnation method. These catalysts were fully characterized by both experimental techniques and theoretical calculations, and then successfully applied to the selective conversion of anilines into azoxybenzene derivatives, with up to 98% conversion and 92% isolated yield in the presence of violet light. Control experiments and DFT calculations revealed that the catalyst has a dual role in this transformation, acting both as a Lewis acid in the oxidative step and as a photocatalyst in the dimerization of the nitrosobenzene intermediate.
• De Carvalho, Gustavo Senra Gon?alves,Chagas, Luciano Honorato,Fonseca, Carla Grijó,De Castro, Pedro P?ssa,Sant'Ana, Ant?nio Carlos,Leit?o, Alexandre Amaral,Amarante, Giovanni Wilson
• supporting information

  p. 5863 - 5871

  (2019/04/17)
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• Modulating the catalytic behavior of non-noble metal nanoparticles by inter-particle interaction for chemoselective hydrogenation of nitroarenes into corresponding azoxy or azo compounds
• Aromatic azoxy compounds have wide applications and they can be prepared by stoichiometric or catalytic reactions with H2O2 or N2H4 starting from anilines or nitroarenes. In this work, we will present the direct chemoselective hydrogenation of nitroarenes with H2 to give aromatic azoxy compounds under base-free mild conditions, with a bifunctional catalytic system formed by Ni nanoparticles covered by a few layers of carbon (Ni@C NPs) and CeO2 nanoparticles. The catalytic performance of Ni@C-CeO2 catalyst surpasses the state-of-art Au/CeO2 catalyst for the direct production of azoxybenzene from nitrobenzene. By means of kinetic and spectroscopic results, a bifunctional mechanism is proposed in which, the hydrogenation of nitrobenzene can be stopped at the formation of azoxybenzene with >95% conversion and >93% selectivity, or can be further driven to the formation of azobenzene with >85% selectivity. By making a bifunctional catalyst with a non-noble metal, one can achieve chemoselective hydrogenation of nitroarenes not only to anilines, but also to corresponding azoxy and azo compounds.
• Liu, Lichen,Concepción, Patricia,Corma, Avelino

• p. 312 - 323

  (2018/12/11)
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• Controllable synthesis of azoxybenzenes and anilines with alcohol as the reducing agent promoted by KOH
• Nitrobenzene and its derivatives can be selectively reduced to the corresponding azoxybenzene and aniline compounds with alcohols as the hydrogen source and KOH as the promoter only by simple changes of reaction conditions.
• Wei, Rui Ping,Shi, Feng

• p. 688 - 696

  (2019/02/16)
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• Catalytic Selective Oxidative Coupling of Secondary N-Alkylanilines: An Approach to Azoxyarene
• Azoxyarenes are among important scaffolds in organic molecules. Direct oxidative coupling of primary anilines provides a concise fashion to construct them. However, whether these scaffolds can be prepared from secondary N-alkylanilines is not well explored. Here, we present a catalytic selective oxidative coupling of secondary N-alkylaniline to afford azoxyarene with tungsten catalyst under mild conditions. In addition, azoxy can be viewed as a bioisostere of alkene and amide. Several "azoxyarene analogues" of the corresponding bioactive alkenes and amides showed comparable promising anticancer activities.
• Ke, Lei,Zhu, Guirong,Qian, Hui,Xiang, Guangya,Chen, Qin,Chen, Zhilong
• supporting information

  p. 4008 - 4013

  (2019/06/04)
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• Highly selective reduction of nitrobenzenes to azoxybenzenes with a copper catalyst
• A convenient protocol for highly selective delivery of azoxybenzenes from reduction of nitrobenzenes was developed by utilizing a copper catalyst. A variety of functional groups and substitution were well tolerated.
• Chen, Zhichao,Qiu, Yatao,Wu, Xiaoxing,Ni, Yong,Shen, Li,Wu, Jun,Jiang, Sheng
• supporting information

  p. 1382 - 1384

  (2018/03/06)
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• Aromatic amine oxidation process for preparing aromatic liquid discharge method
• The invention relates to a preparation method for aromatic-azoxybenzene by oxidizing aromatic amine. According to the method, air or oxygen is used as an oxygen source, and aromatic amine is oxidized to be aromatic-azoxybenzene under the effect of metal oxide catalyst. The method has the advantage of high product yield and is easy to separate the catalyst.
• -
• Paragraph 0014; 0015; 0016; 0017; 0018; 0019-0023; 0025

  (2017/08/26)
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• Synthesis of Azoxybenzenes by Reductive Dimerization of Nitrosobenzene
• Herein we report an effective and simple preparation method of substituted azoxybenzenes by reductive dimerization of nitrosobenzenes. This procedure requires no additional catalyst/reagent and can be applied to substrates with a wide range of substitution patterns.
• Chen, Yu-Feng,Chen, Jing,Lin, Li-Jen,Chuang, Gary Jing

• p. 11626 - 11630

  (2017/11/10)
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• Stabilisation of gold nanoparticles by N-heterocyclic thiones
• Gold nanoparticles (Au-NPs) have been prepared using N-heterocyclic thiones (NHTs) as ligand stabilisers. These Au-NPs have been shown to be very stable, even in air, and have been characterized by a combination of several techniques (TEM, HR-TEM, STEM-HAADF, EDX, DLS, elemental analysis and 1H NMR). These nanoparticles are active in the catalytic reduction of nitroarenes to anilines.
• Moraes, Leonardo C.,Lacroix, Bertrand,Figueiredo, Rute C.,Lara, Patricia,Rojo, Javier,Conejero, Salvador
• supporting information

  p. 8367 - 8371

  (2017/07/12)
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• Organocatalytic oxidation of substituted anilines to azoxybenzenes and nitro compounds: Mechanistic studies excluding the involvement of a dioxirane intermediate
• An organocatalytic and environmentally friendly approach for the selective oxidation of substituted anilines was developed. Utilizing a 2,2,2-trifluoroacetophenone-mediated oxidation process, substituted anilines can be transformed into azoxybenzenes, while a simple treatment with MeCN and H2O2 leads to the corresponding nitro compounds, providing user-friendly protocols that can be easily scaled up. Various substitution patterns and functional groups were tolerated leading to products in high to excellent yields. Mechanistic studies utilizing HRMS provide clear evidence for the distinct mechanistic intermediates that are involved. This study constitutes an indirect proof excluding the involvement of a dioxirane intermediate in the green organocatalytic oxidation, utilizing 2,2,2-trifluoroacetophenone as the catalyst.
• Voutyritsa, Errika,Theodorou, Alexis,Kokotou, Maroula G.,Kokotos, Christoforos G.
• supporting information

  p. 1291 - 1298

  (2017/06/06)
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• Rh(III)-Catalyzed [4 + 1]-Annulation of Azoxy Compounds with Alkynes: A Regioselective Approach to 2H-Indazoles
• A rhodium-catalyzed regioselective C-H activation/cyclization of azoxy compounds with alkynes has been disclosed to construct a variety of 2H-indazoles. A [4 + 1]-cycloaddition rather than a normal [4 + 2] mode is observed in the process of cyclative capture along with an oxygen-atom transfer and a C≡C triple bond cleavage. This protocol features a broad substrate scope, a good functional group tolerance, and an exclusive regioselectivity.
• Long, Zhen,Yang, Yudong,You, Jingsong
• supporting information

  p. 2781 - 2784

  (2017/06/07)
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• Rh(III)-Catalyzed Regio- and Chemoselective [4 + 1]-Annulation of Azoxy Compounds with Diazoesters for the Synthesis of 2H-Indazoles: Roles of the Azoxy Oxygen Atom
• A Rh(III)-catalyzed tandem C-H alkylation/intramolecular decarboxylative cyclization of azoxy compounds with diazoesters for the synthesis of 3-acyl-2H-indazoles is disclosed. The azoxy instead of the azo group enables a distinct approach for cyclative capture, leading to a [4 + 1]-annulation rather than a classic [4 + 2] manner. The azoxy oxygen atom is traceless after annulation, and further removal from the product is not required. This reaction features a complete regioselectivity for unsymmetrical azoxybenzenes and a compatibility of monoaryldiazene oxides.
• Long, Zhen,Wang, Zhigang,Zhou, Danni,Wan, Danyang,You, Jingsong
• supporting information

  p. 2777 - 2780

  (2017/06/07)
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• Titania-Supported Gold Nanoparticles Catalyze the Selective Oxidation of Amines into Nitroso Compounds in the Presence of Hydrogen Peroxide
• In this article, the catalytic activity of titania-supported gold nanoparticles (Au/TiO2) was studied for the selective oxidation of amines into nitroso compounds using hydrogen peroxide (H2O2). Gold nanoparticles deposited on Degussa P25 polymorphs of titania (TiO2) have been found to promote the selective formation of a variety of nitroso arenes in high yields and selectivities, even in a large-scale synthesis. In contrast, alkyl amines are oxidized to the corresponding oximes under the examined conditions. Kinetic studies indicated that aryl amines substituted with electron-donating groups are oxidized faster than the corresponding amines bearing an electron-withdrawing functionality. A Hammett-type kinetic analysis of a range of para-X-substituted aryl amines implicates an electron transfer (ET) mechanism (ρ=-1.15) for oxidation reactions with concomitant formation of the corresponding N-aryl hydroxylamine as possible intermediate. We also show that the oxidation protocol of aryl amines in the presence of 1,3-cyclohexadiene leads in excellent yields to the corresponding hetero Diels-Alder adducts between the diene and the in situ formed nitrosoarenes.
• Fountoulaki, Stella,Gkizis, Petros L.,Symeonidis, Theodoros S.,Kaminioti, Eleni,Karina, Athanasia,Tamiolakis, Ioannis,Armatas, Gerasimos S.,Lykakis, Ioannis N.
• supporting information

  p. 1500 - 1508

  (2016/05/19)
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• Selective reduction of nitroaromatics to azoxy compounds on supported Ag-Cu alloy nanoparticles through visible light irradiation
• The selective hydrogenation of aromatic nitrocompounds to their corresponding azoxy compounds is challenging in organic synthesis, which are typically performed under harsh reaction conditions. The core issue involved in this reduction is to finely control the product selectivity. Herein, we report an efficient photocatalytic process using supported silver-copper alloy nanoparticles (Ag-Cu alloy NPs) to selectively transform nitrobenzene to azoxybenzene by visible light irradiation under green mild reaction conditions. Ag-Cu alloy NPs can absorb visible light, causing excited hot-electrons due to the localized surface plasmon resonance (LSPR) effect, and the excited electrons can activate the reactant molecule adsorbed on the NP surface to induce a reaction. The photocatalytic performance was affected by the Ag-Cu ratio, and the catalyst with an Ag-Cu molar ratio of 4-1 exhibited the optimal performance. Tuning the wavelength of incident light manipulated the product selectivity between azoxybenzene and aniline. Compared to pure Ag NPs, the alloying of Cu was found to be responsible for the product selectivity shifting from azobenzene to azoxybenzene. The reaction pathway was investigated to explain the selectivity difference and thus a tentative reaction pathway was proposed.
• Liu, Zhe,Huang, Yiming,Xiao, Qi,Zhu, Huaiyong
• supporting information

  p. 817 - 825

  (2016/02/12)
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• A Green Chemoenzymatic Process for the Synthesis of Azoxybenzenes
• An efficient chemoenzymatic process for the synthesis of azoxybenzenes was developed. A peracid was generated in situ by Novozym 435, and then a range of anilines were oxidized by the produced peracid to afford azoxybenzenes in yields ranging from 63.1 to 94.1 %. This method expands the application of lipase in organic synthesis and provides an alternative method for the synthesis of azoxybenzenes.
• Yang, Fengjuan,Wang, Zhi,Zhang, Xiaowen,Jiang, Liyan,Li, Yazhuo,Wang, Lei

• p. 3450 - 3453

  (2015/11/10)
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• Ultrasound-accelerated selective oxidation of primary aromatic amines to azoxy derivatives with trans-3,5-dihydroperoxy-3,5-dimethyl-1,2-dioxolane catalyzed by Preyssler acid-mediated nano-TiO2
• Preyssler-type heteropolyacid supported on TiO2 nanoparticles has been explored as an efficient catalyst in selective oxidation of primary aromatic amines to azoxy derivatives using trans-3,5-dihydroperoxy-3,5-dimethyl- 1,2-dioxolane as oxidant. The reactions proceeded smoothly under mild and green ultrasound-accelerated conditions to afford the products in high yields. The catalyst recovered from the reaction mixture exhibits long-term stability with no significant drop in its catalytic activity. Graphical abstract: [Figure not available: see fulltext.].
• Azarifar, Davood,Khatami, Seyed-Mola,Najminejad, Zohreh

• p. 587 - 592

  (2014/04/03)
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• A novel, efficient synthesis of N-aryl pyrroles via reaction of 1-boronodienes with arylnitroso compounds
• A one-pot hetero-Diels-Alder/ring contraction cascade is presented from the reaction of 1-boronodienes and arylnitroso derivatives to derive N-arylpyrroles in moderate to good yields (up to 82%).
• Tripoteau, Fabien,Eberlin, Ludovic,Fox, Mark A.,Carboni, Bertrand,Whiting, Andrew
• supporting information

  p. 5414 - 5416

  (2013/06/27)
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• Gold-catalyzed cyclization/oxidative [3+2] cycloadditions of 1,5-enynes with nitrosobenzenes without additional oxidants
• Golden control: The title reaction (see scheme) proceeds with high stereocontrol to generate the heterocyclic products in good yield. Experiments to probe the mechanism were performed. Copyright
• Chen, Chun-Hao,Tsai, Yen-Ching,Liu, Rai-Shung
• supporting information

  p. 4599 - 4603

  (2013/05/21)
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• Silica encapsulated magnetic nanoparticles-supported Zn(II) nanocatalyst: A versatile integration of excellent reactivity and selectivity for the synthesis of azoxyarenes, combined with facile catalyst recovery and recyclability
• A novel and highly efficient zinc based nanocatalyst has been synthesized by covalent grafting of 2-acetylpyridine on amine functionalized silica@magnetite nanoparticles, followed by metallation with zinc acetate. The resulting nano-composite was found to be highly efficient for oxidation of various aromatic amines to give azoxyarenes. The prepared nanocatalyst was characterized by Electron microscopy techniques (SEM and TEM with EDS), X-ray diffraction (XRD), vibrational sampling magnetometer (VSM), Fourier transform infrared spectroscopy (FT-IR) and atomic absorption spectroscopy (AAS) techniques. High turnover number (TON), mild reaction conditions and high selectivity for azoxyarenes with sustained catalytic activity makes present protocol worthy and highly compliant as compared to the other non-magnetic heterogeneous catalytic system. The acquisition of this nanocatalyst is also exemplified by employing the catalyst in leaching and reusability test and the results from the tests showing negligible zinc leaching and recycling was achieved multiple times just by sequestering using an external magnet.
• Sharma,Monga, Yukti

• p. 1 - 10

  (2013/08/25)
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• Mild, selective and switchable transfer reduction of nitroarenes catalyzed by supported gold nanoparticles
• A highly versatile and flexible gold-based catalytic system has been developed for the controlled and selective transfer reduction of nitroarene using 2-propanol as a convenient hydrogen source under mild conditions. Depending on the specific reaction conditions, multiple products including azoxyarenes, symmetric or asymmetric azoarenes and anilines can be obtained respectively via a controlled reduction of the nitro aromatics with good to excellent yields in the presence of a reusable mesostructured ceria-supported gold (Au/meso-CeO2) catalyst. The overall operational simplicity, high chemoselectivity, functional-group tolerance and reusability of the catalyst make this approach an attractive and reliable tool for organic and process chemists. The Royal Society of Chemistry.
• Liu, Xiang,Ye, Sen,Li, Hai-Qian,Liu, Yong-Mei,Cao, Yong,Fan, Kang-Nian

• p. 3200 - 3206

  (2013/12/04)
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• Mechanosynthesis of nitrosobenzenes: A proof-of-principle study in combining solvent-free synthesis with solvent-free separations
• Mechanochemical Oxone oxidation of selected para-substituted anilines was used as a rapid and solvent-free route to nitrosobenzenes; besides avoiding bulk solvents and short reaction times, this method exploits high vapour pressures of nitrosobenzenes for the solvent-free separation of the product by sublimation, demonstrating an entirely solvent-free route to chemical synthesis and product isolation. The Royal Society of Chemistry.
• Huskic, Igor,Halasz, Ivan,Friscic, Tomislav,Vancik, Hrvoj
• supporting information

  p. 1597 - 1600

  (2013/02/23)
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• Ruthenium nanoparticle-catalyzed, controlled and chemoselective hydrogenation of nitroarenes using ethanol as a hydrogen source
• 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
• supporting information

  p. 2412 - 2418

  (2012/11/07)
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• Reduction of nitroarenes to azoxybenzenes by NaOH-PEG 400
• The reduction of nitroarenes to azoxybenzenes by NaOH-PEG 400 in benzene is described. The protocol is facile, economical, and effective.
• Liu, Yufang,Liu, Bo,Guo, Ailing,Dong, Zhenming,Jin, Shuo,Lu, Yun
• experimental part

  p. 2201 - 2206

  (2012/06/16)
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• Reduction of nitroarenes to azoxybenzenes by potassium borohydride in water
• The synthesis of the azoxybenzenes by the reduction of nitroarenes with reducing agent potassium borohydride in water was reported for the first time. PEG-400 was used as a phase transfer catalyst and could effectively catalyze the reduction. The electronic effects of substituent groups play an important role in determining the reduction efficiencies. Electron-withdrawing substituents promote the formation of the azoxybenzene products, while electron-releasing groups retard the reductions to various degrees depending on the extent of their electron-donating ability.
• Liu, Yufang,Liu, Bo,Guo, Ailing,Dong, Zhenming,Jin, Shuo,Lu, Yun
• experimental part

  p. 3563 - 3568

  (2011/06/26)
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• Switchable selectivity during oxidation of anilines in a ball mill
• A solvent-free method for the direct oxidation of anilines to the corresponding azo and azoxy homocoupling products by using a planetary ball mill was developed. Various oxidants and grinding auxiliaries were tested and a variety of substituted anilines were investigated. It was possible to form chemoselectively either azo, azoxy, or the nitro compounds from reaction of aromatic anilines. The selectivity of the solvent-free reaction is switchable by applying a combination of oxidant and grinding auxiliary. Furthermore, a comparison with other methods of energy input (microwave, classical heating, and ultrasound) highlighted the advantages of the ball mill approach and its high energy efficiency. Grinding reactions: Highly efficient oxidative homocoupling of aromatic amines was performed under solvent-free conditions in a planetary ball mill (see scheme). The choice of solid oxidants and grinding auxiliaries allowed selective generation of the oxidized products. Other methods of energy input are compared with respect to reaction time and energy consumption.
• Thorwirth, Rico,Bernhardt, Franziska,Stolle, Achim,Ondruschka, Bernd,Asghari, Jila
• supporting information; experimental part

  p. 13236 - 13242

  (2011/02/21)
• 

• Highly selective conversion of nitrobenzenes using a simple reducing system combined with a trivalent indium salt and a hydrosilane
• Controlling the type of indium salt and hydrosilane enables a highly selective reduction of aromatic nitro compounds into three coupling compounds, azoxybenzenes, azobenzenes and diphenylhydrazines, and one reductive compound, anilines. The Royal Society of Chemistry 2010.
• Sakai, Norio,Fujii, Kohji,Nabeshima, Shinya,Ikeda, Reiko,Konakahara, Takeo
• scheme or table

  p. 3173 - 3175

  (2010/08/19)
• 

• Reaction of aromatic nitroso compounds with chemical models of 'thiamine active aldehyde'
• Aromatic nitroso compounds in the presence of base and 2-(α-hydroxyalkyl)-3,4-dimethylthiazolium trifluoromethanesulfonate and related salts furnish in variable yields O- and N-acyl-aryl hydroxylamines and 3,4-dimethylthiazolium trifluoromethanesulfonate. A primary kinetic isotope effect of 4.9, obtained for the appropriate 2α-deuterated thiazolium salt, points to the C2α-H bond cleavage as the rate determining step. Radical species detected by ESR were unambiguously identified as phenylhydronitroxide, but attempted trapping of the corresponding C-heterocyclic radicals by TEMPO was not successful, and substrates incorporating a potential cyclopropyl radical clock gave products with the cyclopropyl ring intact. Theoretical calculations revealed a large activation energy for such reaction, which thus cannot per se exclude the intervention of such radical species. Evidence for the likely operation of two concurrent mechanisms, a radical and a preponderant ionic pathway, involving the conjugate base of the thiazolium salt, as the chemical model for 'active thiamine', and ArNO is presented for the formation of the products of the reaction.
• Ferreira, Luísa M.,Marques, M. Manuel B.,Glória, Paulo M.C.,Chaves, Humberto T.,Franco, Jo?o-Pedro P.,Mourato, Isabel,Antunes, José-Rafael T.,Rzepa, Henry S.,Lobo, Ana M.,Prabhakar, Sundaresan

• p. 7759 - 7770

  (2008/12/21)
• 

• Oxidation of anilines with hydrogen peroxide and selenium dioxide as catalyst
• A variety of substituted anilines are selectively oxidized to afford high yields of azoxyarenes by using 30% hydrogen peroxide and selenium dioxide as catalyst in methanol at room temperature. The oxidation of 4-alkoxyanilines under the same reaction conditions furnishes the corresponding 4-alkoxy-N-(4-nitrophenyl)anilines in reasonable yields, alongside other oxidation byproducts. The structure of 4-methoxy-N-(4-nitrophenyl)aniline is elucidated by X-ray crystal structure analysis. From these results, some general aspects of the reaction pathways of aniline oxidation are discussed.
• Gebhardt, Christin,Priewisch, Beate,Irran, Elisabeth,Rueck-Braun, Karola
• scheme or table

  p. 1889 - 1894

  (2009/04/04)
• 

• Reduction of mononitroarenes by hydroxide ion in water catalyzed by β-cyclodextrin: enhanced reactivity of hydroxide ion
• Ordinarily the reducing ability of HO- in water is extremely low as a result of its stabilization by hydration. Reductions by hydroxide ion have only been observed previously in aprotic organic solvents. We find that several mononitroarenes are reduced to azoxyarenes by NaOH in water in the presence of β-cyclodextrin. HO- acts as a one-electron reductant with enhanced reactivity.
• Lu, Yun,Liu, Jiancheng,Diffee, Garry,Liu, Diansheng,Liu, Bo

• p. 4597 - 4599

  (2007/10/03)
• 

• The newborn surface of dull metals in organic synthesis. Bismuth-mediated solvent-free one-step conversion of nitroarenes to azoxy- and azoarenes
• When milled together with bismuth shots, nitroarenes are readily converted to azoxy- and/or azoarenes depending on substrates and conditions employed. Simple extraction with organic solvent followed by evaporation of the resulting dark pasty solid gave the product in good yield.
• Wada, Shinobu,Urano, Mika,Suzuki, Hitomi

• p. 8254 - 8257

  (2007/10/03)
• 

• Bi-KOH. An efficient reagent for the coupling of nitroarenes to azo and azoxy compounds
• A simple and inexpensive procedure for the coupling of nitroarenes to azoxy compounds with bismuth and potassium hydroxide in methanol at ambient temperature is achieved. When carried out under microwave irradiation it gives exclusively azo compounds in excellent yields.
• Laskar, Dhrubojyoti Dey,Prajapati, Dipak,Sandhu, Jagir S.

• p. 67 - 70

  (2007/10/03)
• 

• Anti-androgenic activity of substituted azo- and azoxy-benzene derivatives.
• Substituted phenylazo and phenylazoxy compounds were systematically prepared and their anti-androgenic activity was measured in terms of (1) the growth-inhibiting effect on an androgen-dependent cell line, SC-3, and (2) the binding affinity to nuclear androgen receptor. Generally, azo/azoxy compounds showed cell toxicity, and the growth-inhibiting effects on SC-3 cells correlated with the toxicity. However, some compounds, including 4,4'-dinitroazobenzene (25), 4,4'-dimethoxyazobenzene (33), and 2,2'-dichloroazoxybenzene (47), possessed potent anti-androgenic activity without apparent cell toxicity.
• Takahashi,Ishioka,Koiso,Sodeoka,Hashimoto

• p. 1387 - 1390

  (2007/10/03)
• 

• Reactions of 2-acylthiazolium salts with N-arylhydroxylamines
• 2-Acylthiazolium salts, easily obtained by alkylation of the corresponding 2-acylthiazoles with methyl triflate, react with N- arylhydroxylamines to furnish the O-acyl derivatives of relevance in the induction of cancer by aromatic mines.
• Ferreira, Luisa M.,Lobo, Ana M.,Prabhakar, Sundaresan,Teixeira, Antonieta C.

• p. 3541 - 3552

  (2007/10/03)
• 

• Reduction of aromatic azo-,azoxy- and nitro-compounds by ultrasonically activated nickel
• Substituted hydrazobenzenes were obtained in excellent yields from reduction of the corresponding azo- or azoxy- compounds by hydrazine hydrate under the catalysis of ultrasonically activated nickel (UAN). Reduction of nitroarenes by UAN produced azoxyarenes as the major products.
• Wang, Xiaolun,Xu, Minghua,Lian, Hongzhen,Pan, Yi,Shi, Yaozeng

• p. 3031 - 3037

  (2007/10/03)
• 

• Synthesis of functionalized carbamates through a palladium-catalyzed reductive carbonylation of substituted nitrobenzenes
• The palladium-catalyzed reductive carbonylation of ortho and para-substituted nitrobenzenes has proven to be an attractive route for the synthesis of functionalized carbamates. For the Pd(1,10-phenanthroline)2(triilate}2 catalyst system, the scope of the reaction has been studied. Substrates with electron-donating substituents at the para position were found to decrease the catalytic activity, most probably as a result of their relatively low oxidizing capacity. The selectivity towards the desired carbamate, however, was increased for these substrates. Under the influence of electron-withdrawing substituents the azoxybenzene and azobenzene derivatives became important side products. Introduction of large steric hindrance at the ortho position of the nitro substrates gave rise to an interesting side reaction, viz. methoxylation of the aromatic ring. The methoxylation reaction appeared to occur on an intermediate species in the catalytic cycle. Several functionalities have shown to be resistant to the reaction conditions required for the conversion of the nitro group. Especially with 4-nitrobenzoic acid, an extremely high activity and selectivity was found, thus yielding a very convenient synthesis for N-protected amines containing carboxylic acid functions. VCH Verlagsgesellschaft mbH.
• Wchman, Petra,Borst, Leo,Kamer, Paul C. J.,Van Leeuwen, Piet W. N. M.

• p. 13 - 21

  (2007/10/03)
• 

• Nitrenium Ions. Part 1. Acid-catalysed Reactions of 2-Methylindole with Nitrosobenzenes. Crystal Structures of 2-Phenylamino-3-phenylimino-3H-indole, 2-(o-Tolylamino)-3-(o-tolylimino)-3H-indole, N-Phenyl-N-(2-phenylamino-3H-indol-3-ylidene)amine N-Oxide and Bis(2-methyl-1H-indol-3-yl)...
• 2-Methylindole 3b reacts with nitrosobenzenes 1a-c in the presence of monochloroacetic acid affording compounds which are characterized by the formation of carbon-nitrogen bonds and other compounds which clearly could arise from a radical mechanism.The radical component of the reaction is also supported by the EPR spectroscopy as well as the reaction products distribution.Although these reactions cannot be considered of synthetic value for the number of isolated products, they could be regarded as clear examples of the electrophilic character and of the oxidative power of nitrogen in activated nitrosobenzenes.Crystal structures of 2-phenylamino-3-phenylimino-3H-indole 7a, 2-(o-tolylamino)-3-(o-tolylimino)-3H-indole 7b, N-phenyl-N-(2-phenylamino-3H-indol-3-ylidene)amine N-oxide 9a and bis(2-methyl-1H-indol-3-yl)methane 10 are also reported.
• Cardellini, Liberato,Carloni, Patricia,Damiani, Elisabetta,Greci, Lucedio,Stipa, Pierluigi,et al.

• p. 1589 - 1596

  (2007/10/02)
• 

• Bismuth(III) Chloride-Zinc Promoted Selective Reduction of Aromatic Nitro Compounds to Azoxy Compounds
• In the presence of bismuth(III)chloride-metalllic zinc aromatic nitro compounds have been found to be selectively reduced inter and intramolecularly to the corresponding N-oxides at ambient temperature in high yields.
• Borah, Harsha N.,Prajapati, Dipak,Sandhu, Jagir S.,Ghosh, Anil C.

• p. 3167 - 3170

  (2007/10/02)
• 

• REACTION OF 1,1-DISUBSTITUTED HYDRAZINES WITH BROMINE IN THE PRESENCE OF ARYL- AND HETEROARYLNITROSO COMPOUNDS IN ACID MEDIA: A GENERAL METHOD FOR THE SYNTHESIS OF 1-ARYL(HETEROARYL)-3,3-DISUBSTITUTED TRIAZENE 1-OXIDES
• We have worked out a method for the synthesis of 1,3,3-trisubstituted triazene 1-oxides based upon reaction of 1,1-disubstituted hydrazines with bromine in the presence of aryl- and heteroarylnitroso compounds in acid media.Obtained are a broad range of t
• Zlotin, S. G.,Prokshits, O. V.,Karpenko, N. F.,Strelenko, Yu. A.,Luk'yanov, O. A.

• p. 1400 - 1413

  (2007/10/02)
•