- Catalytic oxidation of primary aromatic amines with sodium periodate catalyzed by Mn(III)salophen complex supported on polystyrene-bound imidazole
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The catalytic activity of Mn(III)salophen complex supported on polystyrene-bound imidazole, [Mn(salophen)Cl-PSI], was studied in the oxidation of primary aromatic amines in acetonitrile/water, using sodium periodate as an oxygen source. Amines were oxidized efficiently to their corresponding azo derivatives in the presence of this catalyst. The heterogeneous catalyst showed high stability and reusability in the oxidation reactions and could be reused several times without loss of its activity. The effect of different solvents was studied in the oxidation of p-toluidine and CH3CN/H2O was chosen as the solvent.
- Mirkhani,Moghadam,Tangestaninejad,Hajibagheri
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- Cytochrome P-450 dependent monooxygenases model system: Rapid and efficient oxidation of primary aromatic amines to azo derivatives with sodium periodate catalyzed by manganese(III) Schiff base complexes
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Rapid and efficient oxidation of primary aromatic amines was investigated. Mn(III)-salophen catalyst can catalyze the oxidation of primary aromatic amines to azo derivatives with sodium periodate. The ability of various Schiff base complexes in this oxidation system was also investigated.
- Mirkhani, Valiollah,Tangestaninejad, Shahram,Moghadam, Majid,Moghbel, Maryam
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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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- Synthesis, characterization and photophysical studies of self-assembled azo biphenyl urea derivatives
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We reported the synthesis of a new series of azobiphenyl based urea derivatives 7 and their stimulus-responsive supramolecular structures in the form of sheet like self-assembled formations. The self-assembled nanostructural formations of azo derivatives
- Sivamani, Jayaraman,Balasaravanan, Rajendiran,Duraimurugan, Kumaraguru,Siva, Ayyanar
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- Continuous and green microflow synthesis of azobenzene compounds catalyzed by consecutively prepared tetrahedron CuBr
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An environmentally friendly and cross-selective process intensification for the continuous synthesis of symmetric aromatic azo compounds by using self-made cuprous bromide as the catalyst under mild conditions in the microreactor was developed. A novel tetrahedron cuprous bromide catalyst which shows outstanding catalytic activity and satisfactory stability has been synthesized in continuous flow microreactor. The online immobilization of self-made cuprous bromide on the catalyst bed achieved oxidative coupling of aromatic amines (oxygen as oxidant) and high-performance gas–liquid–solid three-phase reaction, which strongly limited the possibility of undesired reaction pathways, improving product selectivity and reducing waste generation. Meanwhile, the yield of azo-coupling reaction was up to 98% under optimized condition. As compared with earlier traditional method (diazotization reaction) for synthesizing azobenzene, the designed micro-flow process displays signi?cant advances in terms of selectivity, waste emissions, sustainability and productivity. The combination of online immobilization of self-made cuprous bromide and precise and safe control through the microreactor provides a green solution for the industrial production of valuable aromatic azo compounds.
- Qin, Hong,Liu, Chengkou,Lv, Niuniu,He, Wei,Meng, Jingjing,Fang, Zheng,Guo, Kai
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- Aerobic Oxidative coupling of aniline catalyzed by one-dimensional manganese hydroxide nanomaterials
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The aerobic oxidative coupling of aniline is an effective process for producing aromatic azo compounds, which are widely used in the organic chemical industry. The development of heterogeneous catalysts for this reaction would be advantageous because of their recyclability and convenience in posttreatment. In this work, one-dimensional Mn(OH) 2 nanostructure with various shapes were synthesized through the adjustment of various surfactants. The as-synthesized Mn(OH) 2 nanobelts and nanowires showed superior catalytic activity in the activation of oxygen and aniline. Aromatic azo compounds with a variety of substituents were produced through the coupling of the corresponding anilines without additives under ambient conditions.
- Miao, Hui,Ma, Kelong,Hu, Shiwei,Li, Ruiqian,Sun, Lin,Cui, Yumin
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- Efficient Catalytic Oxidation of Primary Aromatic Amines to Azo Derivatives by Manganese(III) Tetraphenylporphyrin
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The oxidation of primary aromatic amines to the corresponding azo derivatives has been observed in catalytic systems containing manganese(III) tetraphenylporphyrin and sodium periodate in the presence of heterocyclic nitrogen bases acting as axial ligands.
- Habibi, Mohammad Hossein,Tangestaninejad, Shahram,Mirkhani, Valiollah
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- Correlation studies in the oxidation of Vanillin Schiff bases by acid bromate - A kinetic and semi-empirical approach
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Kinetics and mechanistic aspects of oxidation of Vanillin Schiff bases (obtained from Vanillin and p-substituted anilines) by bromate in acid medium has been studied at 313 ?K. The reaction exhibited first order in [bromate] and less than unity order each in [Vanillin Schiff base] and [acid]. The increase in the rate of reaction with decrease in dielectric constant of the medium is observed with all the studied substrates. The reaction failed to induce the polymerization of acrylonitrile. Electron withdrawing substituents in the aniline ring moiety of Vanillin Schiff base accelerate the rate of oxidation to a large extent and electron releasing substituents retard the rate. The order of reactivity is found to be p-nitro ?> ?p-bromo ?> ?p-chloro ?> ?–H ?> ?p-fluoro ?> ?p-methyl ?> ?p-methoxy ?> ?p-ethoxy and the sensitivity of the substrates towards the reaction rate is further supported by the semi-empirical calculation of electronic properties and global descriptors of the substrates (Vanillin Schiff bases) with different substituents in the aniline ring moiety. The observed trend in the reactivity of the substrates was correlated with the calculated descriptors like electronegativity, chemical potential, electrophilicity index, chemical hardness and frontier molecular orbitals. The linear free-energy relationship is characterized by a straight line in the Hammett's plot of log k versus σ. The ρ values are positive and increase with increase in temperature. From the Exner and Arrhenius plots, the isokinetic relationship is discussed. Oxidation products identified are p-substituted azobenzene and vanillic acid. Based on the experimental observations, a plausible mechanism is proposed and rate law is derived.
- Sathish,Teja, P. Ravi,Ramudu, M. Parusha,Manjari, P. Sunitha,Rao, R. Koteshwar
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- Selective Oxidation of Anilines to Azobenzenes and Azoxybenzenes by a Molecular Mo Oxide Catalyst
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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
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supporting information
p. 6382 - 6385
(2021/02/09)
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- Bifunctional Cs?Au/Co3O4 (Basic and Redox)-Catalyzed Oxidative Synthesis of Aromatic Azo Compounds from Anilines
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An eco-friendly alkali-promoted (Cs?Au/Co3O4) catalyst, with redox and basic properties for the oxidative dehydrogenative coupling of anilines to symmetrical and unsymmetrical aromatic azo compounds, was developed. We realized a base additive- and molecular O2 oxidant-free process (using air), with reasonable reusability of the catalyst achieved under milder reaction conditions. Notably, the enhanced catalytic activity was also linked to the increased basic site concentration, low reduction temperatures, and the effect of lattice oxygen on the nanomaterials. The increased basic strength of the cation-promoted catalyst improved the electron density of the active Au species, resulting in higher yields of the desired aromatic azo compounds.
- Akinnawo, Christianah Aarinola,Alimi, Oyekunle Azeez,Fapojuwo, Dele Peter,Meijboom, Reinout,Mogudi, Batsile M.,Onisuru, Oluwatayo Racheal,Oseghale, Charles O.
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supporting information
p. 5063 - 5073
(2021/09/30)
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- Electrosynthesis of Azobenzenes Directly from Nitrobenzenes
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The electrochemical reduction strategy of nitrobenzenes is developed. The chemistry occurs under ambient conditions. The protocol uses inert electrodes and the solvent, DMSO, plays a dual role as a reducing agent. Its synthetic value has been demonstrated by the highly efficient synthesis of symmetric, unsymmetric and cyclic azo compounds.
- Ma, Yanfeng,Wu, Shanghui,Jiang, Shuxin,Xiao, Fuhong,Deng, Guo-Jun
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p. 3334 - 3338
(2021/10/29)
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- Oxidative dehydrogenation of hydrazines and diarylamines using a polyoxomolybdate-based iron catalyst
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We report an efficient method for the oxidative dehydrogenation of hydrazines and diarylamines in aqueous ethanol using Anderson-type polyoxomolybdate-based iron(iii) as a catalyst and hydrogen peroxide as an oxidant. A series of azo compounds and tetraarylhydrazines were obtained in moderate to excellent yields. The reaction conditions and substrate scopes are complementary or superior to those of more established protocols. In addition, the catalyst shows good stability and reusability in water. The preliminary mechanistic studies suggest that a radical process is involved in the reaction.
- Huang, Lei,Qiu, Shiqin,Wei, Yongge,Xie, Jingyan,Yu, Han,Zeng, Xianghua,Zhao, Weizhe
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supporting information
p. 7677 - 7680
(2021/08/09)
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- Heterocoupling of Different Aryl Nitrenes to Produce Asymmetric Azoarenes Using Iron-Alkoxide Catalysis and Investigation of the Cis-Trans Isomerism of Selected Bulky Asymmetric Azoarenes
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Heterocoupling of different aryl nitrenes (originating in organoazides) to produce asymmetric azoarenes using two different iron-alkoxide catalysts is reported. Fe(OCtBu2(3,5-Ph2C6H3))2(THF)2 was previously shown to catalyze the homocoupling of a variety of aryl nitrenes. While bulky nitrenes featuring ortho substituents were coupled more efficiently, coupling of the less bulky meta- and para-substituted aryl nitrenes was also demonstrated. In contrast, the iron(II) complex of a chelating bis(alkoxide) ligand, Fe[OO]Ph(THF)2, was previously shown to efficiently couple nonbulky aryl nitrenes lacking substituents in ortho positions. In the present work, we demonstrate that the combination of two different nitrenes (10 equiv overall, 5 equiv each) with Fe(OCtBu2(3,5-Ph2C6H3))2(THF)2 (10 mol %) produced a statistical or close to statistical distribution (25:25:50 for the two homocoupled products and the heterocoupled product, respectively) for various combinations containing one or two ortho alkyl substituents at one nitrene and a single ortho alkyl group at another. Surprisingly, the combination of Fe[OO]Ph(THF)2 with two different nonbulky organoazides was found to primarily catalyze the homocoupling of the resulting aryl nitrenes (21-49%), with a smaller proportion (～8-15%) of asymmetric product formation. Six different heterocoupled products featuring one or two alkyl groups in the ortho positions were isolated as a mixture of cis and trans isomers at room temperature and characterized by NMR spectroscopy, UV-vis spectroscopy, and high-resolution mass spectrometry. Following their isolation, cis-trans isomerism in these species was investigated. Heating the cis-trans mixture to 60 °C produced the trans isomer cleanly, while shining UV light on the cis-trans mixture significantly increased the amount of the cis isomer (up to 90%). The cis isomer was found to be relatively stable, exhibiting t1/2 values of approximately 10 days at room temperature.
- Groysman, Stanislav,Kurup, Sudheer S.,Wannipurage, Duleeka
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p. 3637 - 3644
(2021/11/12)
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- Iron-Catalyzed Hydrogen Transfer Reduction of Nitroarenes with Alcohols: Synthesis of Imines and Aza Heterocycles
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A straightforward and selective reduction of nitroarenes with various alcohols was efficiently developed using an iron catalyst via a hydrogen transfer methodology. This protocol led specifically to imines in 30-91% yields, with a good functional group tolerance. Noticeably, starting from o-nitroaniline derivatives, in the presence of alcohols, benzimidazoles can be obtained in 64-72% yields when the reaction was performed with an additional oxidant, DDQ, and quinoxalines were prepared from 1,2-diols in 28-96% yields. This methodology, unprecedented at iron for imines, also provides a sustainable alternative for the preparation of quinoxalines and benzimidazoles.
- Wu, Jiajun,Darcel, Christophe
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supporting information
p. 1023 - 1036
(2021/01/09)
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- Metal- and oxidant-free electrochemically promoted oxidative coupling of amines
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The selective oxidation of amines into imines is a priority research topic in organic synthesis and has attracted much attention over the past few decades. However, the oxidation of amines generally suffers from the drawback of transition-metal, even noble-metal catalysts. Thus, the strategy of metal- and oxidant-free selective synthesis of imines is highly desirable yet largely unmet. This paper unravels a metal-free and external oxidant-free electrochemical strategy for the oxidative coupling methodology of amines. This general transformation is compatible with various functional amines and led to functionalized imines in moderate to satisfactory yields.
- Chen, Hengyu,Hu, Xiude,Huang, Xianqiang,Li, Jiashuai,Li, Zhen,Liu, Gang,Liu, Sen,Shen, Guodong,Yang, Bingchuan,Zhang, Yalin
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p. 118 - 122
(2022/01/19)
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- Tuneable Copper Catalysed Transfer Hydrogenation of Nitrobenzenes to Aniline or Azo Derivatives
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A highly versatile and flexible copper nanoparticle (Cu(0) NPs) catalytic system has been developed for the controlled and selective transfer hydrogenation of nitroarene. Interestingly, the final catalytic product is strongly dependent on the nature of the hydrogen donor source. The yield of nitrobenzene reduction to aniline increased from 20% to an almost quantitative yield over a range of alcohols, diols and aminoalcohols. In glycerol at 130 °C aniline was isolated in 93% yield. In ethanolamine, the reaction was conveniently performed at a lower temperature (55 °C) and gave selectively substituted azobenzene (92% yield). Experimental studies provide support for a reaction pathway in which the Cu(0) NPs catalysed transfer hydrogenation of nitrobenzene to aniline proceeds via the condensation route. The high chemoselectivity of both protocols has been proved in experiments on a panel of variously substituted nitroarenes. Enabling technologies, microwaves and ultrasound, used both separately and in combination, have successfully increased the reaction rate and reaction yield. (Figure presented.).
- Moran, Maria Jesus,Martina, Katia,Baricco, Francesca,Tagliapietra, Silvia,Manzoli, Maela,Cravotto, Giancarlo
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supporting information
p. 2689 - 2700
(2020/05/18)
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- Tandem selective reduction of nitroarenes catalyzed by palladium nanoclusters
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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
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supporting information
p. 1301 - 1307
(2020/03/11)
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- Trichloroisocyanuric Acid Mediated Oxidative Dehydrogenation of Hydrazines: A Practical Chemical Oxidation to Access Azo Compounds
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A highly efficient, metal-free, chemical oxidation of hydrazines has been implemented using environmentally friendly TCCA as oxidant. This benign protocol provides straightforward access to a wide range of azo compounds in THF in excellent yield. Altogether, 35 azo compounds were obtained in this way and scale-up preparations were performed. Additionally, a plausible mechanism was also proposed. Step-economical process, mild reaction conditions, operational simplicity, high reaction efficiency, and easy scale-up highlight the practicality of this methodology.
- Cao, Guiyan,Hu, Yulai,Huang, Danfeng,Huo, Congde,Liu, Xuan,Su, Yingpeng,Wang, Ke-Hu,Yu, Jie,Zhang, Rong,Zhao, Yanan
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supporting information
p. 1103 - 1112
(2020/04/01)
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- Synthesis of novel 1,2-diarylpyrazolidin-3-one–based compounds and their evaluation as broad spectrum antibacterial agents
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There is a continuous need to develop new antibacterial agents with non-traditional mechanisms to combat the nonstop emerging resistance to most of the antibiotics used in clinical settings. We identified novel pyrazolidinone derivatives as antibacterial hits in an in-house library screening and synthesized several derivatives in order to improve the potency and increase the polarity of the discovered hit compounds. The oxime derivative 24 exhibited promising antibacterial activity against E. coli TolC, B. subtilis and S. aureus with MIC values of 4, 10 and 20 μg/mL, respectively. The new lead compound 24 was found to exhibit a weak dual inhibitory activity against both the E. coli MurA and MurB enzymes with IC50 values of 88.1 and 79.5 μM, respectively, which could partially explain its antibacterial effect. A comparison with the previously reported, structurally related pyrazolidinediones suggested that the oxime functionality at position 4 enhanced the activity against MurA and recovered the activity against the MurB enzyme. Compound 24 can serve as a lead for further development of novel and safe antibiotics with potential broad spectrum activity.
- Abadi, Ashraf H.,Abdel-Halim, Mohammad,El-Sharkawy, Lina Y.,Engel, Matthias,Fathalla, Reem K.,Mokbel, Salma A.
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- Electrochemical dehydrogenation of hydrazines to azo compounds
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A strategy for the electrochemical dehydrogenation of hydrazine compounds is disclosed under ambient conditions. This protocol proceeded smoothly in ethanol by employing electrons as clean oxidants. Its synthetic value is well demonstrated by the highly efficient synthesis of symmetric and unsymmetric azo compounds. It is an environmentally friendly transformation and the present protocol was effective on a large scale.
- Du, Ke-Si,Huang, Jing-Mei
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p. 1680 - 1685
(2019/04/08)
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- Iron and Nitrogen Co-Doped Mesoporous Carbon-Based Heterogeneous Catalysts for Selective Reduction of Nitroarenes
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A facile fabrication of Fe and N co-doped mesoporous carbon (MC), as an efficient heterogeneous catalyst for the highly selective reduction of nitroarenes, is described. The Fe and N co-doped MC nanosheets are easily synthesized via a hydrothermal reaction between citrate acid and magnesium citrate, followed by calcination in the presence of melamine and potassium ferrocyanide. The Fe?N complex provides a unique active site for the selective reduction of 1-chloro-4-nitrobenzene, leading to the production of (E)-1,2-bis(4-chlorophenyl)diazene with a selectivity of >96%, in 40 mins. Control experiments based on non-doped, N-doped, and Fe-doped MC nanosheets demonstrate that selectivity greatly depends on the catalyst active component type, and that non-doped MC significantly contributes to the high efficiencies observed in the selective synthesis of azoxy compound intermediates. A broad range of substrates, including extra-functional groups on the nitroarenes rings, were successfully converted to the corresponding azo compounds at mild conditions with high selectivity. (Figure presented.).
- Wang, Jitao,Yu, Xiaochun,Shi, Chongyang,Lin, Dajie,Li, Jun,Jin, Huile,Chen, Xian,Wang, Shun
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supporting information
p. 3525 - 3531
(2019/06/24)
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- Synthesis of methyl-substituted azobenzene–carbazole conjugated copolymers with photoinduced structural changes
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Azobenzene switches its structure instantaneously by reversible trans-to-cis and cis-to-trans photoisomerization with light irradiations. Dynamic change in polymer structure is expected via introducing an azobenzene unit into the main chain. In this study
- Otaki, Masashi,Kumai, Reiji,Goto, Hiromasa
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p. 1756 - 1764
(2019/08/01)
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- Tying the alkoxides together: An iron complex of a new chelating bulky bis(alkoxide) demonstrates selectivity for coupling of non-bulky aryl nitrenes
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New chelating bis(alkoxide) ligand H2[OO]Ph and its iron(ii) complex Fe[OO]Ph(THF)2 are described. The coordination of the ligand to the metal center is reminiscent of the coordination of two monodentate alkoxides in previously reported Fe(OR)2(THF)2 species. Fe[OO]Ph(THF)2 catalyzes selective and efficient dimerization of non-bulky aryl nitrenes to yield the corresponding azoarenes.
- Kurup, Sudheer S.,Wannipurage, Duleeka,Lord, Richard L.,Groysman, Stanislav
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supporting information
p. 10780 - 10783
(2019/09/13)
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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
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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
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p. 312 - 323
(2018/12/11)
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- Visible-light triggered selective reduction of nitroarenes to azo compounds catalysed by Ag@organic molecular cages
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Herein, a new Ag nanoparticle (Ag NP) loaded organic molecular cage is reported. The obtained Ag@1 can act as a highly efficient heterogeneous catalyst for the selective reduction of nitroarenes to azo compounds under visible-light irradiation.
- Chen, Gong-Jun,Xin, Wen-Ling,Wang, Jing-Si,Cheng, Jun-Yan,Dong, Yu-Bin
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supporting information
p. 3586 - 3589
(2019/03/26)
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- Au@zirconium-phosphonate nanoparticles as an effective catalytic system for the chemoselective and switchable reduction of nitroarenes
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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
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supporting information
p. 614 - 626
(2019/02/13)
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- Transition Metal-Free Oxidative Coupling of Primary Amines in Polyethylene Glycol at Room Temperature: Synthesis of Imines, Azobenzenes, Benzothiazoles, and Disulfides
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A transition metal-free protocol has been developed for the oxidative coupling of primary amines to imines and azobenzenes, thiols to disulfides, and 2-aminothiophenols to benzothiazoles, offering excellent yields. The advantageous features of the present environmentally benign methodology include the usage of biocompatible and green reaction conditions such as, solvent, room temperature reactions and transition metal-free approach. Moreover, it offers a broader substrate scope.
- Hudwekar, Abhinandan D.,Verma, Praveen K.,Kour, Jaspreet,Balgotra, Shilpi,Sawant, Sanghapal D.
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p. 1242 - 1250
(2019/01/09)
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- Chitosan-derived N-doped carbon catalysts with a metallic core for the oxidative dehydrogenation of NH-NH bonds
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Sustainable metal-encased (Ni-Co/Fe/Cu)?N-doped-C catalysts were prepared from bio-waste and used for the oxidative dehydrogenation reaction. A unique combination of bimetals, in situ N doping, and porous carbon surfaces resulted in the formation of the effective "three-in-one" catalysts. These N-doped graphene-like carbon shells with bimetals were synthesized via the complexation of metal salts with chitosan and the subsequent pyrolysis at 700 °C. A well-developed thin-layer structure with large lateral dimensions could be obtained by using Ni-Fe as the precursor. Importantly, the Ni-Fe?N-doped-C catalyst was found to be superior for the dehydrogenation of hydrazobenzene under additive/oxidant-free conditions compared to the conventional and other synthesized catalysts. Characterizations by TEM and XPS accompanied by BET analysis revealed that the enhanced catalytic properties of the catalysts arose from their bimetals and could be attributed to the graphitic shell structure and graphitic N species, respectively.
- Thombal, Priyanka Raju,Thombal, Raju S.,Han, Sung Soo
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p. 474 - 481
(2020/01/13)
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- Conversion of anilines into azobenzenes in acetic acid with perborate and Mo(VI): correlation of reactivities
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Azobenzenes are extensively used to dye textiles and leather and by tuning the substituent in the ring, vivid colours are obtained. Here, we report preparation of a large number of azobenzenes in good yield from commercially available anilines using sodium perborate (SPB) and catalytic amount of Na2MoO4 under mild conditions. Glacial acetic acid is the solvent of choice and the aniline to azobenzene conversion is zero, first and first orders with respect to SPB, Na2MoO4 and aniline, respectively. Based on the kinetic orders, UV–visible spectra and cyclic voltammograms, the conversion mechanism has been suggested. The reaction rates of about 50 anilines at 20–50?°C and their energy and entropy of activation conform to the isokinetic or Exner relationship and compensation effect, respectively. However, the reaction rates, deduced by the so far adopted method, fail to comply with the Hammett correlation. The specific reaction rates of molecular anilines, obtained through a modified calculation, conform to the Hammett relationship. Thus, this work presents a convenient inexpensive non-hazardous method of preparation of a larger number of azobenzenes, and shows the requirement of modification in obtaining the true reaction rates of anilines in acetic acid and the validity of Hammett relationship in the conversion process, indicating operation of a common mechanism.
- Karunakaran,Venkataramanan
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p. 375 - 385
(2019/02/14)
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- Method for catalytically synthesizing azobenzene compound through double-metal composite oxide
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The invention discloses a method for catalytically synthesizing an azobenzene compound through a double-metal composite oxide and belongs to the technical field of catalytic synthesis of azobenzene. According to the method disclosed by the invention, under the action of the double-metal composite oxide, air or oxygen is used as an oxidant, so that amines containing different substituent groups aredirectly oxidized and coupled under a moderate condition to synthesize the azobenzene compound. A catalysis system adopted by the method has moderate reaction conditions and high selectivity; the synthesis of the azobenzene compound can be efficiently catalyzed by carrying out reacting at 60 DEG C and in the air; transition metal which is cheap and easy to obtain and contains iron, cobalt, nickel, aluminum, manganese and copper is used as the double-metal composite oxide, so that the availability of a double-metal composite oxide catalyst is improved.
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Paragraph 0055; 0056
(2019/03/08)
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- Synthesis of 2 - fluoro aniline compounds of the method
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The invention discloses a method for synthesizing 2 - fluoro aniline compounds of the method, the method is: shown in formula Ia aniline compound of formula Ib α and β shown aniline compound as raw materials, through coupling reaction shown [...] azobenzene compound II, then the type II shown azobenzene compound with a palladium catalyst, fluorination reagent, additive, organic solvent, in the 30 - 150 °C temperature closed agitating the fluorination reaction, [...] compound of formula III, type III compounds are shown in the reaction under the action of a reducing [...] shown IV 2 - fluoro aniline compounds; this invention synthetic 2 - fluoro aniline compounds substrate wide adaptability, mild reaction conditions, the operation is simple, fluorinated and good selectivity, [...] aniline compounds is prepared by many drug molecule is an important intermediate and starting material, wide application prospects.
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Paragraph 0116; 0118
(2019/05/15)
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- A metal-catalyst-free oxidative coupling of anilines to aromatic azo compounds in water using bleach
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A simple route toward the synthesis of symmetrical and unsymmetrical aromatic azo compounds through oxidative coupling of anilines using widely available NaOCl is presented. This metal catalyst-free protocol is performed in water and affords the desired products in high yields.
- de Souza, Gabriela F.P.,von Zuben, Theodora W.,Salles, Airton G.
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supporting information
p. 3753 - 3755
(2018/09/21)
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- Preparation of carbon-based AuAg alloy nanoparticles by using the heterometallic [Au4Ag4] cluster for efficient oxidative coupling of anilines
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We herein report the preparation of unique heteroatom-doped and carbon-based AuAg alloy nanoparticles (NPs) via the pyrolysis of a structurally defined octanuclear heterometallic Au(i)-Ag(i) cluster [Au4Ag4(Dppy)4(Tab)sub
- Gao, Bin-Bin,Zhang, Min,Chen, Xu-Ran,Zhu, Da-Liang,Yu, Hong,Zhang, Wen-Hua,Lang, Jian-Ping
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supporting information
p. 5780 - 5788
(2018/04/30)
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- Cage Encapsulated Gold Nanoparticles as Heterogeneous Photocatalyst for Facile and Selective Reduction of Nitroarenes to Azo Compounds
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A discrete nanoscopic organic cage (OC1R) has been synthesized from a phenothiazine based trialdehyde treating with chiral 1,2-cyclohexanediamine building block via dynamic imine bond formation followed by reductive amination. The cage compound has been characterized by several spectroscopic methods, which advocate that OC1R has trigonal prismatic shape formed via [2 + 3] self-assembled imine condensation followed by imine reduction. This newly designed cage has aromatic walls and porous interior decorated with two cyclic thioether and three vicinal diamine moieties suitable for binding gold ions to engineer the controlled nucleation and stabilization of ultrafine gold nanoparticles (AuNPs). The functionalized confined pocket of the cage has been used for the controlled synthesis of AuNPs with narrow size distribution via encapsulation of Au(III) ions. Inductively coupled plasma mass spectrometric (ICP-MS) analysis revealed that the composite Au@OC1R has very high (?68 wt %) gold loading. In distinction, reduction of gold salts in absence of the cage yielded structureless agglomerates. The fine-dispersed cage anchored AuNPs (Au@OC1R) have been finally used as potential heterogeneous photocatalyst for very facile and selective conversion of nitroarenes to respective azo compounds at ambient temperature in just 2 h reaction time. Exceptional chemical stability and reusability without any agglomeration of AuNPs even after several cycles of use are the potential features of this material. The composite Au@OC1R represents the first example of organic cage supported gold nanoparticles as photocatalyst.
- Mondal, Bijnaneswar,Mukherjee, Partha Sarathi
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p. 12592 - 12601
(2018/10/05)
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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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- Efficient Solar-Driven Hydrogen Transfer by Bismuth-Based Photocatalyst with Engineered Basic Sites
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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
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supporting information
p. 16711 - 16719
(2018/12/11)
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- When Do Strongly Coupled Diradicals Show Strongly Coupled Reactivity? Thermodynamics and Kinetics of Hydrogen Atom Transfer Reactions of Palladium and Platinum Bis(iminosemiquinone) Complexes
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The 2,2′-biphenylene-bridged bis(iminosemiquinone) complexes (tBuClip)M [tBuClipH4 = 4,4′-di-tert-butyl-N,N′-bis(3,5-di-tert-butyl-2-hydroxyphenyl)-2,2′-diaminobiphenyl; M = Pd, Pt] can be reduced to the bis(aminophenoxide) complexes (tBuClipH2)M by reaction with hydrazobenzene (M = Pd) or by catalytic hydrogenation (M = Pt). The palladium complex with one aminophenoxide ligand and one iminosemiquinone ligand, (tBuClipH)Pd, is generated by comproportionation of (tBuClip)Pd with (tBuClipH2)Pd in a process that is both slow (0.06 M-1 s-1 in toluene at 23 °C) and only modestly favorable (Kcom = 1.9 in CDCl3), indicating that both N-H bonds have essentially the same bond strength. The mono(iminoquinone) complex (tBuClipH)Pt has not been observed, indicating that the platinum analogue shows no tendency to comproportionate (Kcom tBuClipH2)Pt to (tBuClip)Pd occurring with ?G° = ?8.9 kcal mol-1. The palladium complex (tBuClipH2)Pd reacts with nitroxyl radicals in two observable steps, with the first hydrogen transfer taking place slightly faster than the second. In the platinum analogue, the first hydrogen transfer is much slower than the second, presumably because the N-H bond in the monoradical complex (tBuClipH)Pt is unusually weak. Using driving force-rate correlations, it is estimated that this bond has a BDFE of 55.1 kcal mol-1, which is 7.1 kcal mol-1 weaker than that of the first N-H bond in (tBuClipH2)Pt. The two radical centers in the platinum, but not the palladium, complex thus act in concert with each other and display a strong thermodynamic bias toward two-electron reactivity. The greater thermodynamic and kinetic coupling in the platinum complex is attributed to the stronger metal-ligand ? interactions in this compound.
- Conner, Kyle M.,Arostegui, AnnaMaria C.,Swanson, Daniel D.,Brown, Seth N.
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p. 9696 - 9707
(2018/08/28)
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- Photocatalysis Enabling Acceptorless Dehydrogenation of Diaryl Hydrazines at Room Temperature
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Aromatic azo compounds are privileged structural motifs, and they exhibit a myriad of pharmaceutical as well as industrial applications. Here, we report a catalytic acceptorless dehydrogenation of diarylhydrazine derivatives to access a wide variety of aryl-azo compounds with the removal of molecular hydrogen as the sole byproduct. This distinctive reactivity has been achieved under dual catalytic conditions by merging the visible-light active [Ru(bpy)3]2+ as the photoredox catalyst and Co(dmgH)2(py)Cl as the proton-reduction catalyst. The reaction proceeds smoothly under very mild and benign conditions and operates at ambient temperature. This dual catalytic approach is highly compatible with many different functional groups and has a broad substrate scope. We have also demonstrated the reversible hydrogen storage and release phenomenon on hydrazobenzene/azobenzene couple to show the utility of these compounds as hydrogen storage materials. Further diversification of azobenzene was shown by a transition-metal-catalyzed azo-group-directed ortho-C-H bond functionalization.
- Sahoo, Manoj K.,Saravanakumar, Krishnasamy,Jaiswal, Garima,Balaraman, Ekambaram
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p. 7727 - 7733
(2018/07/25)
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- Method for preparing azobenzene compound with continuous flow
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The invention discloses a method for preparing an azobenzene compound with continuous flows. The method comprises the following steps: (1) carrying out on-line filling of a columnar microreactor withcuprous bromide prepared with continuous flows; (2) carrying out on-line water washing and ethanol washing on the columnar microreactor filled with the cuprous bromide; (3) dissolving aromatic amine and pyridine into a solvent so as to obtain a mixed solution; (4) respectively inputting and mixing the mixed solution and oxygen into a casing type flow reactor simultaneously so as to obtain a gas-liquid mixture; (5) pumping the gas-liquid mixture into the columnar microreactor of the step (2) to carry out an oxidative coupling reaction, thereby obtaining an azobenzene compound. By adopting the method, integration of preparation, on-line filling and washing of a cuprous bromide catalyst and synthesis of an azo product in a synthesis process of the azobenzene compound is achieved, oxidation ofthe cuprous bromide in preparation and manual filling processes and a process of joining in catalytic synthesis of the azobenzene compound is reduced, and the mixing efficiency of three phases of gases, liquids and solids is improved.
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Paragraph 0047; 0048; 0085; 0086; 0089
(2018/11/03)
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- Ruthenium-catalyzed meta/ortho-selective C-H alkylation of azoarenes using alkyl bromides
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meta/ortho-Selective CAr-H (di)alkylation reactions of azoarenes have been achieved via [Ru(p-cymene)Cl2]2 catalyzed ortho-metalation using various types of alkyl bromides. Particularly, dual meta-alkylation of azoarene and reduction offer an attractive strategy for the synthesis of meta-alkylanilines, which are difficult to access via traditional aniline functionalization methods.
- Li, Gang,Ma, Xingxing,Jia, Chunqi,Han, Qingqing,Wang, Ya,Wang, Junjie,Yu, Liuyang,Yang, Suling
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supporting information
p. 1261 - 1264
(2017/02/05)
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- Dehydrogenation of the NH?NH Bond Triggered by Potassium tert-Butoxide in Liquid Ammonia
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A novel strategy for the dehydrogenation of the NH?NH bond is disclosed using potassium tert-butoxide (tBuOK) in liquid ammonia (NH3) under air at room temperature. Its synthetic value is well demonstrated by the highly efficient synthesis of aromatic azo compounds (up to 100 % yield, 3 min), heterocyclic azo compounds, and dehydrazination of phenylhydrazine. The broad application of this strategy and its benefit to chemical biology is proved by a novel, convenient, one-pot synthesis of aliphatic diazirines, which are important photoreactive agents for photoaffinity labeling.
- Wang, Lei,Ishida, Akiko,Hashidoko, Yasuyuki,Hashimoto, Makoto
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p. 870 - 873
(2017/01/14)
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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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- Stabilisation of gold nanoparticles by N-heterocyclic thiones
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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
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supporting information
p. 8367 - 8371
(2017/07/12)
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- Aromatic amine oxidation process for preparing aromatic azobenzene method
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The invention relates to a method for preparing an aromatic azo compound by utilizing aromatic amine oxidation. In the method, air or oxygen serves as an oxygen source, and under the effect of a catalyst, aromatic amine is oxidized into the aromatic azo compound. The method is high in oxidization efficiency and product yield; the air or the oxygen serves as the oxygen source, and the method is economical and environmentally friendly. The product and the catalyst can be separated easily, and the aftertreatment is simple. The catalyst is easy to reuse, and the method has very good application prospect.
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Paragraph 0013; 0017
(2017/10/11)
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- Synthesis of Azobenzenes Using N-Chlorosuccinimide and 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU)
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A convenient method for the synthesis of symmetrical azobenzenes is reported. This one-step procedure involves treatment of anilines with N-chlorosuccinimide (NCS) and organic base 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). A wide range of commercially available substituted anilines readily participate in this reaction to produce the corresponding azobenzenes in moderate-to-excellent yields in minutes.
- Antoine John, Alford,Lin, Qing
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p. 9873 - 9876
(2017/09/23)
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- Substrate-Controlled Transformation of Azobenzenes to Indazoles and Indoles via Rh(III)-Catalysis
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Rh(III)-catalyzed substrate-controlled transformation of azobenzenes to indazoles and 2-acyl (NH) indoles is achieved via C-H functionalization. Generally, good functional groups tolerance, satisfying yields, and excellent regio-selectivity are achieved in this reaction. Mechanistically, the reaction with acrylates undergoes β-hydride elimination, while the reaction with vinyl ketones or acrylamides undergoes nucleophilic addition. Copper acetate was supposed to play different roles in the β-hydride elimination to furnish indazoles and nucleophilic addition of C-Rh bond to deliver 2-acyl (NH) indoles.
- Cai, Shangjun,Lin, Songyun,Yi, Xiangli,Xi, Chanjuan
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p. 512 - 520
(2017/04/26)
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- First use of p-tert-butylcalix[4]arene-tetra-O-acetate as a nanoreactor having tunable selectivity towards cross azo-compounds by trapping silver ions
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p-tert-Butylcalix[4]arene-tetra-O-acetate was established for the first time as a member of the nanoreactor series, even without having any -OH group. The nano range distribution of this nanoreactor was ascertained by DLS, SEM and TEM studies. The capability of this cavitand towards hosting amines in a competitive manner generates a new green pathway for cross coupling of aromatic amines to give the corresponding azo-compounds. In this context, using p-tert-butylcalix[4]arene-tetra-O-acetate as a nanoreactor and silver nitrate as a catalyst, we got the cross azo-compound in good to excellent yields in the eco-friendly solvent water. This green methodology is also applicable for the synthesis of respective homo-compounds.
- Sarkar, Piyali,Mukhopadhyay, Chhanda
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supporting information
p. 442 - 451
(2016/01/30)
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- Palladium-Catalyzed Oxidative Synthesis of Unsymmetrical Azophenols
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A straightforward palladium-catalyzed oxidative hydroxylation of azobenzenes is reported. The developed methodology tolerates various functional groups and allows the synthesis of diverse unsymmetrical azophenols under mild conditions in good to excellent yields. A complementary procedure was also investigated by in situ generation of PIFA. This study represents the first general method for the synthesis of o-hydroxyazobenzenes starting from simple azoarenes.
- Nguyen, Thi Hong Long,Gigant, Nicolas,Delarue-Cochin, Sandrine,Joseph, Delphine
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p. 1850 - 1857
(2016/03/15)
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- AgNO3 as nitrogen source for rhodium(III)-catalyzed synthesis of 2-aryl-2H -benzotriazoles from azobenzenes
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A new approach has been established for Rh(iii)-catalyzed direct aza oxidative cyclization of non-prefunctionalized azobenzenes to provide 2-aryl-2H-benzotriazoles in good yields, in which AgNO3 instead of conventional azide reagents for the first time functions as the nitrogen source for the nitrogenation reaction. Preliminary mechanistic studies suggest that the Rh(iii)-catalyst could account for the nitration reaction, and subsequently cationic silver species might both play a vital role in the fission of the nitrogen-oxygen bonds in nitro groups and promote aza oxidative cyclization.
- Li, Jixing,Zhou, Hui,Zhang, Jinlong,Yang, Huameng,Jiang, Gaoxi
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supporting information
p. 9589 - 9592
(2016/08/01)
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- Affinity modulation of photoresponsive hosts for fullerenes: Light-gated corannulene tweezers
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Six azobenzene derivatives bearing polyaromatic fragments have been prepared and their reversible photoisomerization has been assessed. Corannulene-functionalized molecules have demonstrated excellent switchable hosting abilities towards fullerenes in which an interesting range of affinities has been found. The success of this design relies upon the reversible formation and destruction of tweezer-like structures.
- Barbero, Héctor,Ferrero, Sergio,álvarez-Miguel, Lucía,Gómez-Iglesias, Patricia,Miguel, Daniel,álvarez, Celedonio M.
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supporting information
p. 12964 - 12967
(2016/11/11)
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- B(C6F5)3-Catalyzed Reduction of Aromatic and Aliphatic Nitro Groups with Hydrosilanes
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A transition-metal-free method for the hydrosilane reduction of aromatic and aliphatic nitro compounds to the corresponding amines is reported. Et3SiH is found to be the optimal reductant in this B(C6F5)3-catalyzed deoxygenation. The functional-group tolerance is, however, moderate.
- Porwal, Digvijay,Oestreich, Martin
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supporting information
p. 3307 - 3309
(2016/07/23)
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- Oxidative coupling of anilines to azobenzenes using heterogeneous manganese oxide catalysts
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We herein report the transition metal oxide-catalyzed synthesis of azobenzenes through the oxidative coupling of anilines. An octahedral molecular sieve of manganese oxide, OMS-2, exhibited the best activity and selectivity. Nine examples of symmetric azobenzenes and twenty unsymmetric ones were synthesized with 62-99% conversion and 64-99% selectivity. In the aniline cross-coupling reactions, the difference of the Hammett constants of two substituted groups (Δσ) determines the selectivity to unsymmetric azobenzenes, which are the major products at Δσ 0.32. In-depth studies reveal that the surface defect sites of the mixed-valence manganese oxide play a key role in facilitating electron transfer and activating molecular oxygen. The single-electron transfer (SET) reaction mechanism is proposed based on electron paramagnetic resonance and X-ray powder diffraction characterization.
- Wang, Min,Ma, Jiping,Yu, Miao,Zhang, Zhe,Wang, Feng
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p. 1940 - 1945
(2016/04/05)
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- Copper-Manganese Spinel Oxide Catalyzed Synthesis of Amides and Azobenzenes via Aminyl Radical Cations
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A highly efficient Cu-Mn-catalyzed process for the aminolysis of esters was developed. Also, the catalyst promoted the self- And cross-dehydrogenative coupling of anilines to generate symmetrical and unsymmetrical azobenzenes, respectively. The reactions were performed under neutral conditions with an inexpensive catalyst, gave high yields, and offered wide functional group tolerance. Spinel tap: A novel facet of aminyl radical cation reactivity with esters for the synthesis of amides is presented. The developed method also gives access to symmetrical and unsymmetrical azobenzenes. The reactions are performed under neutral conditions with an inexpensive catalyst, give high yields, and have a wide functional group tolerance.
- Sultan, Shaista,Kumar, Manjeet,Devari, Shekaraiah,Mukherjee, Debaraj,Ali Shah, Bhahwal
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p. 703 - 707
(2016/03/05)
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