- Manganese Catalyzed Hydrogenation of Azo (N=N) Bonds to Amines
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We report the first example of homogeneously catalyzed hydrogenation of the N=N bond of azo compounds using a complex of an earth-abundant-metal. The hydrogenation reaction is catalyzed by a manganese pincer complex, proceeds under mild conditions, and yields amines, which makes this methodology a sustainable alternative route for the conversion of azo compounds. A plausible mechanism involving metal-ligand cooperation and hydrazine intermediacy is proposed based on mechanistic studies. (Figure presented.).
- Ben-David, Yehoshoa,Das, Uttam Kumar,Diskin-Posner, Yael,Kar, Sayan,Milstein, David
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supporting information
p. 3744 - 3749
(2021/07/09)
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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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- Nitrate promoted mild and versatile Pd-catalysed C(sp2)-H oxidation with carboxylic acids
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A nitrate-promoted Pd-catalysed mild cross-dehydrogenative C(sp2)-H bond oxidation of oximes or azobenzenes with diverse carboxylic acids has been developed. In contrast to the previous catalytic systems, this protocol features mild conditions (close to room temperature for most cases) and a broad substrate scope (up to 64 examples), thus constituting a versatile method to directly prepare diverse O-aryl esters. Moreover, the superiority of the nitrate additive in this mild transformation was further determined by experimental and computational evidence.
- Hao, Hong-Yan,He, Yu-Ting,Lou, Shao-Jie,Luo, Gen,Mao, Yang-Jie,Xiong, Xue,Xu, Dan-Qian,Xu, Zhen-Yuan
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supporting information
p. 6732 - 6737
(2020/09/21)
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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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- Visible-light-promoted oxidative dehydrogenation of hydrazobenzenes and transfer hydrogenation of azobenzenes
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Azo compounds are widely used in the pharmaceutical and chemical industries. Here, we report the use of a non-metal photo-redox catalyst, Eosin Y, to synthesize azo compounds from hydrazine derivatives. The use of visible-light with air as the oxidant makes this process sustainable and practical. Moreover, the visible-light-driven, photo-redox-catalyzed transfer hydrogenation of azobenzenes is compatible with a series of hydrogen donors such as phenyl hydrazine and cyclic amines. Compared with traditional (thermal/transition-metal) methods, our process avoids the issue of over-reduction to aniline, which extends the applicability of photo-redox catalysis and confirms it as a useful tool for synthetic organic chemistry.
- Wang, Xianya,Wang, Xianjin,Xia, Chungu,Wu, Lipeng
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supporting information
p. 4189 - 4193
(2019/08/07)
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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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- Palladium-catalyzed cyclizative carbonylation of azobenzenes toward 3H-Indazol-3-ones using formic acid as CO source
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A palladium-catalyzed cyclizative carbonylation of azobenzenes has been developed to access 1-acyl 2-aryl 3H-indazol-3-ones in moderate to good yields with good functional compatibility. This procedure proceeded with the sequential ortho-C–H carbonylation and cyclization, where formic acid served as the CO source. The practicability of this transformation was further increased by the employment of facilely available azobenzenes derivatives as one-handled starting materials.
- Gu, Ning,Sun, Song,Cheng, Jiang
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supporting information
p. 1069 - 1072
(2018/02/14)
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- Single-atom dispersed Co-N-C catalyst: Structure identification and performance for hydrogenative coupling of nitroarenes
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Co-N-C catalysts are promising candidates for substituting platinum in electrocatalysis and organic transformations. The heterogeneity of the Co species resulting from high-temperature pyrolysis, however, encumbers the structural identification of active sites. Herein, we report a self-supporting Co-N-C catalyst wherein cobalt is dispersed exclusively as single atoms. By using sub-?ngstr?m-resolution HAADF-STEM in combination with XAFS and DFT calculation, the exact structure of the Co-N-C is identified to be CoN4C8-1-2O2, where the Co center atom is coordinated with four pyridinic N atoms in the graphitic layer, while two oxygen molecules are weakly adsorbed on Co atoms in perpendicular to the Co-N4 plane. This single-atom dispersed Co-N-C catalyst presents excellent performance for the chemoselective hydrogenation of nitroarenes to produce azo compounds under mild reaction conditions.
- Liu, Wengang,Zhang, Leilei,Yan, Wensheng,Liu, Xiaoyan,Yang, Xiaofeng,Miao, Shu,Wang, Wentao,Wang, Aiqin,Zhang, Tao
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p. 5758 - 5764
(2016/08/31)
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- A mild CuBr-NMO oxidative system for the coupling of anilines leading to aromatic azo compounds
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An efficient, mild and cost-effective method has been developed utilizing CuBr with N-methylmorpholine N-oxide (NMO/NMMO) for the oxidative coupling of anilines to access symmetrical and unsymmetrical azo compounds in high yield. The reactivity was found to be governed by electronic and steric factors of anilines.
- Singh, Shikha,Chauhan, Parul,Ravi, Makthala,Taneja, Isha,Wahajuddin,Yadav, Prem. P.
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p. 61876 - 61880
(2015/08/03)
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- Synthesis of 2,5-diferrocenyl five-membered heterocyclic compounds and their electrochemistry
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A series of 2,5-diferrocenyl substituted five-membered heterocyclic compounds, 2,5-diferrocenyl-1-phenylpyrrole (1), 2,5-diferrocenyl-1-(4- fluorophenyl)-pyrrole (2), 2,5-diferrocenyl-1-(4-ethoxyphenyl)-pyrrole (3), 2,5-diferrocenyl-1-(4-ethylphenyl)-pyrrole (4), 2,5-diferrocenylthiophene (5), and 2,5-diferrocenylfuran (6), were synthesized using one-pot cycloaddition of ferrocenyl alkyne and characterized by elemental analysis, FT-IR, MS, and NMR. The molecular structures of 1, 2, 5, and 6 were determined using single-crystal X-ray diffraction. Electronic communication between two ferrocenyl units of 1-6 was investigated using cyclic voltammetry. These compounds have two well-resolved electrochemically reversible one-electron-transfer processes using [NBu4][PF6] as the supporting electrolyte. The electrochemical studies reveal that electronic communication between two ferrocenyl units depend on the heteroatoms.
- Hu, Yu-Qiang,Han, Li-Min,Zhu, Ning,Hong, Hai-Long,Xie, Rui-Jun
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p. 3481 - 3497
(2014/01/06)
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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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p. 4673 - 4677
(2007/10/03)
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- Oxidation of primary aromatic amines to azo derivatives with sodium periodate using polystyrene-bound manganese(III) porphyrin
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The manganese (III) complex of 5,10,15,20-tetrakis(4-aminophenyl)porphyrin covalently bound to crosslinked chloromethylated polystyrene [Mn(H 2NTPP)-CMP] can act as an efficient catalyst for oxidation of primary aromatic amines to the corresponding azo compounds by sodium periodate in the presence of imidazole as axial ligand.
- Mirkhani, Valiollah,Tangestaninejad, Shahram,Moghadam, Majid,Karimian, Zohreh
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p. 792 - 794
(2007/10/03)
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- Bi-KOH. An efficient reagent for the coupling of nitroarenes to azo and azoxy compounds
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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.
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- Anti-androgenic activity of substituted azo- and azoxy-benzene derivatives.
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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
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p. 1387 - 1390
(2007/10/03)
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- Interactive free energy relationship for multiple substituent effects in the oxidative cleavage of aromatic anils by N-chlorobenzamide in aqueous methanol medium
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The kinetics of the oxidation of about forty, two aromatic anils prepared from (i) unsubstituted benzaldehyde and unsubstituted aniline (ii) substituted benzaldehydes and unsubstituted aniline (iii)unsubstituted benzaldehyde and substituted anilines and (iv) substituted benzaldehydes and substituted anilines by N-chlorobenzamide in aqueous methanol medium is enhanced by electron-releasing substituents both in benzaldehydes as well as in aniline moieties while electron withdrawing substituents retarded the rate. For the series with various substituents in the ring-X (benzaldehyde) and with hydrogen in the ring-Y (aniline), the p value is -0.40. For the series with various substituents in the ring-Y and with hydrogen in the ring- X, the ρ value is -2.65. Linear plots are obtained between p(x(y)) (obtained from Hammett's plot for various substituents in the benzaldehyde moiety) and ρ(y) (substituent constants for substituents in aniline moiety) with a slope of -1.46 and between p(y(x)) (obtained from Hammett's plot for various substituents in the aniline moiety) and o (substituent constants for substituents in benzaldehyde moiety) with a slope of -1.51. This relationship has been analysed quantitatively in terms of interactive free energy relationship for multiple substituent effects.
- Mohamed Kassim,Basheer Ahamed
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p. 533 - 540
(2007/10/03)
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- Bis(1-benzyl-4-aza-1-azoniabicyclo[2.2.2]octane) peroxodisulfate: A mild and efficient oxidant for oxidation of thiols, sulfides and aromatic amines to the corresponding disulfides, sulfoxides and azo compounds
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Bis(1-benzyl-4-aza-1-azoniabicyclo[2.2.2]octane) peroxodisulfate (BAABCPS) 1, readily prepared as orange solid from commercially available 1,4-diazabicyclo[2.2.2]octane (DABCO) and potassium peroxodisulfate converts thiols, sulfoxides and aromatic amines to the corresponding disulfides, sulfoxides and azo compounds respectively.
- Hajipour,Mohammadpoor Baltork,Kianfar
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p. 607 - 610
(2007/10/03)
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- Benzyltriphenylphosphonium Peroxodisulfate (PhCH2PPh3)2S2O8: A Mild and Inexpensive Reagent for Efficient Oxidation of Organic Compounds under Nonaqueous and Aprotic Conditions
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Benzyltriphenylphosphonium peroxodisulfate is an easily prepared and stable reagent. It could be used as an oxidant under aprotic and nonaqueous conditions in organic solvents. This reagent oxidizes different classes of alcohols to carbonyl compounds, thiols to disulfides, sulfides to sulfoxides, oximes to carbonyl compounds and aromatic amines to azo compounds efficiently. α-Hydroxy carboxylic acids and phenylacetic acids undergo oxidative decarboxylation to produce carbonyl compounds.
- Mohammadpoor-Baltork, Iraj,Hajipour, Abdol Reza,Mohammadi, Hasan
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p. 1649 - 1653
(2007/10/03)
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- An easy and efficient method for oxidation of alcohols and aromatic amines to the corresponding carbonyl and azo compounds under non-aqueous and neutral conditions
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1-Benzyl-1-aza-4-azoniabicyclooctane periodate 1, readily prepared as an orange solid from commercially available 1,4-diazobicyclooctane, is useful for oxidation in anhydrous conditions.The reagent converts alcohols to die corresponding carbonyl compounds, α hydroxy ketones to diketones, and aromatic amines to azo compounds, in me excellent yields.The reagent ineffective in oxidising double bonds, aldehydes and ketones.
- Hajipour, A. R.,Mahboobkhah, N.
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p. 285 - 287
(2007/10/03)
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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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p. 648 - 649
(2007/10/03)
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- SYNTHESIS AND SOME PHYSICAL PROPERTIES OF UNSYMMETRICAL 4,4 prime -DIALKYLAZOXYBENZENES.
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Two series of unsymmetrical 4,4 prime -dialkylazoxy compounds were obtained. The method of their synthesis and the results of measurements of the phase transition temperatures, dielectric constant, refractive indices and densities are presented. Compounds
- Dabrowski,Kenig,Raszewski,Kedzierski,Sadowska
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