- 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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- Azo synthesis meets molecular iodine catalysis
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A metal-free synthetic protocol for azo compound formation by the direct oxidation of hydrazine HN-NH bonds to azo group functionality catalyzed by molecular iodine is disclosed. The strengths of this reactivity include rapid reaction times, low catalyst loadings, use of ambient dioxygen as a stoichiometric oxidant, and ease of experimental set-up and azo product isolation. Mechanistic studies and density functional theory computations offering insight into this reactivity, as well as the events leading to azo group formation are presented. Collectively, this study expands the potential of main-group element iodine as an inexpensive catalyst, while delivering a useful transformation for forming azo compounds.
- Rowshanpour, Rozhin,Dudding, Travis
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p. 7251 - 7256
(2021/02/26)
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- Catalytic Nitrene Homocoupling by an Iron(II) Bis(alkoxide) Complex: Bulking Up the Alkoxide Enables a Wider Range of Substrates and Provides Insight into the Reaction Mechanism
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The reaction of HOR′ (OR′ = di-t-butyl-(3,5-diphenylphenyl)methoxide) with an iron(II) amide precursor forms the iron(II) bis(alkoxide) complex Fe(OR′)2(THF)2 (2). 2 (5-10 mol %) serves as a catalyst for the conversion of aryl azides
- Yousif, Maryam,Wannipurage, Duleeka,Huizenga, Caleb D.,Washnock-Schmid, Elizabeth,Peraino, Nicholas J.,Ozarowski, Andrew,Stoian, Sebastian A.,Lord, Richard L.,Groysman, Stanislav
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supporting information
p. 9425 - 9438
(2018/08/17)
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- Bismuth nanoparticles: an efficient catalyst for reductive coupling of nitroarenes to azo-compounds
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The synthesis of azoarenes from corresponding nitroarenes was developed by virtue of in situ bismuth nanoparticles. A series of aromatic azo compounds can be obtained under mild reaction conditions with excellent yields.
- Pothula, Kishore,Tang, Lin,Zha, Zhenggen,Wang, Zhiyong
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p. 83144 - 83148
(2015/10/19)
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- POLYMER SUPPORTED REAGENTS AND METHODS OR REDUCING AROMATIC NITRO COMPOUNDS BY USING THE SAME
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The present invention relates to a polymer supported reagent comprising a novel crosslinked mesoporous polymer, enabling a simple and easy production of an azoxy compound or an azo compound from an aromatic nitro compound, and a method of selectively reducing an aromatic nitro compound by using the same. The polymer supported reagent comprises a certain acrylamide mesoporous crosslinked polymer.
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Paragraph 0117
(2013/10/07)
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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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