- 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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- 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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- Method for synthesizing aromatic azo compounds
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The invention disclose a method for synthesizing aromatic azo compounds and especially relates to a method for synthesizing aromatic azo compounds by catalyzing oxidation of aromatic aniline compounds to carry out coupled dehydrogenations by themselves by adopting a manganese oxide compound synthesized by potassium permanganate and manganese nitrate in an alkaline solution as the catalyst. The method can be used to conveniently synthesize symmetrical and dissymmetrical azo compounds; reaction conditions of the method are mild, the air is utilized as an oxygen source, and no additive is added therein; thus, the method has the characteristic of simple operation, strong universality of the catalyst system as well as high yield and selectivity.
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Paragraph 0040; 0041
(2016/11/17)
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- A practical synthesis of azobenzenes through oxidative dimerization of aromatic amines using tert-butyl hypoiodite
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A straightforward, convenient, and efficient synthetic method of azobenzenes through oxidative dimerization of aromatic amines using a unique and cost-effective iodinating reagent is described. This new method allows for easy access to both of symmetrical and unsymmetrical azobenzenes under extremely mild conditions. Georg Thieme Verlag Stuttgart. New York.
- Takeda, Youhei,Okumura, Sota,Minakata, Satoshi
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supporting information
p. 1029 - 1033
(2013/05/09)
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- Oxidative dimerization of (hetero)aromatic amines utilizing t-BuOI leading to (hetero)aromatic azo compounds: Scope and mechanistic studies
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A straightforward synthetic method of both symmetric and unsymmetric aromatic azo compounds through an efficient and cross-selective oxidative dimerization of aromatic amines using tert-butyl hypoiodite (t-BuOI) under metal-free and mild conditions has been developed. This method was also found applicable to the synthesis of heteroaromatic azo compounds. The spectroscopic study indicates the involvement of N,N-diiodoanilines in the oxidative reaction as the key intermediate.
- Okumura, Sota,Lin, Chun-Hsuan,Takeda, Youhei,Minakata, Satoshi
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p. 12090 - 12105
(2014/01/06)
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- Oxidative dimerization of aromatic amines using tBuOI: Entry to unsymmetric aromatic azo compounds
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It's all the hype: An oxidative dimerization reaction of aromatic amines utilizing tert-butyl hypoiodite (tBuOI) under mild reaction conditions leads to aromatic azo compounds (see scheme). The method allows access to unsymmetric aromatic azo compounds, which are difficult to prepare by conventional synthetic methods, in a selective manner. Copyright
- Takeda, Youhei,Okumura, Sota,Minakata, Satoshi
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supporting information; experimental part
p. 7804 - 7808
(2012/09/05)
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- Novel route to azobenzenes via Pd-catalyzed coupling reactions of aryl hydrazides with aryl halides, followed by direct oxidations
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(Matrix presented) N-Boc aryl hydrazines undergo Pd-catalyzed coupling reactions with aryl halides to provide N-Boc diaryl hydrazines in excellent yields. The resulting N-Boc diaryl hydrazines were directly oxidized with NBS/pyridine in CH2Cls
- Lim, Young-Kwan,Lee, Kang-Sang,Cho, Cheon-Gyu
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p. 979 - 982
(2007/10/03)
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