617-22-1Relevant articles and documents
Visible-Light-Promoted Diboron-Mediated Transfer Hydrogenation of Azobenzenes to Hydrazobenzenes
Song, Menghui,Zhou, Hongyan,Wang, Ganggang,Ma, Ben,Jiang, Yajing,Yang, Jingya,Huo, Congde,Wang, Xi-Cun
, p. 4804 - 4811 (2021/04/06)
A visible-light-promoted transfer hydrogenation of azobenzenes has been developed. In the presence of B2pin2 and upon visible-light irradiation, the reactions proceeded smoothly in methanol at ambient temperature. The azobenzenes with diverse functional groups have been reduced to the corresponding hydrazobenzenes with a yield of up to 96%. Preliminary mechanistic studies indicated that the hydrogen atom comes from the solvent and the transformation is achieved through a radical pathway.
Chemoselective electrochemical reduction of nitroarenes with gaseous ammonia
Chang, Liu,Li, Jin,Wu, Na,Cheng, Xu
supporting information, p. 2468 - 2472 (2021/04/02)
Valuable aromatic nitrogen compounds can be synthesized by reduction of nitroarenes. Herein, we report electrochemical reduction of nitroarenes by a protocol that uses inert graphite felt as electrodes and ammonia as a reductant. Depending on the cell voltage and the solvent, the protocol can be used to obtain aromatic azoxy, azo, and hydrazo compounds, as well as aniline derivatives with high chemoselectivities. The protocol can be readily scaled up to >10 g with no decrease in yield, demonstrating its potential synthetic utility. A stepwise cathodic reduction pathway was proposed to account for the generations of products in turn.
Visible-light-promoted decarboxylative addition cyclization of: N -aryl glycines and azobenzenes to access 1,2,4-triazolidines
Ma, Ben,Qi, Yanfang,Song, Menghui,Wang, Xi-Cun,Yang, Jingya,Zhou, Hongyan
supporting information, p. 5806 - 5811 (2021/08/23)
Methods for the synthesis of 1,2,4-triazolidines are scarce. Herein, we report a visible-light-promoted decarboxylative addition cyclization of N-aryl glycines and azobenzenes to access such important compounds. Using commercially available methylene blue (MB) as an organic photocatalyst, the reaction proceeded smoothly in the absence of transition-metal catalysts at ambient temperature, affording the corresponding products, 1,2,4-triaryl 1,2,4-triazolidines, in good to excellent yields. This work demonstrates a new synthetic application of readily available azobenenes and provides a novel strategy for constructing 1,2,4-triazolidines.
Novel o-Toluidine Metabolite in Rat Urine Associated with Urinary Bladder Carcinogenesis
Tajima, Yuya,Toyoda, Takeshi,Hirayama, Yuichiro,Matsushita, Kohei,Yamada, Takanori,Ogawa, Kumiko,Watanabe, Kenji,Takamura-Enya, Takeji,Totsuka, Yukari,Wakabayashi, Keiji,Miyoshi, Noriyuki
, p. 1907 - 1914 (2020/08/14)
o-Toluidine (o-Tol), a monocyclic aromatic amine, causes bladder cancer in humans and experimental animals and is therefore classified as a Group 1 carcinogen (IARC) in which the carcinogenicity of o-Tol is involved in metabolic activation, DNA damage, and DNA adduct formation. In the DNA adduct formation mechanism, o-Tol is metabolized by N-hydroxylation, N-acetoxylation, and then deacetoxylation to produce an electrophilic nitrenium ion, which is able to bind to a DNA base, such as dG-C8. Therefore, dG-C8-o-Tol is thought to be a plausible DNA adduct of o-Tol exposure. However, direct detection of dG-C8-o-Tol in biological samples has not been reported yet. Here, we show that a novel o-Tol metabolite, 2-methyl-N1-(2-methylphenyl)benzene-1,4-diamine (MMBD), a dimer by head-to-tail binding, was identified for the first time in o-Tol-exposed rat urine. MMBD was also detected in a reaction of o-Tol and S9 mix, indicating the formation was catalyzed by an enzymatic reaction. Moreover, MMBD showed a potent stronger mutagenicity in N-acetyltransferase overexpressed Salmonella typhimurium strains,and cytotoxicity in human bladder carcinoma T24 cells and human spleen lymphoblastoid TK6 cells compared with o-Tol. Furthermore, a DNA adduct (m/z 478.1) corresponding to dG-MMBD was detected in the reaction of calf thymus DNA with rat urine containing MMBD, and also in hepatic DNA of rats treated with o-Tol. These results therefore suggested that o-Tol-induced bladder carcinogenesis could be at least partly attributed to MMBD formation. The possible dimerization of monocyclic aromatic amines should be considered in the evaluation of the risk of bladder carcinogenesis after exposure.
Tandem selective reduction of nitroarenes catalyzed by palladium nanoclusters
Yan, Ziqiang,Xie, Xiaoyu,Song, Qun,Ma, Fulei,Sui, Xinyu,Huo, Ziyu,Ma, Mingming
supporting information, p. 1301 - 1307 (2020/03/11)
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.
Transfer Hydrogenation of Azo Compounds with Ammonia Borane Using a Simple Acyclic Phosphite Precatalyst
Chacón-Terán, Miguel A.,Rodríguez-Lugo, Rafael E.,Wolf, Robert,Landaeta, Vanessa R.
supporting information, p. 4336 - 4344 (2019/08/20)
Tris(quinolin-8-yl)phosphite, P(Oquin)3, promotes the dehydrogenation of H3N·BH3 (AB) and the transfer hydrogenation of azoarenes using ammonia borane (AB) as H2 source. The metal-free reduction of azoarenes proceeds under mild reaction conditions upon which several diphenylhydrazine derivatives are obtained in high yields. The reactivity of P(Oquin)3 toward AB was evaluated through NMR in situ tests. The rate of the reaction, activation parameters, deuterium kinetic isotope effect (DKIE) and linear-free energy relationship were investigated. Such mechanistic and kinetic studies suggest that P(Oquin)3 is a precatalyst and that AB is likely involved in more than one stage of the reaction pathway. Furthermore, the kinetic data indicate that the reaction proceeds through an ordered transition state, possibly associative.
Visible-light-promoted oxidative dehydrogenation of hydrazobenzenes and transfer hydrogenation of azobenzenes
Wang, Xianya,Wang, Xianjin,Xia, Chungu,Wu, Lipeng
supporting information, p. 4189 - 4193 (2019/08/07)
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.
Synthetic method for 4,4'-dihalogenated-3,3'-dialkyl(alkoxyl) biphenyl compounds
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Paragraph 0035; 0036; 0037; 0038, (2016/10/07)
The invention relates to a synthetic method for 4,4'-dihalogenated-3,3'-dialkyl(alkoxyl) biphenyl compounds. The method employs o-nitro alkyl (alkoxyl) benzene as an initial raw material, 2,2'-dialkyl(alkoxyl) hydrazobenzene is prepared through catalysis hydrogenation in an alkaline environment, hydrochloric acid acidifying rearrangement is carried out, 4,4'-diamino-3,3'-dialkyl(alkoxyl) biphenyl is prepared, finally, a diazotization reaction is carried out and 4,4'-dihalogenated-3,3'-dialkyl(alkoxyl) biphenyl compounds are prepared. The synthetic method is advantaged by cheap and easily available raw materials, mild reaction conditions, simple operation, high safety coefficient, high yield and low cost.
Mg/Triethylammonium formate: A useful system for reductive dimerization of araldehydes into pinacols; Nitroarenes into azoarenes and azoarenes into hydrazoarenes
Pamar, M. Geeta,Govender,Muthusamy,Krause, Ruiw M.,Nanjundaswamy
, p. 969 - 974 (2014/03/21)
Studies are reported which describes the effectiveness of triethylammonium formate in the presence of magnesium for the efficient intermolecular pinacol coupling using MeOH as solvent, Various aromatic carbonyls underwent smooth reductive coupling to give the corresponding I ,2-diols. A series of azo compounds were obtained by the reductive coupling of nitroaromatics while azo compounds were reduced to the corresponding hydrazoarenes by this system. There was no adverse effect on the other reducible and hydrogenolysable groups such as ether linkage, hydroxy and halogens. The reactions are clean, high yielding and inexpensive. All the reactions proceeded smoothly at ambient temperature.
Highly selective conversion of nitrobenzenes using a simple reducing system combined with a trivalent indium salt and a hydrosilane
Sakai, Norio,Fujii, Kohji,Nabeshima, Shinya,Ikeda, Reiko,Konakahara, Takeo
scheme or table, p. 3173 - 3175 (2010/08/19)
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.
