- Oxidative dehydrogenation of hydrazines and diarylamines using a polyoxomolybdate-based iron catalyst
-
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
-
supporting information
p. 7677 - 7680
(2021/08/09)
-
- Electrosynthesis of Azobenzenes Directly from Nitrobenzenes
-
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
-
p. 3334 - 3338
(2021/10/29)
-
- Selective Oxidation of Anilines to Azobenzenes and Azoxybenzenes by a Molecular Mo Oxide Catalyst
-
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
-
supporting information
p. 6382 - 6385
(2021/02/09)
-
- Bifunctional Cs?Au/Co3O4 (Basic and Redox)-Catalyzed Oxidative Synthesis of Aromatic Azo Compounds from Anilines
-
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.
-
supporting information
p. 5063 - 5073
(2021/09/30)
-
- Trichloroisocyanuric Acid Mediated Oxidative Dehydrogenation of Hydrazines: A Practical Chemical Oxidation to Access Azo Compounds
-
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
-
supporting information
p. 1103 - 1112
(2020/04/01)
-
- Tuneable Copper Catalysed Transfer Hydrogenation of Nitrobenzenes to Aniline or Azo Derivatives
-
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
-
supporting information
p. 2689 - 2700
(2020/05/18)
-
- Electrochemical dehydrogenation of hydrazines to azo compounds
-
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
-
supporting information
p. 1680 - 1685
(2019/04/08)
-
- Iron and Nitrogen Co-Doped Mesoporous Carbon-Based Heterogeneous Catalysts for Selective Reduction of Nitroarenes
-
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
-
supporting information
p. 3525 - 3531
(2019/06/24)
-
- Cage Encapsulated Gold Nanoparticles as Heterogeneous Photocatalyst for Facile and Selective Reduction of Nitroarenes to Azo Compounds
-
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
-
p. 12592 - 12601
(2018/10/05)
-
- A metal-catalyst-free oxidative coupling of anilines to aromatic azo compounds in water using bleach
-
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.
-
supporting information
p. 3753 - 3755
(2018/09/21)
-
- Preparation of carbon-based AuAg alloy nanoparticles by using the heterometallic [Au4Ag4] cluster for efficient oxidative coupling of anilines
-
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
-
supporting information
p. 5780 - 5788
(2018/04/30)
-
- Mechanism of Ti-Catalyzed Oxidative Nitrene Transfer in [2 + 2 + 1] Pyrrole Synthesis from Alkynes and Azobenzene
-
A combined computational and experimental study on the mechanism of Ti-catalyzed formal [2 + 2 + 1] pyrrole synthesis from alkynes and aryl diazenes is reported. This reaction proceeds through a formally TiII/TiIV redox catalytic cycle as determined by natural bond orbital (NBO) and intrinsic bond orbital (IBO) analysis. Kinetic analysis of the reaction of internal alkynes with azobenzene reveals a complex equilibrium involving Ti=NPh monomer/dimer equilibrium and Ti=NPh + alkyne [2 + 2] cycloaddition equilibrium along with azobenzene and pyridine inhibition equilibria prior to rate-determining second alkyne insertion. Computations support this kinetic analysis, provide insights into the structure of the active species in catalysis and the roles of solvent, and provide a new mechanism for regeneration of the Ti imido catalyst via disproportionation. Reductive elimination from a 6-membered azatitanacyclohexadiene species to generate pyrrole-bound TiII is surprisingly facile and occurs through a unique electrocyclic reductive elimination pathway similar to a Nazarov cyclization. The resulting TiII species are stabilized through backbonding into the π? of the pyrrole framework, although solvent effects also significantly stabilize free TiII species that are required for pyrrole loss and catalytic turnover. Further computational and kinetic analysis reveals that in complex reactions with unysmmetric alkynes the resulting pyrrole regioselectivity is driven primarily by steric effects for terminal alkynes and inductive effects for internal alkynes.
- Davis-Gilbert, Zachary W.,Wen, Xuelan,Goodpaster, Jason D.,Tonks, Ian A.
-
supporting information
p. 7267 - 7281
(2018/05/29)
-
- Dehydrogenation of the NH?NH Bond Triggered by Potassium tert-Butoxide in Liquid Ammonia
-
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
-
supporting information
p. 870 - 873
(2017/01/14)
-
- Ruthenium-catalyzed meta/ortho-selective C-H alkylation of azoarenes using alkyl bromides
-
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
-
supporting information
p. 1261 - 1264
(2017/02/05)
-
- 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
-
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
-
supporting information
p. 442 - 451
(2016/01/30)
-
- Palladium-Catalyzed Oxidative Synthesis of Unsymmetrical Azophenols
-
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
-
p. 1850 - 1857
(2016/03/15)
-
- AgNO3 as nitrogen source for rhodium(III)-catalyzed synthesis of 2-aryl-2H -benzotriazoles from azobenzenes
-
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
-
supporting information
p. 9589 - 9592
(2016/08/01)
-
- Mechanistic insight into the Z-E isomerization catalysis of azobenzenes mediated by bare and core-shell gold nanoparticles
-
We explored the catalytic effect of 15 nm diameter gold nanoparticles (AuNPs) upon the thermal Z-E isomerization reaction of azobenzene and nine 4 and 4-4′ substituted azobenzenes (ABs). The kinetics follows a first order rate in ranges of [ABs] = 5 to 50
- Simoncelli, Sabrina,Aramendía, Pedro F.
-
p. 2110 - 2116
(2015/04/14)
-
- Rhenium-Catalyzed [4 + 1] Annulation of Azobenzenes and Aldehydes via Isolable Cyclic Rhenium(I) Complexes
-
The first Re-catalyzed [4 + 1] annulation of azobenzenes with aldehydes was developed to furnish 2H-indazoles via isolable and characterized cyclic ReI-complexes. For the first time, the acetate-acceleration effect is showcased in Re-catalyzed C-H activation reactions. Remarkably, mechanistic studies revealed an irreversible aldehyde-insertion step, which is in sharp contrast to those of previous Rh- and Co-systems. (Chemical Presented).
- Geng, Xiaoyu,Wang, Congyang
-
supporting information
p. 2434 - 2437
(2015/05/27)
-
- Palladium-catalyzed regioselective decarboxylative alkylation of arenes and heteroarenes with aliphatic carboxylic acids
-
An unprecedented Pd(OAc)2-catalyzed decarboxylative alkylation of unactivated arenes, with aliphatic carboxylic acids as inexpensive alkyl sources, is reported. The alkylation, controlled by the directing group, is regioselective, shows high functional group tolerance, and provides mild access to alkylated indolines, 2-phenylpyridines, and azobenzenes under solvent-free conditions in moderate to high yields.
- Premi, Chanchal,Dixit, Ankit,Jain, Nidhi
-
supporting information
p. 2598 - 2601
(2015/06/16)
-
- Palladium-Catalyzed sp2 C-H Arylation of Azoarenes with Arylhydrazines
-
Transition-metal-catalyzed direct functionalization of C-H bonds is important for new compound synthesis, but usually needs special reagents and harsh conditions. With the aid of an azo directing group, the palladium-catalyzed ortho-sp2 C-H bond activation of azoarenes with hydrazines has been explored. In the reaction, the Pd catalyst reacts with azobenzene to form a palladacyclic intermediate, which reacts with a phenyl radical generated from phenylhydrazine under heating and oxygen to produce a PdIV or PdIII intermediate. This finally undergoes reductive elimination to give the ortho-arylated products with the release of the PdII catalyst. This reaction provides a novel access to ortho-aryl azoarenes under mild conditions in high yield. Helpful hydrazines: With the aid of an azo directing group, the palladium-catalyzed ortho-sp2 C-H bond activation of azoarenes with hydrazines has been explored. The catalyst reacts with azobenzene to form a palladacyclic intermediate, which reacts with a phenyl radical generated from phenylhydrazine produce a PdIV or PdIII intermediate. This undergoes reductive elimination to give the ortho-arylated products and regenerate the catalyst. This reaction provides a novel access to ortho-aryl azoarenes under mild conditions in high yield.
- Li, Mingyang,Ye, Yong
-
p. 4137 - 4142
(2015/12/26)
-
- Mechanistic insights into N - N bond cleavage in catalytic guanylation reactions between 1,2-diarylhydrazines and carbodiimides
-
Cleavage of the N - N bond in 1,2-diarylhydrazine was achieved through an alkyllithium-catalyzed guanylation reaction of 1,2-diarylhydrazine with carbodiimide, affording guanidine and azo compounds. This N - N bond cleavage via thermal rearrangement was d
- Xu, Ling,Wang, Yu-Chen,Ma, Wangyang,Zhang, Wen-Xiong,Xi, Zhenfeng
-
p. 12004 - 12009
(2015/02/19)
-
- Reduced graphene oxide as a recyclable catalyst for dehydrogenation of hydrazo compounds
-
Reduced graphene oxide served as a reusable and efficient carbocatalyst for aerobic oxidative dehydrogenation of hydrazo compounds. Azo compounds were obtained in high yields under mild reaction conditions.
- Bai, Li-Sha,Gao, Xiao-Min,Zhang, Xuan,Sun, Fei-Fei,Ma, Ning
-
supporting information
p. 4545 - 4548
(2014/12/10)
-
- Palladium-catalyzed ortho-functionalization of azoarenes with aryl acylperoxides
-
With the aid of an azo directing group, Pd-catalyzed ortho-sp2 C-H bond activation/functionalization of azoarenes with aryl acyl peroxides has been explored. This transformation provides easy access to regioselectively introducing acyloxyl and aryl groups into azoarenes by simply changing the reaction temperature and solvent. This journal is the Partner Organisations 2014.
- Qian, Cheng,Lin, Dongen,Deng, Yuanfu,Zhang, Xiao-Qi,Jiang, Huanfeng,Miao, Guang,Tang, Xihao,Zeng, Wei
-
p. 5866 - 5875
(2014/08/05)
-
- Palladium(II)-catalyzed direct regioselectively oxidative acylation of azobenzenes with toluene derivatives
-
A highly efficient and practical procedure to acylazobenzene via Pd-catalyzed oxidative C-H bond activation from toluene has been developed. Various mono- and diacylazobenzene were afforded simultaneously in moderate to excellent yields for 33 examples. Toluene and its derivatives were served as potential and ideal acylation reagents. The mono- and diacylated products could be controlled by the oxidant loading.
- Song, Hongyu,Chen, Dong,Pi, Chao,Cui, Xiuling,Wu, Yangjie
-
p. 2955 - 2962
(2014/05/06)
-
- Synthesis of 2-Aryl-2 H-benzotrizoles from azobenzenes and N-sulfonyl azides through sequential rhodium-catalyzed amidation and oxidation in one pot
-
An efficient synthetic method of 2-aryl-2H-benzotriazoles from nonprefunctionalized azobenzenes and N-sulfonyl azides via sequential Rh-catalyzed amidation (C-N bond formation) and oxidation (N-N bond formation) with PhI(OAc)2 in one pot is reported.
- Ryu, Taekyu,Min, Jiae,Choi, Wonseok,Jeon, Woo Hyung,Lee, Phil Ho
-
supporting information
p. 2810 - 2813
(2014/06/23)
-
- Oxidative dimerization of (hetero)aromatic amines utilizing t-BuOI leading to (hetero)aromatic azo compounds: Scope and mechanistic studies
-
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
-
p. 12090 - 12105
(2014/01/06)
-
- Gold nanoparticle catalysis of the cis-trans isomerization of azobenzene
-
Ablated, "pseudo-naked" gold nanoparticles (AuNPs) catalyze the cis-trans isomerization of substituted azobenzenes. para-Substitution was found to affect the rate of isomerization, suggesting the participation of AuNP-mediated electron transfer in the isomerization mechanism. The Royal Society of Chemistry 2013.
- Hallett-Tapley, Geniece L.,D'Alfonso, Claudio,Pacioni, Natalia L.,McTiernan, Christopher D.,Gonzalez-Bejar, Maria,Lanzalunga, Osvaldo,Alarcon, Emilio I.,Scaiano, Juan C.
-
supporting information
p. 10073 - 10075
(2013/10/22)
-
- Facile Cu(I)-catalyzed oxidative coupling of anilines to azo compounds and hydrazines with diaziridinone under mild conditions
-
A mild and highly efficient Cu(I)-catalyzed oxidative coupling of anilines is described. Various primary and secondary anilines can be efficiently coupled under mild conditions to the corresponding azo compounds and hydrazines in high yields. This method provides a direct and practical access to these compounds and is also amenable to gram scale with no special precautions to exclude air or moisture.
- Zhu, Yingguang,Shi, Yian
-
supporting information
p. 1942 - 1945
(2013/06/04)
-
- A practical synthesis of azobenzenes through oxidative dimerization of aromatic amines using tert-butyl hypoiodite
-
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
-
supporting information
p. 1029 - 1033
(2013/05/09)
-
- Palladium-catalyzed cascade oxidation/ sp 2 C-H acylation of azoarenes with aryl methanes
-
A Pd-catalyzed cascade oxidation/sp2 C-H bond acylation of azoarenes was developed in which readily available aryl methanes were used as the in situ generated acyl sources. This reaction provides a convenient access to ortho-acyl azoarenes under mild conditions.
- Xiong, Feng,Qian, Cheng,Lin, Dongen,Zeng, Wei,Lu, Xiaoxia
-
supporting information
p. 5444 - 5447
(2013/11/19)
-
- Study of halogen-mediated weak interactions in a series of halogen-substituted azobenzenes
-
The azobenzenes, known for their various importance in the industry, have been chosen as model compounds to understand the role of weak interactions involving the C-X (X = F, Cl, and Br) bond using single-crystal X-ray diffraction technique, especially in the absence of other stronger intermolecular forces such as hydrogen bonds. The fluorinated compounds have been found to pack in the lattice by utilizing C-H···F hydrogen bonds, whereas the chlorinated and brominated analogues have been found to prefer C-X···X-C, C-X···π, and π···π interactions while packing in the lattice. The stabilization energy offered by the C-H···F hydrogen bonds and the C-X···X-C interactions have been estimated by computational methods using Gaussian 09, and the topological properties have been determined by using the AIM2000 package. The lattice energy decomposition has been done using semiclassical density sums (SCDS) PIXEL method. Our studies indicate that the stabilization energy offered by each C- H···F hydrogen bond lies in the range from -0.8 to -1.0 kcal/mol, while that for the C-X···X-C interaction has been found to be -0.35 kcal/mol for the X = Cl interaction and -0.73 kcal/mol for the X = Br interaction. Further, the analysis of these interaction by atoms in molecules (AIM) theory indicates that the electron densities (ρc) at the bond critical points (BCP) for C-H···F and C-X···X-C (X = Cl and Br), calculated using the AIM2000 package, are small (-3), and the values of Laplacian (?2ρc) are positive. This indicates that these interactions are of the hydrogen bond type. A detailed study of these interactions by experimental and computational methods has been described in the manuscript.
- Karanam, Maheswararao,Choudhury, Angshuman Roy
-
p. 4803 - 4814
(2013/12/04)
-
- Oxidative dimerization of aromatic amines using tBuOI: Entry to unsymmetric aromatic azo compounds
-
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
-
supporting information; experimental part
p. 7804 - 7808
(2012/09/05)
-
- Copper-catalyzed aerobic oxidative dehydrogenative coupling of anilines leading to aromatic azo compounds using dioxygen as an oxidant
-
In the air tonight: A novel approach to symmetric and unsymmetric aromatic azo compounds from simple anilines catalyzed by inexpensive CuBr has been disclosed. Air (or dioxygen) was used as an oxidant under mild reaction conditions, with H2O as the byproduct, to make this transformation environmentally benign and very easy to handle.
- Zhang, Chun,Jiao, Ning
-
supporting information; experimental part
p. 6174 - 6177
(2010/11/18)
-
- Oxidation of anilines with hydrogen peroxide and selenium dioxide as catalyst
-
A variety of substituted anilines are selectively oxidized to afford high yields of azoxyarenes by using 30% hydrogen peroxide and selenium dioxide as catalyst in methanol at room temperature. The oxidation of 4-alkoxyanilines under the same reaction conditions furnishes the corresponding 4-alkoxy-N-(4-nitrophenyl)anilines in reasonable yields, alongside other oxidation byproducts. The structure of 4-methoxy-N-(4-nitrophenyl)aniline is elucidated by X-ray crystal structure analysis. From these results, some general aspects of the reaction pathways of aniline oxidation are discussed.
- Gebhardt, Christin,Priewisch, Beate,Irran, Elisabeth,Rueck-Braun, Karola
-
scheme or table
p. 1889 - 1894
(2009/04/04)
-
- Oxidation of primary aromatic amines under irradiation with ultrasound and/or microwaves
-
The oxidation of primary aromatic amines, p-methylaniline, p-ethylaniline and p-chloroaniline to the corresponding azo- and azoxy-compounds has been observed in ultrasound and/or microwaves systems. The individual irradiation of microwaves and its simultaneous irradiation with ultrasound obviously elevate the conversion of amines, as compared with the individual irradiation of ultrasound and the heating in a plain water bath. However, the formation of formamidine resulted in poor selectivity toward azo and azoxy products in the presence of dimethylformamide (DMF). Copyright Taylor & Francis Group, LLC.
- Wu, Zhilin,Ondruschka, Bernd,Cravotto, Giancarlo,Garella, Davide,Asgari, Jila
-
p. 2619 - 2624
(2008/12/22)
-
- Copper(I)-catalysed homo-coupling of aryldiazonium salts: synthesis of symmetrical biaryls
-
Copper(I) triflate acts as an efficient stoichiometric reagent for the homo-coupling of aryldiazonium salts bearing electron-withdrawing group(s), to yield symmetrical biaryls in acetonitrile under mild reaction conditions. Aryldiazonium salts bearing electron-donating groups undergo the reaction by using catalytic amounts of a copper complex prepared in situ from copper(II) triflate and 2,2′-bipyridine with metallic copper as an ultimate reductant.
- Cepanec, Ivica,Litvi?, Mladen,Udikovi?, Josipa,Pogoreli?, Ivan,Lovri?, Marija
-
p. 5614 - 5621
(2007/12/29)
-
- Reactions of dry arenediazonium o-benzenedisulfonimides with triorganoindium compounds
-
The reaction between various arenediazonium o-benzenedisulfonimides and triorganoindium compounds is described. Depending on the reaction conditions, it is possible to obtain biaryls (16 examples, average yield of 79%) or diaryldiazenes (18 examples, average yield of 81 %). o-Benzenedisulfonimide can be recovered and reused to prepare additional arenediazonium o-benzenedisulfonimides. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Barbero, Margherita,Cadamuro, Silvano,Dughera, Stefano,Giaveno, Cinzia
-
p. 4884 - 4890
(2007/10/03)
-
- An efficient and general method for the deoxygenation of organic N-oxides using Zn(OTf)2 and Cu(OTf)2
-
A mild and efficient general method for the deoxygenation of organic N-oxides such as azoxybenzenes, N-arylnitrones, and N-heteroarene N-oxides using Zn(OTf)2 and Cu(OTf)2 in excellent yields is described. Georg Thieme Verlag Stuttgart.
- Saini, Anil,Kumar, Sanjay,Sandhu, Jagir S.
-
p. 395 - 398
(2007/10/03)
-
- Pyrazolidine-3,5-diones and 5-hydroxy-1H-pyrazol-3(2H)-ones, inhibitors of UDP-N-acetylenolpyruvyl glucosamine reductases
-
A series of pyrazolidine-3,5-dione and 5-hydroxy-1H-pyrazol-3(2H)-one inhibitors of Escherichia coli UDP-N-acetylenolpyruvyl glucosamine reductase (MurB) has been prepared. The 5-hydroxy-1H-pyrazol-3(2H)-ones show low micromolar IC50 values versus E. coli MurB and submicromolar minimal inhibitory concentrations (MIC) against Staphylococcus aureus GC 1131, Enterococcus faecalis GC 2242, Streptococcus pneumoniae GC 1894, and E. coli GC 4560 imp, a strain with increased outer membrane permeability. None of these compounds show antimicrobial activity against Candida albicans, a marker of eukaryotic toxicity. Moreover, these compounds inhibit peptidoglycan biosynthesis, as assessed by measuring the amount of soluble peptidoglycan produced by Streptococcus epidermidis upon incubation with compounds. A partial least squares projection to latent structures analysis shows that improving MurB potency and MIC values correlate with increasing lipophilicity of the C-4 substituent of the 5-hydroxy-1H-pyrazol-3(2H)-one core. Docking studies using FLO and PharmDock produced several binding orientations for these molecules in the MurB active site.
- Gilbert, Adam M.,Failli, Amedeo,Shumsky, Jay,Yang, Youjun,Severin, Anatoly,Singh, Guy,Hu, William,Keeney, David,Petersen, Peter J.,Katz, Alan H.
-
p. 6027 - 6036
(2007/10/03)
-
- A general method for the deoxygenation of aromatic N-oxides using RuCl 3?xH2O
-
An efficient, simple and selective method for the deoxygenation of aromatic N-oxides, such as N-arylnitrones, azoxybenzenes, N-heteroarene N-oxides using ruthenium(III) chloride to afford deoxygenated products in excellent yields, is described.
- Kumar, Sanjay,Saini, Anil,Sandhu, Jagir S.
-
p. 8737 - 8739
(2007/10/03)
-
- Amination of benzylic C-H bonds by arylazides catalyzed by CoII-porphyrin complexes: A synthetic and mechanistic study
-
CoII-porphyrin complexes catalyze the reaction of aromatic azides (ArN3) with hydrocarbons that contain a benzylic group (ArR1R2CH) to give the corresponding amines (ArR1R2C-HAr). When at least one of the R substituents is hydrogen, the catalytic reaction proceeds further to give the imine ArRC=NAr in good yields. The reaction mechanism has been investigated. The reaction proceeds through a reversible coordination of the arylazide to the ConII-porphyrin complex. This unstable adduct can either react with the hydrocarbon in the rate-determining step or decompose by a unimolecular mechanism to afford a putative nitrene complex, which reacts with more azide, but not with the hydrocarbon, to afford the byproduct diaryldiazene. The kinetics of the catalytic reaction have been investigated for a range of azides and substituted toluenes. Arvlazides with electron-withdrawing substituents react at a faster rate and a good correlation is found between the log(k) and the Taft parameters. On the other hand, an excellent correlation between the logarithm of the rate for substituted toluenes relative to that of toluene and a radical parameter (σJJ) alone was found, with no significant contribution by polar parameters. An explanation has been proposed for this anomalous effect and for the very high isotopic effect (kH/kD= 14) found.
- Ragaini, Fabio,Penoni, Andrea,Gallo, Emma,Tollari, Stefano,Li Gotti, Claudia,Lapadula, Marta,Mangioni, Enrica,Cenini, Sergio
-
p. 249 - 259
(2007/10/03)
-
- Lead-Catalyzed Synthesis of Azo Compounds by Ammonium Acetate Reduction of Aromatic Nitro Compounds
-
Lead/ammonium acetate is a convenient reagent for the reduction of aromatic nitro compounds to the corresponding symmetrically substituted azo compounds. Various azo compounds containing additional reducible substituents such as halogen, nitrile, acid, phenol, ester, methoxy, etc., functions have been synthesized in a single step by the use of this reagent. The conversion is reasonably fast, clean, high yielding and occurs at room temperature in methanol.
- Srinivasa,Abiraj,Gowda, D. Channe
-
p. 4221 - 4227
(2007/10/03)
-
- Preparation of diazenes by electrophile C-coupling reactions of dry arenediazonium o-benzenedisulfonimides with Grignard reagents
-
The diaryldiazenes (19 examples) and aryl(tertbutyl)diazenes (3 examples) 3 were prepared by electrophilic C-coupling reactions of dry arenediazonium o-benzenedisulfonimides 1 with Grignard reagents. The reactions were carried out in anhyd THF at -78°C un
- Barbero, Margherita,Degani, Iacopo,Dughera, Stefano,Fochi, Rita,Perracino, Paolo
-
p. 1235 - 1237
(2007/10/03)
-
- Dimerization of Anilines and Benzylamines with Mercury(II) Oxide-Iodine Reagent
-
By treatment with mercury(II) oxide-iodine reagent in dichloromethane at room temperature, substituted anilines were transformed to the corresponding azobenzenes. A similar treatment of benzylamines and benzhydrylamine gave N-benzylidenebenzylamines and N-benzhydrylidene-benzhydrylamine, respectively. α-Alkyl-substituted benzylamines gave diazenes and the corresponding phenyl ketones, competitively. An azine was obtained by interaction with the reagent of a benzylamine carrying an electron-withdrawing substituent at the α position, such as ethyl phenylglycinate.
- Orito, Kazuhiko,Hatakeyama, Takahiro,Takeo, Mitsuhiro,Uchiito, Shiho,Tokuda, Masao,Suginome, Hiroshi
-
p. 8403 - 8410
(2007/10/03)
-
- N-ALKYLATION AND N-ARYLATION OF ANILINES STARTING FROM A MILD N-Mg REAGENT: ITS ACTIVATION CAUSING THE 'N-C' COUPLING TO EXTEND THE UNIFIED STRUCTURE-REACTIVITY RELATIONSHIP
-
New N-alkylation and N-arylation procedures starting from anilinomagnesium (ArNHMgBr) are reported.For N-alkylation with alkyl bromides, addition of hexamethylphosphoramide to an ArNHMgBr solution in tetrahydrofuran (THF) is effective.After heating at 55 deg C, N-monoalkylation product was obtained in 60-90percent yield, slight dialkylation taking place.The combined use of aryliminodimagnesium with α,ω-dibromoalkanes led to N-arylazacycloalkanes.For N-arylation with iodobenzene, replacement of THF with pyridine and additional use of copper(I) iodide are effective.After heating at 115 deg C with iodobenzene, mono- and diarylation products were obtained, the former being predominant.The combined use of ArNHMgBr and N,N,N',N'-tetramethylethylenediamine as the ligand of copper species is effective for elimination of diarylation and other undesired products, and leads to diarylamines in excellent yield.The method is of advantage over the conventional Ullmann and Chapman methods.The polar solvents and copper salt are effective additives for inducing 'inert combinations' of ArNHMgBr or ArN(MgBr)2 with alkyl and aryl halides into N-C coupling, to extend the unified view proposed for the reactivity of magnesium reagents.The difference in the roles of N-Mg and N-Cu species is discussed.
- Matsuo, Koji,Shichida, Yoshiaki,Nishida, Hiroshi,Nakata, Satsuki,Okubo, Masao
-
-
- COOPERATION OF ARYLIMINODIMAGNESIUM MOLECULES: DEOXYGENATION OF AZOXYARENES BY MONO- AND BIFUNCTIONAL REAGENTS IN COMPARISON WITH THAT BY PHOSPHORUS(III) REAGENTS
-
Reaction of aryliminodimagnesium with nitrobenzene (Ar1NO2) in tetrahydrofuran (THF) gives unsymmetrical (unsym) azoxybenzene, which is deoxygenated to give unsym-azobenzene.The reaction is utilized for the independent prepar
- Okubo, Masao,Inatomi, Yoshito,Eguchi, Izumi,Nishida, Hiroshi,Gotoh, Seiji,Matsuo, Koji
-
-
- An Efficient General Method for the Deoxygenation of N-Arylnitrones, Azoxybenzenes, and N-Heteroarene N-Oxides
-
A new general method for the deoxygenation of N-oxides such as N-arylnitrones, azoxybenzenes, and N-heteroarene N-oxides uses aluminum iodide in acetonitrile.The deoxygenated products are obtained in high yields.
- Konwar, Dilip,Boruah, Romesh C.,Sandhu, Jagir S.
-
p. 337 - 339
(2007/10/02)
-
- 1,2-Didehydroazepines from the Photolysis of Substituted Aryl Azides: Analysis of Their Chemical and Physical Properties by Time-Resolved Spectroscopic Methods
-
A series of substituted 1,2-didehydroazepines was prepared by photolysis of their precursor aryl azides.The chemical and physical properties of the didehydroazepines were probed by means of conventional chemical trapping experiments and by time-resolved spectroscopy with IR and UV detection.The didehydroazepines are formed from the azides with efficiencies that depend systematically on the nature of the substituent.In some cases, didehydroazepines are not formed at all.The didehydroazepines react relatively rapidly with starting aryl azide and with added amines.The rate of their reaction is largely controlled by the electronic properties of the substituent on the didehydroazepine.These results permit prediction of the reactivity of didehydroazepines from their structure.
- Li, Yu-Zhuo,Kirby, John P.,George, Michael W.,Poliakoff, Martyn,Schuster, Gary B.
-
p. 8092 - 8098
(2007/10/02)
-