- Nickel(II)- And Silver(I)-Catalyzed C-H Bond Halogenation of Anilides and Carbamates
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ortho -C-H bond halogenation of anilides and N -aryl carbamates using easily available N -halosuccinimides (NXS) as the active halogenation reagent in the presence of nickel or silver catalyst has been developed. This method provides a new approach to 2-haloanilides and carbamates, which may serve as starting materials for the synthesis of pharmaceutically and biologically active compounds.
- Kianmehr, Ebrahim,Afaridoun, Hadi
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p. 1513 - 1523
(2020/12/14)
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- Site-Specific Synthesis of Carbazole Derivatives through Aryl Homocoupling and Amination
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We synthesized various carbazoles from anilines through a three-step process with good overall yields (up to 48percent). This process comprises N -acetylation, copper(0)-mediated Ullmann homocoupling, and acid-mediated intramolecular amination. It permits various functional groups on the substrate. Scale-up of the developed three-step synthetic route to carbazoles was also demonstrated.
- Baek, Junghyun,Ban, Jaeyoung,Lim, Minkyung,Rhee, Hakjune,Shabbir, Saira
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p. 917 - 927
(2020/03/13)
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- Aromatic Halogenation Using N-Halosuccinimide and PhSSiMe3 or PhSSPh
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We developed a mild aromatic halogenation reaction using a combination of N-halosuccinimide and PhSSiMe3 or PhSSPh. Less reactive aromatic compounds, such as methyl 4-methoxybenzoate, were brominated with PhSSiMe3 or PhSSPh and N-bromosuccinimide in high yields. No reaction was observed in the absence of PhSSiMe3 or PhSSPh. This method is also applicable to chlorination reactions using N-chlorosuccinimide and PhSSPh.
- Hirose, Yuuka,Yamazaki, Mirai,Nogata, Misa,Nakamura, Akira,Maegawa, Tomohiro
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p. 7405 - 7410
(2019/06/14)
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- A Visible Light-Mediated Regioselective Halogenation of Anilides and Quinolines by Using a Heterogeneous Cu-MnO Catalyst
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A simple and practical heterogeneous Cu-MnO catalyzed regioselective halogenation of anilides and quinolines under irradiation with household 40 W incandescent lamp was developed. This method uses a recyclable Cu-MnO catalyst, acetonitrile as an industrially friendly solvent, and economic N-halo succinimides as a halogenating source. The reaction is scalable and well tolerated with a broad range of functional groups.
- Singh, Harshvardhan,Sen, Chiranjit,Sahoo, Tapan,Ghosh, Subhash Chandra
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p. 4748 - 4753
(2018/09/06)
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- Cobalt(II)-catalyzed regioselective C-H halogenation of anilides
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A cobalt-catalyzed regioselective C-H halogenation methodology is reported herein. The highlight of this work is the highly selective C-H functionalization of anilides, which results in high-yielding, versatile, and practical halogenated products. Thereby, brominations, chlorinations and iodinations of many electron-rich and electron-deficient anilides were achieved in a highly selective fashion. Mechanistic studies with respect to the pathway of the reaction are also described.
- Li, Ze-lin,Sun, Kang-kang,Cai, Chun
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supporting information
p. 5433 - 5440
(2018/08/12)
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- Synthesis of 2-methylbenzoxazoles directly from: N -phenylacetamides catalyzed by palladium acetate
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A method to synthesize 2-methylbenzoxazoles directly from N-phenylacetamides catalyzed by Pd(OAc)2 in the presence of K2S2O8 and TfOH has been developed. The desired products were obtained in moderate to excellent yields. This approach provides a facile procedure to prepare benzoxazoles with available substrates. It is found that TfOH is the key factor for this cyclization reaction. A plausible mechanism of the reaction is proposed according to the control reactions and the literature.
- Wang, Biying,Jiang, Chengfei,Qian, Jiasheng,Zhang, Shuwei,Jia, Xiaodong,Yuan, Yu
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p. 101 - 107
(2017/12/27)
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- Combining Eosin y with Selectfluor: A Regioselective Brominating System for Para-Bromination of Aniline Derivatives
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A mild, metal-free, and absolutely para-selective bromination of aniline derivatives has been developed in excellent yields, wherein the organic dye Eosin Y is employed as the bromine source in company with Selectfluor. Neither air nor moisture sensitive, this facile reaction proceeds smoothly at room temperature and completes within a short time. Mechanistic studies indicate a radical pathway; therefore, the existence of an in situ generated brominating reagent, "Selectbrom", is postulated, which may reasonably account for the unique regioselectivity for the para-bromination of N-acyl- as well as N-sulfonylanilines.
- Huang, Binbin,Zhao, Yating,Yang, Chao,Gao, Yuan,Xia, Wujiong
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supporting information
p. 3799 - 3802
(2017/07/26)
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- Palladium-Catalyzed, ortho-Selective C-H Halogenation of Benzyl Nitriles, Aryl Weinreb Amides, and Anilides
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A palladium-catalyzed, ortho-selective C-H halogenation methodology is reported herein. The highlight of the work is the highly selective C(sp2)-H functionalization of benzyl nitriles in the presence of activated C(sp3)-H bond, which results in good yields of the halogenated products with excellent regioselectivity. Along with benzyl nitriles, aryl Weinreb amides and anilides have been evaluated for the transformation using aprotic conditions. Mechanistic studies yield interesting aspects with respect to the pathway of the reaction and the directing group abilities.
- Das, Riki,Kapur, Manmohan
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p. 1114 - 1126
(2018/06/18)
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- Monoprotected l-Amino Acid (l-MPAA), Accelerated Bromination, Chlorination, and Iodination of C(sp2)?H Bonds by Iridium(III) Catalysis
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Halogenated arenes are important structural motifs commonly found in biologically active molecules and used for a variety of transformations in organic synthesis. Herein, we report the mono-protected l-amino acid (l-MPAA) accelerated iridium(III)-catalyzed halogenation of (hetero)anilides at room temperature. This reaction constitutes the first example of an iridium(III)/l-MPAA-catalyzed general halogenation of (hetero)arenes through C(sp2)?H activation. Furthermore, we demonstrate the potential utility of our method through its use in the synthesis of a quinolone derivative.
- Kathiravan, Subban,Nicholls, Ian A.
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supporting information
p. 7031 - 7036
(2017/05/29)
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- Metal-Free Oxidative C=C Bond Cleavage of Electron-Deficient Enamines Promoted by tert -Butyl Hydroperoxide
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A novel tert -butyl hydroperoxide (TBHP)-promoted oxidative C=C double-bond cleavage of enamines is described. Heating a solution of an electron-deficient enamine in chlorobenzene at 80 °C in the presence of TBHP for two hours led to cleavage of the C=C bond. This study offers a new strategy to carry out C=O double-bond formation by the use of TBHP.
- Adib, Mehdi,Pashazadeh, Rahim,Gohari, Seyed Jamal Adin,Shahsavari, Fatemeh
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supporting information
p. 1481 - 1485
(2017/08/15)
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- Regioselective and efficient bromination of anilides on water using HBr and Selectfluor
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A metal-, additive-, and Br2-free highly regioselective bromination of anilides using HBr and Selectfluor is presented. This reaction proceeded under mild conditions with high efficiency and good functional group tolerance, and water served as the solvent. In general, with substrates bearing no para-substituent, para-mono-bromination occurred exclusively, while ortho-mono-brominated anilides were the only products when para-positions were blocked. The incorporation of a stronger orienting group might result in a reversed regioselectivity, and the reaction was sensitive to steric hindrance.
- Liang, Deqiang,Li, Xiangguang,Wang, Chaowu,Dong, Qishan,Wang, Baoling,Wang, Hai
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supporting information
p. 5390 - 5394
(2016/11/11)
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- Preparation method of scandium diboride
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The invention discloses a preparation method of scandium diboride, and relates to the chemical industry technical field; p-methylacetanilide is obtained through acetylation and bromization, then is used as a raw material and is subjected to an acidification reaction to obtain hydrochloride, then the hydrochloride as a raw material is subjected to a neutralization reaction to obtain scandium diboride. The preparation method has the beneficial effects of convenient and simple preparation, environmental protection, no pollution, easy available raw materials, low equipment investment, high purity and convenient operation, and the obtained product is good in using effect, and is safe and reliable.
- -
-
Paragraph 0023; 0024; 0025; 0026
(2016/12/01)
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- Nuclear versus side-chain bromination of 4-methoxy toluene by an electrochemical method
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GRAPHICAL ABSTRACT The electrochemical bromination of 4-methoxy toluene by two-phase electrolysis yields 3-bromo 4-methoxy toluene at first, which subsequently undergoes side-chain bromination to give 3-bromo 4-methoxy benzyl bromide as a final product in 86% yield. The two-phase electrolysis consists of 25-50% NaBr as aqueous electrolyte and CHCl3 containing aromatic compound as organic phase. The reaction temperature is maintained at 10-25 °C. The probable orientation of bromine atom in an alkyl aromatic compound (nuclear versus side chain) is explained from the experimental result.
- Kulangiappar,Anbukulandainathan,Raju
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p. 2494 - 2502
(2014/08/05)
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- Novel synthesis and antimicrobial activity of 3-substituted 5-bromo-7-methyl-1,2,4-triazolo-[3,4-b]-benzothiazoles
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4-Methyl acetanilide (1) on treatment with bromine in acetic acid, followed by hydrolysis with dilute HCl/NaOH solution, yielded 2-bromo-4-methyl aniline (2), which on treatment with sodium thiocyanate in acetic acid afforded 2-amino-4-bromo-6-methyl benzothiazole (3). Compound 3 in ethylene glycol was heated at 150°C with 80% hydrazine hydrate to get 4-bromo-2-hydrazino-6- methyl benzothiazole (4). This hydrazino compound 4 on heating with formic acid for 3 h yielded 4-bromo-2-hydrazinoformyl-6-methyl benzothiazole (5). Same compound 4 when heated independently with formic acid for 6 h/urea for 3 h/carbon disulfide in alkali afforded 5-bromo-7-methyl (6)/5-bromo-3-hydroxy-7- methyl (7)/5-bromo-3-mercapto-7-methyl (8)-1,2,4-triazolo-[3,4-b]- benzothiazoles, respectively. Compound 4 on heating with acetic acid/acetic anhydride gave acetyl benzothiazolyl derivative 9, which on cyclization with orthophosphoric acid yielded 5-bromo-3,7-dimethyl-1,2,4-triazolo-[3,4-b]- benzothiazole (10). All these newly synthesized compounds were screened for antimicrobial activity against Escherichia coli (Gram -ve), Bacillus subtilis (Gram +ve), Erwinia carotovora, and Xanthomonas citri using ampicillin, streptomycin, and penicillin as a standard for comparison.
- Bhagat,Deshmukh,Kuberkar
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p. 873 - 876
(2012/10/30)
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- Mild C - H halogenation of anilides and the isolation of an unusual palladium(I)-palladium(II) species
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Reducing the load: A facile palladium-catalyzed ortho-selective bromination and chlorination of anilides occurs under aerobic conditions at room temperature when N-halosuccinimides (NXS) are used in the presence of p-toluenesulfonic acid (PTSA). The orthopalladated PTSA complex is not only catalytically competent but also undergoes a reductive process to yield an unusual PdI-PdII tetramer (see structure; Pdgreen, Ored, Syellow, Cgray). Copyright
- Bedford, Robin B.,Haddow, Mairi F.,Mitchell, Charlotte J.,Webster, Ruth L.
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supporting information; experimental part
p. 5524 - 5527
(2011/07/31)
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- The use of sodium chlorate/hydrochloric acid mixtures as a novel and selective chlorination agent
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Sodium chlorate/hydrochloric acid mixtures were used to chlorinate activated arenes and the α-position of ketones. This chlorination method was used to produce selectively mono-, di-, and trichlorinated compounds by controlling the molarity of sodium chlorate. This reagent proved to be much more efficient and easier to handle than chlorine gas.
- Moon, Byung Seok,Choi, Han Young,Koh, Hun Yeong,Chi, Dae Yoon
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experimental part
p. 472 - 476
(2011/12/04)
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- A synthetic approach to carbazoles using electrochemically generated hypervalent iodine oxidant
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Carbazoles were successfully synthesized by oxidative cyclization of the corresponding diaryl derivatives using electrochemically generated hypervalent iodine oxidant. Electron-withdrawing nitro and donating methoxy groups at the para position of the acetamide group interfered with cyclization. Glycozoline (8) was successfully synthesized in five steps with 50% overall yield.
- Kajiyama, Daichi,Inoue, Keisuke,Ishikawa, Yuichi,Nishiyama, Shigeru
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scheme or table
p. 9779 - 9784
(2011/03/17)
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- Solvent free catalytic C-H functionalisation
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Solvent-free reaction conditions facilitate a range of aromatic C-H functionalisations that traditionally require acidic or disfavoured solvents. These reactions include selective ortho- and meta-arylation of aryl carbamates and anilides and selective halogenation reactions. The Royal Society of Chemistry 2010.
- Bedford, Robin B.,Mitchell, Charlotte J.,Webster, Ruth L.
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scheme or table
p. 3095 - 3097
(2010/08/04)
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- Solvent-free aromatic C-H functionalisation/halogenation reactions
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The solvent-free, palladium-catalysed reaction of anilides with CuCl 2 in the presence or absence of copper acetate yields ortho-chlorinated anilides in good to excellent yields, even on a large scale (100 mmol). By contrast, the equivalent reactions with copper bromide, either solvent free or in 1,2-dichloroethane, in the presence or absence of palladium, under air or inert conditions, gave the products of simple electrophilic bromination. Mechanistic studies highlighted the involvement of palladacyclic intermediates, one of which was characterised crystallographically, which undergo subsequent reaction with copper(ii) chloride to yield the chlorinated anilide products.
- Bedford, Robin B.,Engelhart, Jens U.,Haddow, Mairi F.,Mitchell, Charlotte J.,Webster, Ruth L.
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supporting information; experimental part
p. 10464 - 10472
(2011/01/05)
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- Silica-supported quinolinium tribromide: A recoverable solid brominating reagent for regioselective monobromination of aromatic amines
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Silica-supported quinolinium tribromide was synthesized and found to be an efficient, stable, and recoverable solid brominating reagent for the regioselective monobromination of aromatic amines. This protocol has advantages of high yield, mild condition and simple work-up procedure.
- Li, Zheng,Sun, Xiunan,Wang, Lue,Li, Yanbo,Ma, Yuanhong
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scheme or table
p. 496 - 501
(2010/08/06)
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- Highly effective Pd-catalyzed ortho olefination of acetanilides: Broad substrate scope and high tolerability
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Bring it on! An effective Pd-catalyzed ortho olefination of various acetanilides has been developed. This transformation has a broad substrate scope and wide functional-group tolerability, regardless of the electronic and steric properties of acetanilide substrates, providing a straightforward access to highly functionalized arenes.
- Kim, Byung Seok,Jang, Chungsik,Lee, Dong Jin,Youn, So Won
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supporting information; experimental part
p. 2336 - 2340
(2011/06/25)
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- Environmentally benign electrophilic and radical bromination 'on water': H2O2-HBr system versus N-bromosuccinimide
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A H2O2-HBr system and N-bromosuccinimide in an aqueous medium were used as a 'green' approach to electrophilic and radical bromination. Several activated and less activated aromatic molecules, phenylsubstituted ketones and styrene were efficiently brominated 'on water' using both systems at ambient temperature and without an added metal or acid catalyst, whereas various non-activated toluenes were functionalized at the benzyl position in the presence of visible light as a radical activator. A comparison of reactivity and selectivity of both brominating systems reveals the H2O2-HBr system to be more reactive than NBS for benzyl bromination and for the bromination of ketones, while for electrophilic aromatic substitution of methoxy-substituted tetralone it was higher for NBS. Also, higher yields of brominated aromatics were observed when using H2O2-HBr 'on water'. Bromination of styrene reveals that not just the structure of the brominating reagent but the reaction conditions: amount of water, organic solvent, stirring rate and interface structure, play a key role in defining the outcome of bromination (dibromination vs bromohydroxylation). In addition, mild reaction conditions, a straightforward isolation procedure, inexpensive reagents and a lower environment impact make aqueous brominating methods a possible alternative to other reported brominating protocols.
- Podgor?ek, Ajda,Stavber, Stojan,Zupan, Marko,Iskra, Jernej
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experimental part
p. 4429 - 4439
(2009/10/09)
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- Copper-catalyzed regiospecific synthesis of N-alkylbenzimidazoles
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(Chemical Equation Presented) A copper-catalyzed method is described for the preparation of N-alkylbenzimidazoles in regioisomerically pure form starting from o-haloanilines. The method utilizing CuI and trans-N,N′-dimethyl-1, 2-cyclohexanediamine allows the preparation of N-alkylbenzimidazoles in good to excellent yields.
- Zheng, Nan,Buchwald, Stephen L.
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p. 4749 - 4751
(2008/03/14)
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- Visible light induced 'on water' benzylic bromination with N-bromosuccinimide
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Benzylic bromination of various 4-substituted toluenes (Me, tert-Bu, COOEt and COMe) was effectively conducted with NBS in pure water and with a 40 W incandescent light-bulb as an initiator of the radical chain process, while electron donating groups (OMe and NHAc) directed the reaction to electrophilic aromatic substitution.
- Podgor?ek, Ajda,Stavber, Stojan,Zupan, Marko,Iskra, Jernej
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p. 1097 - 1099
(2007/10/03)
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- Association of fluorous "phase-vanishing" method with visible-light activation in benzylic bromination by bromine
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In this study the "phase-vanishing" method for diffusion-controlled addition of a reagent (Br2) to a reaction phase via a fluorous membrane (C8F18) is combined with an additional mode of activation (visible-light) to achieve the benzyl bromination of various alkyl-substituted aromatic compounds in a concentrated solution. Benzyl bromination of p-tert-butyl-toluene proceeded in various solvents including hexane and methanol, while the reaction of the neat substrate showed a similar selectivity as in carbon tetrachloride. The effect of the substituent on the para position of toluene on the course of bromination revealed three processes: benzyl bromination with H, Me, tBu and CO2Et substituents, aromatic bromination with OMe and NHAc substituents and the reaction of the 4-acetyl derivative at the substituent to form an α-bromo ketone. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Podgorsek, Ajda,Stavber, Stojan,Zupan, Marko,Iskra, Jernej
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p. 483 - 488
(2007/10/03)
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- Combined C-H functionalization/C-N bond formation route to carbazoles
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A new method in which a series of substituted carbazoles is efficiently produced by the combination of an amide and an arene is described. The key feature of this method is the palladium-catalyzed tandem directed C-H functionalization and amide arylation. The method tolerates substitution on either ring of the biaryl amide substrates, and the products can be assembled in a simple two-step protocol from readily available reagents. The Pd(0) species generated are reoxidized to Pd(II) in the presence of Cu(OAc)2 and an atmosphere of oxygen. Copyright
- Tsang, W. C. Peter,Zheng, Nan,Buchwald, Stephen L.
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p. 14560 - 14561
(2007/10/03)
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- Oxidative Bromination of Aromatic Amides using Sodium Perborate as Oxidant
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Sodium perborate in glacial acetic acid-acetic anhydride with potassium bromide and sodium tungstate as a catalyst, provides a novel system for the bromination of aromatic amides.
- Hanson, James R.,Harpel, Simone,Medina, Inmaculada C. Rodriguez,Rose, Dorian
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p. 432 - 433
(2007/10/03)
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- Convenient strategies for the preparation of modified 2(3H)-benzothiazolethiones
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4-Alkyl-2-bromoanilines and 4-alkoxy-2-chloroanilines were synthesized conveniently and submitted to cyclization reaction with potassium O-ethyl dithiocarbonate to afford 6-substituted 2(3H)-benzothiazolethiones in good yields.
- Chaudhuri, Narayan C.
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p. 3783 - 3790
(2007/10/03)
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- Catalysts for the Oxidative Bromination of Aromatic Amines and their N-Acetyl Derivatives
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In the nuclear bromination of aromatic amines by bromide and hydrogen peroxide in acetic acid, sodium tungstate has been compared with ammonium molybdate and ammonium vanadate, and found to be an effective catalyst.
- Hanson, James R.,Opakunle, Alexander,Petit, Philippe
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- REACTION OF HYDROGEN BROMIDE WITH N-(p-TOLYL)- AND N-(p-TOLYLSULFONYL)-1,4-BENZOQUINONE MONOIMINES
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In the reaction of hydrogen bromide with N-(p-tolyl)-1,4-benzoquinone monoimines bromination of the p-tolyl fragment takes place as well as nucleophilic addition.Bromination is fully suppressed by the addition of resorcinol to the reaction mass.In the case of N-(p-tolylsulfonyl)-1,4-benzoquinone monoimine the products from the entry of two bromine atoms at the ortho position to the oxygen atom are formed sucessively.
- Toropin, N. V.,Burmistrov, K. S.,Burmistrov, S. I.,Zaichenko, N. L.
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p. 894 - 899
(2007/10/02)
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- Kinetics of Bromination of Acetanilide and Some Substituted Acetanilides by N-Bromoacetamide
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Bromination of acetanilide and p-methyl-, p-chloro-, p-bromo- and p-nitro-acetanilides by N-bromoacetamide (NBA) in aqueous perchloric acid medium is first order in and fractional order in .The reaction is acid-catalysed with first order dependence in .The effects of varying ionic strength and dielectric constant of the solvent mixture are marginal.Added Cl(-) and Br(-) ions have a pronounced catalytic effect.A mechanism involving the formation of a N-halo intermediate followed by Orton rearrangement has been postulated.
- Murti, P. S. Radhakrishna,Sasmal, B. M.,Patnaik, D. P.
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p. 948 - 949
(2007/10/02)
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- Bromination of p-Acetotoluidide in Aqueous Medium: Substituent Effect
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The kinetics of bromination of p-acetotoluidide in aqueous solution has been studied using a rotating platinum electrode.The specific reaction rate and the energy of activation for the reaction at 25.4 deg C are 319 dm3 mol-1 s-
- Dangat, V. T.,Bonde, S. L.,Rohokale, G. Y.
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p. 237 - 238
(2007/10/02)
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