- One-pot synthesis of 2-aminobenzothiazoles using a new reagent of [Bmim]Br3 in [Bmim]BF4
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The one-pot direct synthesis of 2-aminobenzothiazoles from phenyl isothiocyanate and amines using a new reagent of 1-butyl-3-methylimidazolium tribromide ([Bmim]Br3) in ionic liquid 1-butyl-3-methyl-imidazolium tetraflouoroborate ([Bmim]BF4) is described.
- Le, Zhang-Gao,Xu, Jian-Ping,Rao, Huo-Yu,Ying, Min
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- Synthesis and properties of esters of benzothiazolylamino(imino)propionic acids
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Reaction of 2-alkylaminothiazoles with methyl acrylate leads predominantly to the formation of N-alkyl-N-(β-methoxycarbonylethyl)-2-aminobenzothiazoles on boiling or to 2-(alkylimino)-3-(β-methoxycarbonylethyl)-benzothiazolines at room temperature. A complex mixture of products was obtained from unsubstituted 2-aminobenzothiazole and methyl acrylate, of which the main was 2-oxo-3,4-dihydro-2H-pyrimido[2,1-b]benzothiazole. Complete or partial destruction of the benzothiazolines occurred on heating to 140°C. 1998 Plenum Publishing Corporation.
- Ambartsumova
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Read Online
- Borane-Trimethylamine Complex as a Reducing Agent for Selective Methylation and Formylation of Amines with CO2
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We report herein that a borane-trimethylamine complex worked as an efficient reducing agent for the selective methylation and formylation of amines with 1 atm CO2 under metal-free conditions. 6-Amino-2-picoline serves as a highly efficient catalyst for the methylation of various secondary amines, whereas in its absence, the formylation of primary and secondary amines was achieved in high yield with high chemoselectivity. Mechanistic studies suggest that the 6-amino-2-picoline-borane catalytic system operates like an intramolecular frustrated Lewis pair to activate CO2.
- Zhang, Yanmeng,Zhang, He,Gao, Ke
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supporting information
p. 8282 - 8286
(2021/10/25)
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- Recyclable covalent triazine framework-supported iridium catalyst for the N-methylation of amines with methanol in the presence of carbonate
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An iridium complex Cp*Ir@CTF, which is synthesized by the coordinative immobilization of [Cp*IrCl2]2 on a functionalized covalent triazine framework (CTF), was found to be a general and highly efficient catalyst for the N-methylation of amines with methanol in the presence of carbonate. Under environmentally benign conditions, a variety of desirable products were obtained in high yields with complete selectivities and functional group friendliness. Furthermore, the synthesized catalyst could be recycled by simple filtration without obvious loss of catalytic activity after sixth cycle. Notably, this research exhibited the potential of covalent triazine framework-supported transition metal catalysts for hydrogen autotransfer process.
- Liu, Peng,Yang, Jiazhi,Ai, Yao,Hao, Shushu,Chen, Xiaozhong,Li, Feng
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p. 281 - 290
(2021/03/26)
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- N-Methylation of Amines with Methanol in the Presence of Carbonate Salt Catalyzed by a Metal-Ligand Bifunctional Ruthenium Catalyst [(p-cymene)Ru(2,2′-bpyO)(H2O)]
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A ruthenium complex [(p-cymene)Ru(2,2′-bpyO)(H2O)] was found to be a general and efficient catalyst for the N-methylation of amines with methanol in the presence of carbonate salt. Moreover, a series of sensitive substituents, such as nitro, ester, cyano, and vinyl groups, were tolerated under present conditions. It was confirmed that OH units in the ligand are crucial for the catalytic activity. Notably, this research exhibited the potential of metal-ligand bifunctional ruthenium catalysts for the hydrogen autotransfer process.
- Liu, Peng,Tung, Nguyen Thanh,Xu, Xiangchao,Yang, Jiazhi,Li, Feng
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p. 2621 - 2631
(2021/02/27)
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- C-H Functionalization of Benzothiazoles via Thiazol-2-yl-phosphonium Intermediates
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Benzothiazoles undergo regioselective C2-H functionalization with triphenylphosphine to form thiazol-2-yl-triphenylphosphonium salts, and these phosphonium salts react with a wide range of O- A nd N-centered nucleophiles to give the corresponding ethers, amines, and C-N biaryls. The reactions proceed under mild conditions and allow for the recovery of triphenylphosphine at the end of the sequence. In the presence of hydroxide, phosphonium salts undergo disproportionation, resulting in the reduction of the benzothiazole, which is useful for specific C2 deuteration of benzothiazoles.
- Sch?mberg, Fritz,Vilotijevic, Ivan,Wagner, Konrad,Zi, You
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supporting information
(2020/05/05)
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- Bimetallic Bis-NHC-Ir(III) Complex Bearing 2-Arylbenzo[d]oxazolyl Ligand: Synthesis, Catalysis, and Bimetallic Effects
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Herein, an unprecedented bimetallic bis-NHC Cp*Ir complex 1 bearing 2-arylbenzo[d]oxazolyl and NHC ligands is reported. A significant increase in activity was observed for N-methylation of amines and reduction of aldehydes with MeOH catalyzed by 1 compared to the monometallic analogues (2-11). Under the optimal conditions, it showed to be highly effective in N-methylation of nitroarenes with MeOH as both C1 and H2 source. Substrates, including aromatic amines, ketones, and nitro compounds with various functional groups, can be well-tolerated. Mechanistic studies and DFT calculation highlight the significance of bimetallic centers cooperativity.
- Huang, Shuang,Hong, Xi,Cui, He-Zhen,Zhan, Bing,Li, Zhi-Ming,Hou, Xiu-Feng
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p. 3514 - 3523
(2020/10/09)
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- Method for synthesizing benzothiazole by microwave radiation of benzothioamide compound in aqueous phase
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The invention discloses a method for synthesizing benzothiazole by microwave radiation of a benzothioamide compound in an aqueous phase. The method includes the steps: adding the benzothioamide compound into the aqueous phase under microwave conditions; performing cyclization under alkaline conditions to generate the benzothiazole. The method for preparing the benzothiazole is environmentally friendly, simple and convenient in operation, safe, cheap and efficient. Compared with the prior art, the method is applicable to a lot of functional groups, high in yield, few in by-products, simple in operation, safe, low in cost and environmentally friendly.
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Paragraph 0013; 0019
(2019/02/13)
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- Convenient and reliable routes towards 2-aminothiazoles: Palladium-catalyzed versus copper-catalyzed aminations of halothiazoles
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Two efficient methods for the amination of 2-halothiazoles are presented here. A first protocol requires a Pd/L system. Several 2-aminothiazoles were synthesized under optimized conditions and isolated in good yields. The first palladium-catalyzed C-N coupling reactions between 2-halothiazoles and primary alkylamines are presented. In a second part, ligand-free copper-catalyzed aminations of 2-halothiazoles by alkylamines and aniline in a green solvent have been developed. The protocol is very effective for primary and secondary amines and perfectly tolerates the presence of another halide moiety on the 2-halothiazole. The reaction occurs under the assistance of microwave irradiation, which drastically decreases the reaction time. The reaction leads to the formation of 2-aminothiazoles, key molecules in pharmaceutical research. Copyright
- Toulot, Stephanie,Heinrich, Timo,Leroux, Frederic R.
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supporting information
p. 3263 - 3272
(2013/12/04)
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- Laccase-catalysed homocoupling of primary aromatic amines towards the biosynthesis of dyes
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Coloured disubstituted benzoquinonimine trimeric structures are obtained as main reaction products of the oxidation of p-electron donor pri-mary aromatic amines using two different laccases, CotA-laccase from Baccilus subtilus and TvL from Trametes versicolor. These orange-red to purple products, presenting high molar extinction coeffi-cients, presumably result from oxidative homocou-pling reactions, through the formation of N-C bonds at positions 2 and 5, of the laccase oxidised inter-mediate as showed in the proposed oxidative path-way. The product of 1,4-phenylenediamine is shown to be the trimer known as Bandrowski's base which has an established role in hair and fur dyeing. Our results also show that the occurrence and/or rates of oxidation of aromatic amines are strongly dependent on the presence of p-electron releasing substituents in the aromatic ring and are independent on the properties of the enzyme used. Overall our data con-tribute for (i) understanding key features of laccase reactivity with p-substituted aromatic amines and (ii) establishing enzymatic processes that lead to the syn-thesis of coloured bio-products under mild condi-tions with potential impact in the cosmetic and dye industries.
- Sousa, Ana Catarina,Martins, Lígia O.,Robalo, M. Paula
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supporting information
p. 2908 - 2917
(2014/03/21)
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- Novel solid-phase parallel synthesis of N-substituted-2-aminobenzo [d]thiazole derivatives via cyclization reactions of 2-iodophenyl thiourea intermediate resin
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A novel solid-phase methodology has been developed for the synthesis of N-alkyl, N-acyl, and N-sulfonyl-2-aminobenzo[d]thiazole derivatives. The key step in this procedure involves the preparation of polymer-bound 2-aminobenzo[d]thiazole resins 5 by cyclization reaction of 2-iodophenyl thiourea resin 3. The resin-bound 2-iodophenyl thiourea 3 is produced by addition of 2-iodophenyl isothiocyanate 2 to the amine-terminated linker amide resin 1. These core skeleton 2-aminobenzo[d]thiazole resins 5 undergo functionalization reactions with various electrophiles, such as alkyl halides, acid chlorides, and sulfonyl chlorides to generate N-alkyl, N-acyl, and N-sulfonyl-2-aminobenzo[d]thiazole resins 6, 7, and 8, respectively. Finally, N-alkyl, N-acyl, and N-sulfonyl-2-aminobenzo[d]thiazole derivatives 9, 10, and 11 are then generated in good yields and purities by cleavage of the respective resins 6, 7, and 8 using trifluoroacetic acid (TFA) in dichloromethane (DCM).
- Kim, Seul-Gi,Jung, Se-Lin,Lee, Gee-Hyung,Gong, Young-Dae
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- General and efficient method for direct N-monomethylation of aromatic primary amines with methanol
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The direct N-monomethylation of aromatic primary amines, including arylamines, arylsulfonamides and amino-azoles, using methanol as a methylating agent has been accomplished in the presence of a [CpIrCl2]2/NaOH system. From both synthetic and environmental points of view, the reaction is highly attractive because of low catalyst loading, broad substrate scope and excellent selectivities.
- Li, Feng,Xie, Jianjiang,Shan, Haixia,Sun, Chunlou,Chen, Lin
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p. 8645 - 8652
(2015/03/05)
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- Reaction discovery by using a sandwich immunoassay
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Mmm, a reaction sandwich Using an immunoassay-based technique able to monitor any kind of cross-coupling reaction, a systematic and rapid evaluation of a large panel of random reactions was carried out. This approach led to the discovery of two new copper-promoted reactions: a desulfurization reaction of thioureas leading to isoureas and a cyclization reaction leading to thiazole derivatives from alkynes and N-hydroxy thioureas. Copyright
- Quinton, Julia,Kolodych, Sergii,Chaumonet, Manon,Bevilacqua, Valentina,Nevers, Marie-Claire,Volland, Herve,Gabillet, Sandra,Thuery, Pierre,Creminon, Christophe,Taran, Frederic
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p. 6144 - 6148
(2012/07/17)
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- Copper-catalyzed tandem reactions of 2-halobenzenamines with isothiocyanates under ligand- and base-free conditions
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A ligand-free copper-catalyzed reaction of 2-halobenzenamines with isothiocyanates has been developed for the synthesis of 2-aminobenzothiazoles. In the presence of CuBr and TBAB (tetra-n-butyl ammonium bromide, additive), a variety of 2-halobenzenamines underwent the reaction with isothiocyanates at 40 °C, affording 2-aminobenzothiazoles in moderate to excellent yields. It is noteworthy that the reaction is conducted under mild, relatively low catalyst loading, and ligand- and base-free conditions.
- Guo, Yan-Jin,Tang, Ri-Yuan,Zhong, Ping,Li, Jin-Heng
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supporting information; experimental part
p. 649 - 652
(2010/04/23)
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- Iron-catalyzed tandem reactions of 2-halobenzenamines with isothiocyanates leading to 2-aminobenzothiazoles
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A highly practical method for the synthesis of 2-aminobenzothiazoles has been developed through an iron-catalyzed tandem reaction. The present tandem process allows the assembly of a wide range of 2-aminobenzothiazoles by the reactions of 2-halobenzenamin
- Qiu, Jing-Wen,Zhang, Xing-Guo,Tang, Ri-Yuan,Zhong, Ping,Li, Jin-Heng
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supporting information; scheme or table
p. 2319 - 2323
(2009/12/29)
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- Unexpected formation of benzothiazoles in the synthesis of new heterocycles: Benzo-1,2,4-dithiazines
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The synthesis of benzo-1,2,4-dithiazines was investigated presuming a reversible sulfur-sulfur bond formation. 2-Aminothiophenol, when allowed to react with isothiocyanates, provided benzothiazoles. 2,2′-Diaminodiphenyl disulfide underwent cyclizations very readily without any reducing agent to give, according to the reaction conditions, benzothiazoles or benzo-1,2,4-dithiazines. The developed procedure offers a simple and convenient way to prepare the title compounds in very good to excellent yields. Until now, benzo-1,2,4-dithiazines as well as 2,2′-diaminodiphenyl disulfides bearing aminocarbonothioyl groups were unknown. Georg Thieme Verlag Stuttgart.
- Fajkusova, Dagmar,Pazdera, Pavel
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p. 1297 - 1305
(2008/12/22)
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- Efficient Conversion of Substituted Aryl Thioureas to 2-Aminobenzothiazoles Using Benzyltrimethylammonium Tribromide
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The reaction of molecular bromine (Br2) with arylthioureas is known to produce 2-aminobenzothiazoles (Hugerschoff reaction). We show here that benzyltrimethylammonium tribromide (1, PhCH2NMe 3Br3), a stable, crystalline organic ammonium tribromide (OATB), can be readily utilized as an alternative electrophilic bromine source. It is easier to control the stoichiometry of addition with an OATB, which minimizes aromatic bromination caused by excess reagent. We have developed a direct procedure from isothiocyanates and amines using tetrabutylammonium thiocyanate (Bu4NSCN) and PhCH2NMe3Br 3 to afford functionalized 2-aminobenzothiazoles.
- Jordan, Alfonzo D.,Luo, Chi,Reitz, Allen B.
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p. 8693 - 8696
(2007/10/03)
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- Synthesis of 2-substituted-benzothiazoles by palladium-catalyzed intramolecular cyclization of o-bromophenylthioureas and o-bromophenylthioamides
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2-Amino-, and 2-alkyl-benzothiazoles have been efficiently prepared by palladium catalyzed cyclization of o-bromophenylthioureas and o-bromophenylthiamides. Results were best with the Pd2(dba)3/monophosphine catalytic system.
- Benedí, Carolina,Bravo, Fernando,Uriz, Pedro,Fernández, Elena,Claver, Carmen,Castillón, Sergio
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p. 6073 - 6077
(2007/10/03)
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- A facile synthesis of 2-N(methyl amino) benzothiazoles
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Reaction of aromatic primary amines with methylisothiocyanate (MITC) yielded N-methyl-N1-(benzelene-1-yl)thioureas which underwent oxidative cyclization in the presence of bromine in acetic acid, at room temperature, affording the title compounds.
- Ambati, Narahari Babu,Anand,Hanumanthu
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p. 1487 - 1493
(2007/10/03)
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- Cycloaddition-Elimination Reactions of 4-Methyl-5-phenylimino-Δ2-1,2,3,4-thiatriazoline with Electrophilic Nitriles
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4-Methyl-5-phenyliminothiatriazoline 4 undergoes two consecutive cycloaddition-elimination reactions with ethyl cyanoformate and p-toluenesulfonyl cyanide in refluxing chloroform, and yields the 1,2,4-thiadiazolines 6a,b via the isomers 5a,b.In acetone as the solvent, the reactions occur at room temperature, due to the formation of the 1,2,4-oxathiazolidine 12 as the intermediate.When trichloroacetonitrile was used, only the decomposition products of 4, namely 7 and 8 were obtained.
- L'abbe, Gerrit,Sannen, Ingrid
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p. 333 - 336
(2007/10/02)
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- EIN NEUER WEG ZU 2H-1,2,4-BENZOTHIADIAZINDERIVATEN
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2-Substituted 2H-1,2,4-benzothiadiazine-1-oxides are prepared by reaction of aryl guanidines with SOCl2 in presence or without Lewis acids.The scope of this reaction and some transformations of the products are investigated.
- Kresze, Guenter,Hatjiissaak, Anastassios
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- A NOVEL SYNTHESIS OF 2-BENZOTHIAZOLAMINE AND ITS DERIVATIVES BY A NICKEL(0)-CATALYZED REACTION OF 1,2-AMINOIODOARENES WITH THIOUREAS
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In the presence of a nickel(0) complex, 1,2-aminoiodoarenes underwent the reaction with thioureas to provide a facile, site-specific, and general synthetic procedure of 2-benzothiazolamine and its derivatives under non-oxidative conditions.
- Takagi, Kentaro
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p. 265 - 266
(2007/10/02)
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- Synthesis of 4-Oxo-4H-benzothiazolopyrimidin-1-ium-2-olates and their Cycloaddition Reactions to Electron-poor and Electron-rich Alkynes as well as to o-Chloranil
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The synthesis and physical properties of the title compounds 3a-d, prepared from 1 and bis(2,4,6-trichlorophenyl) malonates 2a-d, are described.As cyclic 1,4-dipoles, the betaines 3 combine with dimethyl acetylenedicarboxylate, dibenzoylethylene or bis(diethylamino)ethyne with formation of primary adducts of type 4, which release methyl isocyanate to give pyridobenzothiazole derivatives 5a-g, whereas the reaction of 3a with bis(dimethylamino)ethyne yields the betaine 7.With unsymmetrically substituted alkynes like methyl propiolate or 1-(diethylamino)propyne, 3 reacts with regiospecific formation of 8a-f.On the other hand, the reaction of 3a with o-chloranil proceeds with regiospecific formation of the 1,4-benzodioxin derivative 11.In case of 8, the observed regiospecificities are in agreement with the results of MNDO calculations and MO-perturbation theory.
- Gotthardt, Hans,Blum, Joachim
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p. 2079 - 2094
(2007/10/02)
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- Benzenesulfonyl-ureas
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Sulfonyl-ureas of the formula STR1 wherein X represents a heteroaromatic 5- or 6-ring substituted, if desired, by one or two methyl groups and/or annellated with benzene, which ring may contain in addition to a nitrogen atom a further nitrogen, oxygen or sulfur atom and which, in vicinal position to the nitrogen atom, is linked to the rest of the molecule portion, R is alkyl having 1 to 3 carbon atoms, R1 is alkyl having 3 to 6 carbon atoms, cycloalkyl, alkylcycloalkyl, cycloalkylalkyl, cycloalkenyl, alkylcycloalkenyl having each 5 to 9 carbon atoms, cyclohexenylmethyl, chlorocyclohexyl, bicycloheptenylmethyl, bicycloheptylmethyl, bicycloheptenyl, bicycloheptyl, nortricyclyl, adamantyl, benzyl, which as substance or in form of the salts thereof have hypoglycemic properties and are distinguished by a strong and continuous lowering of the blood sugar level, process for preparing them as well as pharmaceutical preparations containing the sulfonyl-ureas as an active substance.
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