- Microwave-assisted preparation of 2-substituted benzothiazoles
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2-Substituted benzothiazoles (3a-h) were prepared from the condensation reaction of 2-aminothiophenol 1 with aldehydes 2 in the presence of P-Ts-OH and graphite on the surface of solid mineral supports without using any oxidizing agent under microwave irr
- Rostamizadeh, Shahnaz,Housaini
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Read Online
- Synthesis of amidine and bis amidine percursors
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The reactions of substituted o-phenylene diamines, o-aminophenol, o-aminothiophenol, 3,4-diaminopyridine with p-cyanobenzaldehyde by refluxing in nitrobenzene gave corresponding benzimidazole, benzoxazole, benzthiazole and imidazopyridine derivatives Ia,b
- Singhal, Nidhi,Johar, Monika,Lown,Sondhi
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Read Online
- Fast and high-efficiency synthesis of 2-substituted benzothiazoles via combining enzyme catalysis and photoredox catalysis in one-pot
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An efficient and green method, combining enzymatic and visible-light catalysis for synthesis of the widely applicable 2-substituted benzothiazoles, has been developed. This method features a relay catalysis protocol consisting of biocatalytic promiscuity
- Yang, Zeng-Jie,Gong, Qing-Tian,Yu, Yuan,Lu, Wei-Fan,Wu, Zhe-Ning,Wang, Na,Yu, Xiao-Qi
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supporting information
(2021/01/14)
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- Ultrasound-assisted efficient and green synthesis of 2-substituted benzothiazoles under solvent-free condition using recyclable sulfated tungstate
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Sulfated tungstate catalyzed an efficient and ecofriendly protocol has been described for the synthesis of 2-substituted benzothiazoles. The corresponding benzothiazoles were obtained using a condensation reaction of 2-aminothiophenol with various aldehydes under ultrasound irradiation at room temperature. Various functional groups on the 2-aminothiophenol as well as on the aldehydes were tolerated to provide 2-substituted benzothiazoles derivatives in excellent yields. The faster reaction rate, solvent-free or mild reaction conditions, wide functional group compatibility, excellent yields, easy work-up procedure, and excellent catalyst recyclability are the advantages of this protocol. These advantages make this process more practicable, cost-effective, and environmentally benign.
- Pise, Ashok S.,Ingale, Ajit P.,Dalvi, Navnath R.
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supporting information
p. 3629 - 3641
(2021/10/12)
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- An efficient rapid synthesis of benzoxazoles and benzothiazoles using pma.Sio2 at room temperature under heterogeneous conditions
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Treatment of 2-aminophenol (or 2-aminothiophenol) with aromatic aldehydes in the presence of phosphomolybdic acid on silica at room temperature affords the corresponding benzoxazoles (or benzothiazoles) in excellent yields (88-96%) under heterogeneous conditions. Benzoxazoles and benzothiazoles are formed in less than 10 min.
- Sudhakar, Chithaluri,Shekhar, Vanam,Shyamsunder, Manchi,Suryakumari, Adurthi,Manojkumar, Vala
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p. 583 - 587
(2021/09/30)
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- Photocatalytic green synthesis of benzazoles from alcohol oxidation/toluene sp3C-H activation over metal-free BCN: effect of crystallinity and N-B pair exposure
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Porous borocarbonitride (P-BCN), with the characteristics of enhanced crystallinity and improved N-B pair exposure, was prepared with a simple KCl-assisted molten salt strategy. Efficient heterogeneous photocatalytic tandem synthesis of benzazoles from alcohol oxidation/toluene sp3C-H activation was achieved firstly over the metal-free P-BCN using visible light and the green oxidant O2, with only water as a by-product. Variouso-thio/hydroxy/aminoanilines and alcohols or toluenes could be converted to the corresponding 2-substituted benzothiazoles, benzoxazoles and benzimidazoles with good to excellent photocatalytic performance. The improved photocatalytic performance in comparison to bulk BCN should be due to the crystallinity-enhancement-induced improvement in charge separation and transmission. The increased N-B pair exposure promoted superoxide radical generation due to the electron-enriched N atoms, as well as improved oxidation ability due to the valence band constructed by the B 2p orbital. This work presents a green and efficient synthetic strategy towards benzazoles and other fine chemicalsviametal-free heterogeneous photocatalysis.
- Cheng, Hongmei,Gao, Xue,Jiang, Heyan,Sun, Bin,Zang, Cuicui
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p. 7955 - 7962
(2021/12/27)
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- Radical Borylative Cyclization of Isocyanoarenes with N-Heterocyclic Carbene Borane: Synthesis of Borylated Aza-arenes
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Borylated aza-arenes are of great importance in the area of organic synthesis. A radical borylative cyclization of isocyanoarenes with N-heterocyclic carbene borane (NHC-BH3) under metal-free conditions was developed. The reaction allows the efficient assembly of several types of borylated aza-arenes (phenanthridines, benzothiazoles, etc.), which are difficult to access using alternative methods. Mild reaction conditions, a good functional-group tolerance, and generally good efficiencies were observed. The utility of these products is demonstrated, and the mechanism is discussed.
- Liu, Yao,Li, Ji-Lin,Liu, Xu-Ge,Wu, Jia-Qiang,Huang, Zhi-Shu,Li, Qingjiang,Wang, Honggen
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p. 1891 - 1897
(2021/03/08)
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- ZnO-NPs catalyzed condensation of 2-aminothiophenol and aryl/alkyl nitriles: Efficient green synthesis of 2-substituted benzothiazoles
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The synthesis of 2-substituted benzothiazoles has been described using ZnO-nanoparticles as a catalyst. The condensation of 2-aminothiophenol and aryl/alkyl nitriles resulted in the formation of various 2-substituted benzothiazoles under solvent-free reaction conditions. The library of 2-substituted benzothiazoles has been synthesized in good to excellent yield. The reaction has shown a wide range of functional group compatibility for both varyingly substituted 2-aminothiophenols and nitriles. The protocol has many advantages such as faster reaction rate, mild reaction conditions, various functional group compatibility, excellent yield, solvent-free reaction conditions, easy recovery of materials, and excellent catalyst recyclability, among others. The various advantages of this protocol make it a more feasible, economical, and environmentally benign process.
- Dhawale, Kiran D.,Ingale, Ajit P.,Shinde, Sandeep V.,Thorat, Nitin M.,Patil, Limbraj R.
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p. 1588 - 1601
(2021/03/18)
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- "Metal-Free" Nanoassemblies of AIEE-ICT-Active Pyrazine Derivative: Efficient Photoredox System for the Synthesis of Benzimidazoles
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Supramolecular nanoassemblies of an AIEE-ICT-active pyrazine derivative (TETPY) having strong absorption in the visible region and excellent transportability have been utilized as an efficient photoredox catalytic system for the synthesis of a variety of benzimidazoles having electron-withdrawing/electron-releasing/aliphatic groups under "metal-free"conditions. The reaction protocol involves the successful harvesting of visible light by TETPY assemblies to catalyze the coupling of o-phenylenediamine/substituted diamines and substituted aromatic/heterocyclic/aliphatic aldehydes under aerial conditions using mixed aqueous media as the reaction solvent. TETPY assemblies could activate aerial oxygen to generate superoxide for completing the vital proton abstraction step without the need for any external metal/base/oxidant. Moreover, all the products are purified by recrystallization from organic solvents. The TETPY assemblies also exhibited high efficiency in catalyzing the synthesis of 2-substituted benzothiazoles and quinazolines in excellent yields.
- Dadwal, Shruti,Kumar, Manoj,Bhalla, Vandana
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p. 13906 - 13919
(2020/11/20)
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- Sulfamic acid-catalyzed conversion of o-aminothiophenol and aromatic aldehydes to 2-arylbenzothiazoles
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Non-metallic, non-toxic, and cheap sulfamic acid was used as a catalyst for the synthesis of 2-arylbenzothiazole from o-aminothiophenol and aromatic aldehydes bearing electron-donating or electron-withdrawing groups. The sulfamic acid catalyst can be reus
- Shi, Chunjie,Song, Renyuan,Wang, Guangrong,Yu, Xiaofeng
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p. 871 - 879
(2020/09/09)
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- A fluorinated phenylbenzothiazole arrests the trypanosoma cruzi cell cycle and diminishes the infection of mammalian host cells
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Chagas disease (CD) is a human infection caused by Trypanosoma cruzi. CD was traditionally endemic to the Americas; however, due to migration it has spread to countries where it is not endemic. The current chemotherapy to treat CD induces several side eff
- Crispim, Marcell,Da Silva, Marcelo Santos,Elias, Maria Carolina,Girard, RichardM. B. M.,Silber, Ariel Mariano,Cuevas-Hernández, Roberto I.,Martínez-Cerón, Sarai,Trujillo-Ferrara, José G.
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- Photocatalytic Conversion of Benzyl Alcohols/Methyl Arenes to Aryl Nitriles via H-Abstraction by Azide Radical
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This report presents the visible-light-assisted synthesis of aryl nitriles from easily accessible alcohols or methyl arenes in the presence of O2. Organic photoredox catalyst, 4CzIPN (1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene), induces single electron transfer (SET) from azide N3? and generates azide radical N3?.The photogenerated N3? abstracts H atom from α-C?H bond of benzylic system, which provides aldehyde and hydrazoic acid (HN3) in situ. This reaction subsequently forms azido alcohol intermediate that transforms into nitrile with the assistance of triflic acid (Br?nsted acid). A range of alcohols and methyl arenes successfully underwent cyanation at room temperature with good to excellent yields and showed good functional group tolerance.
- Shee, Maniklal,Shah, Sk. Sheriff,Singh, N. D. Pradeep
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supporting information
p. 14070 - 14074
(2020/10/12)
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- Organophotoredox assisted cyanation of bromoarenes: via silyl-radical-mediated bromine abstraction
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The insertion of a nitrile (-CN) group into arenes through the direct functionalization of the C(sp2)-Br bond is a challenging reaction. Herein, we report an organophotoredox method for the cyanation of aryl bromides using the organic photoredox catalyst 4CzIPN and tosyl cyanide (TsCN) as the nitrile source. A photogenerated silyl radical, via a single electron transfer (SET) mechanism, was employed to abstract bromine from aryl bromide to provide an aryl radical, which was concomitantly intercepted by TsCN to afford the aromatic nitrile. A range of substrates containing electron-donating and -withdrawing groups was demonstrated to undergo cyanation at room temperature in good yields.
- Shah, Sk. Sheriff,Shee, Maniklal,Singh, N. D. Pradeep
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supporting information
p. 4240 - 4243
(2020/04/22)
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- Visible light initiated amino group: Ortho -directed copper(i)-catalysed aerobic oxidative C(sp)-S coupling reaction: Synthesis of substituted 2-phenylbenzothiazoles via thia-Wolff rearrangement
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A facile amino group ortho-directed visible-light-driven copper-catalysed aerobic oxidative C(sp)-S coupling reaction of a dimer of 2-aminothiophenol with terminal alkynes was achieved. This photochemical reaction shows an excellent conversion and chemoselectivity towards the formation of C(sp)-S coupling and has been employed for a wide range of thiol dimers, and alkynes. Furthermore, the synthetic utility of the synthesized alkynyl sulfides was demonstrated as a direct method for the construction of 2-phenylbenzothiazoles from the corresponding alkynyl sulfides via "thia-Wolff rearrangement" using AgNO3 and visible light using 9-mesityl-10-methylacridinium ions (Acr+-Mes) as photoredox catalyst system.
- Anandhan, Ramasamy,Reddy, Mandapati Bhargava
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p. 3781 - 3784
(2020/04/10)
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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; 0047
(2019/02/13)
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- Method used for rapid preparation of benzo-heterocycle compound with physical grinding under solvent-free room temperature conditions
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The invention discloses a method used for rapid preparation of benzo-heterocycle compound with physical grinding under solvent-free room temperature conditions. According to the method, glacial aceticacid is taken as a catalyst; at solvent-free room temperature conditions, physical grinding is adopted, reaction of 2-substituted arylamines (2-mercapto arylamine, 2-aminophenol, and o-phenylenediamine) and aromatic aldehydes is carried out using physical grinding. The method is friendly to the environment, is simple in operation, is safe, is low in cost, and is high in efficiency. Compared withthe prior art, the advantages are that: the method is suitable for a large amount of functional groups, yield is high, less by-product is generated, operation is simple, the method is safe, cost is low, and the method is friendly to the environment.
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Paragraph 0062; 0131
(2019/01/21)
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- TBHP/KI-Promoted Annulation of Anilines, Ethers, and Elemental Sulfur: Access to 2-Aryl-, 2-Heteroaryl-, or 2-Alkyl-Substituted Benzothiazoles
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An efficient TBHP/KI-promoted annulation of anilines with ethers and elemental sulfur has been developed through the selective C-O bond cleavage of ethers under transition-metal-free conditions. A wide range of 2-aryl-, 2-heteroaryl-, and 2-alkyl-substituted benzothiazoles were easily prepared with satisfactory yields and good functional group compatibility.
- Zhang, Jie,Zhao, Xin,Liu, Ping,Sun, Peipei
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p. 12596 - 12605
(2019/10/11)
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- I2/TBHP-Mediated tandem cyclization and oxidation reaction: Facile access to 2-substituted thiazoles and benzothiazoles
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The efficient synthesis of 2-substituted thiazoles and benzothiazoles has been accomplished employing readily available cysteine esters and 2-aminobenzenethiols as N and S sources. The reaction proceeds under an I2/TBHP system and involves a on
- Liu, Li,Tan, Chen,Fan, Rong,Wang, Zihan,Du, Hongguang,Xu, Kun,Tan, Jiajing
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supporting information
p. 252 - 256
(2019/01/10)
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- Copper-Catalyzed Benzylic C—H Functionalization, Oxidation and Cyclization of Methylarenes: Direct Access to 2-Arylbenzothiazoles
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The direct C—H functionalization of methylarenes is of great significance. Herein, a copper-catalyzed oxidative C—N/C—S bond formation through benzylic C(sp3)—H functionalization, oxidation and cyclization of methylarenes is reported. Various 2-arylbenzothiazoles have been synthesized in moderate to excellent yields with readily available o-iodoaniline, potassium sulfide, and methylarenes as raw materials.
- Yu, Wentao,Wu, Wanqing,Jiang, Huanfeng
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p. 1158 - 1166
(2019/10/22)
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- Displacement of η5-cyclopentadienyl ligands from half-sandwich: C, C -(NHC-cyanoalkyl)-nickel(II) metallacycles: Further insight into the structure of the resulting Cp-free nickelacycles and a catalytic activity study
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Four cationic C,C-(NHC-cyanoalkyl)-nickel(ii) metallacyclic complexes, [Ni{Me-NHC-CH2CH(CN)}(NCMe)](PF6) (2a), [Ni{Mes-NHC-CH2CH(CN)}(NCMe)](PF6) (2b), [Ni{Mes-NHC-(CH2)2CH(CN)}(NCMe)](PF6) (2c) and [Ni{DiPP-NHC-(CH2)2CH(CN)}(NCMe)](PF6) (2d), were prepared by the removal of the Cp ligand under acidic conditions at 0 °C from the corresponding half-sandwich nickelacycles [NiCp{R-NHC-(CH2)nCH(CN)}] (1a-1d; Cp = η5-C5H5; n = 1 or 2; R-NHC-(CH2)nCH(CN) = 1-R-3-[(CH2)nCH(CN)]-imidazol-2-ylidene). Full characterization of 2a-d by 1H and 13C{1H} NMR spectroscopy in CD3CN and pyridine-d5, ATR-FTIR spectroscopy, mass spectrometry, and CHN microanalyses established the presence of only one acetonitrile ligand per nickel atom in the solid state. A DFT structural study conducted on the cations of the methyl-substituted 5-membered nickelacycle 2a and the mesityl-substituted 6-membered cycle 2c found a small energetic cost (ΔG = 7-12 kcal mol-1) for the loss of one acetonitrile ligand from the square-planar structures existing in solution, that should be easily amenable upon solvent evaporation (ΔG? = 14 kcal mol-1 in the case of 2c). Two structures with one acetonitrile ligand could be optimized in both cases: (i) a truly T-shaped 14-electron structure with an end-on acetonitrile ligand, and (ii) a masked T-shaped structure stabilized by the π-coordination of the dangling CN group of the metallated alkyl chain, the latter being favoured by 2.4 kcal mol-1 in the case of the flexible 6-membered ring 2c. A comparison of calculated vibrational frequencies with experimental FTIR spectra ruled out π-coordination of the dangling CN group as a ν(CN) band at low frequency was absent. Complexes 2a-d thus probably exist as rare three-coordinate T-shaped 14-electron species in the solid state. Their catalytic activity was studied for the direct arylation of azoles, and 2c proved to be moderately active for the coupling of benzothiazole with aryl iodides. Mechanistic insights suggest that competing processes or a radical process catalysed by nickel particles could follow an initial reduction of 2c by the dimerization of a sacrificial amount of benzothiazole.
- Cardoso, Bernardo De P.,Bernard-Schaaf, Jean-Marie,Shahane, Saurabh,Veiros, Luis F.,Chetcuti, Michael J.,Ritleng, Vincent
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p. 1535 - 1547
(2018/02/09)
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- (Phosphinito)aryl benzimidazole PCN pincer palladium(II) complexes: Synthesis, characterization and catalytic activity in C–H arylation of azoles with aryl iodides
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The PCN pincer Pd(II) complexes 4a–c with (phosphinito)aryl benzimidazole ligands were conveniently synthesized by one-pot phosphorylation/palladation reaction of a (2-benzimidazolyl)-containing m-phenol derivative 3. The three complexes were well characterized by spectroscopic methods, elemental analysis and their molecular structures were further determined by X-ray single-crystal diffraction. The Pd(II) center in each complex adopts a typical distorted-square-planar geometry. With a catalyst loading of 0.25–0.5 mol%, complex 4a could effectively catalyze C–H arylation of benzothiazole, benzoxazole and thiazole with various aryl iodides in the presence of CuI as a cocatalyst.
- Wang, Cong,Li, Yang,Lu, Beibei,Hao, Xin-Qi,Gong, Jun-Fang,Song, Mao-Ping
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p. 184 - 192
(2017/11/03)
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- Solid Acid Supported on Magnetic Nanoparticles as a Highly Efficient and Retrievable Catalyst for the Synthesis 2-Substituted Benzothiazoles
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The use of a recyclable heterogeneous nanomagnetic solid acid catalyst, [Fe3O4@SiO2@(CH2)3NPC–SO3H]Cl, in a simple and highly efficient synthesis of benzothiazole derivatives by the reactio
- Gorjizadeh,Sayyahi
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p. 1899 - 1903
(2018/11/24)
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- Metallaphotoredox-Mediated Csp2-H Hydroxylation of Arenes under Aerobic Conditions
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The direct hydroxylation of 2-arylpyridines and 2-arylbenzothiazoles via the merger of organic photoredox and metal catalysis is reported where 4CzIPN is used as the visible-light photocatalyst and Pd(OAc)2 as the metal catalyst. This method has been employed to synthesize organic molecules exhibiting excited-state intramolecular proton transfer properties for generating tunable luminescence responses.
- Shah, Sk. Sheriff,Paul, Amrita,Bera, Manoranjan,Venkatesh, Yarra,Singh, N. D. Pradeep
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supporting information
p. 5533 - 5536
(2018/09/21)
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- Selective Construction of 2-Substituted Benzothiazoles from o-Iodoaniline Derivatives S8 and N-Tosylhydrazones
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Selective construction of 2-substituted benzothiazoles from o-iodoaniline derivatives S8 and N-tosylhydrazone via a copper-promoted [3 + 1 + 1]-type cyclization reaction has been realized. In the protocol, the carbon atom on N-tosylhydrazone could be regulated to construct benzothiazole by changing the reaction system. Furthermore, the transformation has achieved the construction of multiple carbon-heteroatom bonds.
- Huang, Yubing,Zhou, Peiqi,Wu, Wanqing,Jiang, Huanfeng
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p. 2460 - 2466
(2018/02/23)
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- Controllable assembly of the benzothiazole framework using a CC triple bond as a one-carbon synthon
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A concise and efficient protocol to assemble diverse benzothiazole derivatives in high yields was provided via copper catalyzed tandem cyclization with o-haloanilines, elemental sulfur and terminal alkynes as raw materials. In this protocol, C atoms on the CC triple bond were controllably involved in the construction of the benzothiazole framework and multiple carbon-heteroatom bonds through divergent routes.
- Huang, Yubing,Yan, Donghao,Wang, Xu,Zhou, Peiqi,Wu, Wanqing,Jiang, Huanfeng
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supporting information
p. 1742 - 1745
(2018/02/21)
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- Preparation method of aromatic nitrile compound or heteroaromatic nitrile compound
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The invention discloses a preparation method of an aromatic nitrile compound or a heteroaromatic nitrile compound. The preparation method comprises: under the protection of an inert gas, in a solvent,under the actions of a nickel catalyst, a ligand, metal zinc and an additive, carrying out a reaction on a cyanation reagent and halogenated aromatic hydrocarbon or halogenated heteroaromatic hydrocarbon. According to the present invention, by using the inexpensive and easily-available nickel catalyst and the ligand, the halogenated aromatic hydrocarbon or halogenated heteroaromatic hydrocarbon,especially the chlorinated aromatic hydrocarbon or chlorinated heteroaromatic hydrocarbon with characteristics of low price, easy obtaining and low reaction activity can mildly and efficiently react with the cyanation reagent with low toxicity to prepare the aromatic nitrile compound or heteroaromatic nitrile compound; and the preparation method has advantages of simple operation, mildness, high efficiency and the like, and further has characteristics of good functional group compatibility, good universality of substrate and the like.
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Paragraph 0043; 0045; 0154-0156
(2018/11/03)
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- Silver-mediated 2-arylation/alkylation/acylation of benzothiazoles with aldehydes in water
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An efficient and environmentally benign method was developed for the facile synthesis of various 2-aryl and 2-alkyl substituted benzothiazoles in moderate to good yields, using a silver-mediated redox condensation of benzothiazoles and aldehydes in water. Furthermore, this method is also applicable to prepare 2-acyl benzothiazoles.
- Hua, Min,Wang, Chunqin,Liu, Qixing,Chen, Danyi,Fu, Hao,Zhou, Haifeng
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p. 1226 - 1237
(2018/08/06)
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- Elemental sulfur as a polyvalent reagent in redox condensation with: O -chloronitrobenzenes and benzaldehydes: Three-component access to 2-arylbenzothiazoles
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Sulfur was found to be a polyvalent reagent in the multicomponent redox condensation with o-chloronitrobenzenes and benzaldehydes. 2-Arylbenzothiazoles was obtained in moderate to good yields in a highly atom-economical pathway.
- Nguyen, Le Anh,Ngo, Quoc Anh,Retailleau, Pascal,Nguyen, Thanh Binh
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supporting information
p. 4289 - 4293
(2017/09/29)
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- Elemental sulfur mediated cyclization via redox strategy: Synthesis of benzothiazoles from o-chloronitrobenzenes and benzyl chlorides
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A novel metal-free synthesis of 2-substituted benzothiazoles from easily available o-chloronitrobenzenes and benzyl chlorides using elemental sulfur as traceless oxidizing agent has been developed. The protocol provides a simple, efficient, and atom-economic way to access to benzothiazoles in moderate to excellent yields. And the approach exhibited good functional group tolerance.
- Wang, Xin,Miao, Dazhuang,Li, Xiaotong,Hu, Renhe,Yang, Zhao,Gu, Ren,Han, Shiqing
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supporting information
p. 5194 - 5199
(2017/07/28)
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- One-pot copper-catalyzed synthesis of 2-substituted benzothiazoles from 2-iodoanilines, benzyl chlorides and elemental sulfur
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An efficient one-pot three-component reaction of 2-iodoanilines, benzyl chlorides and elemental sulfur to form 2-substituted benzothiazoles in satisfactory yields (up to 98%) has been described. The reaction tolerated a wide range of functional groups on the aromatic ring. And heterocycle methylene chlorides substrates were also found to be compatible.
- Yang, Zhao,Hu, Renhe,Li, Xiaotong,Wang, Xin,Gu, Ren,Han, Shiqing
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supporting information
p. 2366 - 2369
(2017/05/29)
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- Synthesis of 2-arylbenzothiazoles via direct condensation between in situ generated 2-aminothiophenol from disulfide cleavage and carboxylic acids
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In this work we describe a simple and efficient general methodology for 2-arylbenzothiazole preparation employing disulfides and carboxylic acids. The reaction is promoted by tributylphosphine that acts both in disulfide bond cleavage and as activating agent for coupling with carboxylic acids. The reaction scope was studied using bis(2-aminophenyl)disulfide and different carboxylic acids with donor/withdrawing substituents, which resulted in the desired 2-arylbenzothiazole with moderate to good yields. The method was tested with success in preparation of the amyloid probe 2-(4-aminophenyl)-6-methoxybenzothiazole that employed a substituted bis(2-aminophenyl)disulfide.
- Coelho, Felipe L.,Campo, Leandra F.
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supporting information
p. 2330 - 2333
(2017/05/29)
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- General and Mild Nickel-Catalyzed Cyanation of Aryl/Heteroaryl Chlorides with Zn(CN)2: Key Roles of DMAP
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A new and general nickel-catalyzed cyanation of hetero(aryl) chlorides using less toxic Zn(CN)2 as the cyanide source has been developed. The reaction relies on the use of inexpensive NiCl2·6H2O/dppf/Zn as the catalytic system and DMAP as the additive, allowing the cyanation to occur under mild reaction conditions (50-80 °C) with wide functional group tolerance. DMAP was found to be crucial for successful transformation, and the reaction likely proceeds via a Ni(0)/Ni(II) catalysis based on mechanistic studies. The method was also successfully extended to aryl bromides and aryl iodides.
- Zhang, Xingjie,Xia, Aiyou,Chen, Haoyi,Liu, Yuanhong
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supporting information
p. 2118 - 2121
(2017/04/27)
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- Synthesis of 2 - substituted benzothiazole derivatives
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The invention discloses a method of synthesizing a 2-substituted benzothiazole-type derivative, wherein the method includes a step of synthesizing the 2-substituted benzothiazole-type derivative with an aldehyde and a disulphide as raw materials under a combined effect of at least one from NaHCO3 and AcOH with a metal sulfide. The particular reaction is represented as follows, wherein the R comprises one or more from a hydrogen atom, a C1-C4 alkyl, a fluorine atom, a chlorine atom, a bromine atom, an amino group, a cyan group and a nitryl group; the R' substituent group comprises at least one from a C1-C6 alkyl, a furan group, a thienyl group, a pyrryl group, a pridyl group and a substituted phenyl group. The method employs the raw material being stable and easy to obtain, and can quickly and conveniently synthesize the 2-substituted benzothiazole-type derivative at a high production yield.
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Paragraph 0063-0067
(2017/07/23)
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- Efficient synthesis of benzothiazole derivatives by reaction of bis(2-aminophenyl) disulfides with aldehydes mediated by NaSH under microwave irradiation
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2-Substituted benzothiazoles were synthesized through condensation of bis(2-aminophenyl) disulfides with arylaldehydes catalyzed by inexpensive NaSH in PEG-300 and assisted by low energy microwave irradiation(25?W). Various 2-substitutedbenzothiazoles were obtained in moderate to high yields after simple post-reaction processing including adding distilled water, filtrating, and drying. Moreover, it was found that the S-S bond of the disulfide was reduced by NaSH and also by the intermediate benzothiazoline.
- Liu, Lei,Zhang, Fa,Wang, Hongliang,Zhu, Ning,Liu, Bo,Hong, Hailong,Han, Limin
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p. 464 - 468
(2017/04/03)
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- Mechanistic Insights into Pincer-Ligated Palladium-Catalyzed Arylation of Azoles with Aryl Iodides: Evidence of a PdII-PdIV-PdII Pathway
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Pincer-based (R2POCNR′2)PdCl complexes along with CuI cocatalyst catalyze the arylation of azoles with aryl iodides to give the 2-arylated azole products. Herein, we report an extensive mechanistic investigation for the direct arylation of azoles involving a well-defined and highly efficient (iPr2POCNEt2)PdCl (2a) catalyst, which emphasizes a rare PdII-PdIV-PdII redox catalytic pathway. Kinetic studies and deuterium labeling experiments indicate that the C-H bond cleavage on azoles occurs via two distinct routes in a reversible manner. Controlled reactivity of the catalyst 2a underlines the iodo derivative (iPr2POCNEt2)PdI (3a) to be the resting state of the catalyst. The intermediate species (iPr2POCNEt2)Pd-benzothiazolyl (4a) has been isolated and structurally characterized. A determination of reaction rates of compound 4a with electronically different aryl iodides has revealed the kinetic significance of the oxidative addition of the C(sp2)-X electrophile, aryl iodide, to complex 4a. Furthermore, the reactivity behavior of 4a suggests that the arylation of benzothiazole proceeds via an oxidative addition/reductive elimination pathway involving a (iPr2POCNEt2)PdIV(benzothiazolyl)(Ar)I species, which is strongly supported by DFT calculations.
- Khake, Shrikant M.,Jagtap, Rahul A.,Dangat, Yuvraj B.,Gonnade, Rajesh G.,Vanka, Kumar,Punji, Benudhar
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supporting information
p. 875 - 886
(2016/04/19)
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- Reusable proline-based ionic liquid catalyst for the simple synthesis of 2-arylbenzothiazoles in a biomass medium
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A simple, efficient, and eco-friendly aerobic procedure for synthesis of 2-substituted benzothiazoles catalyzed by facile prepared [N2222][Pro] in a biomass medium (ethyl lactate) has been developed. The reactions afford the target 2-arylbenzot
- Yu, Zhi-Yu,Fang, Qiu-Sheng,Zhou, Jia,Song, Zhi-Bin
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p. 2035 - 2045
(2016/03/16)
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- Fe3O4@SiO2/collagen: An efficient magnetic nanocatalyst for the synthesis of benzimidazole and benzothiazole derivatives
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In this project, Fe3O4@SiO2 was synthesized and combined with collagen for the preparation of Fe3O4@SiO2/collagen. It was characterized by FT-IR, 1H NMR, VSM, XRD, EDX, SEM and T
- Ghafuri, Hossein,Esmaili, Elahe,Talebi, Majid
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p. 942 - 950
(2016/08/08)
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- Synthesis of some novel 4-benzothiazol-2-yl-benzoyl-1H-pyrazoles, and evaluation as antiangiogenic agents
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Some 4-(1,3-benzothiazol-2-yl)-benzoyl-1H-pyrazole derivatives have been synthesized by reaction of o-aminothiophenol (1) with different electrophilic and nucleophilic reagents. All of the newly synthesized compounds were evaluated for cytotoxicity against breast cancer cell line MCF-7. Two of the compounds were more potent than tamoxifen and three were as potent as tamoxifen. These results were consistent with percentage inhibition of human VEGF compared with control untreated cells.
- El-Meguid, Eman Ali Abd,Ali, Mamdouh Moawad
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p. 1521 - 1536
(2016/04/26)
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- Synthesis and Antitumor Activity Evaluation of New 2-(4-aminophenyl) benzothiazole/oxazole/imidazole Derivatives
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A NEW series of 2-(4-aminophenyl)benzothiazole and related structure compounds, bearing thiocyanate, thiol in the 3′postion as well as new condensed benzothiazoles and related structure compounds having thiazolones, tetrazole, oxadiazole have been synthesized. All the newly synthesized compounds were screened for their anti-tumor activities. The results revealed promising effects against most of the cancer cell lines.
- El-Arab, Elham Ezz,El-Said,Amine,Moharram
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p. 967 - 984
(2017/04/17)
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- Synthesis and antitumor activity evaluation of NEW 2-(4-aminophenyl) benzothiazole/oxazole/imidazole derivatives
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A NEW series of 2-(4-aminophenyl)benzothiazole and related structure compounds, bearing thiocyanate, thiol in the 3'postion as well as new condensed benzothiazoles and related structure compounds having thiazolones,tetrazole, oxadiazole have been synthesized. All the newly synthesized compounds were screened for their anti-tumor activities. The results revealed promising effects against most of the cancer cell lines.
- El-Arab, Elham Ezz,El-Said,Amine,Moharram
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p. 967 - 984
(2017/04/17)
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- Method for realizing green synthesis of 2-substituted benzothiazole derivatives
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The invention provides a method for realizing green synthesis of 2-substituted benzothiazole derivatives. The method comprises the following steps of: contacting aldehyde, o-amido aroma disulphide and metal sulfide by taking water as a solvent in the present of CO2, so as to obtain 2-substituted benzothiazole derivatives. Compared with the prior art, the method has the characteristics that o-amido aroma disulphide and multiple types of aldehyde react under the effects of water and CO2, so that the 2-substituted benzothiazole derivatives are rapidly and efficiently synthetized, and the used raw materials are easily obtained and low in cost; the synthesis method has the advantages of simplicity and convenience in operation, short steps, high yield, easiness for product purification, environmental friendliness and the like.
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Paragraph 0068; 0069; 0070; 0071; 0072; 0073; 0074; 0075
(2016/10/10)
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- Acylperoxycoumarins as ortho-C?H Acylating Agent via a Palladium(II)-Catalyzed Redox-Neutral Process
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An unprecedented palladium(II)-catalyzed biomimetic aliphatic acyl (-COR) group transfer was observed from acyl-α-peroxycoumarins to the ortho C?H sites of directing arenes. Here, the C?H activation is associated with a concomitant acyl group transfer via a Pd(II)-catalyzed, redox-neutral process. While methods for ortho aroylation (-COAr) are well documented ortho acylation (-COR) processes are scarce, hence the present redox-neutral method is most ideal for o-acylation of directing substrates. (Figure presented.) .
- Ranjan Mohanta, Prakash,Banerjee, Arghya,Kumar Santra, Sourav,Behera, Ahalya,Patel, Bhisma K.
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supporting information
p. 2047 - 2052
(2016/07/16)
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- Magnetically separable nano CeO2: A highly efficient catalyst for ligand free direct C-H arylation of heterocycles
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An efficient, ligand free, nano CeO2-Fe3O4 catalyzed direct C-H arylation of heteroarenes such as benzoxazole and benzothiazole has been carried out with aryl halides in DMSO or arenediazonium salts in water. The catalyst exhibited high activity with moderate to excellent product yields under mild reaction conditions. Nano CeO2-Fe3O4 was synthesized and characterized by SEM, TEM, EDAX, XRD, FTIR, DSC-TGA, and ICP-MS analyses. The catalytic activity and stability of the catalyst were excellent, even after the ten cycle of recyclability
- Shelkar, Radheshyam S.,Balsane, Kishor E.,Nagarkar, Jayashree M.
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supporting information
p. 693 - 699
(2015/01/30)
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- Direct C-H arylation of benzothiazoles by magnetically separable nano copper ferrite, a recyclable catalyst
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Abstract A simple and highly practical method for the direct C-H arylation of benzothiazoles has been developed by using nano copper ferrite as a recyclable catalyst. The CuFe2O4 nano could be recovered and reused without significant loss of catalytic activity.
- Satish,Reddy, K. Harsha Vardhan,Anil,Ramesh,Kumar, R. Uday,Nageswar
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supporting information
p. 4950 - 4953
(2015/07/28)
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- Synthesis and diverse general oxidative cyclization catalysis of high-valent MoVIO2(HL) to ubiquitous heterocycles and their chiral analogues with high selectivity
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The first synthesis and diverse oxidative cyclization catalysis properties of high-valent MoVI-triazole are demonstrated towards highly selective construction of benzimidazoles, benzothiazoles, isoxazolines, isoxazoles and their chiral analogue
- Pramanik, Nabyendu,Sarkar, Satinath,Roy, Dipanwita,Debnath, Sudipto,Ghosh, Sukla,Khamarui, Saikat,Maiti, Dilip K.
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p. 101959 - 101964
(2015/12/08)
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- FeCl3/ultrasound mediated reaction of 2-aminothiophenol with aldehydes in water: Synthesis of 2-substituted benzothiazoles of pharmacological interest
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We report a FeCl3?6H2O mediated green and rapid access to benzothiazole derivatives having a substituent at C-2 via the condensation of 2-aminothiophenol with various aldehydes under ultrasound irradiation and air. The reaction progressed well in water affording the expected products in good yields. Two of these compounds known to be potent anticancer agents showed good interactions with PDE4B in silico and inhibited this enzyme when tested in vitro.
- Srinivas, Ponasanapalli Tirumala Venkata Ankayya,Bhavani, Sallagundla,Rambabu, Dandela,Rao, Mandava Venkata Basaveswara,Kapavarapu, Ravikumar,Pal, Manojit
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p. 457 - 465
(2015/06/22)
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- Metal-free synthesis of benzothiazoles from disulfides of 2-aminobenzenethiol and carboxylic acid via PCl3-promoted tandem reaction
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A metal-free process for the synthesis of benzothiazoles via PCl3-promoted cleavage/acylation/ cyclization of disulfides and carboxylic acids has been developed. In addition to acting as the acylating reagent which converted carboxylic acids into acyl chlorides, PCl3 also converted disulfides to thiols, which promoted disulfides of 2-aminobenzenethiol reacted with carboxylic acid to produce benzothiazoles. The developed method is applicable to a wide range of carboxylic acids containing different functional groups.
- Du, Guangyan,Zhu, Ning,Han, Limin,Hong, Hailong,Suo, Quanling
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p. 1723 - 1734
(2015/12/12)
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- An iron and copper system catalyzed C-H arylation of azoles with arylboronic acids
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An efficient, environmentally friendly, and economical new method for arylation reactions of azoles with arylboronic acids via copper-iron-catalyzed C-H and C-B bond activation has been developed. The protocol tolerates a series of functional groups, such as methoxy, nitro, cyano, chloro, and trifluoromethyl groups.
- Hu, Wei-Ye,Wang, Pei-Pei,Zhang, Song-Lin
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supporting information
p. 42 - 48
(2015/02/02)
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- Novel synthesis of benzothiazole by self-redox tandem reaction of disulfide with aldehyde
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A novel methodology for the preparation of benzothiazole derivatives via the reaction of ortho-anilino disulfides with aryl and heteroaryl aldehydes catalyzed by Na2S·9H2O has been developed. The reaction mechanism was investigated by LC-MS and 1H NMR. The disulfide was cleaved firstly by the interchange reaction of the disulfide and metal sulfide, and the resulting thiol reacted in situ with the aldehyde to form the corresponding benzothiazoline. Subsequently, the intermediate benzothiazoline reduced the disulfide to thiol and it was oxidized to benzothiazole. The excess benzothiazoline was oxidized by air and both halves of the disulfide were ultimately converted to the desired benzothiazole.
- Liu, Bo,Zhu, Ning,Hong, Hailong,Han, Limin
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p. 9287 - 9292
(2015/11/27)
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- Iron-catalyzed arylation or aroylation of benzothiazoles with benzylic alcohols and aryl ketones
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An iron-catalyzed arylation or aroylation of benzothiazoles with alcohols and aryl ketones via an in situ cross-trapping strategy has been described. Both the use of an iron catalyst and the ratio of substrates are important for this transformation, and this reaction is sensitive to the electronic effects of the substituents.
- Wang, Jian,Zhang, Xiao-Zhuan,Chen, Shan-Yong,Yu, Xiao-Qi
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supporting information
p. 245 - 250
(2014/01/06)
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- Bismuth nitrate as an efficient catalyst for the preparation of 2-arylbenzothiazole derivatives
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A simple and eco-friendly procedure for synthesis of 2-arylbenzothiazoles in high yields by cyclo-condensation reaction of 2-aminothiophenol and aldehydes in the presence of bismuth nitrate (Bi(NO3)3) as heterogeneous catalyst is des
- Ghashang, Majid
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p. 1669 - 1674
(2014/05/06)
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- Sonicated assisted synthesis of benzimidazoles, benzoxazoles and benzothiazoles in aqueous media
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Ammonium nickel sulphate [(NH4)2SO4.NiSO4.6H2O] was found as a new catalyst to synthesis 2-aryl benzimidazole, 2-aryl benzothiazole and 2-aryl benzoxazole in aqueous media under sonication irradiation. The procedure is an eco-friendly, efficient and provides simple workup and good yield.
- Pardeshi, Sandeep D.,Sonar, Jayant P.,Pawar, Shivaji S.,Dekhane, Deepak,Gupta, Sunil,Zine, Ashok M.,Thore, Shivaji N.
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p. 2335 - 2340
(2014/07/22)
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