- Recyclable copper-catalyzed cyclization of o-haloanilides and metal sulfides: An efficient and practical access to substituted benzothiazoles
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An efficient heterogeneous copper-catalyzed cyclization of o-haloanilides and metal sulfides has been achieved via the C–S coupling in DMF at 80 or 140 °C in the existence of an MCM-41-bound NHC-Cu(I) catalyst and then intramolecular condensation, delivering a wide range of substituted benzothiazoles in mostly good to high yields. This new MCM-41-NHC-CuI complex can facilely be obtained by a two-step procedure starting from easily accessible and inexpensive reagents and reused more than seven times without any significant loss of its catalytic efficiency. The present protocol has been successfully applied to the gram-scale synthesis of two antitumor agents 5F203 and PMX 610.
- Cai, Mingzhong,Hao, Wenyan,Huang, Wencheng,Ye, Qian
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- Photocatalyst- And Transition-Metal-Free Visible-Light-Promoted Intramolecular C(sp2)-S Formation
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A photocatalyst- and transition-metal-free visible-light-induced cyclization of ortho-halothiobenzanilides has been developed. Upon irradiation with visible light, substrates undergo dehalogenative cyclization to 2-aryl benzothiazoles with high efficiency and selectivity. This photocyclization exhibits a high tolerance to various functional groups, is applicable for the synthesis of 2-alkyl benzothiazoles, and is easy to set up for gram-scale reaction.
- Wang, Hao,Wu, Qi,Zhang, Jian-Dong,Li, Hai-Yan,Li, Hong-Xi
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p. 2078 - 2083
(2021/04/05)
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- Method for preparing benzothiazole compound from visible light promoted N-(2-bromophenyl) thioamide
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The invention discloses a method for preparing a benzothiazole compound from N-(2-bromophenyl) thioamide under the promotion of visible light. Specifically, under the protection of inert gas, according to the molar ratio of N-(2-bromophenyl) thioamide to inorganic base being 1: 0.5, reactants are added into a reaction container provided with a stirring device, then dimethyl sulfoxide is added, and stirring reaction is carried out for 2-24 hours at room temperature under the irradiation of visible light to obtain the benzothiazole compound. Under the condition of not adding any photosensitizer or transition metal catalyst, sodium phosphate is used as alkali, and under the irradiation of a 45W household compact fluorescent lamp, a series of intramolecular cross-coupling reactions of N-(2-bromophenyl) thioamide are realized. In addition, the benzothiazole compound can be obtained with high yield. The whole process is green, efficient and easy to operate, and the method is a good method for synthesizing the benzothiazole compound.
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Paragraph 0121-0124
(2021/06/22)
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- Preparation method of benzothiazole-derived drug molecules
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The present invention discloses a benzothiazole derivative drug molecule preparation method, the iodoaniline, heterocyclic aldehyde and potassium sulfide in the reaction bottle, and then added molecular sieve and acetic acid, and then the reaction system
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Paragraph 0039-0041
(2022/01/08)
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- Elemental Sulfur-Mediated Decarboxylative Redox Cyclization Reaction: Copper-Catalyzed Synthesis of 2-Substituted Benzothiazoles
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A S 8 -mediated directed decarboxylative redox-cyclization strategy for the synthesis of 2-substituted benzothiazoles from o -iodoanilines, arylacetic acids, and elemental sulfur catalyzed by cheap copper metal has been developed. This reaction is operationally simple, ligand-free, compatible with a wide range of functional groups, and provides the desired products in good to excellent yields. In addition, a gram-scale experiment was carried out to furnish PMX 610, an antitumor drug.
- Wang, Xin,Li, Xiaotong,Hu, Renhe,Yang, Zhao,Gu, Ren,Ding, Sai,Li, Pengyi,Han, Shiqing
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supporting information
p. 219 - 224
(2017/10/09)
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- The invention relates to a thiourea as the sulfur source synthesis of substituted 2 - aryl benzo thiazole
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The invention discloses a method for synthesizing poly-substituted 2-aryl benzothiazoles by utilizing thiourea as a sulphur source. According to the method, thiourea reacts with benzyl chloride to generate an S-benzylisothiourea salt in situ. After that, through the aromatic nucleophilic substitution reaction of the obtained S-benzylisothiourea salt with 2-fluoronitrobenzene and then the one-step reduction (one-pot reaction) process, o-amino phenyl benzyl thioether as an intermediate product can be obtained. Finally, through the iron-catalyzed cross-dehydrogenative-coupling reaction of the o-amino phenyl benzyl thioether, a target product can be obtained. Compared with the traditional synthetic method, the method has the significant advantages of (1) short reaction step, wherein the target product can be synthesized through only three steps of simple reactions by utilizing simple chemical raw materials; (2) mild reaction condition, high atom economy, and relatively safe and cheap reaction reagents; (3) high reaction yield, good substrate tolerance and free of any dangerous or high-toxicity reagent. Therefore, the method might be applied to the large-scale production.
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- Synthesis of 2-Arylbenzothiazoles by Copper-Catalyzed One-Pot Three-Component Reactions in Water
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Copper-catalyzed three-component reactions of 2-iodoanilines, benzylamines, and sulfur powder are reported to afford benzothiazoles in a simple one-pot procedure by using water as solvent. A variety of 2-arylbenzothiazoles were obtained in moderate to good yields up to 88%.
- Xu, Hualong,Luo, Chun,Li, Zhengkai,Xiang, Haifeng,Zhou, Xiangge
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supporting information
p. 1207 - 1213
(2016/07/29)
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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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- An odorless, one-pot synthesis of nitroaryl thioethers via SNAr reactions through the in situ generation of S-alkylisothiouronium salts
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A newly developed C-S bond formation nucleophilic aromatic substitution (SNAr) reaction in aqueous Triton X-100 (TX100) micelles has been disclosed. This chemistry, in which odorless, cheap and stable thiourea in place of thiols is used as the sulfur reagent, provides an efficient approach for the generation of nitroaryl thioethers, which are useful structural units of many bioactive molecules, rendering this methodology attractive to both synthetic and medicinal chemistry.
- Lu, Guo-Ping,Cai, Chun
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p. 59990 - 59996
(2015/02/19)
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- Elemental sulfur disproportionation in the redox condensation reaction between o-halonitrobenzenes and benzylamines
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The disproportionation of elemental sulfur at moderate temperatures is investigated in the redox condensation involving o-halonitrobenzenes 1 and benzylamines 2. As a redox moderator, elemental sulfur plays the dual role of both electron donor and acceptor, generating its lowest and highest oxidation states: S-2 (sulfide equivalent) in benzothiazole 3 and S+6 (sulfate equivalent) in sulfamate 4, and filling the electron gap of the global redox condensation process. Along with this process, a cascade of reactions of reduction of the nitro group of 1, oxidation of the aminomethyl group of 2, metal-free aromatic halogen substitution, and condensation finally led to 2-arylbenzothiazoles 3.
- Nguyen, Thanh Binh,Ermolenko, Ludmila,Retailleau, Pascal,Al-Mourabit, Ali
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supporting information
p. 13808 - 13812
(2015/02/19)
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- Cu-catalyzed in situ generation of thiol using xanthate as a thiol surrogate for the one-pot synthesis of benzothiazoles and benzothiophenes
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A new copper-catalyzed in situ generation of aryl thiolates strategy was successfully developed for the one-pot synthesis of substituted benzothiazoles from 2-iodoanilides using xanthate as a thiol precursor. A wide range of 2-iodoanilides with both electron-releasing and electron-withdrawing groups produced the corresponding benzothiazoles in good yields. Further, this one-pot protocol was successfully utilized for the synthesis of a potent antitumor agent 2-(3,4-dimethoxyphenyl)-5-fluorobenzo[d]thiazole (PMX 610). Finally, the copper-catalyzed in situ generation of aryl thiolates strategy was successfully applied for the domino synthesis of substituted benzothiophenes from o-haloalkynyl benzenes using xanthate as a thiol precursor.
- Prasad,Sekar
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p. 1659 - 1665
(2013/03/28)
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- Cu-catalyzed three-component synthesis of substituted benzothiazoles in water
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Three in one: Copper-catalyzed three-component reactions, involving 2-iodoanilines, aldehydes, and sulfur powder, afford 2-phenylbenzothiazoles in water. A variety of 2-substituted benzothiazoles can be obtained in good to excellent yields of up to 96% (see scheme). Copyright
- Deng, Hang,Li, Zhengkai,Ke, Fang,Zhou, Xiangge
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supporting information; experimental part
p. 4840 - 4843
(2012/05/20)
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- Bioactivation of fluorinated 2-aryl-benzothiazole antitumor molecules by human cytochrome P450s 1A1 and 2W1 and deactivation by cytochrome P450 2S1
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Both 2-(4-amino-3-methylphenyl)-5-fluorobenzothiazole (5F 203) and 5-fluoro-2-(3,4-dimethoxyphenyl)-benzothiazole (GW 610) contain the benzothiazole pharmacophore and possess potent and selective in vitro antitumor properties. Prior studies suggested the involvement of cytochrome P450 (P450) 1A1 and 2W1-mediated bioactivation in the antitumor activities and P450 2S1-mediated deactivation of 5F 203 and GW 610. In the present study, the biotransformation pathways of 5F 203 and GW 610 by P450s 1A1, 2W1, and 2S1 were investigated, and the catalytic parameters of P450 1A1- and 2W1-catalyzed oxidation were determined in steady-state kinetic studies. The oxidations of 5F 203 catalyzed by P450s 1A1 and 2W1 yielded different products, and the formation of a hydroxylamine was observed for the first time in the latter process. Liquid chromatography-mass spectrometry (LC-MS) analysis with the synthetic hydroxylamine and also a P450 2W1/5F 203 incubation mixture indicated the formation of dGuo adduct via a putative nitrenium intermediate. P450 2W1-catalyzed oxidation of GW 610 was 5-fold more efficient than the P450 1A1-catalyzed reaction. GW 610 underwent a two-step oxidation process catalyzed by P450 1A1 or 2W1: a regiospecific O-demethylation and a further hydroxylation. Glutathione (GSH) conjugates of 5F 203 and GW 610, presumably through a quninoneimine and a 1,2-quinone intermediate, respectively, were detected. These results demonstrate that human P450s 1A1 and 2W1 mediate 5F 203 and GW 610 bioactivation to reactive intermediates and lead to GSH conjugates and a dGuo adduct, which may account for the antitumor activities of 5F 203 and GW 610 and also be involved in cell toxicity. P450 2S1 can catalyze the reduction of the hydroxylamine to the amine 5F 203 under anaerobic conditions and, to a lesser extent, under aerobic conditions, thus attenuating the anticancer activity.
- Wang, Kai,Guengerich, F. Peter
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p. 1740 - 1751
(2012/11/07)
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- An efficient synthetic route to biologically relevant 2- phenylbenzothiazoles substituted on the benzothiazole ring
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Certain 2-phenylbenzothiazoles containing substituents on the benzothiazole ring possess important biological properties, yet the majority of synthetic methods to 2-phenylbenzothiazoles described to date focus on their unsubstituted ring counterparts. Her
- Weekes, Ashley A.,Bagley, Mark C.,Westwell, Andrew D.
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supporting information; experimental part
p. 7743 - 7747
(2011/10/13)
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- Synthesis of carbon-11 labeled fluorinated 2-arylbenzothiazoles as novel potential PET cancer imaging agents
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Fluorinated 2-arylbenzothiazoles are new potential antitumor drugs, which show potent and selective inhibitory activity against breast, lung, and colon cancer cell lines. Carbon-11 labeled fluorinated 2-arylbenzothiazoles may serve as novel probes for positron emission tomography (PET) to image tyrosine kinase in cancers. The preparation of 4-fluorinated 2-arylbenzothiazoles 4-fluoro-2-(3-benzloxy-4-methoxyphenyl)benzothiazole (6a) and 4-fluoro-2-(3,4-dimethoxyphenyl)benzothiazole (6b) was achieved by a modification of Jacobson thioanilide radical cyclization chemistry. Hydrogenolytic cleavage of the benzyl ether group of compound 6a using H2/Pd-C provided the precursor 4-fluoro-2-(3-hydroxy-4-methoxyphenyl)benzothiazole (7) for radiolabeling. Synthesis of radiolabeling precursors and the reference standards 5- and 6-fluorinated arylbenzothiazoles (11c-n) was achieved via the reaction of o-aminothiophenol disulfides with substituted benzaldehydes under reducing conditions. The target radiotracers carbon-11 labeled 4-, 5-, and 6-fluorinated arylbenzothiazoles (3-[11C]6b, 4-[11C]11c, 3-[11C]11c, 5-[11C]11f, 4-[11C]11f, 4-[11C]11i, 3-[11C]11i, 5-[11C]11l, and 4-[11C]11l) were prepared by O-[11C]methylation of the phenolic hydroxyl precursors (7, 11d, 11e, 11g, 11h, 11j, 11k, 11m, and 11n) with [11C]methyl triflate and isolated by solid-phase extraction (SPE) purification in 30-55% radiochemical yields.
- Wang, Min,Gao, Mingzhang,Mock, Bruce H.,Miller, Kathy D.,Sledge, George W.,Hutchins, Gary D.,Zheng, Qi-Huang
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p. 8599 - 8607
(2008/02/07)
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- Antitumor benzothiazoles. 26.1 2-(3,4-dimethoxyphenyl)-5- fluorobenzothiazole (GW 610, NSC 721648), a simple fluorinated 2-arylbenzothiazole, shows potent and selective inhibitory activity against lung, colon, and breast cancer cell lines
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A series of new 2-phenylbenzothiazoles has been synthesized on the basis of the discovery of the potent and selective in vitro antitumor properties of 2-(3,4-dimethoxyphenyl)-5-fluorobenzothiazole (8n; GW 610, NSC 721648). Synthesis of analogues substituted in the benzothiazole ring was achieved via the reaction of o-aminothiophenol disulfides with substituted benzaldehydes under reducing conditions. Compounds were evaluated in vitro in four human cancer cell lines, and compound 8n was found to possess exquisitely potent antiproliferative activity (GI50 0.1 nM for MCF-7 and MDA 468). Potent and selective activity was also observed in the NCI 60 human cancer cell line panel. Structure-activity relationships established that the compound 8n stands on a pinnacle of potent activity, with most structural variations having a deactivating in vitro effect. Mechanistically, this new series of agents contrasts with the previously reported 2-(4-aminophenyl)benzothiazoles; compound 8n is not reliant on induction of CYP1A1 expression for antitumor activity.
- Mortimer, Catriona G.,Wells, Geoffrey,Crochard, Jean-Philippe,Stone, Erica L.,Bradshaw, Tracey D.,Stevens, Malcolm F. G.,Westwell, Andrew D.
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p. 179 - 185
(2007/10/03)
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- 2-Arylbenzothiazole derivatives
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A compound of general structure I, wherein the compound is optionally in the form of an N-oxide or S-oxide or prodrug form and/or pharmaceutically acceptable salt thereof wherein: each of R1 to R9 is independently selected from hydro
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Page/Page column 8
(2008/06/13)
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