- A highly regioselective synthesis of 2-aryl-6-chlorobenzothiazoles employing microwave-promoted Suzuki-Miyaura coupling reaction
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Suzuki-Miyaura coupling reactions of 2,6-dichlorobenzothiazole with arylboronic acids, promoted by microwave heating, efficiently produce 2-aryl-6-chlorobenzothiazoles in a highly regioselective manner. This process serves as the foundation for a simple m
- Heo, Yeon,Song, Young Seob,Kim, Bum Tae,Heo, Jung-Nyoung
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- 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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- Graphene oxide-catalyzed synthesis of benzothiazoles with amines and elemental sulfur via oxidative coupling strategy of amines to imines
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The graphene oxide-catalyzed coupling and cyclization reactions of primary amines with elemental sulfur was developed to afford various optically property benzothiazoles. This coupling and cyclization strategies proceeded under the oxidant system graphene oxide/O2 and constructed carbon-heteroatom (N, S) bonds with amines and elemental sulfur. Due to benzothiazoles as common chromophores, these products exhibited intriguing fluorescence properties, including outstanding Stokes shifts (up to 161 nm) and quantum yields (up to 74%). Utilizing the products’ unique fluorescence response in different solvents, β-naphthothiazole 4a showed excellent aggregation-induced emission properties in 1,2-dichloroethane, which was 60 times higher than in tetrahydrofuran.
- Duan, Dehao,Han, Xiaowei,He, Haiping,Huang, Panpan,Li, Hong,Nie, Liang,Peng, Xiangjun,Tang, Bo,Wang, Hanyu,Wei, Yifei
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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 0040-0042
(2021/06/22)
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- Visible-Light Carbon Nitride-Catalyzed Aerobic Cyclization of Thiobenzanilides under Ambient Air Conditions
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A metal-free heterogeneous photocatalysis has been developed for the synthesis of benzothiazoles via intramolecular C-H functionalization/C-S bond formation of thiobenzanilides by inexpensive graphitic carbon nitride (g-C3N4) under visible-light irradiation. This reaction provides access to a broad range of 2-substituted benzothiazoles in high yields under an air atmosphere at room temperature without addition of a strong base or organic oxidizing reagents. In addition, the catalyst was found to be stable and reusable after five reaction cycles.
- Bai, Jin,Yan, Sijia,Zhang, Zhuxia,Guo, Zhen,Zhou, Cong-Ying
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p. 4843 - 4848
(2021/06/28)
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- Copper-Catalyzed Aerobic Oxidation of Amines to Benzothiazoles via Cross Coupling of Amines and Arene Thiolation Sequence
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A one-pot three-component synthesis of benzothiazoles has been developed using the copper-catalyzed aerobic cross coupling of amines followed by arene thiolation using elemental sulfur. The dual roles of elemental sulfur and CuCl(OH)-TMEDA in the aerobic amine oxidation and the aniline thiolation enable the facile access to benzothiazole derivatives from readily available starting materials. The operational simplicity of the current promiscuous catalyst system suggests the high synthetic potential in the preparation of heterocyclic compounds. (Figure presented.).
- Kim, Jihyeon,Oh, Kyungsoo
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supporting information
p. 3576 - 3582
(2020/08/05)
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- Preparation method of 2-substituted benzothiazole
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The invention discloses a preparation method of 2-substituted benzothiazole, and belongs to the field of organic chemical synthesis. The preparation method of the 2-substituted benzothiazole specifically comprises the following steps: by taking an N-aryl thioamide compound as a raw material and taking graphite-phase carbon nitride (g-C3N4) prepared by urea thermal polymerization condensation as aphotocatalyst, carrying out a cyclization reaction under a mild condition to prepare the 2-substituted benzothiazole. The method has the advantages of simple operation, cheap and easily available catalyst, mild reaction conditions, wide substrate application range, no strong oxidant and no metal residue, and provides an economical, practical, green and environment-friendly new method for synthesisof 2-substituted benzothiazole widely applied to the fields of medicines, dyes, pesticides and the like.
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Paragraph 0046-0051
(2020/11/09)
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- Riboflavin as Photoredox Catalyst in the Cyclization of Thiobenzanilides: Synthesis of 2-Substituted Benzothiazoles
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Benzothiazoles are synthesized from thiobenzanilides using riboflavin as a photosensitizer and potassium peroxydisulfate as a sacrificial oxidizing agent under visible light irradiation. The methodology accepts a broad range of functional groups and affords the 2-substituted benzothiazoles by transition-metal-free organic photoredox catalysis under very mild conditions.
- Bouchet, Lydia M.,Heredia, Adrián A.,Argüello, Juan E.,Schmidt, Luciana C.
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supporting information
p. 610 - 614
(2020/01/31)
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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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- 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; 0177
(2019/01/21)
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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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- Exogenous Photosensitizer-, Metal-, and Base-Free Visible-Light-Promoted C-H Thiolation via Reverse Hydrogen Atom Transfer
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Visible-light-driven, intramolecular C(sp2)-H thiolation has been achieved without addition of a photosensitizer, metal catalyst, or base. This reaction induces the cyclization of thiobenzanilides to benzothiazoles. The substrate absorbs visible light, and its excited state undergoes a reverse hydrogen-atom transfer (RHAT) with 2,2,6,6-tetramethylpiperidine N-oxyl to form a sulfur radical. The addition of the sulfur radical to the benzene ring gives an aryl radical, which then rearomatizes to benzothiazole via RHAT.
- Xu, Ze-Ming,Li, Hong-Xi,Young, David James,Zhu, Da-Liang,Li, Hai-Yan,Lang, Jian-Ping
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p. 237 - 241
(2019/01/10)
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- Method for preparing benzothiazole compound through microwave catalysis in water phase
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The invention discloses a method for preparing a benzothiazole compound through/under microwave catalysis in a water phase. A water-soluble coordination compound is used as a catalyst, and a reactionof inorganic sulfide, 2-iodoaniline and aldehyde is efficiently catalyzed through microwaves in a pure water phase. The method for preparing the benzothiazole compound is environmentally friendly, convenient to operate, safe, cheap and efficient. Compared with the prior art, the method is applied to a large quantity of functional groups, high in yield, simple to operate, safe, low in cost and environmentally friendly and produces a few byproducts.
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Paragraph 0045; 0049
(2018/05/16)
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- Cascade C(sp3)-S Bond Cleavage and Imidoyl C-S Formation: Radical Cyclization of 2-Isocyanoaryl Thioethers toward 2-Substituted Benzothiazoles
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A cascade radical cyclization of 2-isocyanoaryl thioethers with H-phosphorus oxides, organoboronic acids, or alkyl radical precursors has been efficiently developed, providing a novel and highly efficient methodology to structurally diverse C2-substituted benzothiazole derivatives with broad functional group tolerance and good yields. This cascade radical process achieves the first cycloaddition of an imidoyl radical from isocyanide to sulfur atom, rending C(sp2)-S bond formation.
- Yang, Wen-Chao,Wei, Kai,Sun, Xue,Zhu, Jie,Wu, Lei
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p. 3144 - 3147
(2018/05/28)
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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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- Copper-Catalyzed Arylation of Benzothiazoles with Toluene Derivatives: Synthesis of 2-Arylbenzothiazole
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A copper-catalyzed reaction of benzothiazole and readily available toluene derivatives has been disclosed. This protocol is proposed to proceed through the oxidation of toluene and ring opening of benzothiazole, thus providing a new pathway for the synthesis of 2-arylbenzothiazoles..
- Li, Chengliang,Deng, Hongmei,Jin, Tao,Liu, Zhiqiang,Jiang, Ruolan,Li, Chunju,Jia, Xueshun,Li, Jian
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p. 4350 - 4356
(2017/09/12)
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- Iron(ii)-catalyzed sulfur directed C(sp3)-H bond amination/C-S cross coupling reaction
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An efficient iron(ii)-catalyzed sulfur directed C(sp3)-H bond amination/C-S cross coupling reaction has been developed. The reaction had high tolerance of functional groups under moderate conditions. The results of a deuterium labeling study and in situ ESI-MS experiments indicated that the reaction mechanism probably corresponds to a Fe(ii)/Fe(iii) catalytic cycle.
- Duan, Fang-Fang,Song, Shi-Qian,Xu, Run-Sheng
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supporting information
p. 2737 - 2739
(2017/03/10)
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- Visible-light-promoted synthesis of benzothiazoles from 2-aminothiophenols and aldehydes
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A visible-light-promoted synthesis of benzothiazoles from 2-aminothiophenols and aldehydes has been developed. A wide range of aromatic, heteroaromatic and aliphatic aldehydes were successfully applied. The benzothiazole products were prepared in good yields. The reaction was carried out in the absence of transition-metal catalysts and extra additives. A radical reaction pathway was proposed.
- Ye, Lin-miao,Chen, Jie,Mao, Peng,Mao, Zhi-feng,Zhang, Xue-jing,Yan, Ming
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supporting information
p. 874 - 876
(2017/02/18)
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- N-Heterocyclic carbene copper(i) complex-catalyzed synthesis of 2-aryl benzoxazoles and benzothiazoles
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A new and efficient synthesis of 2-arylbenzoxazoles and benzothiazoles using a copper N-heterocyclic carbene complex is described. In a simple protocol a variety of 2-substituted benzoxazoles and benzothiazoles were obtained via intramolecular coupling cyclization of 2-haloanilides/2-halothioanilides in good to excellent yields.
- Urzúa, Julio I.,Contreras, Renato,Salas, Cristian O.,Tapia, Ricardo A.
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p. 82401 - 82408
(2016/09/09)
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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 0124; 0125; 0126; 0127; 0128; 0129; 0130
(2016/10/10)
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- Elemental sulfur mediated decarboxylative redox cyclization reaction of o -chloronitroarenes and arylacetic acids
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A decarboxylative redox cyclization strategy has been developed for the synthesis of 2-substituted benzothiazoles by the reaction of o-chloronitroarenes and arylacetic acids in the presence of elemental sulfur/N-methylmorpholine under metal- and solvent-free conditions.
- Guntreddi, Tirumaleswararao,Vanjari, Rajeshwer,Singh, Krishna Nand
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supporting information
p. 976 - 978
(2015/03/30)
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- External Oxidant-Free Oxidative Cross-Coupling: A Photoredox Cobalt-Catalyzed Aromatic C-H Thiolation for Constructing C-S Bonds
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An external oxidant-free oxidative coupling for aromatic C-H thiolation by visible-light photoredox cobalt-catalysis has been developed. Various substrates could afford benzothiazoles in good to excellent yields, and only H2 is generated as a side product. When catalytic TBAOH was used as the base, not only 2-aryl but also 2-alkylbenzothiazoles could be obtained through this novel dehydrogenative coupling reaction. This method could be scaled up and applied to the synthesis of biologically active molecules bearing benzothiazole structural scaffolds (potent antitumor agents). Furthermore, the unexpected oxidation byproduct amides, which are often generated in oxidative cyclization of thiobenzanilides, can be completely avoided. Mechanistic studies showed that the H2 originates from the substrates. The kinetic studies indicate that the interaction between the cobalt catalyst and proton might be involved in the rate-limiting process. (Chemical Equation Presented).
- Zhang, Guoting,Liu, Chao,Yi, Hong,Meng, Qingyuan,Bian, Changliang,Chen, Hong,Jian, Jing-Xin,Wu, Li-Zhu,Lei, Aiwen
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supporting information
p. 9273 - 9280
(2015/08/11)
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- Copper-catalyzed double c-s bonds formation via different paths: Synthesis of benzothiazoles from n -benzyl-2-iodoaniline and potassium sulfide
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A new, highly efficient procedure for the synthesis of benzothiazoles from easily available N-benzyl-2-iodoaniline and potassium sulfide has been developed. The results show copper-catalyzed double C-S bond formation via a traditional cross-coupling reaction and an oxidative cross-coupling reaction.
- Zhang, Xiaoyun,Zeng, Weilan,Yang, Yuan,Huang, Hui,Liang, Yun
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supporting information
p. 876 - 879
(2014/03/21)
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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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- Quaternary ammonium salt as alkylation agent in three-component reactions for the synthesis of benzothiazoles in water
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Substituted benzothiazoles are synthesized by metal-catalyst-free three-component reactions of o-iodoaniline, quaternary ammonium salt, and sulfur powder in water with moderate-to-excellent yields up to 95%. This journal is the Partner Organisations 2014.
- Pan, Lei,Yu, Lintao,Wu, Zhiqing,Li, Zhengkai,Xiang, Haifeng,Zhou, Xiangge
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p. 27775 - 27779
(2014/07/21)
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- KI-catalyzed arylation of benzothiazoles from the coupling of aryl aldehydes with benzothiazoles in neat water
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A KI-catalyzed oxidative coupling of benzothiazoles with aryl aldehydes has been developed using TBHP as an oxidant in neat water under metal free conditions. Various 2-aryl benzothiazoles were prepared in 36-79% yields for 28 examples. The mechanistic studies suggested that this transformation proceeded via a radical process. The Royal Society of Chemistry.
- Gao, Yuyu,Song, Qiuling,Cheng, Guolin,Cui, Xiuling
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supporting information
p. 1044 - 1047
(2014/02/14)
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- Organocatalytic syntheses of benzoxazoles and benzothiazoles using aryl iodide and oxone via C-H functionalization and C-O/S bond formation
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An organocatalytic protocol for the syntheses of 2-substituted benzoxazoles and benzothiazoles is described from alkyl-/arylanilides and alkyl-/arylthioanilides using 1-iodo-4-nitrobenzene as catalyst and oxone as an inexpensive and environmentally safe terminal oxidant at room temperature in air via oxidative C-H functionalization and C-O/S bond formation. The procedure is simple and general and provides an effective route for the construction of functionalized 2-alkyl-/arylbenzoxazoles and 2-alkyl-/arylbenzothiazoles with moderate to high yields. The synthetic and mechanistic aspects have been described.
- Alla, Santhosh Kumar,Sadhu, Pradeep,Punniyamurthy, Tharmalingam
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p. 7502 - 7511
(2014/09/16)
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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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- Synthesis, catalytic activity and phytotoxicity of a supported nickel(II) Schiff base complex
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A supported Ni(II) complex has been synthesized and characterized by FTIR, UV-vis diffuse reflectance spectroscopy, thermogravimetric analysis and scanning electron microscopy. Its catalytic activity was evaluated for alkyne-azide coupling and benzothiazo
- Islam,Paul, Sumantra,Roy, Anupam Singha,Banerjee, Satabdi,Mobarok, Manir,Santra
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p. 855 - 864
(2013/11/19)
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- Synthesis of 2-aryl benzothiazoles via K2S2O 8-mediated oxidative condensation of benzothiazoles with benzylamines
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A novel way to synthesize 2-arylbenzothiazoles is described. Reactions of benzothiazoles with diverse benzylamines in the presence of K2S 2O8 and KOt-Bu in DMSO-H2O afforded the desired 2-arylbenzothiazoles in good yields. It is notable that no transition-metal catalyst is needed in this reaction. Compared with other known methods, this method of synthesizing 2-arylbenzothiazoles can be advantageous in cases where substituted benzothiazoles and benzylamines are readily available. Georg Thieme Verlag Stuttgart. New York.
- Yang, Zhiyong,Wang, Anwei,Chen, Xiang,Gui, Qingwen,Liu, Jidan,Tan, Ze,Wang, Hua,Shi, Ji-Cheng
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supporting information
p. 1549 - 1554
(2013/08/23)
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- Copper-catalyzed synthesis of benzo[ b ]thiophenes and benzothiazoles using thiocarboxylic acids as a coupling partner
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An efficient copper-catalyzed approach to benzo[b]thiophene and benzothiazole derivatives using thiocarboxylic acids as a sulfur source has been developed. In the presence of CuI and 1,10-phen, and n-Pr3N as the base, (2-iodobenzyl)triphenylphosphonium bromide and (2-iodophenylimino) triphenylphosphorane reacted smoothly with thiocarboxylic acids to give benzo[b]thiophene and benzothiazole derivatives in good yields via sequential Ullmann-type C-S bond coupling and Wittig condensation.
- Yu, Hui,Zhang, Meishu,Li, Yuzhe
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p. 8898 - 8903
(2013/09/24)
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- Efficient 2-aryl benzothiazole formation from aryl ketones and 2-aminobenzenethiols under metal-free conditions
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2-Aryl benzothiazole formation from aryl ketones and 2-aminobenzenethiols under metal- and I2-free conditions was described. Various 2-aryl benzothiazoles were selectively obtained in good yields using molecular oxygen as oxidant. DMSO played an important role in this transformation. Functional groups such as methyl, methoxy, fluoro, chloro, bromo and nitro groups were tolerated under the optimized reaction conditions.
- Liao, Yunfeng,Qi, Hongrui,Chen, Shanping,Jiang, Pengcheng,Zhou, Wang,Deng, Guo-Jun
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supporting information
p. 6004 - 6007
(2013/02/22)
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- Palladium-catalyzed C-H cyclization in water: A milder route to 2-arylbenzothiazoles
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Water was successfully employed as a reaction medium in palladium-catalyzed C-H cyclization of thiobenzanilides. Reactions efficiently proceeded under considerably mild conditions such as 40 °C in water, providing a more practical, greener method for the synthesis of 2-arylbenzothiazoles. For some substrates, the addition of an amphiphilic surfactant greatly enhanced the process. The method represents a rare example of palladium-catalyzed C-H functionalization processes performed in water. Georg Thieme Verlag Stuttgart · New York.
- Inamoto, Kiyofumi,Nozawa, Kanako,Kondo, Yoshinori
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p. 1678 - 1682
(2012/07/17)
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- Aerobic visible-light photoredox radical C-H functionalization: Catalytic synthesis of 2-substituted benzothiazoles
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An aerobic visible-light driven photoredox catalytic formation of 2-substituted benzothiazoles through radical cyclization of thioanilides has been accomplished. The reaction features C-H functionalization and C-S bond formation with no direct metal involvement except the sensitizer. The reaction highlights the following: (1) visible-light is the reaction driving force; (2) molecular oxygen is the terminal oxidant, and (3) water is the only byproduct.
- Cheng, Yannan,Yang, Jun,Qu, Yue,Li, Pixu
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supporting information; experimental part
p. 98 - 101
(2012/02/04)
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- Use of molecular oxygen as a reoxidant in the synthesis of 2-substituted benzothiazoles via palladium-catalyzed C-H functionalization/intramolecular C-S bond formation
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Molecular oxygen (O2) was successfully employed as a reoxidant in cyclizations of thiobenzanilides 1a-s through a palladium-catalyzed C-H functionalization/intramolecular C-S bond formation process, leading to an efficient, green method for the synthesis of 2-arylbenzothiazoles 2a-s. Addition of cesium fluoride (CsF) greatly enhanced the reactions, which produced variously substituted 2-arylbenzothiazoles with good functional group tolerance. Thioureas 4a-j were also found to be suitable substrates for the cyclization process using a palladium/O2 catalyst system, thus generating 2-aminobenzothiazoles 5a-j. One-pot syntheses of 2-aminobenzothiazoles 5a-j from aryl isothiocyanates 6 and amines 7 were also successful.
- Inamoto, Kiyofumi,Hasegawa, Chisa,Kawasaki, Junpei,Hiroya, Kou,Doi, Takayuki
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experimental part
p. 2643 - 2655
(2010/12/25)
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- Alum (KAl(SO4)2·12H2O)-catalyzed, eco-friendly, and efficient one-pot synthesis of 2-arylbenzothiazoles and 2-arylbenzoxazole in aqueous medium
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Alum (KAl(SO4)212H2O) performs as a novel catalyst for the synthesis of 2-arylbenzothiazoles and 2-arylbenzoxazole from o-aminothiophenol and o-aminophenol with various substituted aldehydes in good to excellent isolated yields (8595%) using water as a solvent at ambient temperature. Several solvents were examined for this reaction; however, in terms of reaction yield and time, water was found to be the optimum solvent. The remarkable advantages offered by this method are an inexpensive and easily available catalyst, a simple procedure, mild conditions, much faster (6090 min) reactions, and good to excellent yields of products.
- Pawar, Shivaji S.,Dekhane, Deepak V.,Shingare, Murlidhar S.,Thore, Shivaji N.
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experimental part
p. 905 - 909
(2009/04/11)
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- Palladium-catalyzed synthesis of 2-substituted benzothiazoles via a C-H functionalization/intramolecular C-S bond formation process
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(Chemical Equation Presented) Catalytic synthesis of 2-substituted benzothiazoles from thiobenzanilides was achieved in the presence of a palladium catalyst through C-H functionalization/C-S bond formation. This method features the use of a novel catalytic system consisting of 10 mol % of Pd(II), 50 mol % of Cu(I), and 2 equiv of Bu4NBr that produced variously substituted benzothiazoles in high yields with good functional group tolerance.
- Inamoto, Kiyofumi,Hasegawa, Chisa,Hiroya, Kou,Doi, Takayuki
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supporting information; experimental part
p. 5147 - 5150
(2009/05/30)
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- Microwave-assisted "green" synthesis of 2-alkyl/ arylbenzothiazoles in one pot: A facile approach to anti-tumor drugs
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A series of new 2-alkyl/arylbenzothiazoles has been synthesized on the basis of the potent and selective in vitro anti-tumor properties of 2-(3,4-diethoxyphenyl)-5-fluorobenzothiazole. The synthesis of benzothiazole analogs was achieved via microwave irradiation of a 1:1 mixture of o-aminothiophenol and alkyl/aryl acylacetonitriles at temperature of 200 °C for 10 min. The yields are very good to excellent. All the products were characterized by 1H nmr, 13C nmr and elemental analysis.
- Kamila, Sukanta,Koh, Benjamin,Biehl, Edward R.
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p. 1609 - 1612
(2007/10/03)
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- Oxidative cyclization of thiobenzanilides to benzothiazoles using N-Benzyl-DABCO tribromide under mild conditions
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N-benzyl-DABCO tribromide, a stable, crystalline organic ammonium tribromide (OATB), have been used as an alternative electrophilic bromine source for the efficient oxidative cyclization of thiobenzanilides to the corresponding benzothiazoles under mild conditions. Georg Thieme Verlag Stuttgart.
- Moghaddam, Firouz Matloubi,Boeini, Hassan Zali
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p. 1612 - 1614
(2007/10/03)
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- 3-H-1,2,3-Benzodithiazole-2-oxides as synthons for the synthesis of five- and six-membered heterocycles containing sulphur and nitrogen
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The reaction of 6-substituted-1,2,3-benzodithiazole-2-oxides (2) with aromatic aldehydes, carboxylic acids and acid chlorides in the presence of an organic base such as triethylamine and N,N-dimethylaniline lead to the formation of 6-substituted-2-arylben
- Sawhney, S N,Sharma, P. K.,Bajaj, K,Gupta, A
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p. 280 - 284
(2007/10/02)
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- A new synthesis of 2-arylbenzothiazoles from 1,2,3-benzodithiazole-2-oxides
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The reaction of 6-substituted-1,2,3-benzodithiazole-2-oxides (3a-3d) with aromatic aldehydes, carboxylic acids, and their chlorides in the presence of an organic base provides a new method for the synthesis of 6-substituted-2-arylbenzothiazoles (4a-4d) without involving the preparation of intermediate 2-aminobenzenethiols.
- Sawhney,Sharma,Bajaj,Gupta
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p. 263 - 270
(2007/10/02)
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