883-93-2Relevant academic research and scientific papers
Synthesis of 2-Arylbenzothiazoles from Nitrobenzenes, Benzylamines, and Elemental Sulfur via Redox Cyclization
Imoto, Mitsutaka,Mizuno, Takumi,Nomoto, Akihiro,Ogawa, Akiya,Takeda, Motonori,Teramoto, Masahiro
supporting information, p. 386 - 390 (2022/03/02)
A sustainable advanced synthetic method was developed based on redox cyclization for the synthesis of 2-arylbenzothiazoles in good to excellent yields from readily available nitrobenzenes, benzylamines, and elemental sulfur without the use of transition-metal catalysts. This method is remarkable: nitro group reduction, a benzylamine redox reaction, sulfuration, condensation, and cyclization, all proceed in a single step to generate a heterocycle. It is also highly atom-economical and does not require any external oxidizing or reducing agents.
Graphene oxide-catalyzed synthesis of benzothiazoles with amines and elemental sulfur via oxidative coupling strategy of amines to imines
Duan, Dehao,Han, Xiaowei,He, Haiping,Huang, Panpan,Li, Hong,Nie, Liang,Peng, Xiangjun,Tang, Bo,Wang, Hanyu,Wei, Yifei
, (2022/01/13)
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.
Visible-Light Carbon Nitride-Catalyzed Aerobic Cyclization of Thiobenzanilides under Ambient Air Conditions
Bai, Jin,Yan, Sijia,Zhang, Zhuxia,Guo, Zhen,Zhou, Cong-Ying
supporting information, p. 4843 - 4848 (2021/06/28)
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.
Visible-light-mediated organoboron-catalysed metal-free dehydrogenation of N-heterocycles using molecular oxygen
Wei, Lanfeng,Wei, Yu,Xu, Liang,Zhang, Jinli
supporting information, p. 4446 - 4450 (2021/06/30)
The surge of photocatalytic transformation not only provides unprecedented synthetic methods, but also triggers the enthusiasm for more sustainable photocatalysts. On the other hand, oxygen is an ideal oxidant in terms of atom economy and environmental friendliness. However, the poor reactivity of oxygen at the ground state makes its utilization challenging. Herein, a visible-light-induced oxidative dehydrogenative process is disclosed, which uses an organoboron compound as the photocatalyst and molecular oxygen as the sole oxidant.Viathis approach, an array of N-heterocycles have been accessed under metal-free mild conditions, in good to excellent yields.
Highly Ordered Mesoporous Cobalt Oxide as Heterogeneous Catalyst for Aerobic Oxidative Aromatization of N-Heterocycles
Cao, Yue,Wu, Yong,Zhang, Yuanteng,Zhou, Jing,Xiao, Wei,Gu, Dong
, p. 3679 - 3686 (2021/06/18)
N-heterocycles are key structures for many pharmaceutical intermediates. The synthesis of such units normally is conducted under homogeneous catalytic conditions. Among all methods, aerobic oxidative aromatization is one of the most effective. However, in homogeneous conditions, catalysts are difficult to be recycled. Herein, we report a heterogeneous catalytic strategy with a mesoporous cobalt oxide as catalyst. The developed protocol shows a broad applicability for the synthesis of N-heterocycles (32 examples, up to 99 % yield), and the catalyst presents high turnover numbers (7.41) in the absence of any additives. Such a heterogenous approach can be easily scaled up. Furthermore, the catalyst can be recycled by simply filtration and be reused for at least six times without obvious deactivation. Comparative studies reveal that the high surface area of mesoporous cobalt oxide plays an important role on the catalytic reactivity. The outstanding recycling capacity makes the catalyst industrially practical and sustainable for the synthesis of diverse N-heterocycles.
Orderly cascade of immobilized-enzyme catalysis and photocatalysis for continuous-microflow production of 2-phenylbenzothiazole
Chen, Qiang,Luo, Guang-Sheng,Wang, Yu-Jun
supporting information, p. 7074 - 7083 (2021/09/28)
Green, economic, efficient, and sustainable synthesis of 2-phenylbenzothiazole (2-PBZ)—an important versatile scaffold—remains challenging. Here, for the first time, we propose to cascade immobilized enzyme catalysis and photocatalysis in a continuous-microflow manner to realize the online reuse of the enzyme, eliminate cross-inhibitions between the two-step reaction processes, provide stronger and more uniform illumination, and enhance process efficiency. This novel microflow system required only 4.6 min of the total residence time to achieve >99% product yield, and 93.7% of the total catalytic activity was retained after running for 300 min. This orderly cascaded continuous-flow microreactor system widens the limitations of photo-biocatalytic approaches and provides the potential foundation for the industrial green production of 2-PBZ.
Photocatalyst- And Transition-Metal-Free Visible-Light-Promoted Intramolecular C(sp2)-S Formation
Wang, Hao,Wu, Qi,Zhang, Jian-Dong,Li, Hai-Yan,Li, Hong-Xi
supporting information, p. 2078 - 2083 (2021/04/05)
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.
KOtBu-Promoted Halogen-Bond-Assisted Intramolecular C-S Cross-Coupling of o-Iodothioanilides for the Synthesis of 2-Substituted Benzothiazoles
Nandy, Anuradha,Sekar, Govindasamy
, p. 15825 - 15834 (2021/11/01)
An efficacious and mild KOtBu-promoted intramolecular C-S cross-coupling of ortho-iodothioanilides in conjunction with a catalytic quantity of phenanthroline as an additive has been described for the convenient synthesis of 2-substituted benzothiazoles. The methodology is suitable for attaining a wide variety of 2-alkyl- and 2-aryl-substituted benzothiazoles. Single-crystal XRD, DFT calculations, NMR, and UV studies suggest that halogen bonds between the units of ortho-iodothioanilides may assist in the electron transfer process.
Preparation method of benzothiazole phosphate compound
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Paragraph 0013-0018, (2021/06/13)
The invention discloses a preparation method of a benzothiazole phosphate compound. Under the irradiation of visible light, N-(2-bromophenyl) alkyl thioamide such as N-(2-bromophenyl) alkyl thioamide derivatives and the like are used as raw materials, sodium phosphate is used as alkali, a series of 2-substituted alkyl benzothiazole derivatives are smoothly synthesized, and further, under the irradiation of visible light, the benzothiazole phosphate compound is prepared through reaction with diethyl phosphate, and the benzothiazole phosphate compound has the calcium antagonist capability.
Method for preparing biphenyl benzothiazole compound
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Paragraph 0011; 0013-0018; 0035, (2021/06/12)
The invention discloses a preparation method of a biphenyl benzothiazole compound. N-(2-bromophenyl) alkyl thioamide such as an N-(2-bromophenyl) alkyl thioamide derivative is used as a raw material, sodium phosphate is used as alkali, the biphenyl benzothiazole compound is prepared through a one-pot method, the reaction is carried out under visible light irradiation, metal ions disclosed in the prior art are not needed, and the reaction yield is high.
