883-93-2Relevant academic research and scientific papers
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.
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.
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.
Preparation method of benzothiazole phosphate compound
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Paragraph 0013-0016, (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 benzothiazole compound from visible light promoted N-(2-bromophenyl) thioamide
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Paragraph 0016-0027; 0125-0129, (2021/06/22)
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.
Method for preparing alkyl benzothiazole derivative under visible light
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Paragraph 0014-0023, (2021/06/22)
The invention discloses a method for preparing an alkyl benzothiazole derivative under visible light, which specifically comprises the following steps: under the protection of inert gas, adding N-(2-bromophenyl) alkyl thioamide and inorganic base into a reaction container provided with a stirring device, then adding dimethyl sulfoxide, stirring and reacting for 24 hours at room temperature under the irradiation of visible light, and obtaining the alkyl benzothiazole derivative. 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) alkyl thioamide are realized. In addition, the alkylbenzothiazole derivative 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 alkylbenzothiazole derivative.
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.
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.
α-Keto Acids as Triggers and Partners for the Synthesis of Quinazolinones, Quinoxalinones, Benzooxazinones, and Benzothiazoles in Water
Huang, Jian,Chen, Wei,Liang, Jiazhi,Yang, Qin,Fan, Yan,Chen, Mu-Wang,Peng, Yiyuan
, p. 14866 - 14882 (2021/10/25)
A general and efficient method for the synthesis of quinazolinones, quinoxalinones, benzooxazinones, and benzothiazoles from the reactions of α-keto acids with 2-aminobenzamides, benzene-1,2-diamines, 2-aminophenols, and 2-aminobenzenethiols, respectively, is described. The reactions were conducted under catalyst-free conditions, using water as the sole solvent with no additive required, and successfully applied to the synthesis of sildenafil. More importantly, these reactions can be conducted on a mass scale, and the products can be easily purified through filtration and washing with ethanol (or crystallized).
Possible competitive modes of decarboxylation in the annulation reactions ofortho-substituted anilines and arylglyoxylates
Laha, Joydev K.,Panday, Surabhi,Tomar, Monika,Patel, Ketul V.
supporting information, p. 845 - 853 (2021/02/09)
Annulation reactions ofortho-substituted anilines and arylglyoxylates in the presence of K2S2O8at 80 °C under metal-free neutral conditions have been investigated, which extended a platform for the tandem synthesis of nitrogen heterocycles. While arylglyoxylic acids are known to undergo decarboxylation to form an acyl radical in the presence of K2S2O8and used in the Minisci acylation of electron-deficient (hetero)aromatics, their reactions with electron-richortho-substituted anilines to form nitrogen heterocycles have recently been studied. Depending upon the experimental conditions used in the reactions, the mechanism of the formation of heterocycles involving reactions of an acyl radical or aryl iminocarboxylic acids has been postulated. Given the subtle understanding of the mechanisms of annulation reactions of 2-substituted anilines and arylglyoxylates in the presence of K2S2O8, an extensive mechanistic investigation was undertaken. In the current study, the various mechanistic pathways including the generation of acyl, imidoyl, aminal, and N,O-hemiketal radicals have been postulated based on different possible decarboxylation modes. Some of the proposed intermediates are supported based on the available analytical data. The protocol uses a single, inexpensive reagent K2S2O8, which offers not only transition-metal-free conditions but also serves as the reagent for the key decarboxylation step. Taken together, this study complements the current development of the annulation reactions of 2-substituted anilines and arylglyoxylates in terms of synthesis and mechanistic understanding.
