22868-31-1Relevant academic research and scientific papers
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).
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.
Sulfur-Promoted Redox Cyclization of 2,2′-Dinitrodiphenyl Disulfides and Benzylamines
Teramoto, Masahiro,Imoto, Mitsutaka,Takeda, Motonori,Mizuno, Takumi,Nomoto, Akihiro,Ogawa, Akiya
, p. 2485 - 2493 (2021/04/15)
This study aims to develop green and sustainable advanced synthetic methods based on redox cyclization. Elemental sulfur is shown to promote the efficient synthesis of 2-substituted benzothiazoles from 2,2′-dinitrodiphenyl disulfides and benzylamines via redox cyclization in the absence of transition-metal catalysts and solvents. The 2-substituted benzothiazoles are obtained in good to excellent yields. This synthetic methodology is highly atom-economical and does not require any external oxidizing and/or reducing agents.
Improved, gram-scale synthesis of sildenafil in water using arylacetic acid as the acyl source in the pyrazolo[4,3-d]pyrimidin-7-one ring formation
Laha, Joydev K.,Gulati, Upma,Saima,Gupta, Anjali,Indurthi, Harish Kumar
supporting information, p. 2643 - 2648 (2021/02/16)
An improved, gram-scale synthesis of the blockbuster drug sildenafil, used for the treatment of male erectile dysfunction, has been developed. Unlike the previous literature, the current method demonstrates the use of arylacetic acid as an acyl source, a cheap oxidant K2S2O8, and water as the reaction medium in the key step of pyrrazolo[4,3-d]pyrimidin-7-one ring formation. As well as being a green and benign approach, the current method reduces the cost by half compared to our previous strategy. In addition, the general relevance of the method has been demonstrated in the synthesis of a variety of quinazolinone and benzothiazole derivatives with excellent functional group tolerance.
Oxidant/Solvent-Controlled I2-Catalyzed Domino Annulation for Selective Synthesis of 2-Aroylbenzothiazoles and 2-Arylbenzothiazoles under Metal-Free Conditions
Ma, Renchao,Ding, Yuxin,Chen, Rener,Wang, Zhiming,Wang, Lei,Ma, Yongmin
, p. 310 - 321 (2021/01/09)
A simple and practical domino protocol for the selective synthesis of 2-aroylbenzothiazoles and 2-aryl benzothiazoles catalyzed by I2 is developed under metal-free conditions. The reaction outcomes are exclusively controlled by the reaction oxidant/medium. With DMSO employed as both the solvent and the oxidant, an oxidation of aromatic methyl ketones takes precedence over the condensation with 2-aminobenzenethiols. On the other hand, when the reaction was carried out in PhNO2 or in 1,4-dioxane containing PhNO2, the condensation of aromatic methyl ketones with 2-aminobenzenethiols has priority to form imines which is followed by an oxidation of the methyl group from ketones to afford 2-arylbenzothiazoles as a sole product. The PhNO2/I2 co-catalytic system is proposed first time.
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.
Fast and high-efficiency synthesis of 2-substituted benzothiazoles via combining enzyme catalysis and photoredox catalysis in one-pot
Yang, Zeng-Jie,Gong, Qing-Tian,Yu, Yuan,Lu, Wei-Fan,Wu, Zhe-Ning,Wang, Na,Yu, Xiao-Qi
supporting information, (2021/01/14)
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
Synthesis, characterization, crystal structures, and anticancer activity of some new 2,3-dihydro-1,5-benzoxazepines
Odame, Felix,Schoeman, Recardia,Krause, Jason,Hosten, Eric C.,Tshentu, Zenixole R.,Frost, Carminita
supporting information, p. 987 - 1004 (2021/02/16)
Various benzoxazepine derivatives have been synthesized and characterized using IR, NMR, GC–MS, and microanalysis. The single-crystal X-ray structures of 2,2-dimethyl-4-[(E)-2-(4-methylphenyl)ethenyl]-2,3-dihydro-1,5-benzoxazepine (RS01), 4-[(E)-2-(2-chlo
Preparation method of 2-substituted benzothiazole
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Paragraph 0106-0111, (2020/11/09)
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.
NCS/TBHP promoted C2 arylation of benzothiazoles with aldehydes in DMSO
Xu, Wen-Xiu,Ye, Fei-Xia,Liu, Xing-Hai,Weng, Jian-Quan
, (2020/03/19)
A N-chlorosuccinimide catalyzed oxidative synthesis of 2-aryl benzothiazole from benzothiazoles and aryl aldehydes using tert-butyl peroxybenzoate as an oxidant in dimethyl sulfoxide (DMSO) has been developed in moderate to good yields. Solvent DMSO as a strong Lewis base plays an efficient role in the reaction. Various substrates were tolerated under optimized conditions affording the arylated products in 12–94% yields for 28 examples. Additionally, acylated benzothiazoles were produced with 4 examples.
