- Switchable and Scalable Heteroarylation of Primary Amines with 2-Chlorobenzothiazoles under Transition-Metal-Free and Solvent-Free Conditions
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2-Aminobenzothiazoles comprise a valuable structural motif, which prevails in versatile natural products and biologically active compounds. Herein, a switchable and scalable C-N coupling protocol was developed for the synthesis of these compounds from 2-chlorobenzothiazoles and primary amines. Gratifyingly, this protocol was achieved under transition-metal-free and solvent-free conditions. Moreover, introducing an appropriate amount of NaH completely switched the selectivity from mono- toward di-heteroarylation, and further investigations provided a rationale for this new finding. Furthermore, gram-scale synthesis of representative products 3a and 4a was realized by applying operationally simple and glovebox-free procedures, which revealed the practical usefulness of this work. Finally, evaluation of the quantitative green metrics provided evidence that our protocol was superior over the literature ones in terms of green chemistry and sustainability.
- Cheng, Hua,Zhu, Yan-Qiu,Liu, Peng-Fei,Yang, Kai-Qiang,Yan, Jin,Sang, Wei,Tang, Xiao-Sheng,Zhang, Rui,Chen, Cheng
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p. 10288 - 10302
(2021/08/16)
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- Synthesis of Benz-Fused Azoles via C-Heteroatom Coupling Reactions Catalyzed by Cu(I) in the Presence of Glycosyltriazole Ligands
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Glycosyl triazoles are conveniently accessible and contain multiple metal-binding units that may assist in metal-mediated catalysis. Azide derivatives of d-glucose have been converted to their respective aryltriazoles and screened as ligands for the synthesis of 2-substituted benz-fused azoles and benzimidazoquinazolinones by Cu-catalyzed intramolecular Ullmann type C-heteroatom coupling. Good to excellent yields for a variety of benz-fused heterocyles were obtained for this readily accessible catalytic system.
- Mishra, Nidhi,Singh, Anoop S.,Agrahari, Anand K.,Singh, Sumit K.,Singh, Mala,Tiwari, Vinod K.
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supporting information
p. 389 - 399
(2019/05/06)
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- "on Water" Promoted Ullmann-Type C-N Bond-Forming Reactions: Application to Carbazole Alkaloids by Selective N-Arylation of Aminophenols
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The Ullmann-type cross coupling of a variety of aromatic, aliphatic amines with aryl halides is reported using a CuI-based catalytic system in combination with an easily accessible prolinamide ligand in aqueous media. The method is mild and tolerant to air, moisture, and a wide range of functional groups, providing a novel way to access a variety of aminated products. Secondary amines like heteroaromatic amines and nucleobases have also been used, affording the corresponding coupling products in good to excellent yields. Moreover, this method has been employed for chemoselective C-N arylation of aminophenols and further utilized for the synthesis of carbazole natural products, avoiding the protection and deprotection steps.
- Chakraborti, Gargi,Paladhi, Sushovan,Mandal, Tirtha,Dash, Jyotirmayee
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p. 7347 - 7359
(2018/07/29)
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- Iodine-catalyzed formation of substituted 2-aminobenzothiazole derivatives in PEG400
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An iodine-catalyzed formation of substituted 2-aminobenzothiazole derivatives is herein described using hydrogen peroxide as an oxidant in PEG400. The method enabled an efficient environmentally sound access to this valuable scaffold in moderate to excellent yields under metal-free conditions.
- Dumonteil,Hiebel,Scherrmann,Berteina-Raboin
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p. 73517 - 73521
(2016/08/19)
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- A practical synthesis of 2-aminobenzothiazoles via copper(I)-catalyzed tandem reaction of 2-iodoanilines with isothiocyanates in ionic liquids
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A copper(I)-catalyzed tandem reaction of 2-iodoanilines with isothiocyanates was achieved in hydrophobic [bmim][PF6] ionic liquid under mild conditions, generating a variety of 2-aminobenzothiazoles in good to excellent yields. The tandem reaction that was carried out in [bmim][PF6] has some obvious advantages such as accelerated reaction rate and increased yield as compared with the reaction run in volatile solvents such as toluene. Furthermore, the CuI/1,10-phenanthroline catalytic system can be reused up to eight times without loss of activity and efficiency.
- Chen, Ling,Huang, Bin,Nie, Quan,Cai, Mingzhong
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p. 446 - 450
(2016/05/19)
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- Straightforward synthesis of 2-anilinobenzoxazoles and -benzothiazoles via mechanochemical ball-milling-promoted one-pot reactions
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Under mechanochemical ball-milling and solvent-free conditions, a series of 2-anilinobenzoxazoles and -thiazoles were synthesized directly from the one-pot reaction of anilines, CS2, and 2-aminophenol and -thiophenol. This protocol exhibits the
- Zhang, Ze,Wang, Fang-Jian,Wu, Hao-Hao,Tan, Ya-Jun
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supporting information
p. 440 - 441
(2015/05/27)
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- Dithiocarbamate promoted practical synthesis of N-Aryl-2-aminobenzazoles: Synthesis of novel Aurora-A kinase inhibitor
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Various N-aryl-2-aminobenzoxazoles and N-aryl-2-aminobenzothiazoles were synthesized from o-aminophenol and o-aminothiophenol, respectively, mediated by dithiocarbamate in one step. The salient features of this method include mild reaction condition, high
- Katari, Naresh Kumar,Venkatanarayana,Srinivas, Kummari
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p. 447 - 453
(2015/05/20)
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- Postsynthetic modification of IRMOF-3 with a copper iminopyridine complex as heterogeneous catalyst for the synthesis of 2-aminobenzothiazoles
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A copper iminopyridine complex has been immobilized on to a metal-organic framework (MOF) through postsynthetic modification of IRMOF-3. The modified MOFs were fully demonstrated by using a variety of methods, and the structural integrity of the modified
- Liu, Jie,Zhang, Xiaobin,Yang, Jin,Wang, Lei
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p. 198 - 203
(2014/03/21)
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- Synthesis of N-substituted-2-aminobenzothiazoles using nano copper oxide as a recyclable catalyst under ligand-free conditions, in reusable PEG-400 medium
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A simple and practical method for the synthesis of N-substituted-2- aminobenzothiazoles via a cross-coupling reaction of 2-iodo anilines with isothiocyanates is envisaged using nano copper oxide as a recyclable catalyst and Cs2CO3 as a base in PEG-400, as a bio-degradable, reusable, inexpensive and non-toxic reaction medium, under ligand-free conditions. The present tandem process underlines environmental acceptability to access a wide range of N-substituted-2-aminobenzothiazoles in good to excellent yields.
- Gaddam, Satish,Kasireddy, Harshavardhan Reddy,Konkala, Karnakar,Katla, Ramesh,Durga, Nageswar Yadavalli Venkata
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p. 732 - 736
(2014/06/09)
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- A new and efficient synthesis of 2-aminobenzothiazoles derivatives from o-nitroaniline
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A novel sy nthesis of 2-aminobenzothia zoles from a transition-met al-free reaction between aryl isothioc yanates and o-nitroaniline in the presence of K2CO3 is reported. The newly developed method is an efficient and cost-effective approach to synthesise 2-aminobenzothiazoles.
- Mirza, Behrooz,Mirzazadeh, Roghieh,Zeeb, Mohsen
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p. 778 - 779
(2014/01/23)
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- Ligand- and solvent-free synthesis of 2-aminobenzothiazoles by copper-catalyzed tandem reaction of 2-haloanilines with isothiocyanates
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We report an environmentally friendly, efficient and practical method for the synthesis of 2-aminobenzothiazoles by a copper(II)-catalyzed tandem reaction of 2-haloanilines with isothiocyanates under ligand- and solvent-free conditions in air. The developed methodology conforms to the principles of 'green chemistry' and addresses the shortage of such methods for the synthesis of 2-aminobenzothiazoles. The reaction is quite general and generates a variety of 2-aminobenzothiazoles in good to excellent yields. Copyright
- Yao, Ruiya,Liu, Haiyi,Wu, Yichao,Cai, Mingzhong
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p. 109 - 113
(2013/03/13)
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- An "on-water" exploration of CuO nanoparticle catalysed synthesis of 2-aminobenzothiazoles
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An "on-water" one-pot process has been engineered for the preparation of 2-aminobenzothiazole from ortho-halo (-F, -Cl, -Br and -I) substituted unsymmetrical thioureas. For ortho -I and -Br substrates the reactions afford 2-aminobenzothiazoles under metal free condition promoted by base. However, the relatively inert ortho -Cl and -F substrates undergo intramolecular arylthiolation only in the presence of CuO nanoparticles yielding 2-aminobenzothiazoles. This methodology provides easy access to aminobenzothiazoles utilising even the ortho -Cl and -F substrates. The catalyst is recyclable several times without loss of substantial activity. Other remarkable features include the wide range of functional group tolerance, absence of chromatographic purification (for ortho -I and -Br substrates) and providing moderate to excellent yield of the products under mild conditions, thus rendering the methodology as a highly eco-friendly alternative to the existing methods.
- Rout, Saroj Kumar,Guin, Srimanta,Nath, Jayashree,Patel, Bhisma K.
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p. 2491 - 2498
(2013/02/21)
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- Stereoselective olefination and regiospecific vicinal difunctionalization of imines with α-(benzothiazol-2-ylsulfonyl) carbonyl compounds
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Depending on their structures, imines are able to undergo either olefination or vicinal difunctionalization with various α-(benzothiazol-2- ylsulfonyl) carbonyl compounds in the absence of external bases. The olefination reaction of aromatic imines with α-(benzothiazol-2-ylsulfonyl) carbonyl compounds proceeds smoothly in tetrahydrofuran at 70 °C to give structurally diverse α,β-unsaturated esters, amides, and ketones in good to excellent yields and with extremely high (E) selectivity. In contrast, the carbon-nitrogen double bonds of cyclic imines and the carbon-carbon double bonds of α,β-unsaturated imines are subjected to regiospecific vicinal difunctionalization with α-(benzothiazol-2-ylsulfonyl) carbonyl compounds under the same reaction conditions to give a variety of benzothiazole derivatives in good to excellent yields. It is noteworthy that the benzothiazole moiety is present in a number of antitumor agents and bioluminescent molecules. In addition, plausible reaction pathways have been proposed to account for these transformations, and these are substantially supported by ESI-MS analysis of the reaction mixtures.
- Shao, You-Dong,Wu, Xue-Song,Tian, Shi-Kai
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supporting information; experimental part
p. 1590 - 1596
(2012/05/07)
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- A practical synthesis of 2-aminobenzothiazoles via the tandem reactions of 2-haloanilines with isothiocyanates catalyzed by immobilization of copper in MCM-41
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The heterogeneous tandem reactions of 2-haloanilines with isothiocyanates were achieved in DMSO using Et3N as base at 80 °C in the presence of a 3-(2-aminoethylamino)propyl-functionalized MCM-41-immobilized copper(II) complex [MCM-41-2N-CuSO4], yielding a variety of 2- aminobenzothiazoles in good to excellent yields. This heterogeneous copper catalyst exhibited higher activity than CuSO4 and can be recovered and recycled by a simple filtration of the reaction solution and used for at least 10 consecutive trials without any decreases in activity.
- Xiao, Ruian,Hao, Wenyan,Ai, Jinting,Cai, Ming-Zhong
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experimental part
p. 44 - 50
(2012/04/17)
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- Iron-catalyzed tandem reactions of ortho-aminobenzenethiols with isothiocyanates leading to 2-aminobenzoazoles under ligand-and solvent-free conditions
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An efficient route to synthesize a variety of 2-aminobenzoazoles has been discovered. It involves the reaction of ortho-aminobenzenethiols with isothiocyanates via iron-catalyzed tandem addition-annulations process under ligand and solvent free conditions on silica gel surface. Copyright Taylor &Francis Group, LLC.
- Ding, Qiuping,Cao, Banpeng,Yang, Qin,Liu, Xianjin,Peng, Yiyuan
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experimental part
p. 1782 - 1789
(2011/10/02)
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- Merrifield resin supported phenanthroline-Cu(I): A highly efficient and recyclable catalyst for the synthesis of 2-aminobenzothiazoles via the reaction of 2-haloanilines with isothiocyanates
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A novel Merrifield resin supported phenanthroline-Cu(I) complex has been developed and used as a highly efficient and recyclable catalyst in the reaction of 2-halobenzenamines with isothiocyanates for the synthesis of 2-aminobenzothiazoles. The reactions
- Yang, Jin,Li, Pinhua,Wang, Lei
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experimental part
p. 5543 - 5549
(2011/08/06)
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- Synthesis of 2-aminobenzothiazoles via copper(I)-catalyzed cross-coupling with part-per-million catalyst loadings
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An efficient protocol has been developed for the preparation of 2-aminobenzothiazoles via a copper(I)-catalyzed tandem reaction of 2-iodoanilines with isothiocyanates at very low catalyst loadings [typically 50ppm of copper(I) iodide (CuI)]. A variety of 2-iodoanilines could be cross-coupled with isothiocyanates, affording 2-aminobenzothiazoles in moderate to good yields (49-93%) under the given conditions. The turnover number (TON) of this reaction reaches 67,000 and the reaction could be scaled up, at least, to the gram-scale. Copyright
- Sun, Ya-Lei,Zhang, Yuan,Cui, Xiao-Hui,Wang, Wei
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supporting information; experimental part
p. 1174 - 1178
(2011/07/09)
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- An effcient synthesis of 2-aminobenzoxazoles and 2-aminobenzothiazazoles from 2-aminophenols or 2-aminothiophenols and isoselenocyanates
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An expeditious method to access 2-aminobenzoxazoles and 2-aminobenzothiazoles from various substituted 2-aminophenols and 2-aminothiophenols, respectively, with isoselenocyanates in a one pot procedure is reported. Elemental Se precipitates nearly quantitatively in the reaction without any deselenizing agent and it can be reused. A possible mechanism for the formation of the target products is proposed. The Japan Institute of Heterocyclic Chemistry.
- Xie, Yuanyuan,Zhang, Fan,Chen, Xiaodong,Li, Jianjun
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experimental part
p. 2087 - 2096
(2011/03/23)
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- One-pot synthesis of five and six membered N, O, S-heterocycles using a ditribromide reagent
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In a one-pot procedure, bromine less brominating reagent 1,1′-(ethane-1,2-diyl)dipyridinium bistribromide (EDPBT) has been utilized as an efficient desulfurizing agent for the construction of a library of heterocycles containing N, O, and S starting from aryl/alkyl isothiocyanates. In this approach, aryl/alkyl isothiocyanate reacts with o-phenylenediamine (o-PD), o-aminophenol, and o-aminothiophenol to form their monothiourea which on desulfurization with EDPBT led to the formation of corresponding 2-aminobenzimidazoles, 2-aminobenzoxazoles, and 2-aminobenzothiazoles, respectively. An interesting regioselectivity was observed for unsymmetrical thiourea having a naphthyl moiety on the one side and an ortho amino or an ortho hydroxy phenyl group on the other side giving a completely different product which is mainly dependent on the nature of the nucleophiles (-OH or -NH 2). Further, the bis-thioureas resulted from the aliphatic 1,2-diamine with 2 equiv of aryl isothiocyanates on treatment with EDPBT gave imidazolidenecarbothioamides, whereas bis-thioureas resulted from aromatic 1,2-diamine yielded benzimidazoles with concurrent expulsion of an isothiocyanate unit. This method is simple and applied to various substrates which are amenable to bromination that reveals the desulfurizing ability of EDPBT predominating over its brominating ability. Finally, the spent reagent EDPDB can be recovered, regenerated, and reused without any loss of activity.
- Yella, Ramesh,Patel, Bhisma K.
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experimental part
p. 754 - 763
(2010/11/03)
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- Copper-catalyzed tandem reactions of 2-halobenzenamines with isothiocyanates under ligand- and base-free conditions
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A ligand-free copper-catalyzed reaction of 2-halobenzenamines with isothiocyanates has been developed for the synthesis of 2-aminobenzothiazoles. In the presence of CuBr and TBAB (tetra-n-butyl ammonium bromide, additive), a variety of 2-halobenzenamines underwent the reaction with isothiocyanates at 40 °C, affording 2-aminobenzothiazoles in moderate to excellent yields. It is noteworthy that the reaction is conducted under mild, relatively low catalyst loading, and ligand- and base-free conditions.
- Guo, Yan-Jin,Tang, Ri-Yuan,Zhong, Ping,Li, Jin-Heng
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supporting information; experimental part
p. 649 - 652
(2010/04/23)
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- Synthesis of 2-aminobenzothiazole via FeCl3-catalyzed tandem reaction of 2-iodoaniline with isothiocyanate in water
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An FeCl3-catalyzed tandem reaction of 2-iodoaniline with isothiocyanate in water is described, which provides an environmentally benign, efficient, and practical route for the generation of 2-aminobenzothiazole. This present tandem process shows broad substrate scope in the presence of octadecyltrimethylammonium chloride as a phase-transfer catalyst. In addition, the reaction media can be recovered and recycled without loss of efficiency.
- Ding, Qiuping,Cao, Banpeng,Liu, Xianjin,Zong, Zhenzhen,Peng, Yi-Yuan
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supporting information; experimental part
p. 1607 - 1610
(2010/12/19)
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- Ligand-free copper-catalyzed synthesis of substituted benzimidazoles, 2-aminobenzimidazoles, 2-aminobenzothiazoles, and benzoxazoles
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(Chemical Equation Presented) The synthesis of substituted benzimidazoles, 2-aminobenzimidazoles, 2-aminobenzothiazoles, and benzoxazoles is described via intramolecular cyclization of o-bromoaryl derivatives using copper(II) oxide nanoparticles in DMSO under air. The procedure is experimentally simple, general, efficient, and free from addition of external chelating ligands. It is a heterogeneous process and the copper(II) oxide nanoparticles can be recovered and recycled without loss of activity. 2009 American Chemical Society.
- Saha, Prasenjit,Ramana, Tamminana,Purkait, Nibadita,Ali, Md. Ashif,Paul, Rajesh,Punniyamurthy, Tharmalingam
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supporting information; experimental part
p. 8719 - 8725
(2010/02/28)
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- Synthesis of N-substituted-2-Aminobenzothiazoles by ligand-Free copper(I)-Catalyzed cross-Coupling reaction of 2-haloanilines with isothiocyanates www.eurjoc.org
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A novel and efficient formation of N-substituted-2-aminobenzothiazoles by a ligand-free copper(I)-catalyzed one-pot cascade process was developed. A variety of isothiocyanates coupled with 2-iodoanilines to give N-substituted-2-amino-benzothiazoles in mod
- Shen, Guodong,Lv, Xin,Bao, Weiliang
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scheme or table
p. 5897 - 5901
(2010/03/01)
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- Iron-catalyzed tandem reactions of 2-halobenzenamines with isothiocyanates leading to 2-aminobenzothiazoles
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A highly practical method for the synthesis of 2-aminobenzothiazoles has been developed through an iron-catalyzed tandem reaction. The present tandem process allows the assembly of a wide range of 2-aminobenzothiazoles by the reactions of 2-halobenzenamin
- Qiu, Jing-Wen,Zhang, Xing-Guo,Tang, Ri-Yuan,Zhong, Ping,Li, Jin-Heng
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supporting information; scheme or table
p. 2319 - 2323
(2009/12/29)
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- Cyanamides in the synthesis of 1,3-thiazole and 1,3-thiazine derivatives
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Hetaryl, aroyl, and aryl cyanamides react with 2-sulfanylbenzoic acid, 2-aminobenzenethiol, and 2-aminoethanethiol to give derivatives of 2-amino-4H-1,3-benzothiazin-4-one, 1,3-benzothiazol-2-amine, and 4,5-dihydro-1,3-thiazol-2-amine.
- Shestakov,Gusakova,Shikhaliev,Timoshkina
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experimental part
p. 1825 - 1829
(2009/09/25)
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- Benzothiazolyl derivatives
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The present invention relates to compounds of formula (I) wherein R1, R2, R3°R3a and R3b are as provided in the description, and pharmaceutically acceptable salts thereof, for use in the treatment and
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