- Synthesis, photo- and electro-luminescence of red-emitting Ir(III) complexes with 2-(1-naphthyl)benzothiazole and carrier transporting group-functionalized picolinate ligands
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Two new red-emitting Ir(III) complexes containing 2-(1-naphthyl)benzothiazole as cyclometalated ligands and the carrier transporting group-functionalized picolinate as ancillary ligands have been successfully synthesized and characterized. The Ir(III) complexes have good thermal stability with less than 2% weight-reduction occurring at 285 °C, and exhibit strong red emissions. The doped light-emitting devices using the Ir(III) complexes as dopants were fabricated. The result indicated that the light-emitting devices fabricated by the carbazole-functionalized complex and the diaryl-1,3,4-oxadiazole-functionalized complex exhibited red emissions with a maximum brightness of 3074 and 2520 cd/m2at 10.7 V and a maximum current efficiency of 4.84 and 5.18 cd/A, respectively.
- Yu, Tianzhi,Bao, Yanjun,Zhao, Yuling,Zhang, Hui,Xu, Zixuan,Wu, Xiaomeng
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Read Online
- Room temperature HFIP/Ag-promoted palladium-catalyzed C–H functionalization of benzothiazole with iodoarenes
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A versatile synthetic protocol involving the room temperature direct arylation of benzothiazole with a wide variety of iodoarenes under Ag-promoted Pd-catalyzed conditions in HFIP as the reaction solvent has been presented. A sequential HFIP-promoted sele
- Bhujbal, Yuvraj,Gharpure, Santosh J.,Kapdi, Anant R.,Kommyreddy, Saidurga Prasad,Kori, Santosh,Vadagaonkar, Kamlesh
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supporting information
p. 847 - 850
(2022/02/01)
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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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- Ultrasound-assisted efficient and green synthesis of 2-substituted benzothiazoles under solvent-free condition using recyclable sulfated tungstate
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Sulfated tungstate catalyzed an efficient and ecofriendly protocol has been described for the synthesis of 2-substituted benzothiazoles. The corresponding benzothiazoles were obtained using a condensation reaction of 2-aminothiophenol with various aldehydes under ultrasound irradiation at room temperature. Various functional groups on the 2-aminothiophenol as well as on the aldehydes were tolerated to provide 2-substituted benzothiazoles derivatives in excellent yields. The faster reaction rate, solvent-free or mild reaction conditions, wide functional group compatibility, excellent yields, easy work-up procedure, and excellent catalyst recyclability are the advantages of this protocol. These advantages make this process more practicable, cost-effective, and environmentally benign.
- Pise, Ashok S.,Ingale, Ajit P.,Dalvi, Navnath R.
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supporting information
p. 3629 - 3641
(2021/10/12)
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- ZnO-NPs catalyzed condensation of 2-aminothiophenol and aryl/alkyl nitriles: Efficient green synthesis of 2-substituted benzothiazoles
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The synthesis of 2-substituted benzothiazoles has been described using ZnO-nanoparticles as a catalyst. The condensation of 2-aminothiophenol and aryl/alkyl nitriles resulted in the formation of various 2-substituted benzothiazoles under solvent-free reaction conditions. The library of 2-substituted benzothiazoles has been synthesized in good to excellent yield. The reaction has shown a wide range of functional group compatibility for both varyingly substituted 2-aminothiophenols and nitriles. The protocol has many advantages such as faster reaction rate, mild reaction conditions, various functional group compatibility, excellent yield, solvent-free reaction conditions, easy recovery of materials, and excellent catalyst recyclability, among others. The various advantages of this protocol make it a more feasible, economical, and environmentally benign process.
- Dhawale, Kiran D.,Ingale, Ajit P.,Shinde, Sandeep V.,Thorat, Nitin M.,Patil, Limbraj R.
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p. 1588 - 1601
(2021/03/18)
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- Sulfamic acid-catalyzed conversion of o-aminothiophenol and aromatic aldehydes to 2-arylbenzothiazoles
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Non-metallic, non-toxic, and cheap sulfamic acid was used as a catalyst for the synthesis of 2-arylbenzothiazole from o-aminothiophenol and aromatic aldehydes bearing electron-donating or electron-withdrawing groups. The sulfamic acid catalyst can be reus
- Shi, Chunjie,Song, Renyuan,Wang, Guangrong,Yu, Xiaofeng
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p. 871 - 879
(2020/09/09)
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- Aerobic oxidative synthesis of quinazolinones and benzothiazoles in the presence of laccase/DDQ as a bioinspired cooperative catalytic system under mild conditions
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The current study applied laccase/DDQ as a bioinspired cooperative catalytic system for the synthesis of quinazolinones (80-95% yield) and benzothiazoles (65-98% yield) using air or O2 as ideal oxidants in aqueous media at ambient temperature. The aerobic oxidative cyclization reactions occur in two steps: (i) chemical cyclization; (ii) chemoenzymatic oxidation. These methods are more environment-friendly, efficient, simple and practical than other reported methods due to the use of O2 as an oxidant, laccase as an eco-friendly biocatalyst, aqueous media as the solvent and free from any toxic transition metal and halide catalysts. Therefore, these methods can be applied in pharmaceutical and other sensitive synthetic procedures.
- Abdelrasoul, Amira,Ghorashi, Nadia,Moradi, Reza,Rostami, Amin,Shokri, Zahra
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p. 14254 - 14261
(2020/04/23)
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- Direct Oxygenation of C-H Bonds through Photoredox and Palladium Catalysis
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This report presents the oxygenation of C-H bonds via the merger of photocatalysis and Pd catalysis. Herein, we describe the utilization of a photocatalyst to oxidize an organopalladium(II) intermediate to high-valent PdIII or PdIV intermediates, which promotes the formation of C-O bonds. The demonstrated method works efficiently with various directing groups, such as oxime ether and benzothiazole. The applicability of this direct C-O bond formation method is shown by synthesizing several metal complexes of 2-(benzo[d]thiazol-2-yl)phenol that can be used in organic light-emitting diodes and pharmaceuticals.
- Paul, Amrita,Shah, Sk. Sheriff,Shee, Maniklal,Singh, Amit Kumar,Singh, N. D. Pradeep
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p. 3426 - 3439
(2020/03/23)
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- Iron(0)-Catalyzed Transfer Hydrogenative Condensation of Nitroarenes with Alcohols: A Straightforward Approach to Benzoxazoles, Benzothiazoles, and Benzimidazoles
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The iron-catalyzed hydrogen transfer strategy has been applied to the redox condensation of o-hydroxynitrobenzene with alcohol, leading to the formation of benzoxazole derivatives. A wide range of 2-substituted benzoxazoles were synthesized in good to excellent yields without the addition of an external redox agent. A series of control experiments provided a plausible mechanism. Furthermore, the reaction system was successfully extended to the synthesis of benzothiazoles and benzimidazoles.
- Putta, Ramachandra Reddy,Chun, Simin,Choi, Seung Hyun,Lee, Seok Beom,Oh, Dong-Chan,Hong, Suckchang
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p. 15396 - 15405
(2020/12/02)
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- Liebeskind-Srogl-type cross-coupling reaction of azole-2-thiones with triarylbismuthines: Synthesis of 2-arylazoles
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Liebeskind-Srogl-type C(HetAr)–C(Ar) bond formation using trivalent organobismuth compounds as a new class of arylating reagents is described. The reaction of benzazole-2-thiones with triarylbismuthines in the presence of 10 mol% Pd(dba)2 and 2.0 equiv. Cu(OAc)2 at 80 °C affords 2-arylbenzothiazoles, benzoxazoles, and N-methyl benzimidazole in moderate-to-high yield. The reaction is sensitive to the electronic nature of triarylbismuthines: compounds bearing an electron-withdrawing group on the phenyl ring showed higher reactivity than those having an electron-donating group.
- Murata, Yuki,Terazoe, Aki,Kiba, Misato,Kitamura, Yuki,Matsumura, Mio,Yasuike, Shuji
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supporting information
(2020/07/03)
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- Visible light initiated amino group: Ortho -directed copper(i)-catalysed aerobic oxidative C(sp)-S coupling reaction: Synthesis of substituted 2-phenylbenzothiazoles via thia-Wolff rearrangement
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A facile amino group ortho-directed visible-light-driven copper-catalysed aerobic oxidative C(sp)-S coupling reaction of a dimer of 2-aminothiophenol with terminal alkynes was achieved. This photochemical reaction shows an excellent conversion and chemoselectivity towards the formation of C(sp)-S coupling and has been employed for a wide range of thiol dimers, and alkynes. Furthermore, the synthetic utility of the synthesized alkynyl sulfides was demonstrated as a direct method for the construction of 2-phenylbenzothiazoles from the corresponding alkynyl sulfides via "thia-Wolff rearrangement" using AgNO3 and visible light using 9-mesityl-10-methylacridinium ions (Acr+-Mes) as photoredox catalyst system.
- Anandhan, Ramasamy,Reddy, Mandapati Bhargava
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p. 3781 - 3784
(2020/04/10)
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- Synthesis of 2-aryl-benzothiazoles via Ni-catalyzed coupling of benzothiazoles and aryl sulfamates
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2-Aryl-benzothiazoles have been successfully synthesized via a simple coupling reaction between benzothiazoles and aryl sulfamates using a nickel catalyst. The nickel catalyst is inexpensive, reusable and commercially available. In addition, the use of highly expensive palladium catalysts and unstable raw materials has been avoided. 2-Aryl-benzothiazoles bearing various substituents on the aryl groups were obtained in good yield.
- Gou, Liping,Song, Renyuan,Wang, Guangrong,Yu, Xiaofeng,Zhang, Zhen
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- Iodine-catalyzed convergent aerobic dehydro-aromatization toward benzazoles and benzazines
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An iodine-catalyzed aerobic dehydro-aromatization has been developed, providing straightforward and efficient access to various benzoazoles and benzoazines. The present transition-metal-free protocol enables the dehydro-aromatization of tetrahydrobenzazoles and tetrahydroquinolines with molecular oxygen as the green oxidant, along with some other N-heterocycles. Hence, a broad range of heteroaromatic compounds are generated in moderate to good yields under facile reaction conditions.
- Chen, Shanping,Deng, Guo-Jun,Jiang, Pingyu,Ni, Penghui,Tuo, Xiaolong,Wang, Xiaodong
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p. 8348 - 8351
(2020/03/11)
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- Ultrafine Pt nanoparticles supported on a dendrimer containing thiol groups: An efficient catalyst for the synthesis of benzimidazoles and benzothiazoles from benzyl alcohol derivatives in water
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A novel and unique platform was prepared based on a dendrimer containing thiol groups supported on nanosilica (nSTDP), and ultrafine platinum nanoparticles were synthesized and immobilized on the thiol decorated branches of nSTPD. The new catalyst, (Ptnp?nSTDP), was characterized by different techniques such as FE-SEM, TEM, ICP, XPS and DR UV-vis. This heterogeneous catalyst presented an outstanding performance for the synthesis of benzimidazole and benzothiazole derivatives through a reaction between benzyl alcohol derivatives and 2-aminothiophenol or 1,2-phenylenediamine. No requirement for the pre-reduction of catalysts and using water as a green solvent make it an individual catalyst for these reactions. Furthermore, the catalyst can be easily recovered and reused five consecutive times in the production of benzimidazoles and benzothiazoles without significant leaching of Pt and loss of its activity which illustrated the chemical stability of the catalyst during the reaction.
- Bahadori, Mehrnaz,Landarani-Isfahani, Amir,Mirkhani, Valiollah,Moghadam, Majid,Mohammadpoor-Baltork, Iraj,Nori, Zahra Zamani,Tangestaninejad, Shahram
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p. 33137 - 33147
(2020/10/02)
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- Transition Metal-Free Oxidative Coupling of Primary Amines in Polyethylene Glycol at Room Temperature: Synthesis of Imines, Azobenzenes, Benzothiazoles, and Disulfides
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A transition metal-free protocol has been developed for the oxidative coupling of primary amines to imines and azobenzenes, thiols to disulfides, and 2-aminothiophenols to benzothiazoles, offering excellent yields. The advantageous features of the present environmentally benign methodology include the usage of biocompatible and green reaction conditions such as, solvent, room temperature reactions and transition metal-free approach. Moreover, it offers a broader substrate scope.
- Hudwekar, Abhinandan D.,Verma, Praveen K.,Kour, Jaspreet,Balgotra, Shilpi,Sawant, Sanghapal D.
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p. 1242 - 1250
(2019/01/09)
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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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- Metal-free synthesis of N-containing heterocycles from O-substituted aniline derivatives via 2,4,6-trihydroxybenzoic acid-catalyzed oxidative dehydrogenation of benzylamines under oxygen atmosphere
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A series of N-heterocycles, i.e., benzimidazoles, benzoxazoles, and benzothiazoles, can be conveniently synthesized by the oxidative cyclization of benzylamines with o-substituted aniline derivatives, i.e., o-phenylenediamines, o-aminophenols, and o-aminothiophenols, using 2,4,6-trihydroxybenzoic acid as an organocatalyst under an oxygen atmosphere. This approach provides a mild and efficient tool towards benzimidazoles and benzothiazoles with good yields and a broad substrate scope. The developed synthesis of N-heterocycles might proceed via the oxidative dehydrogenation of benzylamines (ArCH2NH2), generating the corresponding imines (ArCH=NH) as key intermediates.
- Kumazawa, Shun,Uematsu, Akinori,Dong, Chun-Ping,Kodama, Shintaro,Nomoto, Akihiro,Ueshima, Michio,Ogawa, Akiya
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p. 842 - 853
(2019/04/26)
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- Copper containing nanosilica thioalated dendritic material: A recyclable catalyst for synthesis of benzimidazoles and benzothiazoles
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In this paper, the design and characterization of a new heterogeneous catalyst by incorporation of copper ions into the nanosilica modified by thiole–based dendrimer are reported. The prepared catalyst was characterized by FT–IR, TGA, elemental analysis,
- Zakeri, Maryam,Moghadam, Majid,Mirkhani, Valiollah,Tangestaninejad, Shahram,Mohammadpoor-Baltork, Iraj,Pahlevanneshan, Zari
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- Sulfonic-acid-functionalized activated carbon made from tea leaves as green catalyst for synthesis of 2-substituted benzimidazole and benzothiazole
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Abstract: A simple and efficient procedure for synthesis of 2-substituted benzimidazole and benzothiazole has been developed by using sulfonic-acid-functionalized activated carbon as heterogeneous catalyst. The activated material was prepared from matured tea leaf in presence of phosphoric acid as activating agent. The final catalyst was prepared by anchoring –SO3H group on the surface of the activated carbon. The catalyst could be easily recovered and reused for more than three catalytic cycles without significant loss in catalytic activity. The catalytic performance of the catalyst was found to be superior to that of a similar catalyst prepared from montmorillonite K10. Graphical Abstract: [Figure not available: see fulltext.].
- Goswami, Mridusmita,Dutta, Mintu Maan,Phukan, Prodeep
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p. 1597 - 1615
(2017/11/17)
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- Pd-Catalyzed Decarbonylative C?H Coupling of Azoles and Aromatic Esters
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A decarbonylative C?H coupling of azoles and aromatic esters by palladium catalysis is described. Our previously reported Ni-catalyzed C?H coupling of azoles and aromatic esters has a significant drawback regarding the substrate scope. Herein, we employ p
- Matsushita, Kaoru,Takise, Ryosuke,Hisada, Tomoya,Suzuki, Shin,Isshiki, Ryota,Itami, Kenichiro,Muto, Kei,Yamaguchi, Junichiro
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supporting information
p. 2393 - 2396
(2018/05/30)
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- Selective Construction of 2-Substituted Benzothiazoles from o-Iodoaniline Derivatives S8 and N-Tosylhydrazones
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Selective construction of 2-substituted benzothiazoles from o-iodoaniline derivatives S8 and N-tosylhydrazone via a copper-promoted [3 + 1 + 1]-type cyclization reaction has been realized. In the protocol, the carbon atom on N-tosylhydrazone could be regulated to construct benzothiazole by changing the reaction system. Furthermore, the transformation has achieved the construction of multiple carbon-heteroatom bonds.
- Huang, Yubing,Zhou, Peiqi,Wu, Wanqing,Jiang, Huanfeng
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p. 2460 - 2466
(2018/02/23)
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- Silver-mediated 2-arylation/alkylation/acylation of benzothiazoles with aldehydes in water
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An efficient and environmentally benign method was developed for the facile synthesis of various 2-aryl and 2-alkyl substituted benzothiazoles in moderate to good yields, using a silver-mediated redox condensation of benzothiazoles and aldehydes in water. Furthermore, this method is also applicable to prepare 2-acyl benzothiazoles.
- Hua, Min,Wang, Chunqin,Liu, Qixing,Chen, Danyi,Fu, Hao,Zhou, Haifeng
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p. 1226 - 1237
(2018/08/06)
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- Development of (quinolinyl)amido-based pincer palladium complexes: A robust and phosphine-free catalyst system for C-H arylation of benzothiazoles
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(Quinolinyl)amido-ligated palladium(ii) complexes have been synthesized and applied in the catalytic C-H bond arylation of benzothiazoles. The tridentate ligand precursors R2N-C(O)CH2-(NH)-C9H6N [(R2NNN8-Q)-H; R2N = morpholinyl, Me-N-piperazinyl] and the pincer palladium complexes [κN,κN,κN-{R2N-C(O)CH2-(μ-N)-C9H6N}]PdX [(R2NNN8-Q)PdX {R2N = Et2N, morpholinyl, Me-N-piperazinyl; X = OAc or Cl}] were efficiently synthesized, and characterized by various analytical techniques. The iodo derivative (Et2NNN8-Q)PdI was obtained in excellent yield by the treatment of the complex (Et2NNN8-Q)PdCl with KI. The molecular structures of complexes (Et2NNN8-Q)Pd(OAc) (2a), (Et2NNN8-Q)PdCl (3a) and (Et2NNN8-Q)PdI (4a) were elucidated by X-ray crystallography. Complex 3a was found to be the most efficient catalyst for direct C-H bond arylation of substituted benzothiazoles with diverse aryl iodides using a mild base, K2CO3. The working catalyst system 3a is highly robust and can be recycled and reused several times for the arylation of benzothiazole without loss of catalytic activity. Preliminary mechanistic investigations using controlled studies and kinetic analysis have been performed, which greatly support a molecular mechanism for the arylation.
- Pandiri, Hanumanprasad,Soni, Vineeta,Gonnade, Rajesh G.,Punji, Benudhar
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p. 3543 - 3554
(2017/07/12)
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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-Methyl-Benzothiazolium Salts as Carbon Lewis Acids for Si?H σ-Bond Activation and Catalytic (De)hydrosilylation
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N?Me-Benzothiazolium salts are introduced as a new family of Lewis acids able to activate Si?H σ bonds. These carbon-centred Lewis acids were demonstrated to have comparable Lewis acidity towards hydride as found for the triarylboranes widely used in Si?H σ-bond activation. However, they display low Lewis acidity towards hard Lewis bases such as Et3PO and H2O in contrast to triarylboranes. The N?Me-benzothiazolium salts are effective catalysts for a range of hydrosilylation and dehydrosilylation reactions. Judicious selection of the C2 aryl substituent in these cations enables tuning of the steric and electronic environment around the electrophilic centre to generate more active catalysts. Finally, related benzoxazolium and benzimidazolium salts were found also to be active for Si?H bond activation and as catalysts for the hydrosilylation of imines.
- Fasano, Valerio,Radcliffe, James E.,Curless, Liam D.,Ingleson, Michael J.
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supporting information
p. 187 - 193
(2017/01/09)
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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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- Elemental sulfur mediated cyclization via redox strategy: Synthesis of benzothiazoles from o-chloronitrobenzenes and benzyl chlorides
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A novel metal-free synthesis of 2-substituted benzothiazoles from easily available o-chloronitrobenzenes and benzyl chlorides using elemental sulfur as traceless oxidizing agent has been developed. The protocol provides a simple, efficient, and atom-economic way to access to benzothiazoles in moderate to excellent yields. And the approach exhibited good functional group tolerance.
- Wang, Xin,Miao, Dazhuang,Li, Xiaotong,Hu, Renhe,Yang, Zhao,Gu, Ren,Han, Shiqing
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supporting information
p. 5194 - 5199
(2017/07/28)
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- One-pot copper-catalyzed synthesis of 2-substituted benzothiazoles from 2-iodoanilines, benzyl chlorides and elemental sulfur
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An efficient one-pot three-component reaction of 2-iodoanilines, benzyl chlorides and elemental sulfur to form 2-substituted benzothiazoles in satisfactory yields (up to 98%) has been described. The reaction tolerated a wide range of functional groups on the aromatic ring. And heterocycle methylene chlorides substrates were also found to be compatible.
- Yang, Zhao,Hu, Renhe,Li, Xiaotong,Wang, Xin,Gu, Ren,Han, Shiqing
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supporting information
p. 2366 - 2369
(2017/05/29)
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- Direct arylation of benzoazoles with aldehydes utilizing metal-organic framework Fe3O(BDC)3 as a recyclable heterogeneous catalyst
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A metal-organic framework Fe3O(BDC)3 was synthesized and used as a recyclable heterogeneous catalyst for the direct arylation of azoles with benzaldehydes. Following this protocol, inexpensive and commercially available benzaldehydes could act as an aryl source for the transformation, replacing the aryl halides normally employed in the conventional cross-coupling reactions. The catalyst disclosed higher catalytic productivity for the formation of aryl-substituted azoles than various MOFs and diverse homogeneous iron catalysts. The conversion was considerably regulated by the solvent and the oxidant, and the combination of N-methyl-2-pyrrolidone with di-tert-butyl peroxide offered the best yield. Heterogeneous catalysis was verified for the reaction, and the production of aryl-substituted azoles was only feasible in the presence of the iron framework. It was possible to reuse the catalyst for the direct arylation of azoles with aldehydes while its catalytic activity was preserved for multiple cycles. To our best judgment, this direct arylation of azoles with aldehydes utilizing solid catalysts has not been previously reported.
- Doan, Son H.,Nguyen, Khoa D.,Nguyen, Tung T.,Phan, Nam T. S.
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p. 1423 - 1431
(2017/01/21)
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- Mechanistic Insights into Pincer-Ligated Palladium-Catalyzed Arylation of Azoles with Aryl Iodides: Evidence of a PdII-PdIV-PdII Pathway
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Pincer-based (R2POCNR′2)PdCl complexes along with CuI cocatalyst catalyze the arylation of azoles with aryl iodides to give the 2-arylated azole products. Herein, we report an extensive mechanistic investigation for the direct arylation of azoles involving a well-defined and highly efficient (iPr2POCNEt2)PdCl (2a) catalyst, which emphasizes a rare PdII-PdIV-PdII redox catalytic pathway. Kinetic studies and deuterium labeling experiments indicate that the C-H bond cleavage on azoles occurs via two distinct routes in a reversible manner. Controlled reactivity of the catalyst 2a underlines the iodo derivative (iPr2POCNEt2)PdI (3a) to be the resting state of the catalyst. The intermediate species (iPr2POCNEt2)Pd-benzothiazolyl (4a) has been isolated and structurally characterized. A determination of reaction rates of compound 4a with electronically different aryl iodides has revealed the kinetic significance of the oxidative addition of the C(sp2)-X electrophile, aryl iodide, to complex 4a. Furthermore, the reactivity behavior of 4a suggests that the arylation of benzothiazole proceeds via an oxidative addition/reductive elimination pathway involving a (iPr2POCNEt2)PdIV(benzothiazolyl)(Ar)I species, which is strongly supported by DFT calculations.
- Khake, Shrikant M.,Jagtap, Rahul A.,Dangat, Yuvraj B.,Gonnade, Rajesh G.,Vanka, Kumar,Punji, Benudhar
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supporting information
p. 875 - 886
(2016/04/19)
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- Anchoring of Cu(II) onto surface of porous metal-organic framework through post-synthesis modification for the synthesis of benzimidazoles and benzothiazoles
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Efficient synthesis of various benzimidazoles and benzothiazoles under mild conditions catalyzed by Cu(II) anchored onto UiO-66-NH2 metal organic framework is reported. In this manner, first, the aminated UiO-66 was modified with thiophene-2-ca
- Kardanpour, Reihaneh,Tangestaninejad, Shahram,Mirkhani, Valiollah,Moghadam, Majid,Mohammadpoor-Baltork, Iraj,Zadehahmadi, Farnaz
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p. 145 - 153
(2016/01/09)
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- Tris(pentafluorophenyl)borane-Catalyzed Acceptorless Dehydrogenation of N-Heterocycles
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Catalytic acceptorless dehydrogenation is an environmentally benign way to desaturate organic compounds. This process is traditionally accomplished with transition-metal-based catalysts. Herein, a borane-catalyzed, metal-free acceptorless dehydrogenation of saturated N-heterocycles is disclosed. Tris(pentafluorophenyl)borane was identified as a versatile catalyst, which afforded several synthetically important N-heteroarenes in up to quantitative yield. Specifically, the present metal-free catalytic system exhibited a uniquely high tolerance toward sulfur functionalities, and demonstrated superior reactivity in the synthesis of benzothiazoles compared to conventional metal-catalyzed systems. This protocol can thus be regarded as the first example of metal-free acceptorless dehydrogenation in synthetic organic chemistry.
- Kojima, Masahiro,Kanai, Motomu
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supporting information
p. 12224 - 12227
(2016/10/13)
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- Photocatalytic Generation of 2-Azolyl Radicals: Intermediates for the Azolylation of Arenes and Heteroarenes via C-H Functionalization
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The 2-azolyl radical, generated from 2-bromoazoles via photocatalysis, is a powerful intermediate for the intermolecular arylation of unmodified (hetero)arenes. The reaction is characterized by mild conditions, operational simplicity, tolerance toward functional and sterically demanding groups, broad scope, and anti-Minisci selectivity. A working mechanism is provided, and a low-solubility amine is essential for successful coupling. The utility of the reaction is demonstrated via late-stage functionalization of methyl estrone and application toward other bromoarenes.
- Arora, Amandeep,Weaver, Jimmie D.
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supporting information
p. 3996 - 3999
(2016/08/30)
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- Electrochemical Synthesis of Benzazoles from Alcohols and o-Substituted Anilines with a Catalytic Amount of CoII Salt
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An electrochemical synthesis of benzazoles directly from alcohols and o-substituted anilines has been developed. The reaction conditions have been optimized by varying the composition of the electrolyte and the metal salt used as catalyst. The cyclization proceeds smoothly with a catalytic amount of a cobalt salt under air at room temperature to afford 2-substituted benzimidazoles, benzothiazoles, and benzoxazoles in good to excellent yields with a wide substrate scope.
- Lai, Yin-Long,Ye, Jian-Shan,Huang, Jing-Mei
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supporting information
p. 5425 - 5429
(2016/04/09)
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- S8-Mediated Cyclization of 2-Aminophenols/thiophenols with Arylmethyl Chloride: Approach to Benzoxazoles and Benzothiazoles
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A metal-free approach to benzazoles from arylmethyl chlorides and 2-mercaptan/2-hydroxyanilines using elemental sulfur as a traceless oxidizing agent has been developed. The reactions proceeded in good to excellent yields, exhibiting good functional groups tolerance and gram-scale ability. A key mechanistic investigation indicated that the key intermediate trisulfide 6, which was characterized by NMR, HRMS and crystal X-ray crystallography, was separated in the reaction prior to the formation of the product.
- Gan, Haifeng,Miao, Dazhuang,Pan, Qiang,Hu, Renhe,Li, Xiaotong,Han, Shiqing
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supporting information
p. 1770 - 1774
(2016/07/07)
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- Palladium-Catalyzed C-H Arylation of (Benzo)oxazoles or (Benzo)thiazoles with Aryltrimethylammonium Triflates
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The C-H arylation of (benzo)oxazoles or (benzo)thiazoles with aryltrimethylammonium triflates was carried out via Pd-catalyzed C-H/C-N cleavage. Oxazoles, thiazoles, benzoxazole, and benzothiazole were arylated using activated and deactivated aryltrimethylammonium triflates to give 2-aryl(benzo)oxazoles or 2-aryl(benzo)thiazoles in reasonable to excellent yields.
- Zhu, Feng,Tao, Jian-Long,Wang, Zhong-Xia
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p. 4926 - 4929
(2015/10/12)
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- Iron(II) bromide-catalyzed oxidative coupling of benzylamines with ortho-substituted anilines: Synthesis of 1,3-benzazoles
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An iron(II) bromide-catalyzed oxidative coupling of benzylamines with 2-amino/hydroxy/mercapto-anilines has been developed, allowing the synthesis of a diversity of substituted 1,3-benzazoles in good to excellent yields. This transformation is compatible with a wide range of functional groups. The method is practical, economical and employs molecular oxygen as an oxidant.
- Gopalaiah, Kovuru,Chandrudu, Sankala Naga
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p. 5015 - 5023
(2015/03/03)
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- Reversible conversion of valence-tautomeric copper metal-organic frameworks dependent single-crystal-to-single-crystal oxidation/reduction: A redox-switchable catalyst for C-H bonds activation reaction
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Upon single-crystal-to-single-crystal (SCSC) oxidation/reduction, reversible structural transformations take place between the anionic porous zeolite-like CuI framework and a topologically equivalent neutral CuICuII mixed-valent framework. The unique conversion behavior of the CuI framework endowed it as a redox-switchable catalyst for the direct arylation of heterocycle C-H bonds.
- Huang, Chao,Wu, Jie,Song, Chuanjun,Ding, Ran,Qiao, Yan,Hou, Hongwei,Chang, Junbiao,Fan, Yaoting
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supporting information
p. 10353 - 10356
(2015/06/25)
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- Antileishmanial activities of benzothiazole derivatives
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Benzothiazole derivatives 1-22 were synthesized from 2-aminothiophenol and all synthetic compounds were screened for in vitro antileishmanial activity. These compound showed different types activities against leishmania with IC50 values ranging
- Rahim, Fazal,Samreen,Taha, Muhammad,Saad, Syed Muhammad,Perveen, Shahnaz,Khan, Momin,Alam, Muhammad Tanveer,Khan, Khalid Mohammed,Choudhary, M. Iqbal
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p. 157 - 161
(2015/05/20)
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- An efficient desulfitative C-C cross coupling of fused thiazolidine-2-thione with boronic acids and boronic acid pinacol esters: Formation of fused thiazoles
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An efficient Pd(0)-catalyzed Cu(i)-mediated desulfitative C-C cross-coupling of benzo-fused thiazolidine-2-thione with boronic acids under neutral Liebeskind-Srogl conditions is described. The desulfitative cross coupling of boronic acid pinacol esters has also been demonstrated with fused thiazolidine-2-thione under basic conditions to afford fused thiazoles with good to excellent yields.
- Rajaguru, Kandasamy,Mariappan, Arumugam,Manjusri, Ramachandran,Muthusubramanian, Shanmugam,Bhuvanesh, Nattamai
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p. 86832 - 86839
(2015/11/03)
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- Unexpectedly Simple Synthesis of Benzazoles by tBuONa-Catalyzed Direct Aerobic Oxidative Cyclocondensation of o-Thio/Hydroxy/Aminoanilines with Alcohols under Air
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tBuONa-catalyzed direct aerobic oxidative cyclocondensation reactions of readily available alcohols and o-thio/hydroxy/aminoanilines under air have been developed and provide an efficient, practical, and green method for the synthesis of benzazoles. Mechanistic studies revealed that o-substituted anilines promote the initial aerobic alcohol-oxidation step, which explains the high reactivity and success of this unexpectedly simple and practical cyclocondensation method. Simple and straight: tBuONa-catalyzed direct aerobic oxidative cyclocondensation reactions of readily available alcohols and o-thio/hydroxy/aminoanilines under air provide an efficient, practical, and green method for the synthesis of benzazole heterocycles (see scheme). Mechanistic studies revealed that o-substituted anilines promote the initial aerobic alcohol-oxidation step.
- Shi, Xinkang,Guo, Junmei,Liu, Jianping,Ye, Mingde,Xu, Qing
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supporting information
p. 9988 - 9993
(2015/07/07)
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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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- Iron-catalyzed aerobic oxidative functionalization of sp3 C-H bonds: A versatile strategy for the construction of N-heterocycles
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Iron-catalyzed aerobic oxidative functionalization of sp3 C-H bonds has been developed for the construction of N-heterocycles from easily available carboxylic acid derivatives and o-substituted anilines. This transformation represents a widely applicable protocol to N-heterocycles using biofriendly iron as a catalyst in combination with molecular oxygen or air as the sole oxidant. This journal is
- Chen, Xiuling,Chen, Tieqiao,Ji, Fangyan,Zhou, Yongbo,Yin, Shuang-Feng
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p. 2197 - 2202
(2015/04/14)
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- Copper-catalyzed multicomponent reactions of 2-iodoanilines, benzylamines, and elemental sulfur toward 2-arylbenzothiazoles
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A relatively cheap copper salt-catalyzed, three-component approach providing 2-arylbenzothiazoles in good to excellent yields from readily available 2-iodoanilines, benzylamines, and sulfur powder is reported. This methodology allows preparation of various classes of 2-arylbenzothiazoles and provides a general, reliable approach.
- Wang, Rui,Ding, Yong-Liang,Liu, Hong,Peng, Shu,Ren, Jie,Li, Lei
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p. 945 - 949
(2015/02/19)
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- Syntheses of 2-aryl benzothiazoles via photocatalyzed oxidative condensation of amines with 2-aminothiophenol in the presence of bodipy derivatives
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A simple, convenient, and efficient new method for synthesis of 2-aryl benzothiazoles under mild conditions with nonmetal catalyst has been developed. Boron-dipyrromethene (BODIPY) dyes were used as photocatalysts for aerobic oxidative reactions of amine with 2-aminothiophenol. The approach will be very useful for the synthesis of benzothiazole derivatives and the development of photocatalytic reactions.
- Zhou, Zeyin,Yang, Weijun
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supporting information
p. 3189 - 3198
(2015/10/06)
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- Decarboxylative thioamidation of arylacetic and cinnamic acids: A new approach to thioamides
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A new decarboxylative strategy has been developed for the synthesis of thioamides via a three-component reaction involving arylacetic or cinnamic acids, amines and elemental sulfur powder, without the need of a transition metal and an external oxidant.
- Guntreddi, Tirumaleswararao,Vanjari, Rajeshwer,Singh, Krishna Nand
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supporting information
p. 3624 - 3627
(2014/08/05)
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- Copper-catalyzed multicomponent reactions of 2-iodoanilines, benzylamines, and elemental sulfur toward 2-arylbenzothiazoles
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A relatively cheap copper salt-catalyzed, three-component approach providing 2-arylbenzothiazoles in good to excellent yields from readily available 2-iodoanilines, benzylamines, and sulfur powder is reported. This methodology allows preparation of various classes of 2-arylbenzothiazoles and provides a general, reliable approach.
- Wang, Rui,Ding, Yong-Liang,Liu, Hong,Peng, Shu,Ren, Jie,Li, Lei
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p. 945 - 949
(2014/02/14)
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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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- Synthesis and characterization of Cu(II) containing nanosilica triazine dendrimer: A recyclable nanocomposite material for the synthesis of benzimidazoles, benzothiazoles, bis-benzimidazoles and bis-benzothiazoles
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The present study describes the synthesis, characterization, and catalytic activity of Cu(II) containing nanosilica triazine dendrimer (Cu(II)-TD@nSiO 2). The prepared catalyst was characterized by FT-IR, TGA, elemental analysis, UV-vis, FE-SEM
- Nasr-Esfahani, Mahboobeh,Mohammadpoor-Baltork, Iraj,Khosropour, Ahmad Reza,Moghadam, Majid,Mirkhani, Valiollah,Tangestaninejad, Shahram
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p. 243 - 254
(2013/10/08)
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